A CASE OF ARNOLD-CHIARI TYPE-I MALFORMATION PRESENTING WITH DYSRHYTHMIC BREATHING DURING SLEEP

A 43-year-old woman presented with dull headache, left tinnitus and di zziness. Neurological examination revealed down-beat gaze nystagmus, l eft tinnitus, positive Romberg sign, poor standing on the left foot, p oor tandem gait, left spastic gait and positive pathological reflexes in the bilateral upper and lower extremities. Plain X-ray of the skull and cervical vertebrae demonstrated basilar impression and atlantoaxi al fusion. Magnetic resonance imaging of the brain and cervical spine showed cerebellar tonsil descent and syringomyelia located in the left side of the spine at the II-III vertebral level which communicated wi th the fourth ventricle. The patient was diagnosed as having cervical syringomyelia, Arnold-Chiari type I malformation and basilar impressio n. Preoperative polysomnography showed dysrhythmic breathing and brady pnea during sleep. Abnormal breathing improved after suboccipital deco mpression craniotomy and upper cervical laminectomy. It was suggested that dysrhythmic breathing was caused by a disorder of the medullary r espiratory center. Herniation of the cerebellar tonsil and syringomyel ia might have compressed the medulla.