The carcinomatous neuromyopathy of oat cell lung cancer.

A prospective controlled clinical-neurophysiological-pathological study of 71 patients with oat cell carcinoma of the lung revealed no increased incidence of peripheral neuropathy at the initial stages of illness. All patients developed neuropathy by the time they had lost 15% of their body weight, but the neuropathy was less severe than in 20 age-matched alcoholic patients with an equal degree of weight loss. The weight loss and peripheral neuropathy progressed with atrophy of type II (adenosine triphosphatase-positive) muscle fibers out of proportion to the patient's loss of body weight. By 40% body weight loss, all the patients had moderate symmetrical peripheral neuropathy, 6 had proximal brachial or lumbosacral plexus metastases, and 9 had distal pressure palsies. Mononeuritis multiplex developed in only 1 patient, who had diabetes mellitus. Two patients developed Eaton-Lambert syndrome, which resolved in 1 when chemotherapy controlled the systemic tumor, with no protein in the tumor postmortem which could produce the characteristic electromyographic findings of the syndrome.