Craniocervical Instability

Craniocervical Instability Ribbon

Craniocervical Instability Awareness Ribbon

Instability in the cervical spine (neck) can be horizontal (CCI), rotational (AAI) and vertical (CS)

Craniocervical Instability (CCI) also known as Syndrome of Occipitoatlantialaxial Hypermobility, is a potential complication that people with EDS (and other connective tissue disorders) can experience. Hypermobility in the craniocervical junction (skull, C1 and C2) can lead to structural instability putting pressure on the brainstem and causing Cervical Medullary Syndrome.


This is diagnosed by MRI with images in both flexion, extension and rotation. Some doctors prefer these MRI's are done in an upright MRI machine, while others prefer supine MRIs due to the better quality of the images. Some form of traction is also used to show demonstrate the symptoms are linked with the hypermobility seen in the imaging

Treatment can be conservative through physiotherapy and wearing a hard collar. In some cases, surgery is required to fuse the skull to the spine. Further fusion down the spine may occur depending on how much instability is found further down the spine. 


Heat intolerance

Orthostatic Intolerance


Delayed Gastric Emptying

Chronic Fatigue

Brain Fog

  • Neck Pain

  • Central Sleep Apnoea

  • Facial pain and/or numbness

  • Balance Issues

  • Muscle Weakness

  • Dizziness/Vertigo

  • Gag reflex reduction

  • Swallowing issues

  • Tinnitus - Ringing in ears

  • Nausea and/or vomiting

  • Nystagmus (irregular down-beat eye movements

  • Paralysis

Atlantoaxial Instability (AAI) can occur separately or in conjunction with CCI. This is similar to CCI, but the instability (excessive movement) occurs between the first and second cervical vertebrae (C1 and C2). In the cervical spine C1 (Atlas) and C2 (Axis), this atlantooccipital joint allows the head to nod and rotate.

Diagnosis is AAI uses dynamic imaging with an MRI or CT with the neck in rotation (looking left and right). Symptoms are similar to what has been listed for CCI and are often exacerbated when looking left/right this can cut off the arteries in the neck. 

As with CCI treatment can range from conservative (physio, neck brace) or may require a fusion of C1 and C2. 

Cranial Settling (CS)

Horizontal instability in the craniocervical junction can result in the skull sinking down the spine which causes the top of the spine (Dens) to impinge up into the brainstem. 

Craniocervical Instability, Atlantoaxial Instability and CS can all occur at once, or someone may only have 1 or 2. While these can occur in patients with EDS, those who have EDS and have had a Chiari decompression are at greater risk. It is advised for those who have both to speak to a qualified surgeon who understands the risks. They may require both the Chiari decompression and the fusion to stabilise the neck. This can be difficult as the bone removed for Chiari is a common area to fuse to. 

Instability can occur anywhere in the spine and fusion may be needed anywhere on the spine and in some rare cases the entire skull to spine area fused. Fusing decreases your range of motion and should be done as the last possible treatment option. 

CCI/AAI in Australia

Until around late 2018/2019 there was very little help available for these conditions in Australia. This is improving slowly. There are upright MRI scanners available in both Sydney and Melbourne with the Sydney site seeing a fair share of patients with craniocervical junction instabilities. Sydney has had the most surgeries but they are still in small amounts. 


There has been some interest on the patient boards with Chiropractors diagnosing via DMX imaging. There is no reputable research about this so far to recommend this route. If this changes we will update in the future. Due to this and the neurosurgeons not using this type of imaging we do not carry any information on imaging places or Chiropractors doing this.  

We are endeavouring to have a separate site up specifically in relation to CCI/AAI in Australia. Till then there is the online awareness page mentioned above and a Facebook support group.