Sleep Apnea in Rheumatoid Arthritis Patients with Atlantoaxial Subluxation

Abstract

Obstructive sleep apnea has been reported in rheumatoid arthritis (RA) patients who have lesions of the upper cervical vertebrae. We studied the pathophysiology of sleep apnea in RA patients with atlantoaxial subluxation by monitoring movements of the chest wall and abdomen, airflow, and arterial blood oxygen saturation during sleep. Nine female RA patients aged 49 to 80 years took part in this experiment. Five of them were in stage III, and four of them were in stage IV. Anterior subluxation was seen in six patients, and posterior subluxation was seen in three patients. Sleep apnea syndrome, diagnosed when the apnea index was more than 5, was observed in seven of the nine patients. The three patients with posterior atlantoaxial subluxation had high apnea indices (87.7, 48.6, and 12.6) . Central sleep apnea with absence of airflow and chest wall and abdominal wall movements was observed in two patients with posterior atlantoaxial subluxation. In these patients the anterior arc of the atlas was dislocated posteriorly. Compression of the ventral part of the lower brainstem and the upper cervical spinal cord was also observed. These results suggest that central apnea might be induced when the structures in the caudal part of the ventral medulla are blocked. The dysfunction of respiratory structures might occur in RA patients with posterior atlantoaxial subluxation.