J Korean Neurol Assoc.  1996 Sep;14(3):746-753.

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

• Lee SB
• Kim YD
• Kim WC
• Lee MS

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.

MeSH Terms

Anal Canal*
Anterior Horn Cells
Cerebellum
Denervation
Humans
Multiple System Atrophy*
Muscles
Neurons
Olea
Parkinson Disease*
Putamen
Sensitivity and Specificity
Spinal Cord
Substantia Nigra
Urethra