Cranio-cervical Instability in Patients with Hypermobility Connective Disorders

Cranio-cervical instability is well documented in connective tissue disorders such as rheumatoid arthritis, systemic lupus, and genetic disorders such as Down’s syndrome and Osteogenesis Imperfecta. However, less understood are the more than fifty genetic disorders of collagen characterized by joint laxity, and of course, laxity of the ligaments of the spine. Given the propensity in these patients for spinal instability, it is not surprising that the most severe symptoms arise in the most mobile part of the spine, the cranio-cervical junction. The increased recognition of hypermobility syndromic disorders, of which Ehlers Danlos Syndome (EDS) is emblematic, has prompted questions and concern as to what constitutes pathological instability in this category of patients, and how to best diagnose this instability. These questions assume significant importance, given recent epidemiological evidence that the hypermobility syndromes, exemplified by EDS, are far more prevalent than previously thought.