Acute ventilatory failure in multiple sclerosis.

Life-threatening acute ventilatory failure has been considered to be a very rare manifestation of multiple sclerosis (MS) and only a few cases have been investigated clinicopathologically. We examined 4 patients with MS who developed acute ventilatory failure, accompanied by a constellation of neurological symptoms and signs that were consistent with midline ventral medullary lesions. All but one of them survived the episode with artificial ventilation over a period of 9-11 days. One of the remaining 3 patients died a year later from subsequently developed anoxic encephalopathy. Neuropathological examination of the 2 deceased cases revealed the suspected lesions in the medulla as well as widespread chronic and active MS foci, which were characterized by largely necrotic changes rather than by pure demyelination. MRI in another case revealed a lesion in the caudal medulla. The apparently not so rare occurrence of ventilatory failure among Japanese MS patients might be related to the known differences in pathological features between Japanese and Western MS patients. Since there is a good chance of recovery, early recognition of the symptom complex appears important in the assessment and treatment of such patients.