[Lambert-Eaton syndrome: clinical and electrophysiological study of 18 cases associated with lung cancer].
The clinical and electrophysiological data of 18 consecutive adult patients with paraneoplastic Lambert-Eaton myasthenic syndrome (LMES) have been reviewed. The cancer associated with LEMS was small-cell lung carcinoma (SCLC) in 15 cases and epidermoid lung carcinoma in 3 cases. The main clinical neurological features were proximal lower limb weakness (100%), depressed tendon reflexes (94%) and dryness of the mouth (66%). The results of repetitive nerve stimulation (RNS) were not statistically different in the paraneoplastic LEMS group and in a group of 6 LMS patients in whom no carcinoma had been detected. Low-amplitude compound muscle action potential (CMAP) was present in all cases; decremental response at low stimulation rates was present in 13/15 cases. An abnormal incremental response at high stimulation rates was observed in all cases. A close correlation between CMAP amplitude and clinical condition was found in 4 cases during the long-term follow-up. In one patient the RNS electrical pattern could be misinterpreted as myasthenia gravis in only one muscle tested. We underline the usefulness of a 50 Hz stimulation during 4 seconds to establish the diagnosis unequivocally, and that of post-exercise facilitation in routine detection among an SCLC population. Our results suggest that CAMP amplitude and RNS test could be used to evaluate the short-term improvement of LMS under treatment and, in some cases, for the long-term follow-up. The infraclinical axonal neuropathy detected in 8 patients probably was another associated autoimmune paraneoplastic complication.
Bady
B
B
Service d'Electromyographie, Hôpital Neurologique, Lyon.
Vial
C
C
Chauplannaz
G
G
D000328:Adult; D000368:Aged; D001327:Autoimmune Diseases / Q000175:diagnosis; D004594:Electrophysiology; D005260:Female; D006801:Humans; D015624:Lambert-Eaton Myasthenic Syndrome / Q000175:diagnosis / Q000209:etiology*; D008175:Lung Neoplasms / Q000150:complications*; D008297:Male; D008875:Middle Aged; D010257:Paraneoplastic Syndromes / Q000209:etiology*
Syndrome de Lambert-Eaton: étude clinique et électrophysiologique de 18 cas associés à un cancer du poumon.