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Craniocervical instability

2019-12-22T14:14:39Z

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{{Cleanup|reason=Image copyright issues|date =5 August, 2018}}
[[File:Craniocervical instability MRI.jpg|thumb|A cervical MRI is assessed for possible craniocervical instability.]]
'''Craniocervical instability''' (CCI) is a pathological condition of increased mobility at the craniocervical junction, the area where the skull meets the spine. In CCI the ligamentous connections of the craniocervical junction can be stretched, weakened or ruptured.<ref name=":2">{{Cite journal|last=Henderson|first=Fraser C.|last2=Austin|first2=Claudiu|last3=Benzel|first3=Edward|last4=Bolognese|first4=Paolo|last5=Ellenbogen|first5=Richard|last6=Francomano|first6=Clair A.|last7=Ireton|first7=Candace|last8=Klinge|first8=Petra|last9=Koby|first9=Myles|date=2017|title=Neurological and spinal manifestations of the Ehlers–Danlos syndromes|url=https://onlinelibrary.wiley.com/doi/abs/10.1002/ajmg.c.31549|journal=American Journal of Medical Genetics Part C: Seminars in Medical Genetics|language=en|volume=175|issue=1|pages=195–211|doi=10.1002/ajmg.c.31549|issn=1552-4876}}</ref> This can lead to compression of the [[Brainstem compression|brainstem]], upper [[spinal cord]], or [[cerebellum]] and result in myelopathy, neck pain and a range of other symptoms.<ref name=":11">{{Cite journal|last=Choi|first=Sung Ho|last2=Lee|first2=Sang Gu|last3=Park|first3=Chan Woo|last4=Kim|first4=Woo Kyung|last5=Yoo|first5=Chan Jong|last6=Son|first6=Seong|date=Apr 2013|title=Surgical Outcomes and Complications after Occipito-Cervical Fusion Using the Screw-Rod System in Craniocervical Instability|url=https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3698232/|journal=Journal of Korean Neurosurgical Society|volume=53|issue=4|pages=223–227|doi=10.3340/jkns.2013.53.4.223|issn=2005-3711|pmc=3698232|pmid=23826478}}</ref>

CCI usually develops as a result of physical trauma such as a car accident, an inflammatory disease such as rheumatoid arthritis or a congenital disorder such as Down's syndrome.<ref name=":10">{{Cite journal|last=Ashafai|first=Nabeel S.|last2=Visocchi|first2=Massimiliano|last3=Wąsik|first3=Norbert|date=2019|title=Occipitocervical Fusion: An Updated Review|url=https://www.ncbi.nlm.nih.gov/pubmed/30610329|journal=Acta Neurochirurgica. Supplement|volume=125|pages=247–252|doi=10.1007/978-3-319-62515-7_35|issn=0065-1419|pmid=30610329}}</ref> More recently, physicians have reported an increased prevalence of CCI in patients with hereditary disorders of connective tissue such as Ehlers Danlos Syndromes (EDS).<ref name=":9">{{Cite journal|last=Henderson|first=Fraser C.|date=2016|title=Cranio-cervical Instability in Patients with Hypermobility Connective Disorders|url=https://www.omicsonline.org/open-access/craniocervical-instability-in-patients-with-hypermobility-connective-disorders-2165-7939-1000299.php?aid=71754|journal=Journal of Spine|language=En|volume=05|issue=02|doi=10.4172/2165-7939.1000299|issn=2165-7939}}</ref> There have also been anecdotal reports of patients with myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) who were later diagnosed with CCI,<ref>{{Cite web|url=https://forums.phoenixrising.me/index.php?threads/have-you-ruled-out-chiari-as-a-cause-of-your-cfs.56908/|title=Have you ruled out Chiari as a cause of your CFS|last=|first=|date=|website=Phoenix Rising|archive-url=|archive-date=|dead-url=|access-date=}}</ref><ref>{{Cite web|url=https://medium.com/@jenbrea/cci-tethered-cord-series-e1e098b5edf|title=CCI + Tethered cord series|last=Brea|first=Jennifer|date=2019-06-06|website=Medium|language=en|access-date=2019-06-06}}</ref><ref>{{Cite web|url=https://www.mechanicalbasis.org/interviews.html|title=Craniocervical instability, Atlantoaxial Instability, Myalgic Encephalomyelitis, ME, CFS|website=MEchanical Basis|language=en|access-date=2019-06-06}}</ref> although no scientific publication on this subject exists. It frequently co-occurs with [[atlantoaxial instability]] (AAI).{{Citation needed|reason=|date=10 December 2019}}
== Symptoms ==
Symptoms of craniocervical instability include [[occipital headache]], [[neck pain]] and [[Nervous system|neurological]] abnormalities such as [[numbness]], [[motor weakness]], [[dizziness]], and [[gait instability]].<ref>{{Cite journal|last=Bobinski|first=Lukas|last2=Levivier|first2=Marc|last3=Duff|first3=John M.|date=Feb 2015|title=Occipitoaxial spinal interarticular stabilization with vertebral artery preservation for atlantal lateral mass failure|url=https://www.ncbi.nlm.nih.gov/pubmed/25415481|journal=Journal of Neurosurgery. Spine|volume=22|issue=2|pages=134–138|doi=10.3171/2014.10.SPINE14131|issn=1547-5646|pmid=25415481}}</ref><ref>{{Cite journal|last=O'Brien|first=Michael F.|last2=Casey|first2=Adrian T. H.|last3=Crockard|first3=Alan|last4=Pringle|first4=Jean|last5=Stevens|first5=John M.|date=2002-10-15|title=Histology of the craniocervical junction in chronic rheumatoid arthritis: a clinicopathologic analysis of 33 operative cases|url=https://www.ncbi.nlm.nih.gov/pubmed/12394902|journal=Spine|volume=27|issue=20|pages=2245–2254|doi=10.1097/01.BRS.0000029252.98053.43|issn=1528-1159|pmid=12394902}}</ref><ref>{{Cite journal|last=Young|first=Richard M.|last2=Sherman|first2=Jonathan H.|last3=Wind|first3=Joshua J.|last4=Litvack|first4=Zachary|last5=O'Brien|first5=Joseph|date=Aug 2014|title=Treatment of craniocervical instability using a posterior-only approach: report of 3 cases|url=https://www.ncbi.nlm.nih.gov/pubmed/24785968|journal=Journal of Neurosurgery. Spine|volume=21|issue=2|pages=239–248|doi=10.3171/2014.3.SPINE13684|issn=1547-5646|pmid=24785968}}</ref><ref>{{Cite journal|last=Botelho|first=Ricardo V.|last2=Neto|first2=Eliseu B.|last3=Patriota|first3=Gustavo C.|last4=Daniel|first4=Jefferson W.|last5=Dumont|first5=Paulo A. S.|last6=Rotta|first6=José M.|date=Oct 2007|title=Basilar invagination: craniocervical instability treated with cervical traction and occipitocervical fixation. Case report|url=https://www.ncbi.nlm.nih.gov/pubmed/17933321|journal=Journal of Neurosurgery. Spine|volume=7|issue=4|pages=444–449|doi=10.3171/SPI-07/10/444|issn=1547-5654|pmid=17933321}}</ref><ref>{{Cite journal|last=Henderson|first=Fraser C.|last2=Henderson|first2=Fraser C.|last3=Wilson|first3=William A.|last4=Mark|first4=Alexander S.|last5=Koby|first5=Myles|date=Jan 2018|title=Utility of the clivo-axial angle in assessing brainstem deformity: pilot study and literature review|url=https://www.ncbi.nlm.nih.gov/pubmed/28258417|journal=Neurosurgical Review|volume=41|issue=1|pages=149–163|doi=10.1007/s10143-017-0830-3|issn=1437-2320|pmc=5748419|pmid=28258417|quote=|author-link=|author-link2=|author-link3=|author-link4=|author-link5=|author-link6=|via=}}</ref> Patients sometimes describe the feeling that their head is too heavy for their neck to support (“bobble-head”).<ref name=":9" /> No particular symptom is mandatory for a diagnosis of CCI and each symptom listed might have a cause other than CCI.

Other symptoms reported in patients with CCI include:
* [[Muscle weakness|Muscle weakness,]]<ref name=":0">{{Cite journal|last=Henderson|first=Fraser C.|last2=Francomano|first2=C. A.|last3=Koby|first3=M.|last4=Tuchman|first4=K.|last5=Adcock|first5=J.|last6=Patel|first6=S.|date=2019-01-09|title=Cervical medullary syndrome secondary to craniocervical instability and ventral brainstem compression in hereditary hypermobility connective tissue disorders: 5-year follow-up after craniocervical reduction, fusion, and stabilization|url=https://doi.org/10.1007/s10143-018-01070-4|journal=Neurosurgical Review|language=en|doi=10.1007/s10143-018-01070-4|issn=1437-2320}}</ref> [[numbness|numbness,]]<ref name=":1">{{Cite journal|last=Francomano|first=Clair A.|last2=McDonnell|first2=Nazli B.|last3=Nishikawa|first3=Misao|last4=Bolognese|first4=Paolo A.|last5=Milhorat|first5=Thomas H.|date=2007-12-01|title=Syndrome of occipitoatlantoaxial hypermobility, cranial settling, and Chiari malformation Type I in patients with hereditary disorders of connective tissue|url=https://thejns.org/view/journals/j-neurosurg-spine/7/6/article-p601.xml|journal=Journal of Neurosurgery: Spine|language=en-US|volume=7|issue=6|pages=601–609|doi=10.3171/SPI-07/12/601}}</ref><ref name=":2" /> [[paralysis]], [[parasthesias]]<ref name=":0" /><ref name=":4">{{Cite web|url=https://search.proquest.com/openview/34b3b18a8854c04ffa0fc50273d68313/1?pq-origsite=gscholar&cbl=47886|title=MRI video diagnosis and surgical therapy of soft tissue trauma to the craniocervical junction - ProQuest|website=search.proquest.com|language=en|access-date=2019-06-01}}</ref><ref name=":5">{{Cite journal|last=Rebbeck|first=Trudy|last2=Liebert|first2=Ann|date=2014-12-01|title=Clinical management of cranio-vertebral instability after whiplash, when guidelines should be adapted: A case report|url=http://www.sciencedirect.com/science/article/pii/S1356689X14000101|journal=Manual Therapy|volume=19|issue=6|pages=618–621|doi=10.1016/j.math.2014.01.009|issn=1356-689X}}</ref><ref name=":6">{{Cite journal|last=Mathers|first=K. Sean|last2=Schneider|first2=Michael|last3=Timko|first3=Michael|date=Jun 2011|title=Occult Hypermobility of the Craniocervical Junction: A Case Report and Review|url=https://www.jospt.org/doi/full/10.2519/jospt.2011.3305|journal=Journal of Orthopaedic & Sports Physical Therapy|language=en|volume=41|issue=6|pages=444–457|doi=10.2519/jospt.2011.3305|issn=0190-6011}}</ref>
* Poor [[proprioception]],<ref name=":7">{{Cite journal|last=Bergholm|first=Ulla|last2=Johansson|first2=Bengt H.|last3=Johansson|first3=Hakan|date=2004-01-01|title=New Diagnostic Tools Can Contribute to Better Treatment of Patients with Chronic Whiplash Disorders|url=https://doi.org/10.3109/J180v03n02_02|journal=Journal of Whiplash & Related Disorders|volume=3|issue=2|pages=5–19|doi=10.3109/J180v03n02_02|issn=1533-2888}}</ref> impaired [[coordination]], [[gait]] changes<ref name=":0" /><ref name=":7" />
* [[Dizziness|Dizzinesss]], [[vertigo|vertigo,]]<ref name=":0" /><ref name=":2" /><ref name=":7" /><ref name=":4" /><ref name=":6" /><ref name=":5" /> syncope,<ref name=":0" /><ref name=":1" /><ref name=":2" /><ref name=":7" /> nausea<ref name=":1" /><ref name=":2" />
* [[Tension headache|Headache behind the eyes]],<ref name=":6" /> [[neck stiffness]], [[torticollis]],<ref name=":7" /><ref>{{Cite journal|last=Ghanem|first=Ismat|last2=El Hage|first2=Samer|last3=Rachkidi|first3=Rami|last4=Kharrat|first4=Khalil|last5=Dagher|first5=Fernand|last6=Kreichati|first6=Gabi|date=2008-03-01|title=Pediatric cervical spine instability|url=https://online.boneandjoint.org.uk/doi/full/10.1007/s11832-008-0092-2|journal=Journal of Children's Orthopaedics|volume=2|issue=2|pages=71–84|doi=10.1007/s11832-008-0092-2|issn=1863-2521|pmc=2656787|pmid=19308585}}</ref> [[Scalp Dysesthesia|posterior scalp irritation]],<ref name=":7" /> [[facial pain]]
* [[Apnea]],<ref>{{Cite journal|last=Janjua|first=M. Burhan|last2=Hwang|first2=Steven W.|last3=Samdani|first3=Amer F.|last4=Pahys|first4=Joshua M.|last5=Baaj|first5=Ali A.|last6=Härtl|first6=Roger|last7=Greenfield|first7=Jeffrey P.|date=2019-01-01|title=Instrumented arthrodesis for non-traumatic craniocervical instability in very young children|url=https://doi.org/10.1007/s00381-018-3876-9|journal=Child's Nervous System|language=en|volume=35|issue=1|pages=97–106|doi=10.1007/s00381-018-3876-9|issn=1433-0350}}</ref><ref name=":1" /><ref name=":3">{{Cite journal|last=Henderson|first=Fraser C.|last2=Austin|first2=Claudiu|last3=Benzel|first3=Edward|last4=Bolognese|first4=Paolo|last5=Ellenbogen|first5=Richard|last6=Francomano|first6=Clair A.|last7=Ireton|first7=Candace|last8=Klinge|first8=Petra|last9=Koby|first9=Myles|date=2017|title=Neurological and spinal manifestations of the Ehlers–Danlos syndromes|url=https://onlinelibrary.wiley.com/doi/abs/10.1002/ajmg.c.31549|journal=American Journal of Medical Genetics Part C: Seminars in Medical Genetics|language=en|volume=175|issue=1|pages=195–211|doi=10.1002/ajmg.c.31549|issn=1552-4876}}</ref> [[dyspnea]] (shortness of breath),<ref name=":0" /><ref name=":1" /> and [[dysphagia]] (difficulty swallowing)<ref name=":1" /><ref name=":2" />
* [[Visual disturbance|Visual disturbances]]<ref name=":4" /> downward [[nystagmus]] (irregular eye movements),<ref name=":1" /><ref name=":7" /> [[tinnitus]]<ref>{{Cite journal|last=Montazem|first=Abbas|author-link=|author-link2=|author-link3=|author-link4=|author-link5=|date=2000|title=Secondary tinnitus as a symptom of instability in the upper cervical spine: Operative management|url=https://pdfs.semanticscholar.org/21c4/85984a6ebe07efed38cf82a2f7a49b2a644e.pdf|journal=International Tinnitus Journal|volume=|issue=|pages=|quote=|via=}}</ref><ref name=":4" />
* [[Fatigue]],<ref name=":0" /><ref name=":14">{{Cite journal|last=Henderson|first=Fraser C.|last2=Henderson|first2=Fraser C.|last3=Wilson|first3=William A.|last4=Mark|first4=Alexander S.|last5=Koby|first5=Myles|date=2018-01-01|title=Utility of the clivo-axial angle in assessing brainstem deformity: pilot study and literature review|url=https://doi.org/10.1007/s10143-017-0830-3|journal=Neurosurgical Review|language=en|volume=41|issue=1|pages=149–163|doi=10.1007/s10143-017-0830-3|issn=1437-2320|pmc=5748419|pmid=28258417}}</ref><ref>{{Cite journal|last=Henderson|first=Fraser C.|last2=Wilson|first2=William A.|last3=Mott|first3=Stephen|last4=Mark|first4=Alexander|last5=Schmidt|first5=Kristi|last6=Berry|first6=Joel K.|last7=Vaccaro|first7=Alexander|last8=Benzel|first8=Edward|date=2010-07-16|title=Deformative stress associated with an abnormal clivo-axial angle: A finite element analysis|url=https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2940090/|journal=Surgical Neurology International|volume=1|doi=10.4103/2152-7806.66461|issn=2152-7806|pmc=2940090|pmid=20847911}}</ref> [[Sleep dysfunction|sleep disturbance]],<ref name=":0" /><ref name=":4" /> [[Cognitive dysfunction|cognitive impairment]],<ref name=":4" /> and [[memory loss]].

== Risk factors and comorbidities ==
Established risk factors for CCI include physical [[trauma]], [[inflammatory disease]], [[Neoplasm|neoplasms]] and [[congenital]] disorders.<ref name=":10" /><ref name=":12">{{Cite journal|last=Sapkas|first=George|last2=Papadakis|first2=Stamatios A|last3=Segkos|first3=Dimitrios|last4=Kateros|first4=Konstantinos|last5=Tsakotos|first5=George|last6=Katonis|first6=Pavlos|date=2011-06-02|title=Posterior Instrumentation for Occipitocervical Fusion|url=https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3139273/|journal=The Open Orthopaedics Journal|volume=5|pages=209–218|doi=10.2174/1874325001105010209|issn=1874-3250|pmc=3139273|pmid=21772931}}</ref>

More recently, physicians have reported an increased prevalence of CCI in patients with hereditary [[Connective tissue disorder|connective tissue disorders]].<ref name=":9" /> According to Brodbelt & Flint, however, an "increased range of joint movement, caused by [[ligamentous laxity]], is not the same as [[spinal instability]] resulting from trauma or major inflammatory arthropathies such as (historically) [[rheumatoid arthritis]]."<ref name=":19">{{Cite journal|last=Brodbelt|first=Andrew R.|last2=Flint|first2=Graham|date=Aug 2017|title=Ehlers Danlos, complex Chiari and cranio-cervical fixation: how best should we treat patients with hypermobility?|url=https://www.ncbi.nlm.nih.gov/pubmed/28961036|journal=British Journal of Neurosurgery|volume=31|issue=4|pages=397–398|doi=10.1080/02688697.2017.1386282|issn=1360-046X|pmid=28961036|pmc=|quote=|last3=|first3=|last4=|first4=|last5=|first5=|last6=|first6=|last7=|first7=|last8=|first8=|author-link=|author-link2=|access-date=|author-link3=|author-link4=|author-link5=|author-link6=|via=}}</ref> Others have argued that "pathological instability at the cranio-cervical junction has not been clearly established in the literature for the [[Joint hypermobility|hypermobility]] population."<ref name=":9" />

{| class="wikitable"
|'''Cause of instability'''
|'''Example'''
|-
|Physical trauma<ref>{{Cite journal|last=Ghatan|first=Saadi|last2=Newell|first2=David W.|last3=Grady|first3=M. Sean|last4=Mirza|first4=Sohail K.|last5=Chapman|first5=Jens R.|last6=Mann|first6=Frederick A.|last7=Ellenbogen|first7=Richard G.|date=Aug 2004|title=Severe posttraumatic craniocervical instability in the very young patient. Report of three cases|url=https://www.ncbi.nlm.nih.gov/pubmed/16206980|journal=Journal of Neurosurgery|volume=101|issue=1 Suppl|pages=102–107|doi=10.3171/ped.2004.101.2.0102|issn=0022-3085|pmid=16206980}}</ref>
|Car accident<ref>{{Cite journal|last=Uribe|first=Juan S.|last2=Ramos|first2=Edwin|last3=Baaj|first3=Ali|last4=Youssef|first4=A. Samy|last5=Vale|first5=Fernando L.|date=Dec 2009|title=Occipital cervical stabilization using occipital condyles for cranial fixation: technical case report|url=https://www.ncbi.nlm.nih.gov/pubmed/19934947|journal=Neurosurgery|volume=65|issue=6|pages=E1216–1217; discussion E1217|doi=10.1227/01.NEU.0000349207.98394.FA|issn=1524-4040|pmid=19934947}}</ref><ref>{{Cite journal|last=Volle|first=E.|last2=Montazem|first2=A.|date=Jan 2001|title=MRI video diagnosis and surgical therapy of soft tissue trauma to the craniocervical junction|url=https://www.ncbi.nlm.nih.gov/pubmed/11209518|journal=Ear, Nose, & Throat Journal|volume=80|issue=1|pages=41–44, 46–48|issn=0145-5613|pmid=11209518}}</ref>, blow to the head.<ref>{{Cite journal|last=Mathers|first=K. Sean|last2=Schneider|first2=Michael|last3=Timko|first3=Michael|date=Jun 2011|title=Occult hypermobility of the craniocervical junction: a case report and review|url=https://www.ncbi.nlm.nih.gov/pubmed/21628827|journal=The Journal of Orthopaedic and Sports Physical Therapy|volume=41|issue=6|pages=444–457|doi=10.2519/jospt.2011.3305|issn=1938-1344|pmid=21628827}}</ref>
|-
|Infection & inflammatory disease
|Rheumatoid arthritis<ref>{{Cite journal|last=O'Brien|first=Michael F.|last2=Casey|first2=Adrian T. H.|last3=Crockard|first3=Alan|last4=Pringle|first4=Jean|last5=Stevens|first5=John M.|date=2002-10-15|title=Histology of the craniocervical junction in chronic rheumatoid arthritis: a clinicopathologic analysis of 33 operative cases|url=https://www.ncbi.nlm.nih.gov/pubmed/12394902|journal=Spine|volume=27|issue=20|pages=2245–2254|doi=10.1097/01.BRS.0000029252.98053.43|issn=1528-1159|pmid=12394902}}</ref>, tuberculosis<ref>{{Cite journal|last=Chaudhary|first=Kshitij|last2=Potdar|first2=Prabodhan|last3=Bapat|first3=Mihir|last4=Rathod|first4=Ashok|last5=Laheri|first5=Vinod|date=2012-06-15|title=Structural odontoid lesions in craniovertebral tuberculosis: a review of 15 cases|url=https://www.ncbi.nlm.nih.gov/pubmed/22261632|journal=Spine|volume=37|issue=14|pages=E836–843|doi=10.1097/BRS.0b013e31824a4c8f|issn=1528-1159|pmid=22261632}}</ref>
|-
|Neoplasms
|Tumors<ref name=":12" /> such as haemangioma, aneurysmal bone cyst
|-
|Congenital
|Down’s syndrome<ref>{{Cite journal|last=Hankinson|first=Todd C.|last2=Anderson|first2=Richard C. E.|date=Mar 2010|title=Craniovertebral junction abnormalities in Down syndrome|url=https://www.ncbi.nlm.nih.gov/pubmed/20173525|journal=Neurosurgery|volume=66|issue=3 Suppl|pages=32–38|doi=10.1227/01.NEU.0000365803.22786.F0|issn=1524-4040|pmid=20173525}}</ref>, os odontoideum<ref>{{Cite journal|last=Zhao|first=Deng|last2=Wang|first2=Shenglin|last3=Passias|first3=Peter G.|last4=Wang|first4=Chao|date=May 2015|title=Craniocervical instability in the setting of os odontoideum: assessment of cause, presentation, and surgical outcomes in a series of 279 cases|url=https://www.ncbi.nlm.nih.gov/pubmed/25635883|journal=Neurosurgery|volume=76|issue=5|pages=514–521|doi=10.1227/NEU.0000000000000668|issn=1524-4040|pmid=25635883}}</ref>, dwarfism
|-
|Hereditary connective tissue disorder
|Ehlers Danlos Syndromes<ref name=":0" /><ref name=":1" />
|}
It is not unusual for CCI to co-occur with other structural neurological abnormalities such as [[atlantoaxial instability]] (AAI) and [[chiari malformation]] (CM).<ref>{{Cite journal|last=Camino Willhuber|first=Gaston O.|last2=Bosio|first2=Santiago T.|last3=Puigdevall|first3=Miguel H.|last4=Halliburton|first4=Carolina|last5=Sola|first5=Carlos A.|last6=Maenza|first6=Ruben A.|date=Jan 2017|title=Craniocervical spinal instability after type 1 Arnold Chiari decompression: a case report|url=https://www.ncbi.nlm.nih.gov/pubmed/27258364|journal=Journal of Pediatric Orthopedics. Part B|volume=26|issue=1|pages=80–85|doi=10.1097/BPB.0000000000000346|issn=1473-5865|pmid=27258364}}</ref><ref name=":0" />

== Diagnosis ==
{{Video|id=https://youtu.be/MsYDA3SXTkg|service=youtube|dimensions=550|description=Dr. Paolo Bolognese discusses methods of imaging and measurement for diagnosis.|alignment=right|urlargs=}}
The diagnosis of CCI is based on symptom presentation, a supportive history, demonstrable neurological findings and abnormal imaging.

=== Imaging ===
CCI is typically diagnosed via a [[cervical]] [[Magnetic resonance imaging|MRI]], whether supine or upright. If supine, a [[3 Tesla MRI]] is preferred over a [[1.5 Tesla]]. Most neurosurgeons prefer upright MRI with [[flexion]] and [[extension]].<ref>{{Cite web|url=https://www.mechanicalbasis.org/diagnosis.html|title=Craniocervical instability, Atlantoaxial Instability, Myalgic Encephalomyelitis, ME, CFS|website=MEchanical Basis|language=en|access-date=2019-06-02}}</ref> According to Henderson FC, “ventral [[brainstem]] compression may exist in flexion of the cervical spine, but appear normal on routine imaging.”<ref name=":9" />

{| class="wikitable"
!Imaging
!Sensitive for
|-
|Upright MRI with flexion/extension
|Horizontal instability
|-
|CT scan with rotation
|Rotational instability
|-
|Invasive cervical traction (ICT) with fluroscopy
|Vertical instability
|}

=== Measurements ===
More than twenty radiological measurements have been proposed or used in the diagnosis of CCI. However, three measurements are most commonly used: the [[Grabb-Oakes measurement|Grabb-Oakes]] line, which measures ventral brainstem compression; the [[Clivo-axial angle|Clivo-Axial Angle (CXA)]], which measures brainstem deformity by the [[odontoid]] process; and the Basion Dens Interval, which measures vertical instability ([[cranial settling]]). According to a 2013 consensus statement on the assessment of CCI a CXA of 135 degrees or less should be considered as "potentially pathological."<ref name=":13">{{Cite web|url=https://bobbyjonescsf.org/csf-video/review-colloq-2014/|title=REVIEW OF THE 2013 CSF RESEARCH COLLOQUIUM & CONSENSUS ON CRANIOCERVICAL INSTABILITY – Bobby Jones CSF|last=CSF|first=Bobby Jones {{!}}|language=en-US|access-date=2019-09-18}}</ref> as it is reported to be uncommon in the healthy population.<ref>{{Cite journal|last=Batista|first=Ulysses C.|last2=Joaquim|first2=Andrei F.|last3=Fernandes|first3=Yvens B.|last4=Mathias|first4=Roger N.|last5=Ghizoni|first5=Enrico|last6=Tedeschi|first6=Helder|date=Apr 2015|title=Computed tomography evaluation of the normal craniocervical junction craniometry in 100 asymptomatic patients|url=https://www.ncbi.nlm.nih.gov/pubmed/25828499|journal=Neurosurgical Focus|volume=38|issue=4|pages=E5|doi=10.3171/2015.1.FOCUS14642|issn=1092-0684|pmid=25828499}}</ref><ref>{{Cite journal|last=Botelho|first=Ricardo Vieira|last2=Ferreira|first2=Edson Dener Zandonadi|date=Oct 2013|title=Angular craniometry in craniocervical junction malformation|url=https://www.ncbi.nlm.nih.gov/pubmed/23640096|journal=Neurosurgical Review|volume=36|issue=4|pages=603–610; discussion 610|doi=10.1007/s10143-013-0471-0|issn=1437-2320|pmc=3910287|pmid=23640096}}</ref><ref>{{Cite journal|last=Bundschuh|first=C|last2=Modic|first2=Mt|last3=Kearney|first3=F|last4=Morris|first4=R|last5=Deal|first5=C|date=1988-07-01|title=Rheumatoid arthritis of the cervical spine: surface-coil MR imaging|url=https://www.ajronline.org/doi/abs/10.2214/ajr.151.1.181|journal=American Journal of Roentgenology|volume=151|issue=1|pages=181–187|doi=10.2214/ajr.151.1.181|issn=0361-803X}}</ref> Others have argued that these radiological measurements are "not accepted internationally as indicating instability."<ref name=":19" />
{| class="wikitable"
|+
!Measurement
!Units
!Description
! scope="col" style="width: 75px;" | Normal Range
! scope="col" style="width: 75px;" | Borderline Range
! scope="col" style="width: 75px;" | Pathological Range
! scope="col" style="width: 75px;" | Alternate Ranges
!Instability Measured
!Pathology Measured
!Refs
|-
|'''Clivo-axial angle (CXA)'''
|Degrees
|Angle between clivus line and the posterior axial line
|170 -150
|149 -136
|≤ 135
|
|More sensitive for horizontal
|Brainstem deformity
|<ref>{{Cite journal|last=Bolognese|first=Paolo|author-link=|author-link2=|author-link3=|author-link4=|author-link5=|date=|title=Videoed Presentation at: ASAP Chiari & Syringomyelia Conference Paolo Bolognese, MD "Complex Chiari, 2014. Timecode 14:28|url=https://www.youtube.com/watch?v=uiyk0Qbx2TQ&t=14m28s|journal=|volume=|issue=|pages=|quote=|via=}}</ref>
|-
|'''Grabb-Oakes'''
|mm
|Distance from the dura to the line drawn from the basion to the posterior inferior edge of the C2 vertebra
|< 6
|≥ 6 and < 9
|≥ 9
|Some use pathological ≥ 8
|More sensitive for horizontal
|Brainstem compression
|<ref>{{Cite journal|last=Bolognese|first=Paolo|author-link=|author-link2=|author-link3=|author-link4=|author-link5=|date=|title=Videoed presentation at: EDS Awareness Educational Series, April 12, 2018. Timecodes: 49:30 and 53:47|url=https://www.youtube.com/watch?v=MsYDA3SXTkg&t=49m30s|journal=|volume=|issue=|pages=|quote=|via=}}</ref><ref name=":9" />
|-
|'''Basion-Axial Interval (BAI)'''
|mm
|Distance from tip of basion to posterior axial line
|< 12
|
|≥ 12
|
|
|
|<ref name=":15">{{Cite journal|last=Henderson|first=Fraser|author-link=|author-link2=|author-link3=|author-link4=|author-link5=|date=|title=Videoed presentation at: Chiari & Syringomyelia Foundation, Patient Conference of Action, June 24, 2018. Timecode: 10:34.|url=https://www.youtube.com/watch?list=WL&v=sEi9AlHQTJc&t=10m34s|journal=|volume=|issue=|pages=|quote=|via=}}</ref>
|-
|'''Basion-Dens interval (BDI)'''
|mm
|Vertical distance between the basion and the dens
|< 12
|
|≥ 12
|Some use pathological ≥ 10
|Vertical
|Cranial settling
|<ref name=":15" /><ref name=":9" />
|-
|'''Translational BAI'''
|mm
|Change in BAI between flexion and extension positions of the head
|< 1
|≥ 1 and ≤ 2
|> 2
|For surgery > 4 needed
|Horizontal
|Skull sliding over spine
|<ref>{{Cite journal|last=Henderson|first=Fraser C.|last2=Francomano|first2=C. A.|last3=Koby|first3=M.|last4=Tuchman|first4=K.|last5=Adcock|first5=J.|last6=Patel|first6=S.|date=2019-01-09|title=Cervical medullary syndrome secondary to craniocervical instability and ventral brainstem compression in hereditary hypermobility connective tissue disorders: 5-year follow-up after craniocervical reduction, fusion, and stabilization|url=https://doi.org/10.1007/s10143-018-01070-4|journal=Neurosurgical Review|language=en|doi=10.1007/s10143-018-01070-4|issn=1437-2320}}</ref><ref name=":0" />
|-
|'''Translational BDI'''
|mm
|Change in BDI between flexion and extension positions of the head
|
|
|
|
|
|
|
|-
|'''Dynamic BDI'''
|mm
|Change in BDI value when the head is pulled upward with traction force of typically up to 35 lbs
|
|
|
|
|Vertical
|Cranial settling
|
|-
|'''Dens Over Chamberlain'''
|mm
|How far tip of the dens extends above Chamberlain's line
|< 2
|≥ 2 and ≤ 3
|≥ 3
|
|Vertical
|Basilar invagination
|<ref>{{Cite journal|last=Hain|first=Timothy C. |author-link=|author-link2=|author-link3=|author-link4=|author-link5=|date=|title=Basilar Invagination, Basilar Impression and Atlantoaxial Subluxation|url=https://www.dizziness-and-balance.com/disorders/central/cerebellar/basilar%20invagination.htm|journal=|volume=|issue=|pages=|quote=|via=}}</ref>
|}
Some of the measurement ranges in the above table are also to be found in the 2nd International CSF Dynamics Symposium Consensus Statement (2013).<ref name=":13" />

=== Traction ===
Manual traction, halo and invasive cervical traction are often used to aid in the diagnosis of CCI. Symptomatic improvement with traction can help determine whether a patient with abnormal measurements will benefit from craniocervical fusion surgery.

== Treatment ==
{{Video|id=https://youtu.be/sEi9AlHQTJc|service=youtube|dimensions=550|description=Dr. Fraser Henderson presents the results a five-year follow-up study.|alignment=right|urlargs=}}
=== Conservative treatment ===
Treatment of CCI can include “conservative measures” such as rest, pain management, bracing with a cervical collar, or physical therapy to strengthen neck muscles.<ref>{{Cite journal|last=Mathers|first=K. Sean|last2=Schneider|first2=Michael|last3=Timko|first3=Michael|date=Jun 2011|title=Occult hypermobility of the craniocervical junction: a case report and review|url=https://www.ncbi.nlm.nih.gov/pubmed/21628827|journal=The Journal of Orthopaedic and Sports Physical Therapy|volume=41|issue=6|pages=444–457|doi=10.2519/jospt.2011.3305|issn=1938-1344|pmid=21628827}}</ref> Many conservative therapies have little to no supporting evidence of efficacy.

There is no evidence for the efficacy of experimental treatments for CCI such as prolotherapy and upper cervical chiropractic.

=== Surgery ===
When non-invasive treatments for CCI fail to work, occipito-cervical fusion (OCF) can be considered.<ref name=":0" /> OCF is a surgery that aims at a biomechanical stabilization of the craniocervical junction. Patients with objective radiological findings, a clinical picture supportive of the diagnosis, a positive response to traction, and who are significantly impaired may be candidates for this surgery. A common method involves internal fixation of the upper spine to the skull by mechanical rods and screws. (However, rod-wire, rigid rod-screws, occipital hooks and cervical claws are all methods currently in use.<ref name=":16">{{Cite journal|last=Resnick|first=Daniel K.|last2=Patel|first2=Nirav J.|last3=Lall|first3=Rishi|date=2010-11-01|title=A Review of Complications Associated With Craniocervical Fusion Surgery|url=https://academic.oup.com/neurosurgery/article/67/5/1396/2563905|journal=Neurosurgery|language=en|volume=67|issue=5|pages=1396–1403|doi=10.1227/NEU.0b013e3181f1ec73|issn=0148-396X}}</ref>) During surgery, titanium hardware is used to fixate the occiput, axis and atlas (i.e., C0 to C2) while rib graft or cadaver bone graft is used to help the bones fuse together. Wire methods are less biomechanically stable than rod methods and have high rates of dural laceration.<ref name=":16" /> Screw and rod fixation methods have lower complication rates and higher rates of successful fusion.<ref name=":18" /> Fusion rates across all hardware methods range from 89 to 100%.<ref name=":16" /> When cervical instability is present below C2, additional vertebrae may also be fused if the patient is symptomatic.

==== Outcomes, risks & complications ====
The outcome of OCF is generally favorable with most patients experiencing symptom relief post-surgery.<ref name=":0" /> The complications of OCF however can be serious<ref>{{Cite journal|last=Garrido|first=Ben J.|last2=Sasso|first2=Rick C.|date=Jan 2012|title=Occipitocervical fusion|url=https://www.ncbi.nlm.nih.gov/pubmed/22082624|journal=The Orthopedic Clinics of North America|volume=43|issue=1|pages=1–9, vii|doi=10.1016/j.ocl.2011.08.009|issn=1558-1373|pmid=22082624}}</ref> and occur in an estimated 7% to 33% of patients.<ref name=":10" /><ref name=":18">{{Cite journal|last=Winegar|first=Corbett D.|last2=Lawrence|first2=James P.|last3=Friel|first3=Brian C.|last4=Fernandez|first4=Carmella|last5=Hong|first5=Joseph|last6=Maltenfort|first6=Mitchell|last7=Anderson|first7=Paul A.|last8=Vaccaro|first8=Alexander R.|date=Jul 2010|title=A systematic review of occipital cervical fusion: techniques and outcomes|url=https://www.ncbi.nlm.nih.gov/pubmed/20594011|journal=Journal of Neurosurgery. Spine|volume=13|issue=1|pages=5–16|doi=10.3171/2010.3.SPINE08143|issn=1547-5646|pmid=20594011}}</ref><ref name=":11" /><ref>{{Cite journal|last=Ando|first=Kei|last2=Imagama|first2=Shiro|last3=Ito|first3=Zenya|last4=Kobayashi|first4=Kazuyoshi|last5=Yagi|first5=Hideki|last6=Shinjo|first6=Ryuichi|last7=Hida|first7=Tetsuro|last8=Ito|first8=Kenyu|last9=Ishikawa|first9=Yoshimoto|date=Jun 2017|title=Minimum 5-year Follow-up Results for Occipitocervical Fusion Using the Screw-Rod System in Craniocervical Instability|url=https://www.ncbi.nlm.nih.gov/pubmed/28525489|journal=Clinical Spine Surgery|volume=30|issue=5|pages=E628–E632|doi=10.1097/BSD.0000000000000199|issn=2380-0194|pmid=28525489}}</ref><ref name=":16" /> Common complications include screw failure, wound infection, dural tear and cerebrospinal fluid leakage<ref name=":11" /> In some cases revision surgery is needed to treat infection or to remove hardware. Severe complications can include meningitis and accidental injury of the vertebral artery by misplaced screws.<ref name=":17">{{Cite journal|last=Nockels|first=Russ P.|last2=Shaffrey|first2=Christopher I.|last3=Kanter|first3=Adam S.|last4=Azeem|first4=Syed|last5=York|first5=Julie E.|date=Aug 2007|title=Occipitocervical fusion with rigid internal fixation: long-term follow-up data in 69 patients|url=https://www.ncbi.nlm.nih.gov/pubmed/17688049|journal=Journal of Neurosurgery. Spine|volume=7|issue=2|pages=117–123|doi=10.3171/SPI-07/08/117|issn=1547-5654|pmid=17688049}}</ref>

A meta-study of 2274 procedures across 22 studies<ref name=":16" /> found the following complication rates:

{| class="wikitable"
!Complication type
!Prevalence rate
|-
|Hardware failure after fusion non-union
|7%
|-
|Wound infection
|3.8%-11%
|-
|Vertebral artery damage
|1.3%-4.1%
|-
|Dural tears
|0% to 4.2%
|}
Meta-studies place the rate of death from fusion surgery at 0-0.6%.<ref name=":16" /><ref name=":18" />

==== Side effects ====
OCF causes a substantial reduction in the neck’s range of motion, estimated at approximately 40% of total cervical flexion–extension.<ref name=":8">{{Cite journal|last=Ashafai|first=Nabeel S.|last2=Visocchi|first2=Massimiliano|last3=Wąsik|first3=Norbert|date=2019|editor-last=Visocchi|editor-first=Massimiliano|title=Occipitocervical Fusion: An Updated Review|url=https://doi.org/10.1007/978-3-319-62515-7_35|series=Acta Neurochirurgica Supplement|language=en|location=Cham|publisher=Springer International Publishing|pages=247–252|doi=10.1007/978-3-319-62515-7_35|isbn=9783319625157}}</ref>

==== Cost ====
OCF is estimated to cost tens of thousands of dollars, although some insurance schemes fully cover the cost of surgery depending on the country located and neurosurgeons involved.

=== Stem cell therapy ===
Some clinics offer stem cell therapy in order to regenerate the area, ligaments, connective and other tissues that may be damaged in the area.{{Citation needed|reason=Please name any clinics that offer stem cell therapy for CCI.|date=3 November 2019}}

== Dysautonomia and CCI in EDS ==
As CCI might lead to a compression of the brain stem, some researchers speculate this might cause some of the autonomic symptoms such as tachycardia and orthostatic intolerance that are frequently seen in patients with Ehlers Danlos Syndromes (EDS). In a 2007 influential paper Milhorat et al. followed-up on patients with Chiari malformation who did not improve with treatment and surgery. The authors discovered that many of these patients suffered from EDS and had other structural abnormalities at the upper spine such as CCI and cranial settling. Milhorat et al. speculated that the resulting compression of the brainstem might be the cause of the autonomic and other symptoms these patients were suffering from.<ref>{{Cite journal|last=Milhorat|first=Thomas H.|last2=Bolognese|first2=Paolo A.|last3=Nishikawa|first3=Misao|last4=McDonnell|first4=Nazli B.|last5=Francomano|first5=Clair A.|date=Dec 2007|title=Syndrome of occipitoatlantoaxial hypermobility, cranial settling, and chiari malformation type I in patients with hereditary disorders of connective tissue|url=https://www.ncbi.nlm.nih.gov/pubmed/18074684|journal=Journal of Neurosurgery. Spine|volume=7|issue=6|pages=601–609|doi=10.3171/SPI-07/12/601|issn=1547-5654|pmid=18074684}}</ref> In conference presentations, neurosurgeons have indicated that they think CCI can cause dysautonomia symptoms such as postural orthostatic tachycardia syndrome (POTS) <ref>[https://www.youtube.com/watch?time_continue=735&v=857Jsjsqxjw Craniocervical Instability (Dr Henderson the 2012 EDNF Confrence).] Minute 12.10. </ref><ref>[https://www.youtube.com/watch?v=ntD9NRIvEJ0 Dr Milhorat from The Chiari Institute at the 2005 ASAP.]</ref><ref name=":13" />

Henderson et al. tested this theory by following 20 CCI patients with comorbid Chiari Malformation and hereditary hypermobility connective tissue disorders for a period of 5 years after OCF-surgery. Patients were satisfied with the surgery and experienced significant improvements in some CCI-related symptoms such as vertigo, headaches, imbalance, dysarthria dizziness or frequent daytime urination. There was however only a small increase in objective outcomes such as work resumption with 60% of patients remaining unable to work or go to school. Participants attributed this to other medical problems related to EDS such as musculoskeletal pain, fatigue, gastrointestinal issues and POTS, indicating these were not significantly improved after OCF-surgery.<ref name=":0" />

== Mechanical basis theory ==
Five ME/CFS patients diagnosed with CCI (some also had EDS) reported to have experienced remarkable improvements and even remission of their ME/CFS symptoms following OCF-surgery.<ref>{{Cite web|url=https://www.mechanicalbasis.org/interviews.html|title=Craniocervical instability, Atlantoaxial Instability, Myalgic Encephalomyelitis, ME, CFS|website=MEchanical Basis|language=en|access-date=2019-06-06}}</ref><ref>{{Cite web|url=https://medium.com/@jenbrea/health-update-3-my-me-is-in-remission-dd575e650f71|title=Health update #3: My ME is in remission|last=Brea|first=Jennifer|date=2019-05-20|website=Medium|access-date=2019-06-03}}</ref> They speculate that mechanical compression of the brainstem due to CCI has the potential to cause characteristic ME/CFS symptoms such as post-exertional malaise<ref>{{Cite web|url=https://www.mechanicalbasis.org/|title=Craniocervical instability, Atlantoaxial Instability, Myalgic Encephalomyelitis, ME, CFS|website=MEchanical Basis|language=en|access-date=2019-06-03}}</ref>, although this theory is currently not supported by scientific evidence. The current literature does not suggest a connection between ME/CFS and CCI. Others have raised concerns about CCI surgery in patients with ME/CFS given the lack of research on OCF in this patient population.<ref>{{Cite web|url=https://www.s4me.info/threads/concerns-about-craniocervical-instability-surgery-in-me-cfs.9638/|title=Concerns about craniocervical instability surgery in ME/CFS|website=Science for ME|language=en-US|access-date=2019-06-03}}</ref>

== Synonyms ==
* Syndrome of Occipitoatlantialaxial Hypermobility<ref name=":1" />
* Hypermobility of the Craniocervical Junction<ref>{{Cite journal|last=Mathers|first=K. Sean|last2=Schneider|first2=Michael|last3=Timko|first3=Michael|date=Jun 2011|title=Occult hypermobility of the craniocervical junction: a case report and review|url=https://www.ncbi.nlm.nih.gov/pubmed/21628827|journal=The Journal of Orthopaedic and Sports Physical Therapy|volume=41|issue=6|pages=444–457|doi=10.2519/jospt.2011.3305|issn=1938-1344|pmid=21628827}}</ref>

== See also ==

* [[Atlantoaxial instability|Atlantoaxial instability (AAI)]]
* [[Neural strain]]
* [[Chiari malformation]]
* [[Ehlers-Danlos syndrome]]
* [[Intracranial hypertension]]
* [[Tethered cord syndrome]]

== Learn more ==
* [https://www.healthrising.org/blog/2019/02/27/brainstem-compression-chronic-fatigue-syndrome-me-cfs-fibromyalgia-pots-craniocervical-instability/ Could Craniocervical Instability Be Causing ME/CFS, Fibromyalgia & POTS? Pt I – The Spinal Series] - from Health Rising
* [https://www.healthrising.org/blog/2019/05/21/jennifer-brea-chronic-fatigue-mecfs-recovering-story/ Jennifer Brea’s Amazing ME/CFS Recovering Story: the Spinal Series – Pt. II] - From Health Rising
* [https://www.healthrising.org/treating-chronic-fatigue-syndrome/fibromyalgia-craniocervical-instability-survey-effectivness-survey/ ME/CFS and Fibromyalgia Craniocervical Instability Surgery Effectiveness Poll] - From Health Rising

== References ==
{{reflist}}
[[Category:Diagnoses]]

Craniocervical instability

2019-12-22T14:13:46Z

Cort:/* Learn more */

{{Cleanup|reason=Image copyright issues|date =5 August, 2018}}
[[File:Craniocervical instability MRI.jpg|thumb|A cervical MRI is assessed for possible craniocervical instability.]]
'''Craniocervical instability''' (CCI) is a pathological condition of increased mobility at the craniocervical junction, the area where the skull meets the spine. In CCI the ligamentous connections of the craniocervical junction can be stretched, weakened or ruptured.<ref name=":2">{{Cite journal|last=Henderson|first=Fraser C.|last2=Austin|first2=Claudiu|last3=Benzel|first3=Edward|last4=Bolognese|first4=Paolo|last5=Ellenbogen|first5=Richard|last6=Francomano|first6=Clair A.|last7=Ireton|first7=Candace|last8=Klinge|first8=Petra|last9=Koby|first9=Myles|date=2017|title=Neurological and spinal manifestations of the Ehlers–Danlos syndromes|url=https://onlinelibrary.wiley.com/doi/abs/10.1002/ajmg.c.31549|journal=American Journal of Medical Genetics Part C: Seminars in Medical Genetics|language=en|volume=175|issue=1|pages=195–211|doi=10.1002/ajmg.c.31549|issn=1552-4876}}</ref> This can lead to compression of the [[Brainstem compression|brainstem]], upper [[spinal cord]], or [[cerebellum]] and result in myelopathy, neck pain and a range of other symptoms.<ref name=":11">{{Cite journal|last=Choi|first=Sung Ho|last2=Lee|first2=Sang Gu|last3=Park|first3=Chan Woo|last4=Kim|first4=Woo Kyung|last5=Yoo|first5=Chan Jong|last6=Son|first6=Seong|date=Apr 2013|title=Surgical Outcomes and Complications after Occipito-Cervical Fusion Using the Screw-Rod System in Craniocervical Instability|url=https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3698232/|journal=Journal of Korean Neurosurgical Society|volume=53|issue=4|pages=223–227|doi=10.3340/jkns.2013.53.4.223|issn=2005-3711|pmc=3698232|pmid=23826478}}</ref>

CCI usually develops as a result of physical trauma such as a car accident, an inflammatory disease such as rheumatoid arthritis or a congenital disorder such as Down's syndrome.<ref name=":10">{{Cite journal|last=Ashafai|first=Nabeel S.|last2=Visocchi|first2=Massimiliano|last3=Wąsik|first3=Norbert|date=2019|title=Occipitocervical Fusion: An Updated Review|url=https://www.ncbi.nlm.nih.gov/pubmed/30610329|journal=Acta Neurochirurgica. Supplement|volume=125|pages=247–252|doi=10.1007/978-3-319-62515-7_35|issn=0065-1419|pmid=30610329}}</ref> More recently, physicians have reported an increased prevalence of CCI in patients with hereditary disorders of connective tissue such as Ehlers Danlos Syndromes (EDS).<ref name=":9">{{Cite journal|last=Henderson|first=Fraser C.|date=2016|title=Cranio-cervical Instability in Patients with Hypermobility Connective Disorders|url=https://www.omicsonline.org/open-access/craniocervical-instability-in-patients-with-hypermobility-connective-disorders-2165-7939-1000299.php?aid=71754|journal=Journal of Spine|language=En|volume=05|issue=02|doi=10.4172/2165-7939.1000299|issn=2165-7939}}</ref> There have also been anecdotal reports of patients with myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) who were later diagnosed with CCI,<ref>{{Cite web|url=https://forums.phoenixrising.me/index.php?threads/have-you-ruled-out-chiari-as-a-cause-of-your-cfs.56908/|title=Have you ruled out Chiari as a cause of your CFS|last=|first=|date=|website=Phoenix Rising|archive-url=|archive-date=|dead-url=|access-date=}}</ref><ref>{{Cite web|url=https://medium.com/@jenbrea/cci-tethered-cord-series-e1e098b5edf|title=CCI + Tethered cord series|last=Brea|first=Jennifer|date=2019-06-06|website=Medium|language=en|access-date=2019-06-06}}</ref><ref>{{Cite web|url=https://www.mechanicalbasis.org/interviews.html|title=Craniocervical instability, Atlantoaxial Instability, Myalgic Encephalomyelitis, ME, CFS|website=MEchanical Basis|language=en|access-date=2019-06-06}}</ref> although no scientific publication on this subject exists. It frequently co-occurs with [[atlantoaxial instability]] (AAI).{{Citation needed|reason=|date=10 December 2019}}
== Symptoms ==
Symptoms of craniocervical instability include [[occipital headache]], [[neck pain]] and [[Nervous system|neurological]] abnormalities such as [[numbness]], [[motor weakness]], [[dizziness]], and [[gait instability]].<ref>{{Cite journal|last=Bobinski|first=Lukas|last2=Levivier|first2=Marc|last3=Duff|first3=John M.|date=Feb 2015|title=Occipitoaxial spinal interarticular stabilization with vertebral artery preservation for atlantal lateral mass failure|url=https://www.ncbi.nlm.nih.gov/pubmed/25415481|journal=Journal of Neurosurgery. Spine|volume=22|issue=2|pages=134–138|doi=10.3171/2014.10.SPINE14131|issn=1547-5646|pmid=25415481}}</ref><ref>{{Cite journal|last=O'Brien|first=Michael F.|last2=Casey|first2=Adrian T. H.|last3=Crockard|first3=Alan|last4=Pringle|first4=Jean|last5=Stevens|first5=John M.|date=2002-10-15|title=Histology of the craniocervical junction in chronic rheumatoid arthritis: a clinicopathologic analysis of 33 operative cases|url=https://www.ncbi.nlm.nih.gov/pubmed/12394902|journal=Spine|volume=27|issue=20|pages=2245–2254|doi=10.1097/01.BRS.0000029252.98053.43|issn=1528-1159|pmid=12394902}}</ref><ref>{{Cite journal|last=Young|first=Richard M.|last2=Sherman|first2=Jonathan H.|last3=Wind|first3=Joshua J.|last4=Litvack|first4=Zachary|last5=O'Brien|first5=Joseph|date=Aug 2014|title=Treatment of craniocervical instability using a posterior-only approach: report of 3 cases|url=https://www.ncbi.nlm.nih.gov/pubmed/24785968|journal=Journal of Neurosurgery. Spine|volume=21|issue=2|pages=239–248|doi=10.3171/2014.3.SPINE13684|issn=1547-5646|pmid=24785968}}</ref><ref>{{Cite journal|last=Botelho|first=Ricardo V.|last2=Neto|first2=Eliseu B.|last3=Patriota|first3=Gustavo C.|last4=Daniel|first4=Jefferson W.|last5=Dumont|first5=Paulo A. S.|last6=Rotta|first6=José M.|date=Oct 2007|title=Basilar invagination: craniocervical instability treated with cervical traction and occipitocervical fixation. Case report|url=https://www.ncbi.nlm.nih.gov/pubmed/17933321|journal=Journal of Neurosurgery. Spine|volume=7|issue=4|pages=444–449|doi=10.3171/SPI-07/10/444|issn=1547-5654|pmid=17933321}}</ref><ref>{{Cite journal|last=Henderson|first=Fraser C.|last2=Henderson|first2=Fraser C.|last3=Wilson|first3=William A.|last4=Mark|first4=Alexander S.|last5=Koby|first5=Myles|date=Jan 2018|title=Utility of the clivo-axial angle in assessing brainstem deformity: pilot study and literature review|url=https://www.ncbi.nlm.nih.gov/pubmed/28258417|journal=Neurosurgical Review|volume=41|issue=1|pages=149–163|doi=10.1007/s10143-017-0830-3|issn=1437-2320|pmc=5748419|pmid=28258417|quote=|author-link=|author-link2=|author-link3=|author-link4=|author-link5=|author-link6=|via=}}</ref> Patients sometimes describe the feeling that their head is too heavy for their neck to support (“bobble-head”).<ref name=":9" /> No particular symptom is mandatory for a diagnosis of CCI and each symptom listed might have a cause other than CCI.

Other symptoms reported in patients with CCI include:
* [[Muscle weakness|Muscle weakness,]]<ref name=":0">{{Cite journal|last=Henderson|first=Fraser C.|last2=Francomano|first2=C. A.|last3=Koby|first3=M.|last4=Tuchman|first4=K.|last5=Adcock|first5=J.|last6=Patel|first6=S.|date=2019-01-09|title=Cervical medullary syndrome secondary to craniocervical instability and ventral brainstem compression in hereditary hypermobility connective tissue disorders: 5-year follow-up after craniocervical reduction, fusion, and stabilization|url=https://doi.org/10.1007/s10143-018-01070-4|journal=Neurosurgical Review|language=en|doi=10.1007/s10143-018-01070-4|issn=1437-2320}}</ref> [[numbness|numbness,]]<ref name=":1">{{Cite journal|last=Francomano|first=Clair A.|last2=McDonnell|first2=Nazli B.|last3=Nishikawa|first3=Misao|last4=Bolognese|first4=Paolo A.|last5=Milhorat|first5=Thomas H.|date=2007-12-01|title=Syndrome of occipitoatlantoaxial hypermobility, cranial settling, and Chiari malformation Type I in patients with hereditary disorders of connective tissue|url=https://thejns.org/view/journals/j-neurosurg-spine/7/6/article-p601.xml|journal=Journal of Neurosurgery: Spine|language=en-US|volume=7|issue=6|pages=601–609|doi=10.3171/SPI-07/12/601}}</ref><ref name=":2" /> [[paralysis]], [[parasthesias]]<ref name=":0" /><ref name=":4">{{Cite web|url=https://search.proquest.com/openview/34b3b18a8854c04ffa0fc50273d68313/1?pq-origsite=gscholar&cbl=47886|title=MRI video diagnosis and surgical therapy of soft tissue trauma to the craniocervical junction - ProQuest|website=search.proquest.com|language=en|access-date=2019-06-01}}</ref><ref name=":5">{{Cite journal|last=Rebbeck|first=Trudy|last2=Liebert|first2=Ann|date=2014-12-01|title=Clinical management of cranio-vertebral instability after whiplash, when guidelines should be adapted: A case report|url=http://www.sciencedirect.com/science/article/pii/S1356689X14000101|journal=Manual Therapy|volume=19|issue=6|pages=618–621|doi=10.1016/j.math.2014.01.009|issn=1356-689X}}</ref><ref name=":6">{{Cite journal|last=Mathers|first=K. Sean|last2=Schneider|first2=Michael|last3=Timko|first3=Michael|date=Jun 2011|title=Occult Hypermobility of the Craniocervical Junction: A Case Report and Review|url=https://www.jospt.org/doi/full/10.2519/jospt.2011.3305|journal=Journal of Orthopaedic & Sports Physical Therapy|language=en|volume=41|issue=6|pages=444–457|doi=10.2519/jospt.2011.3305|issn=0190-6011}}</ref>
* Poor [[proprioception]],<ref name=":7">{{Cite journal|last=Bergholm|first=Ulla|last2=Johansson|first2=Bengt H.|last3=Johansson|first3=Hakan|date=2004-01-01|title=New Diagnostic Tools Can Contribute to Better Treatment of Patients with Chronic Whiplash Disorders|url=https://doi.org/10.3109/J180v03n02_02|journal=Journal of Whiplash & Related Disorders|volume=3|issue=2|pages=5–19|doi=10.3109/J180v03n02_02|issn=1533-2888}}</ref> impaired [[coordination]], [[gait]] changes<ref name=":0" /><ref name=":7" />
* [[Dizziness|Dizzinesss]], [[vertigo|vertigo,]]<ref name=":0" /><ref name=":2" /><ref name=":7" /><ref name=":4" /><ref name=":6" /><ref name=":5" /> syncope,<ref name=":0" /><ref name=":1" /><ref name=":2" /><ref name=":7" /> nausea<ref name=":1" /><ref name=":2" />
* [[Tension headache|Headache behind the eyes]],<ref name=":6" /> [[neck stiffness]], [[torticollis]],<ref name=":7" /><ref>{{Cite journal|last=Ghanem|first=Ismat|last2=El Hage|first2=Samer|last3=Rachkidi|first3=Rami|last4=Kharrat|first4=Khalil|last5=Dagher|first5=Fernand|last6=Kreichati|first6=Gabi|date=2008-03-01|title=Pediatric cervical spine instability|url=https://online.boneandjoint.org.uk/doi/full/10.1007/s11832-008-0092-2|journal=Journal of Children's Orthopaedics|volume=2|issue=2|pages=71–84|doi=10.1007/s11832-008-0092-2|issn=1863-2521|pmc=2656787|pmid=19308585}}</ref> [[Scalp Dysesthesia|posterior scalp irritation]],<ref name=":7" /> [[facial pain]]
* [[Apnea]],<ref>{{Cite journal|last=Janjua|first=M. Burhan|last2=Hwang|first2=Steven W.|last3=Samdani|first3=Amer F.|last4=Pahys|first4=Joshua M.|last5=Baaj|first5=Ali A.|last6=Härtl|first6=Roger|last7=Greenfield|first7=Jeffrey P.|date=2019-01-01|title=Instrumented arthrodesis for non-traumatic craniocervical instability in very young children|url=https://doi.org/10.1007/s00381-018-3876-9|journal=Child's Nervous System|language=en|volume=35|issue=1|pages=97–106|doi=10.1007/s00381-018-3876-9|issn=1433-0350}}</ref><ref name=":1" /><ref name=":3">{{Cite journal|last=Henderson|first=Fraser C.|last2=Austin|first2=Claudiu|last3=Benzel|first3=Edward|last4=Bolognese|first4=Paolo|last5=Ellenbogen|first5=Richard|last6=Francomano|first6=Clair A.|last7=Ireton|first7=Candace|last8=Klinge|first8=Petra|last9=Koby|first9=Myles|date=2017|title=Neurological and spinal manifestations of the Ehlers–Danlos syndromes|url=https://onlinelibrary.wiley.com/doi/abs/10.1002/ajmg.c.31549|journal=American Journal of Medical Genetics Part C: Seminars in Medical Genetics|language=en|volume=175|issue=1|pages=195–211|doi=10.1002/ajmg.c.31549|issn=1552-4876}}</ref> [[dyspnea]] (shortness of breath),<ref name=":0" /><ref name=":1" /> and [[dysphagia]] (difficulty swallowing)<ref name=":1" /><ref name=":2" />
* [[Visual disturbance|Visual disturbances]]<ref name=":4" /> downward [[nystagmus]] (irregular eye movements),<ref name=":1" /><ref name=":7" /> [[tinnitus]]<ref>{{Cite journal|last=Montazem|first=Abbas|author-link=|author-link2=|author-link3=|author-link4=|author-link5=|date=2000|title=Secondary tinnitus as a symptom of instability in the upper cervical spine: Operative management|url=https://pdfs.semanticscholar.org/21c4/85984a6ebe07efed38cf82a2f7a49b2a644e.pdf|journal=International Tinnitus Journal|volume=|issue=|pages=|quote=|via=}}</ref><ref name=":4" />
* [[Fatigue]],<ref name=":0" /><ref name=":14">{{Cite journal|last=Henderson|first=Fraser C.|last2=Henderson|first2=Fraser C.|last3=Wilson|first3=William A.|last4=Mark|first4=Alexander S.|last5=Koby|first5=Myles|date=2018-01-01|title=Utility of the clivo-axial angle in assessing brainstem deformity: pilot study and literature review|url=https://doi.org/10.1007/s10143-017-0830-3|journal=Neurosurgical Review|language=en|volume=41|issue=1|pages=149–163|doi=10.1007/s10143-017-0830-3|issn=1437-2320|pmc=5748419|pmid=28258417}}</ref><ref>{{Cite journal|last=Henderson|first=Fraser C.|last2=Wilson|first2=William A.|last3=Mott|first3=Stephen|last4=Mark|first4=Alexander|last5=Schmidt|first5=Kristi|last6=Berry|first6=Joel K.|last7=Vaccaro|first7=Alexander|last8=Benzel|first8=Edward|date=2010-07-16|title=Deformative stress associated with an abnormal clivo-axial angle: A finite element analysis|url=https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2940090/|journal=Surgical Neurology International|volume=1|doi=10.4103/2152-7806.66461|issn=2152-7806|pmc=2940090|pmid=20847911}}</ref> [[Sleep dysfunction|sleep disturbance]],<ref name=":0" /><ref name=":4" /> [[Cognitive dysfunction|cognitive impairment]],<ref name=":4" /> and [[memory loss]].

== Risk factors and comorbidities ==
Established risk factors for CCI include physical [[trauma]], [[inflammatory disease]], [[Neoplasm|neoplasms]] and [[congenital]] disorders.<ref name=":10" /><ref name=":12">{{Cite journal|last=Sapkas|first=George|last2=Papadakis|first2=Stamatios A|last3=Segkos|first3=Dimitrios|last4=Kateros|first4=Konstantinos|last5=Tsakotos|first5=George|last6=Katonis|first6=Pavlos|date=2011-06-02|title=Posterior Instrumentation for Occipitocervical Fusion|url=https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3139273/|journal=The Open Orthopaedics Journal|volume=5|pages=209–218|doi=10.2174/1874325001105010209|issn=1874-3250|pmc=3139273|pmid=21772931}}</ref>

More recently, physicians have reported an increased prevalence of CCI in patients with hereditary [[Connective tissue disorder|connective tissue disorders]].<ref name=":9" /> According to Brodbelt & Flint, however, an "increased range of joint movement, caused by [[ligamentous laxity]], is not the same as [[spinal instability]] resulting from trauma or major inflammatory arthropathies such as (historically) [[rheumatoid arthritis]]."<ref name=":19">{{Cite journal|last=Brodbelt|first=Andrew R.|last2=Flint|first2=Graham|date=Aug 2017|title=Ehlers Danlos, complex Chiari and cranio-cervical fixation: how best should we treat patients with hypermobility?|url=https://www.ncbi.nlm.nih.gov/pubmed/28961036|journal=British Journal of Neurosurgery|volume=31|issue=4|pages=397–398|doi=10.1080/02688697.2017.1386282|issn=1360-046X|pmid=28961036|pmc=|quote=|last3=|first3=|last4=|first4=|last5=|first5=|last6=|first6=|last7=|first7=|last8=|first8=|author-link=|author-link2=|access-date=|author-link3=|author-link4=|author-link5=|author-link6=|via=}}</ref> Others have argued that "pathological instability at the cranio-cervical junction has not been clearly established in the literature for the [[Joint hypermobility|hypermobility]] population."<ref name=":9" />

{| class="wikitable"
|'''Cause of instability'''
|'''Example'''
|-
|Physical trauma<ref>{{Cite journal|last=Ghatan|first=Saadi|last2=Newell|first2=David W.|last3=Grady|first3=M. Sean|last4=Mirza|first4=Sohail K.|last5=Chapman|first5=Jens R.|last6=Mann|first6=Frederick A.|last7=Ellenbogen|first7=Richard G.|date=Aug 2004|title=Severe posttraumatic craniocervical instability in the very young patient. Report of three cases|url=https://www.ncbi.nlm.nih.gov/pubmed/16206980|journal=Journal of Neurosurgery|volume=101|issue=1 Suppl|pages=102–107|doi=10.3171/ped.2004.101.2.0102|issn=0022-3085|pmid=16206980}}</ref>
|Car accident<ref>{{Cite journal|last=Uribe|first=Juan S.|last2=Ramos|first2=Edwin|last3=Baaj|first3=Ali|last4=Youssef|first4=A. Samy|last5=Vale|first5=Fernando L.|date=Dec 2009|title=Occipital cervical stabilization using occipital condyles for cranial fixation: technical case report|url=https://www.ncbi.nlm.nih.gov/pubmed/19934947|journal=Neurosurgery|volume=65|issue=6|pages=E1216–1217; discussion E1217|doi=10.1227/01.NEU.0000349207.98394.FA|issn=1524-4040|pmid=19934947}}</ref><ref>{{Cite journal|last=Volle|first=E.|last2=Montazem|first2=A.|date=Jan 2001|title=MRI video diagnosis and surgical therapy of soft tissue trauma to the craniocervical junction|url=https://www.ncbi.nlm.nih.gov/pubmed/11209518|journal=Ear, Nose, & Throat Journal|volume=80|issue=1|pages=41–44, 46–48|issn=0145-5613|pmid=11209518}}</ref>, blow to the head.<ref>{{Cite journal|last=Mathers|first=K. Sean|last2=Schneider|first2=Michael|last3=Timko|first3=Michael|date=Jun 2011|title=Occult hypermobility of the craniocervical junction: a case report and review|url=https://www.ncbi.nlm.nih.gov/pubmed/21628827|journal=The Journal of Orthopaedic and Sports Physical Therapy|volume=41|issue=6|pages=444–457|doi=10.2519/jospt.2011.3305|issn=1938-1344|pmid=21628827}}</ref>
|-
|Infection & inflammatory disease
|Rheumatoid arthritis<ref>{{Cite journal|last=O'Brien|first=Michael F.|last2=Casey|first2=Adrian T. H.|last3=Crockard|first3=Alan|last4=Pringle|first4=Jean|last5=Stevens|first5=John M.|date=2002-10-15|title=Histology of the craniocervical junction in chronic rheumatoid arthritis: a clinicopathologic analysis of 33 operative cases|url=https://www.ncbi.nlm.nih.gov/pubmed/12394902|journal=Spine|volume=27|issue=20|pages=2245–2254|doi=10.1097/01.BRS.0000029252.98053.43|issn=1528-1159|pmid=12394902}}</ref>, tuberculosis<ref>{{Cite journal|last=Chaudhary|first=Kshitij|last2=Potdar|first2=Prabodhan|last3=Bapat|first3=Mihir|last4=Rathod|first4=Ashok|last5=Laheri|first5=Vinod|date=2012-06-15|title=Structural odontoid lesions in craniovertebral tuberculosis: a review of 15 cases|url=https://www.ncbi.nlm.nih.gov/pubmed/22261632|journal=Spine|volume=37|issue=14|pages=E836–843|doi=10.1097/BRS.0b013e31824a4c8f|issn=1528-1159|pmid=22261632}}</ref>
|-
|Neoplasms
|Tumors<ref name=":12" /> such as haemangioma, aneurysmal bone cyst
|-
|Congenital
|Down’s syndrome<ref>{{Cite journal|last=Hankinson|first=Todd C.|last2=Anderson|first2=Richard C. E.|date=Mar 2010|title=Craniovertebral junction abnormalities in Down syndrome|url=https://www.ncbi.nlm.nih.gov/pubmed/20173525|journal=Neurosurgery|volume=66|issue=3 Suppl|pages=32–38|doi=10.1227/01.NEU.0000365803.22786.F0|issn=1524-4040|pmid=20173525}}</ref>, os odontoideum<ref>{{Cite journal|last=Zhao|first=Deng|last2=Wang|first2=Shenglin|last3=Passias|first3=Peter G.|last4=Wang|first4=Chao|date=May 2015|title=Craniocervical instability in the setting of os odontoideum: assessment of cause, presentation, and surgical outcomes in a series of 279 cases|url=https://www.ncbi.nlm.nih.gov/pubmed/25635883|journal=Neurosurgery|volume=76|issue=5|pages=514–521|doi=10.1227/NEU.0000000000000668|issn=1524-4040|pmid=25635883}}</ref>, dwarfism
|-
|Hereditary connective tissue disorder
|Ehlers Danlos Syndromes<ref name=":0" /><ref name=":1" />
|}
It is not unusual for CCI to co-occur with other structural neurological abnormalities such as [[atlantoaxial instability]] (AAI) and [[chiari malformation]] (CM).<ref>{{Cite journal|last=Camino Willhuber|first=Gaston O.|last2=Bosio|first2=Santiago T.|last3=Puigdevall|first3=Miguel H.|last4=Halliburton|first4=Carolina|last5=Sola|first5=Carlos A.|last6=Maenza|first6=Ruben A.|date=Jan 2017|title=Craniocervical spinal instability after type 1 Arnold Chiari decompression: a case report|url=https://www.ncbi.nlm.nih.gov/pubmed/27258364|journal=Journal of Pediatric Orthopedics. Part B|volume=26|issue=1|pages=80–85|doi=10.1097/BPB.0000000000000346|issn=1473-5865|pmid=27258364}}</ref><ref name=":0" />

== Diagnosis ==
{{Video|id=https://youtu.be/MsYDA3SXTkg|service=youtube|dimensions=550|description=Dr. Paolo Bolognese discusses methods of imaging and measurement for diagnosis.|alignment=right|urlargs=}}
The diagnosis of CCI is based on symptom presentation, a supportive history, demonstrable neurological findings and abnormal imaging.

=== Imaging ===
CCI is typically diagnosed via a [[cervical]] [[Magnetic resonance imaging|MRI]], whether supine or upright. If supine, a [[3 Tesla MRI]] is preferred over a [[1.5 Tesla]]. Most neurosurgeons prefer upright MRI with [[flexion]] and [[extension]].<ref>{{Cite web|url=https://www.mechanicalbasis.org/diagnosis.html|title=Craniocervical instability, Atlantoaxial Instability, Myalgic Encephalomyelitis, ME, CFS|website=MEchanical Basis|language=en|access-date=2019-06-02}}</ref> According to Henderson FC, “ventral [[brainstem]] compression may exist in flexion of the cervical spine, but appear normal on routine imaging.”<ref name=":9" />

{| class="wikitable"
!Imaging
!Sensitive for
|-
|Upright MRI with flexion/extension
|Horizontal instability
|-
|CT scan with rotation
|Rotational instability
|-
|Invasive cervical traction (ICT) with fluroscopy
|Vertical instability
|}

=== Measurements ===
More than twenty radiological measurements have been proposed or used in the diagnosis of CCI. However, three measurements are most commonly used: the [[Grabb-Oakes measurement|Grabb-Oakes]] line, which measures ventral brainstem compression; the [[Clivo-axial angle|Clivo-Axial Angle (CXA)]], which measures brainstem deformity by the [[odontoid]] process; and the Basion Dens Interval, which measures vertical instability ([[cranial settling]]). According to a 2013 consensus statement on the assessment of CCI a CXA of 135 degrees or less should be considered as "potentially pathological."<ref name=":13">{{Cite web|url=https://bobbyjonescsf.org/csf-video/review-colloq-2014/|title=REVIEW OF THE 2013 CSF RESEARCH COLLOQUIUM & CONSENSUS ON CRANIOCERVICAL INSTABILITY – Bobby Jones CSF|last=CSF|first=Bobby Jones {{!}}|language=en-US|access-date=2019-09-18}}</ref> as it is reported to be uncommon in the healthy population.<ref>{{Cite journal|last=Batista|first=Ulysses C.|last2=Joaquim|first2=Andrei F.|last3=Fernandes|first3=Yvens B.|last4=Mathias|first4=Roger N.|last5=Ghizoni|first5=Enrico|last6=Tedeschi|first6=Helder|date=Apr 2015|title=Computed tomography evaluation of the normal craniocervical junction craniometry in 100 asymptomatic patients|url=https://www.ncbi.nlm.nih.gov/pubmed/25828499|journal=Neurosurgical Focus|volume=38|issue=4|pages=E5|doi=10.3171/2015.1.FOCUS14642|issn=1092-0684|pmid=25828499}}</ref><ref>{{Cite journal|last=Botelho|first=Ricardo Vieira|last2=Ferreira|first2=Edson Dener Zandonadi|date=Oct 2013|title=Angular craniometry in craniocervical junction malformation|url=https://www.ncbi.nlm.nih.gov/pubmed/23640096|journal=Neurosurgical Review|volume=36|issue=4|pages=603–610; discussion 610|doi=10.1007/s10143-013-0471-0|issn=1437-2320|pmc=3910287|pmid=23640096}}</ref><ref>{{Cite journal|last=Bundschuh|first=C|last2=Modic|first2=Mt|last3=Kearney|first3=F|last4=Morris|first4=R|last5=Deal|first5=C|date=1988-07-01|title=Rheumatoid arthritis of the cervical spine: surface-coil MR imaging|url=https://www.ajronline.org/doi/abs/10.2214/ajr.151.1.181|journal=American Journal of Roentgenology|volume=151|issue=1|pages=181–187|doi=10.2214/ajr.151.1.181|issn=0361-803X}}</ref> Others have argued that these radiological measurements are "not accepted internationally as indicating instability."<ref name=":19" />
{| class="wikitable"
|+
!Measurement
!Units
!Description
! scope="col" style="width: 75px;" | Normal Range
! scope="col" style="width: 75px;" | Borderline Range
! scope="col" style="width: 75px;" | Pathological Range
! scope="col" style="width: 75px;" | Alternate Ranges
!Instability Measured
!Pathology Measured
!Refs
|-
|'''Clivo-axial angle (CXA)'''
|Degrees
|Angle between clivus line and the posterior axial line
|170 -150
|149 -136
|≤ 135
|
|More sensitive for horizontal
|Brainstem deformity
|<ref>{{Cite journal|last=Bolognese|first=Paolo|author-link=|author-link2=|author-link3=|author-link4=|author-link5=|date=|title=Videoed Presentation at: ASAP Chiari & Syringomyelia Conference Paolo Bolognese, MD "Complex Chiari, 2014. Timecode 14:28|url=https://www.youtube.com/watch?v=uiyk0Qbx2TQ&t=14m28s|journal=|volume=|issue=|pages=|quote=|via=}}</ref>
|-
|'''Grabb-Oakes'''
|mm
|Distance from the dura to the line drawn from the basion to the posterior inferior edge of the C2 vertebra
|< 6
|≥ 6 and < 9
|≥ 9
|Some use pathological ≥ 8
|More sensitive for horizontal
|Brainstem compression
|<ref>{{Cite journal|last=Bolognese|first=Paolo|author-link=|author-link2=|author-link3=|author-link4=|author-link5=|date=|title=Videoed presentation at: EDS Awareness Educational Series, April 12, 2018. Timecodes: 49:30 and 53:47|url=https://www.youtube.com/watch?v=MsYDA3SXTkg&t=49m30s|journal=|volume=|issue=|pages=|quote=|via=}}</ref><ref name=":9" />
|-
|'''Basion-Axial Interval (BAI)'''
|mm
|Distance from tip of basion to posterior axial line
|< 12
|
|≥ 12
|
|
|
|<ref name=":15">{{Cite journal|last=Henderson|first=Fraser|author-link=|author-link2=|author-link3=|author-link4=|author-link5=|date=|title=Videoed presentation at: Chiari & Syringomyelia Foundation, Patient Conference of Action, June 24, 2018. Timecode: 10:34.|url=https://www.youtube.com/watch?list=WL&v=sEi9AlHQTJc&t=10m34s|journal=|volume=|issue=|pages=|quote=|via=}}</ref>
|-
|'''Basion-Dens interval (BDI)'''
|mm
|Vertical distance between the basion and the dens
|< 12
|
|≥ 12
|Some use pathological ≥ 10
|Vertical
|Cranial settling
|<ref name=":15" /><ref name=":9" />
|-
|'''Translational BAI'''
|mm
|Change in BAI between flexion and extension positions of the head
|< 1
|≥ 1 and ≤ 2
|> 2
|For surgery > 4 needed
|Horizontal
|Skull sliding over spine
|<ref>{{Cite journal|last=Henderson|first=Fraser C.|last2=Francomano|first2=C. A.|last3=Koby|first3=M.|last4=Tuchman|first4=K.|last5=Adcock|first5=J.|last6=Patel|first6=S.|date=2019-01-09|title=Cervical medullary syndrome secondary to craniocervical instability and ventral brainstem compression in hereditary hypermobility connective tissue disorders: 5-year follow-up after craniocervical reduction, fusion, and stabilization|url=https://doi.org/10.1007/s10143-018-01070-4|journal=Neurosurgical Review|language=en|doi=10.1007/s10143-018-01070-4|issn=1437-2320}}</ref><ref name=":0" />
|-
|'''Translational BDI'''
|mm
|Change in BDI between flexion and extension positions of the head
|
|
|
|
|
|
|
|-
|'''Dynamic BDI'''
|mm
|Change in BDI value when the head is pulled upward with traction force of typically up to 35 lbs
|
|
|
|
|Vertical
|Cranial settling
|
|-
|'''Dens Over Chamberlain'''
|mm
|How far tip of the dens extends above Chamberlain's line
|< 2
|≥ 2 and ≤ 3
|≥ 3
|
|Vertical
|Basilar invagination
|<ref>{{Cite journal|last=Hain|first=Timothy C. |author-link=|author-link2=|author-link3=|author-link4=|author-link5=|date=|title=Basilar Invagination, Basilar Impression and Atlantoaxial Subluxation|url=https://www.dizziness-and-balance.com/disorders/central/cerebellar/basilar%20invagination.htm|journal=|volume=|issue=|pages=|quote=|via=}}</ref>
|}
Some of the measurement ranges in the above table are also to be found in the 2nd International CSF Dynamics Symposium Consensus Statement (2013).<ref name=":13" />

=== Traction ===
Manual traction, halo and invasive cervical traction are often used to aid in the diagnosis of CCI. Symptomatic improvement with traction can help determine whether a patient with abnormal measurements will benefit from craniocervical fusion surgery.

== Treatment ==
{{Video|id=https://youtu.be/sEi9AlHQTJc|service=youtube|dimensions=550|description=Dr. Fraser Henderson presents the results a five-year follow-up study.|alignment=right|urlargs=}}
=== Conservative treatment ===
Treatment of CCI can include “conservative measures” such as rest, pain management, bracing with a cervical collar, or physical therapy to strengthen neck muscles.<ref>{{Cite journal|last=Mathers|first=K. Sean|last2=Schneider|first2=Michael|last3=Timko|first3=Michael|date=Jun 2011|title=Occult hypermobility of the craniocervical junction: a case report and review|url=https://www.ncbi.nlm.nih.gov/pubmed/21628827|journal=The Journal of Orthopaedic and Sports Physical Therapy|volume=41|issue=6|pages=444–457|doi=10.2519/jospt.2011.3305|issn=1938-1344|pmid=21628827}}</ref> Many conservative therapies have little to no supporting evidence of efficacy.

There is no evidence for the efficacy of experimental treatments for CCI such as prolotherapy and upper cervical chiropractic.

=== Surgery ===
When non-invasive treatments for CCI fail to work, occipito-cervical fusion (OCF) can be considered.<ref name=":0" /> OCF is a surgery that aims at a biomechanical stabilization of the craniocervical junction. Patients with objective radiological findings, a clinical picture supportive of the diagnosis, a positive response to traction, and who are significantly impaired may be candidates for this surgery. A common method involves internal fixation of the upper spine to the skull by mechanical rods and screws. (However, rod-wire, rigid rod-screws, occipital hooks and cervical claws are all methods currently in use.<ref name=":16">{{Cite journal|last=Resnick|first=Daniel K.|last2=Patel|first2=Nirav J.|last3=Lall|first3=Rishi|date=2010-11-01|title=A Review of Complications Associated With Craniocervical Fusion Surgery|url=https://academic.oup.com/neurosurgery/article/67/5/1396/2563905|journal=Neurosurgery|language=en|volume=67|issue=5|pages=1396–1403|doi=10.1227/NEU.0b013e3181f1ec73|issn=0148-396X}}</ref>) During surgery, titanium hardware is used to fixate the occiput, axis and atlas (i.e., C0 to C2) while rib graft or cadaver bone graft is used to help the bones fuse together. Wire methods are less biomechanically stable than rod methods and have high rates of dural laceration.<ref name=":16" /> Screw and rod fixation methods have lower complication rates and higher rates of successful fusion.<ref name=":18" /> Fusion rates across all hardware methods range from 89 to 100%.<ref name=":16" /> When cervical instability is present below C2, additional vertebrae may also be fused if the patient is symptomatic.

==== Outcomes, risks & complications ====
The outcome of OCF is generally favorable with most patients experiencing symptom relief post-surgery.<ref name=":0" /> The complications of OCF however can be serious<ref>{{Cite journal|last=Garrido|first=Ben J.|last2=Sasso|first2=Rick C.|date=Jan 2012|title=Occipitocervical fusion|url=https://www.ncbi.nlm.nih.gov/pubmed/22082624|journal=The Orthopedic Clinics of North America|volume=43|issue=1|pages=1–9, vii|doi=10.1016/j.ocl.2011.08.009|issn=1558-1373|pmid=22082624}}</ref> and occur in an estimated 7% to 33% of patients.<ref name=":10" /><ref name=":18">{{Cite journal|last=Winegar|first=Corbett D.|last2=Lawrence|first2=James P.|last3=Friel|first3=Brian C.|last4=Fernandez|first4=Carmella|last5=Hong|first5=Joseph|last6=Maltenfort|first6=Mitchell|last7=Anderson|first7=Paul A.|last8=Vaccaro|first8=Alexander R.|date=Jul 2010|title=A systematic review of occipital cervical fusion: techniques and outcomes|url=https://www.ncbi.nlm.nih.gov/pubmed/20594011|journal=Journal of Neurosurgery. Spine|volume=13|issue=1|pages=5–16|doi=10.3171/2010.3.SPINE08143|issn=1547-5646|pmid=20594011}}</ref><ref name=":11" /><ref>{{Cite journal|last=Ando|first=Kei|last2=Imagama|first2=Shiro|last3=Ito|first3=Zenya|last4=Kobayashi|first4=Kazuyoshi|last5=Yagi|first5=Hideki|last6=Shinjo|first6=Ryuichi|last7=Hida|first7=Tetsuro|last8=Ito|first8=Kenyu|last9=Ishikawa|first9=Yoshimoto|date=Jun 2017|title=Minimum 5-year Follow-up Results for Occipitocervical Fusion Using the Screw-Rod System in Craniocervical Instability|url=https://www.ncbi.nlm.nih.gov/pubmed/28525489|journal=Clinical Spine Surgery|volume=30|issue=5|pages=E628–E632|doi=10.1097/BSD.0000000000000199|issn=2380-0194|pmid=28525489}}</ref><ref name=":16" /> Common complications include screw failure, wound infection, dural tear and cerebrospinal fluid leakage<ref name=":11" /> In some cases revision surgery is needed to treat infection or to remove hardware. Severe complications can include meningitis and accidental injury of the vertebral artery by misplaced screws.<ref name=":17">{{Cite journal|last=Nockels|first=Russ P.|last2=Shaffrey|first2=Christopher I.|last3=Kanter|first3=Adam S.|last4=Azeem|first4=Syed|last5=York|first5=Julie E.|date=Aug 2007|title=Occipitocervical fusion with rigid internal fixation: long-term follow-up data in 69 patients|url=https://www.ncbi.nlm.nih.gov/pubmed/17688049|journal=Journal of Neurosurgery. Spine|volume=7|issue=2|pages=117–123|doi=10.3171/SPI-07/08/117|issn=1547-5654|pmid=17688049}}</ref>

A meta-study of 2274 procedures across 22 studies<ref name=":16" /> found the following complication rates:

{| class="wikitable"
!Complication type
!Prevalence rate
|-
|Hardware failure after fusion non-union
|7%
|-
|Wound infection
|3.8%-11%
|-
|Vertebral artery damage
|1.3%-4.1%
|-
|Dural tears
|0% to 4.2%
|}
Meta-studies place the rate of death from fusion surgery at 0-0.6%.<ref name=":16" /><ref name=":18" />

==== Side effects ====
OCF causes a substantial reduction in the neck’s range of motion, estimated at approximately 40% of total cervical flexion–extension.<ref name=":8">{{Cite journal|last=Ashafai|first=Nabeel S.|last2=Visocchi|first2=Massimiliano|last3=Wąsik|first3=Norbert|date=2019|editor-last=Visocchi|editor-first=Massimiliano|title=Occipitocervical Fusion: An Updated Review|url=https://doi.org/10.1007/978-3-319-62515-7_35|series=Acta Neurochirurgica Supplement|language=en|location=Cham|publisher=Springer International Publishing|pages=247–252|doi=10.1007/978-3-319-62515-7_35|isbn=9783319625157}}</ref>

==== Cost ====
OCF is estimated to cost tens of thousands of dollars, although some insurance schemes fully cover the cost of surgery depending on the country located and neurosurgeons involved.

=== Stem cell therapy ===
Some clinics offer stem cell therapy in order to regenerate the area, ligaments, connective and other tissues that may be damaged in the area.{{Citation needed|reason=Please name any clinics that offer stem cell therapy for CCI.|date=3 November 2019}}

== Dysautonomia and CCI in EDS ==
As CCI might lead to a compression of the brain stem, some researchers speculate this might cause some of the autonomic symptoms such as tachycardia and orthostatic intolerance that are frequently seen in patients with Ehlers Danlos Syndromes (EDS). In a 2007 influential paper Milhorat et al. followed-up on patients with Chiari malformation who did not improve with treatment and surgery. The authors discovered that many of these patients suffered from EDS and had other structural abnormalities at the upper spine such as CCI and cranial settling. Milhorat et al. speculated that the resulting compression of the brainstem might be the cause of the autonomic and other symptoms these patients were suffering from.<ref>{{Cite journal|last=Milhorat|first=Thomas H.|last2=Bolognese|first2=Paolo A.|last3=Nishikawa|first3=Misao|last4=McDonnell|first4=Nazli B.|last5=Francomano|first5=Clair A.|date=Dec 2007|title=Syndrome of occipitoatlantoaxial hypermobility, cranial settling, and chiari malformation type I in patients with hereditary disorders of connective tissue|url=https://www.ncbi.nlm.nih.gov/pubmed/18074684|journal=Journal of Neurosurgery. Spine|volume=7|issue=6|pages=601–609|doi=10.3171/SPI-07/12/601|issn=1547-5654|pmid=18074684}}</ref> In conference presentations, neurosurgeons have indicated that they think CCI can cause dysautonomia symptoms such as postural orthostatic tachycardia syndrome (POTS) <ref>[https://www.youtube.com/watch?time_continue=735&v=857Jsjsqxjw Craniocervical Instability (Dr Henderson the 2012 EDNF Confrence).] Minute 12.10. </ref><ref>[https://www.youtube.com/watch?v=ntD9NRIvEJ0 Dr Milhorat from The Chiari Institute at the 2005 ASAP.]</ref><ref name=":13" />

Henderson et al. tested this theory by following 20 CCI patients with comorbid Chiari Malformation and hereditary hypermobility connective tissue disorders for a period of 5 years after OCF-surgery. Patients were satisfied with the surgery and experienced significant improvements in some CCI-related symptoms such as vertigo, headaches, imbalance, dysarthria dizziness or frequent daytime urination. There was however only a small increase in objective outcomes such as work resumption with 60% of patients remaining unable to work or go to school. Participants attributed this to other medical problems related to EDS such as musculoskeletal pain, fatigue, gastrointestinal issues and POTS, indicating these were not significantly improved after OCF-surgery.<ref name=":0" />

== Mechanical basis theory ==
Five ME/CFS patients diagnosed with CCI (some also had EDS) reported to have experienced remarkable improvements and even remission of their ME/CFS symptoms following OCF-surgery.<ref>{{Cite web|url=https://www.mechanicalbasis.org/interviews.html|title=Craniocervical instability, Atlantoaxial Instability, Myalgic Encephalomyelitis, ME, CFS|website=MEchanical Basis|language=en|access-date=2019-06-06}}</ref><ref>{{Cite web|url=https://medium.com/@jenbrea/health-update-3-my-me-is-in-remission-dd575e650f71|title=Health update #3: My ME is in remission|last=Brea|first=Jennifer|date=2019-05-20|website=Medium|access-date=2019-06-03}}</ref> They speculate that mechanical compression of the brainstem due to CCI has the potential to cause characteristic ME/CFS symptoms such as post-exertional malaise<ref>{{Cite web|url=https://www.mechanicalbasis.org/|title=Craniocervical instability, Atlantoaxial Instability, Myalgic Encephalomyelitis, ME, CFS|website=MEchanical Basis|language=en|access-date=2019-06-03}}</ref>, although this theory is currently not supported by scientific evidence. The current literature does not suggest a connection between ME/CFS and CCI. Others have raised concerns about CCI surgery in patients with ME/CFS given the lack of research on OCF in this patient population.<ref>{{Cite web|url=https://www.s4me.info/threads/concerns-about-craniocervical-instability-surgery-in-me-cfs.9638/|title=Concerns about craniocervical instability surgery in ME/CFS|website=Science for ME|language=en-US|access-date=2019-06-03}}</ref>

== Synonyms ==
* Syndrome of Occipitoatlantialaxial Hypermobility<ref name=":1" />
* Hypermobility of the Craniocervical Junction<ref>{{Cite journal|last=Mathers|first=K. Sean|last2=Schneider|first2=Michael|last3=Timko|first3=Michael|date=Jun 2011|title=Occult hypermobility of the craniocervical junction: a case report and review|url=https://www.ncbi.nlm.nih.gov/pubmed/21628827|journal=The Journal of Orthopaedic and Sports Physical Therapy|volume=41|issue=6|pages=444–457|doi=10.2519/jospt.2011.3305|issn=1938-1344|pmid=21628827}}</ref>

== See also ==

* [[Atlantoaxial instability|Atlantoaxial instability (AAI)]]
* [[Neural strain]]
* [[Chiari malformation]]
* [[Ehlers-Danlos syndrome]]
* [[Intracranial hypertension]]
* [[Tethered cord syndrome]]

== Learn more ==
* [https://www.healthrising.org/blog/2019/02/27/brainstem-compression-chronic-fatigue-syndrome-me-cfs-fibromyalgia-pots-craniocervical-instability/ Could Craniocervical Instability Be Causing ME/CFS, Fibromyalgia & POTS? Pt I – The Spinal Series] - from Health Rising
* [https://www.healthrising.org/blog/2019/05/21/jennifer-brea-chronic-fatigue-mecfs-recovering-story/ Jennifer Brea’s Amazing ME/CFS Recovering Story: the Spinal Series – Pt. II]
* [https://www.healthrising.org/treating-chronic-fatigue-syndrome/fibromyalgia-craniocervical-instability-survey-effectivness-survey/ ME/CFS and Fibromyalgia Craniocervical Instability Surgery Effectiveness Poll]

== References ==
{{reflist}}
[[Category:Diagnoses]]