Craniocervical Instability (CCI) Basics
Craniocervical Instability (CCI) is a relatively new term but a long-time recognized condition of excessive movement of the atlanto-occipital (i.e. base of skull to first vertebrae) and/or the atlanto-axial segments (i.e. the top two vertebrae of the spine) that lead to the deformation or kinking of the brainstem, mechanical compression of the brainstem, nerves and spinal cord; blood vessels going to and from the brain; and disturbances of cerebral spinal fluid (CSF) flow. This can cause non-specific clinical symptoms like headache, neck pain, disorders of hearing, vision, balance and difficulty swallowing.
Static vs. Dynamic Instability
Craniocervical junction problems can be static, meaning they can be visibly seen when lying down in supine position for a MRI of the head and neck; however, many of these tests come back “normal” if the patient’s instability is dynamic.
However, many CCI patients’ symptoms reduce upon laying down and are more problematic when upright and moving their head around. This is when craniocervical junction problems can be dynamic and when dynamic imaging such as a dynamic digital radiolography (DDR) or an upright MRI Cervical Spine and CCJ in flexion and extension can assess dynamic instability in these positions
Components of Instability
There are several medical articles that have published and categorize the different types of bio-mechanical abnormalities of the craniocervical junction but wouldn’t appear as though many doctors use them. However, the physicians that are using the term Craniocervical Instability seem to use the following categorization for 3 components of craniocervical instability:
- Horizontal Instability, meaning parts of the craniocervical junction (i.e. base of the skull to the 2nd vertebrae, C2, called the Axis) are moving excessively in a horizontal plane (i.e. side to side or front to back).
- Vertical Instability, meaning parts of the craniocervical junction (i.e. base of the skull to the 2nd vertebrae, C2, called the Axis) are moving excessively in a vertical plane (i.e. up and down).
- Rotational Instability, meaning parts of the craniocervical junction (i.e. base of the skull to the 2nd vertebrae, C2, called the Axis) are moving excessively in a rotational motion. However, some physicians don’t review this because studies have not consistently proven abnormal vs. normal degrees of rotation. Instead, they review things like neutral, flexion and extension ADI measurements.
- It is possible to have more than one component of craniocervical instability (i.e. horizontal and vertical instability).
Craniocervical Instability is a relatively new term but a long-time recognized condition. Here are the terms doctors likely studied in school:
- Atlanto-occipital Dissociation / Dislocation (AOD)
- Atanto-axial instability (AAI)
Articles go back several decades using the terms “Atlanto-occipital Dissociation / Dislocation” (AOD) and “Atlantoaxial instability” (AAI). Majority of articles are very specific in referencing when these conditions occur such as a frail senior person’s slip and fall, in cases of severe rheumatoid arthritis, in patients with down syndrome, an adult in a serious motor vehicle accident (whereby they are tossed out of a moving car) or children with new neurological symptoms and neck pain following a respiratory tract or throat infection (Grisel’s Syndrome).
Many medical articles state that these are rare conditions, so that’s likely why there is a lack of most doctor’s clinical suspicion which leads to lack of proper diagnostic imaging. If this is your case, keep discussing possible conditions with your primary physician and share with him/her medical articles that we have posted on our site (i.e. self-advocating and CCI Learning Centre).
A USA Neurosurgeon who specializes in craniocervical instability speaks about seeing more adult patient’s with craniocervical instability due to Ehlers Danlos Disorder and viral onset craniocervical instability here in this video, however, much more research in this area is needed.