Phrenic nerve conduction time in Guillain-Barré syndrome.

Phrenic nerve conduction was studied in 28 patients with Guillain-Barré syndrome. Conduction time was prolonged in 18 (64.3%) patients and serial studies showed progressive improvement with restoration of normal values in the majority by 12 weeks. The conduction abnormalities had a positive correlation with the extent of the disease, morbidity and mortality. Phrenic nerve conduction time was found to be a more sensitive parameter than vital capacity or median nerve motor conduction velocity in assessing the severity of the disease and predicting impending ventilatory failure.