A Case of Isaacs’ Syndrome Associated with Small Cell Lung Cancer

J Korean Neurol Assoc > Volume 18(4); 2000 > Article

Journal of the Korean Neurological Association 2000;18(4): 499-502.

폐소세포암에 동반된 Isaacs 증후군 1예

홍준기, 최낙천 전성철 곽준혁 이연효 박기종 권오영 임병훈

경상대학교 의과대학 신경과학교실,경상대학교 신경과학연구소

A Case of Isaacs’ Syndrome Associated with Small Cell Lung Cancer

Joon Ky Hong, M.D., Nack-Cheon Choi, M.D., Seong-Cheol Jeon, M.D., Junhyeok Gwak, M.D., Yeon-Hyo Lee, M.D., Ki-Jong Park, M.D., Oh-Young Kwon, M.D., Byeong-Hoon Lim, M.D.

Department of Neurology, Gyeongsang National University College of Medicine Gyeongsang Institute for Neuroscience, Gyeongsang National University

Abstract

Isaacs’ syndrome consists of spontaneously occurring muscle activity of peripheral nerve origins. This syndrome arises in association with/without polyneuropathy and rarely with malignancy. A 63-year-old man was admitted to our hospital due to generalized painful muscle stiffness. He complained of difficulty with standing and with finger exten-sion after grasping. Chvostek’s and Trousseau’s signs were noticed. Electrolytes, calcium, CK, and LDH were in the normal range. Small cell lung cancer was diagnosed by a needle biopsy. Electrophysiological testing revealed normal nerve conduction studies with the exception of a grossly abnormal EMG. Continuous neuromyotonic discharges with firing rates of 120-200 Hz were seen at rest. The amplitude of the response typically waned with 0.5-1.5 seconds of duration. The discharges persisted throughout sleep, after diazepam injection, and with brachial plexus blockage.Muscle stiffness improved with the administration of oral phenytoin. Under chemotherapy and radiotherapy, tumor remission was partially achieved and neurological symptoms markedly improved. J Korean Neurol Assoc 18(4):499~502, 2000 Key Words : Isaacs’ syndrome, Neuromyotonic discharges, Small cell lung cancer