Craniocervical Instability
Craniocervical instability is a medical condition where there is excessive movement of the vertebrae at the atlanto-occipital joint and the atlanto-axial joint, that is, between the skull and the top two vertebrae (C1 and C2). This can cause neuronal injury and compression of nearby structures including the spinal cord, vertebral artery or vagus nerve, causing a constellation of symptoms. It is frequently co-morbid with atlanto-axial instability, Chiari malformation and tethered cord syndrome.
It is more common in people with a connective tissue disease, notably Ehlers-Danlos Syndrome, osteogenesis imperfecta and rheumatoid arthritis. It can be brought on by a trauma, frequently whiplash; laxity of the ligaments surrounding the joint; or other damage to the surrounding connective tissue.
Symptoms and signs
The impact of craniocervical instability can range from minor symptoms to severe disability, with some patients being bed-bound. The constellation of symptoms caused by craniocervical instability has been labelled the cervico-medullary syndrome. Common symptoms include:
- Occipital headaches
- Migraine Headaches
- neck, shoulder and jaw pain
- difficulty swallowing, or the sensation of being choked
- tenderness at base of skull
- feeling of 'bobble-head', where the skull may 'fall off' the spine
- photophobia
- double or blurred vision
- tinnitus
- tremors
- orthostatic intolerance
- vertigo or dizziness
- palpitations
- shortness of breath
- nausea
- fatigue
- Lhermitte's sign
- cognitive and memory decline
- clumsiness and motor delay
- fainting
- weakness of the limbs
Symptoms are frequently worsened by a Valsalva maneuver or by being upright for long periods of time. Lying supine can bring short-term relief.
Diagnosis
Craniocervical instability is usually diagnosed through neuro-anatomical measurement using radiography. Upright magnetic resonance imaging is considered the most accurate method, and supine magnetic resonance imaging, CT scan or digital motion X-ray, or Digital X-ray are also used.
The measurements to diagnose craniocervical instability are:
- Clivo-Axial Angle equal or less than 135 degrees
- Grabb-Oakes measurement equal or greater than 9 mm
- Harris measurement greater than 12mm
- Spinal subluxation
Alternatively, craniocervical instability can be diagnosed if a trial of cervical traction, typically using a halo fixation device, results in a significant alleviation of symptoms.
Treatment
Conservative treatment of craniocervical instability includes physical therapy and the use of a cervical collar to keep the neck stable. Cervical spinal fusion is performed on patients with more severe symptoms. Prolotherapy, including with stem cells, is another treatment option used but there is limited scientific evidence on this approach.