Craniocervical instability

Craniocervical instability (CCI), also known as the Syndrome of Occipitoatlantialaxial Hypermobility, is a structural instability of the craniocervical junction which may lead to deformation or compression of the brainstem, upper spinal cord, and cerebellum. CCI as well as atlanto-axial instability (AAI) can occur from an injury, such as whiplash or a high-impact trauma. However, there are several known conditions where CCI/AAI can happen, seemingly spontaneously, in absence of obvious trauma: Down Syndrome, dwarfism, rheumatoid arthritis (RA), Ehlers-Danlos Syndrome (EDS) (itself a common co-morbidity with Myalgic Encephalomyelitis (ME)),and other inflammatory or connective tissue disorders. The ligaments of the craniocervical junction, which are made up of connective tissue, become too lax to hold the skull in normal relationship with the cervical spine.

There have been anecdotal reports of people with ME who meet the International Consensus Criteria (ICC) who were ultimately diagnosed with CCI/AAI and/or Chiari malformation, a related condition. However, there is no systematic evidence supporting a relationship between CCI and ME.

Symptoms
Symptoms of craniocervical instability can include include:
 * a heavy headache: a constant to near constant headache that can be described as feeling like the head is too heavy for the neck to support (feeling like a “bobble-head”)
 * a pressure headache: an impairment of cerebropinsal fluid (CSF) flow causes intracranial pressure which would be aggravated by “valsalva maneuvers” such as yawning, laughing, crying, coughing, sneezing or straining.
 * Dysautonomia (e.g., heat intolerance, orthostatic intolerance, syncope (fainting), polydipsia (extreme thirst), delayed gastric emptying, chronic fatigue)


 * postural orthostatic tachycardia


 * neck pain
 * central or mixed sleep apnea
 * dyspnea (shortness of breath)
 * altered sleep architecture
 * facial pain or numbness
 * balance problems
 * muscle weakness
 * dizziness and vertigo
 * syncope
 * vision problems
 * reduced gag reflex and difficulty swallowing
 * ringing in the ears and hearing loss
 * nausea and vomiting
 * impaired coordination
 * downward nystagmus (irregular eye movements)
 * paralysis
 * parasthesias
 * gait changes

Risk factors
Patients with Ehlers-Danlos syndrome, Down Syndrome, dwarfism and Rheumatoid arthritis are at greater risk.