Comparison of the Repetitive Nerve Stimulation Test(RNST) Findings Between in Upper and Lower Extremity Muscles in Myasthenia Gravis / 영남의대학술지

ABSTRACT

BACKGROUND AND PURPOSE: This study was undertaken to compare the sensitivity of the Repetitive Nerve Stimulation Test (RNST) between the upper and lower extremity muscles in myasthenia gravis(MG) patients. MATERIALS AND METHODS: The study population consisted of 20 normal persons(control group) and 10 MG patients(MG group). Using Stalberg's method. RNST was systemically performed in orbicularis oculi muscle. upper extremity muscles(flexor carpi ulnaris. abductor digiti quinti), and lower extremity muscles(tibialis anterior. extensor digitorum brevis. vastus medialis). RESULTS: There were statistical differences of decremental response(mean+/-SD) in orbicularis oculi and upper extremity muscles between the control and MG groups(p<0.05 or p<0.01). However, there was no statistical difference of decremental response(mean+/-SD) to RNST in lower extremity muscles between the control and MG groups. There were highersensitivity in orbicularis oculi and upper extremity muscles than lower extremity muscles. Although positive reponse were detected in the lower extremity muscles, the positive response rates of lower extremity muscles were lower than o.oculi and upper extremity muscles. CONCLUSIONS: When the response rates of RNST in facial and upper extremity muscles are normal, may not be required RNST in lower extremity muscles.