Chiari / Cranio-cervical instability (CCI)

Chiari malformations describe a group of  rare conditions where a part of the brain shifts through the foramen magnum into the spinal canal. In a study with over 2000 Chiari patients US doctors (Milhoart et al.) were able to discover that 13 percent of all participants had an underlying connective tissue disorder. A huge amount of these patients had failed decompression surgeries which led to cranio-cervical instability.

Milhorat TH, Bolognese PA, Nishikawa M, McDonnell NB, Francomano CA. Syndrome of occipitoatlantoaxial hypermobility, cranial settling, and chiari malformation type I in patients with hereditary disorders of connective tissue.

A complication of Chiari malformation is syringomyelia, a formation of a cyst or cavity within the spinal cord. Chiari malformation can lead to spinal fluid circulation problems and therefore a syrinx may form.

Symptoms could be:
Dysphagia, severe head and neck pain, blurred vision, dizziness, balance problems, muscle weakness, paralysis, sensory disturbances.
Chiari malformations can be diagnosed with MRI of the brain and cervical spine. Some physicians prefer Upright MRI because some Chiari malformations can be missed on static pictures (normal, not weight bearing MRI) or they appear less severe than they are.

In case of Chiari surgery for patients with a connective tissue disorder, some doctors do also fuse the occiput to the cervical spine to avoid cranio-cervical instability as a result of decompression surgery.


In general the symptoms and diagnostic testing for CCI in the EDS population is the same as in patients without EDS and this website provides information for all CCI people no matter what the cause is. The therapeutic approaches are clearly reduced in EDS patients because for them it is very hard to build muscles. Therapeutic information are available here.


General surgeries in patients with EDS and cervical spine instability:

Is an intubation possible through the nose?
Or a fiberoptic intubation?
Could the patient be intubated while awake?
Do not hyperextend the neck!
Wear a hard neck brace!
A perhaps more difficult airway status should be discussed in advance.


Cervical spine fusion surgeries in the EDS population:

Cervical spine fusions especially in the area of the cranio-cervical junction are already very complicated and risky in patients without EDS. With EDS the risk increases because of the connective tissue laxity. It is strongly recommended to have those surgeries only performed by highly experienced neurosurgeons who have knowledge about EDS and cervical spine fusions. Otherwise the risk of complications increases significantly and the chances of success are reduced.
Instabilities of the segments below or above the fusion can occur. Whether this happens more often in EDS patients compared to healthy individuals is controversial.


Very good resources about Chiari and CCI (especially with connective tissue disorders) are available here:


Henderson FC, Geddes JF, Vaccaro AR, Woodard E, Berry KJ, Benzel EC. Stretch-associated injury in cervical spondylotic myelopathy: new concept and review. Neurosurgery. 2005 May 1;56(5):1101-13.

Felbaum D, Spitz S, Sandhu FA. Correction of clivoaxial angle deformity in the setting of suboccipital craniectomy: technical note. Journal of Neurosurgery: Spine. 2015 Jul;23(1):8-15.


Great lectures by Prof. Henderson at the CSF/MUSC Half Day Symposium 2014:

Common Data Elements on Spinal Cord Injury