Intracranial hypertension

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Intracranial hypertension (IH) is a condition of increased cerebrospinal fluid pressure inside the skull.[1] It results from increases in the volume of the brain, blood or spinal fluid within the fixed volume of the cranium (skull).[citation needed] The previous names for intracranial hypertension, pseudotumor cerebri and benign intracranial hypertension, are regarded as inaccurate and downplaying the severity of intercranial hypertension.[1]

Types[edit | edit source]

  • Idiopathic Intercranial Hypertension or IIH, formerly known as Primary intracranial hypertension
  • Secondary Intercranial Hypertension:

has an identifiable caused for example drugs (such as tetracycline, loral or intrathecal steroids, growth hormone treatments and others), sleep apnea and certain systemic diseases such as lupus, leukemia, kidney failure (uremia), and others.[1]

Signs and symptoms[edit | edit source]

The most common sign is papilledema (swelling of the optic nerve sheath).

Diagnosis[edit | edit source]

Arachnoiditis, a progressive inflammatory disorder affecting the middle membrane surrounding the spinal cord and brain (arachnoid membrane), epiduritis (involving inflammation of the tough, outer canvas-like covering surrounding the brain and spinal cord) and meningitis should be ruled out during diagnosis.[1]

There are many tools that can be used in the diagnosis of intracranial hypertension. The most typical method is a lumbar puncture, during which the opening pressure is measured. Opening pressures of 20 H2O or greater are considered abnormal in non-obsese people, 25 H2O or greater in obese people.

However, as pressure can fluctuate and change with position, a more accurate method is a 24 hour intracranial bolt test. This involves inserting an intracranial pressure monitor directly into the cranium to continuously measure pressure over the course of a day. Normal is 7-15 mm Hg in a supine adult.[4]

An MRI can also aid in diagnosis. While generally considered benign, an empty sella can suggest intracranial hypertension, particularly in patients manifesting the symptoms of intracranial hypertension.[5] An empty sella is when the sella, a bony space which holds the pituitary gland, appears “empty” (dark/black) on an MRI. This is because, due to high pressure, the space has been filled with cerebrospinal fluid, flattening the pituitary gland. Patients can also have excess spinal fluid in their optic nerve sheath, which can cause pain behind the eyes and papilledema.

Finally, an MR venogram (a type of MRI that uses contrast to visualizes the veins in the brain) can detect bilateral transverse venous sinus stenosis (TSS), a narrowing of two veins in the back of the head that drain blood from the brain. TSS is found in 83% of cases of intracranial hypertension (compared to 3% of controls).[6] It is not known whether TSS is cause or effect, but there is growing evidence that stenting one of the transverse sinus veins can improve or resolve intracranial hypertension.[7][8][9]

Risk factors[edit | edit source]

  • Young, overweight, women in their reproductive years (ages 20-45) are most at risk of intercranial hypertension, although any age, gender or weight range can be affected.[1]
  • Ehlers-Danlos syndrome[10]

Causes[edit | edit source]

Some causes of intracranial hypertension include:

When the cause of increased pressure is unknown it is called idiopathic intracranial hypertension (IIH). It was previously known as pseudotumor cerebri, as the symptoms can mimic that of a brain tumor, even though no tumor is present. It is considered to be a rare disease, affecting just 1 in 100,000 but milder forms may simply go unrecognized.

Treatment[edit | edit source]

Treatment approaches may depend on the cause and whether it can be identified. In idiopathic intercranial hypertension, treatments can include reducing cerebospinal fluid volume, e.g., through drug treatments like acetazolamide (Diamox) or methazolamide (Neptazane), or surgical treatments like a shunt, or improving venous outflow (blood draining from the brain) by stenting veins in the brain or neck that may be narrowed.[7][8][9][11]

Ketamine is not a standard treatment for intracranial hypertension but was shown to reduce ICP by 30% in a controlled trial of 82 pediatric patients in a trauma setting.[12]

Related conditions[edit | edit source]

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It has been observed by some clinicians that ME/CFS and Ehlers-Danlos syndrome patients may have borderline or subclinical intracranial hypertension and benefit from IIH treatments such as Diamox, venous stents, or shunts. While these treatments are rarely used by ME/CFS clinicians they are more commonly employed in the clinical care of EDS patients.

ME/CFS[edit | edit source]

A case study of a woman presenting with symptoms of CFS and pressure headache, who was diagnosed with borderline intracranial hypertension, found that her CFS symptoms resolved with the placement of a transverse sinus stent.[13] A cross-sectional study of twenty patients presenting at a headache clinic found that a large proportion of patients had borderline intracranial hypertension, with four meeting the diagnostic criteria for IIH (mean cerebrospinal fluid pressure was 19 cm H2O (range 12–41 cm H2O); however, none had clinical signs of IIH. Cerebrospinal fluid drainage via lumbar puncture improved symptoms in 17/20 patients.[14] Researchers speculate that a subset of CFS patients may have borderline cases of idiopathic intracranial hypertension without papillodema, that is, swelling of the optic nerve.[15]

The 2019 Bertilsson/Bragée study[16] found evidence of IH in ME/CFS patients meeting the Canadian Consensus Criteria.

Of 205 patients who underwent brain MRIs, 171 (83%) had an optic nerve sheath diameter/eyeball transverse diameter quotient (ONSD/ETD) >0.22, where the maximum found in healthy patients is 0.23.[17] Eighty-seven patients (42%) had an ONSD/ETD > 0.25, which is the threshold for pathological.[18]

Of 125 patients who underwent a cervical spine MRI, 100 (80%) has some form of obstruction capable of increasing pressure- e.g. spondylolisthesis, osteophytes, cysts, syrinxes. 13.2% had tonsillar herniations severe enough to be considered a Chiari Malformation.[16]

Ehlers-Danlos syndrome[edit | edit source]

A number of EDS neurosurgeons have observed an association between intracranial hypertension and EDS.[10] Penn State vascular neurosurgeon, Dr. Kenneth Liu, has presented case studies of patients with EDS whose symptoms improve with venous stenting.[19]

Notable studies[edit | edit source]

  • 2018, The link between idiopathic intracranial hypertension, fibromyalgia, and chronic fatigue syndrome: exploration of a shared pathophysiology[3] - (Full text)

See also[edit | edit source]

Learn more[edit | edit source]

References[edit | edit source]

  1. 1.0 1.1 1.2 1.3 1.4 1.5 1.6 "Idiopathic Intracranial Hypertension". NORD (National Organization for Rare Disorders). Retrieved November 12, 2018.
  2. Soler, D.; Cox, T.; Bullock, P.; Calver, D.M.; Robinson, R.O. (January 1, 1998). "Diagnosis and management of benign intracranial hypertension". Archives of Disease in Childhood. 78 (1): 89–94. doi:10.1136/adc.78.1.89. ISSN 0003-9888. PMID 9534686.
  3. 3.0 3.1 3.2 Dankaerts, Wim; Bruyninckx, Frans; Stalmans, Ingeborg; Vansant, Greet; Rasschaert, Ricky; Hulens, Mieke (December 10, 2018). "The link between idiopathic intracranial hypertension, fibromyalgia, and chronic fatigue syndrome: exploration of a shared pathophysiology". Journal of Pain Research. doi:10.2147/jpr.s186878. PMID 30573989. Retrieved January 3, 2019.
  4. Pickard, J.D.; Czosnyka, M. (June 1, 2004). "Monitoring and interpretation of intracranial pressure". Journal of Neurology, Neurosurgery & Psychiatry. 75 (6): 813–821. doi:10.1136/jnnp.2003.033126. ISSN 0022-3050. PMID 15145991.
  5. "Empty Sella Syndrome". NORD (National Organization for Rare Disorders). Retrieved June 22, 2019.
  6. Campeau, N.; Port, J.; Black, D.F.; Morris, P.P. (March 1, 2017). "Transverse Sinus Stenosis Is the Most Sensitive MR Imaging Correlate of Idiopathic Intracranial Hypertension". American Journal of Neuroradiology. 38 (3): 471–477. doi:10.3174/ajnr.A5055. ISSN 0195-6108. PMID 28104635.
  7. 7.0 7.1 Higgins, J Nicholas P; Owler, Brian K; Cousins, Claire; Pickard, John D (January 19, 2002). "Venous sinus stenting for refractory benign intracranial hypertension". The Lancet. 359 (9302): 228–230. doi:10.1016/S0140-6736(02)07440-8. ISSN 0140-6736.
  8. 8.0 8.1 Pickard, J.D.; Sarkies, N.; Owler, B.K.; Cousins, C.; Higgins, J. N.P. (December 1, 2003). "Idiopathic intracranial hypertension: 12 cases treated by venous sinus stenting". Journal of Neurology, Neurosurgery & Psychiatry. 74 (12): 1662–1666. doi:10.1136/jnnp.74.12.1662. ISSN 0022-3050. PMID 14638886.
  9. 9.0 9.1 Halmagyi, G.M.; Owler, B.K.; Hanlon, M.; Dunne, V.; Allan, R.; McCluskey, P.J.; Macdonald, J.; Thurtell, M.J.; Parker, G.D. (September 1, 2011). "Transverse Sinus Stenting for Idiopathic Intracranial Hypertension: A Review of 52 Patients and of Model Predictions". American Journal of Neuroradiology. 32 (8): 1408–1414. doi:10.3174/ajnr.A2575. ISSN 0195-6108. PMID 21799038.
  10. 10.0 10.1 Henderson, Fraser C.; Austin, Claudiu; Benzel, Edward; Bolognese, Paolo; Ellenbogen, Richard; Francomano, Clair A.; Ireton, Candace; Klinge, Petra; Koby, Myles (2017). "Neurological and spinal manifestations of the Ehlers–Danlos syndromes". American Journal of Medical Genetics Part C: Seminars in Medical Genetics. 175 (1): 195–211. doi:10.1002/ajmg.c.31549. ISSN 1552-4876.
  11. "Medication and Surgery | Medication and Surgery | Treatment". Intracranial Hypertension Research Foundation. Retrieved February 1, 2022.
  12. Bar-Joseph, Gad; Guilburd, Yoav; Tamir, Ada; Guilburd, Joseph N. (July 2009). "Effectiveness of ketamine in decreasing intracranial pressure in children with intracranial hypertension". Journal of Neurosurgery. Pediatrics. 4 (1): 40–46. doi:10.3171/2009.1.PEDS08319. ISSN 1933-0707. PMID 19569909.
  13. Tanaka, Hidetaka; Matsushima, Reiko; Tamai, Hiroshi; Kajimoto, Yoshinaga (April 1, 2002). "Impaired postural cerebral hemodynamics in young patients with chronic fatigue with and without orthostatic intolerance". The Journal of Pediatrics. 140 (4): 412–417. doi:10.1067/mpd.2002.122725. ISSN 0022-3476.
  14. Higgins, Nicholas; Pickard, John; Lever, Andrew (November 21, 2013). "Lumbar puncture, chronic fatigue syndrome and idiopathic intracranial hypertension: a cross-sectional study". JRSM Short Reports. 4 (12): 204253331350792. doi:10.1177/2042533313507920. ISSN 2042-5333. PMC 3899735. PMID 24475346.
  15. Higgins, J. Nicholas P.; Pickard, JohnD.; Lever, Andrew M.L. (August 2017). "Chronic fatigue syndrome and idiopathic intracranial hypertension: Different manifestations of the same disorder of intracranial pressure?". Medical Hypotheses. 105: 6–9. doi:10.1016/j.mehy.2017.06.014. ISSN 1532-2777. PMID 28735654.
  16. 16.0 16.1 Bragée, Björn; Michos, Anastasios; Drum, Brandon; Fahlgren, Mikael; Szulkin, Robert; Bertilson, Bo C. (August 28, 2020). "Signs of Intracranial Hypertension, Hypermobility, and Craniocervical Obstructions in Patients With Myalgic Encephalomyelitis/Chronic Fatigue Syndrome". Frontiers in Neurology. 11: 828. doi:10.3389/fneur.2020.00828. ISSN 1664-2295.
  17. Kim, Dong Hwan; Jun, Jin-Sun; Kim, Ryul (December 2017). "Ultrasonographic measurement of the optic nerve sheath diameter and its association with eyeball transverse diameter in 585 healthy volunteers". Scientific Reports. 7 (1): 15906. doi:10.1038/s41598-017-16173-z. ISSN 2045-2322. PMC 5698472. PMID 29162911.
  18. Du, Jie; Deng, Yanjun; Li, Hua; Qiao, Shigang; Yu, Mengnan; Xu, Qingya; Wang, Chen (April 2020). "Ratio of Optic Nerve Sheath Diameter to Eyeball Transverse Diameter by Ultrasound Can Predict Intracranial Hypertension in Traumatic Brain Injury Patients: A Prospective Study". Neurocritical Care. 32 (2): 478–485. doi:10.1007/s12028-019-00762-z. ISSN 1541-6933.
  19. Liu, Kenneth. "Venous Stenting in Intracranial Hypertension".