[Central type of sleep apnea syndrome caused by unilateral lateral medullary infarction]

We reported here a 64-year-old man with a central apnea resulted from unilateral medullary infarction. He was admitted because of cerebellar ataxia, dysarthria and dysphasia of abrupt onset. After the injection of diazepam for alcohol forbidden syndrome, he induced complete apnea and required the endotracheal intubation. At the spontaneous respiration under room air, his arterial blood gas showed hypercapnea without hypoxemia, and he fell into severe hypoventilation when hypnotic drug was injected. Respisomnogram revealed the frequent presence of central apnea both while he was awake and asleep. MRI demonstrated an abnormal high intensity area on T2 weighted image at the right lateral medulla just below the ponto-medullary junction. At autopsy, areas of the infarction were limited within the right lateral medulla, including lateral portion of the medullary reticular formation, the ambigual nucleus, one part of the solitary nuclear complex, the inferior cerebellar peduncle and the spinal trigeminal nucleus. However, the dorsomotor nucleus of vagus was completely free from the infarct lesion. There was no other lesion within central nervous system. Such a distribution seemed the minimal extent of the lesion responsible for central, apnea compared to the previous reports. We suggest that central apnea occurs not infrequently in the cases of Wallenberg's syndrome.