[Obstructive sleep apnea syndrome induced by ossification of the anterior longitudinal ligament with ankylosing spondylitis].

A 66-year-old man who had received a diagnosis of ankylosing spondylitis at the age of 50 was referred to our hospital for further evaluation of sleep apnea experienced for the last 3 years. Polysomnography yielded a diagnosis of obstructive sleep apnea syndrome with an apnea index of 41/hr. Computed tomographic scans demonstrated complete closure of the oropharynx during sleep at a site of marked ossification and hypertrophy of the cervical anterior longitudinal ligament. Nasal continuous positive airway pressure (nasal CPAP) with the use of chinstrap, but not nasal CPAP alone, dramatically decreased the patient's apnea index to 2.4/hr. We reported this case because, to the best of our knowledge, it is the first to demonstrate a causative association between ankylosing spondylitis and obstructive sleep apnea syndrome.