Vertical atlanto-axial subluxation in rheumatoid arthritis.

In a prospective survey of 476 hospital in-patients with rheumatoid arthritis, vertical atlanto-axial subluxation (AAL) was found in 13 patients (3.7 per cent). All were women with severe rheumatoid arthritis. Neurological signs were found in ten patients, and in seven they appeared to be due to vertical AAL. The signs caused by vertical AAL were diminished pain and temperature sensation in the upper divisions of the trigeminal nerve, sensory loss in the areas supplied by C2, nystagmus and pyramidal lesions. Disabling involvement due to vertical AAL was not found although it may occur and the lesion may be fatal. The lower cervical spine was involved in all patients and severe lesions were seen in nine. The most severe neurological lesions appeared to be due to subaxial subluxation. Corticosteroid therapy may have been a contributing factor in four patients.