The late sequelae of poliomyelitis.

Progressive functional deterioration following poliomyelitis has been reported after a prolonged period of stability. We present follow up data on 209 patients; the period from the original illness to December 1985 or death was between two and 73 years (mean 33.9). One hundred and sixty-three (78 per cent) patients developed late functional deterioration. This was due to purely respiratory factors in 99 cases, new neurological signs in 20 cases, and orthopaedic problems in 17 cases; 31 patients deteriorated due to a combination of factors. The commonest cause of respiratory deterioration was the development of nocturnal alveolar hypoventilation, sometimes associated with late progressive scoliosis. Eighty-six patients needed respiratory support beginning between one year and 66 years (mean 28.5) after the acute illness. New neurological signs had a clearly defined cause in each of 20 patients. No cases of motor neurone disease or post-poliomyelitis muscular atrophy (PPMA) were identified. This series shows that late sequelae following poliomyelitis are common. There were no patients with functional deterioration after poliomyelitis in whom a clear underlying cause could not be shown. The major causes of deterioration may be treatable or avoidable, and in particular, those who develop chest infections or new respiratory symptoms should be treated with caution as respiratory failure may rapidly supervene.