<unk>  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, brain stem, vertebral artery or vagus nerve, causing a constellation of symptoms. It is frequently co-morbid with atlanto-axial<unk> , 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.
Craniocervical instability
Cerebrospinal fluid leak
Lumbar enlargement
Hydrocephalus
Brain herniation
Binaural fusion
Dislocation of jaw
Epidural hematoma