Atlantooccipital Overlap and Other Craniocervical Junction Abnormalities in Dogs.

The term craniocervical junction abnormality (CJA) is an umbrella term for a variety of malformations that occur in the craniocervical region. These abnormalities include Chiari-like malformation, atlantooccipital overlapping, atlantoaxial instability, occipitoatlantoaxial malformations, atlantoaxial dural bands, and dens abnormalities. Syringomyelia can occur secondary to any of these malformations or a combination. Clinical signs in dogs with a CJA typically include neck pain and varying signs associated with a cervical myelopathy. MRI of CJAs with computed tomography imaging is necessary for a full evaluation. Some dogs with CJAs respond to medical management, but for most surgery is the treatment of choice.