The Value of External Anal Sphincter Motor Unit Potential Analysis in Differentiating Idiopathic Parkinson's Disease and Multiple System Atrophy

J Korean Neurol Assoc > Volume 14(3); 1996 > Article

Journal of the Korean Neurological Association 1996;14(3): 746-753.

특발성 파킨슨씨병과 다계통위축증의 감별진단에 대한 외항문괄약근 운동단위전위 분석의 의의

이상복, 김용덕, 김원찬, 이명식

연세대학교 의과대학 영동세브란스 병원 신경과

The Value of External Anal Sphincter Motor Unit Potential Analysis in Differentiating Idiopathic Parkinson's Disease and Multiple System Atrophy

Sang Bock Lee, M.D., Yong Duk Kim, M.D., Won Chan Kim, M.D., Myung Sik Lee, M.D.

Department of neurology, Yongdong Severance Hospital Yonsei University College of Medicine

Abstract

Multiple system atrophy (MSA) is an idiopathic neuro-degenerative disorder involving many neuronal structures including substantia nigra, putamen, cerebellum, pontine nuclei, olives, intermediolateral cell column of the spinal cord. Anterior horn cells innervating external urethral and external anal sphincter muscles in the sacral cord, so called Onuf's nucleus, are also affected. Neuronal loss of the Onuf's nucleus may cause denervation and reinnervation in the external urethral and the external anal sphincter muscles. As a result, in the patients with MSA electromyographic study of the external urethral and the external anal sphincter muscles may show prolonged duration of motor unit potentials (MUPs) . Such abnormal MUPs of the external urethral sphincter muscles has been known to be a useful indicator distinguishing patients with MSA from those with idiopathic Parkinson's disease (IPD) in which minimal or no abnormal MUPs can be found. However, the results of external anal sphincter MUPs analysis has not been reported yet. In the patients with IPD and probable MSA, we measured the duration, the number of phases and the proportion of pathological MUPs from the external anal sphincter muscles. Cut off value of more than 60% of abnormal MUPs could differentiate patients with MSA and IPD with sensitivity of 70.3% and specificity of 90.9%. External anal sphincter MUP analysis seems to be a helpful laboratory method differentiating patients with MSA and IPD.