• Journal of Yeungnam Medical Science
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• v.17 no.2
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• pp.129-136
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• 2000

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. Material 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($mean{\pm}SD$) 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($mean{\pm}SD$) 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.

• Journal of Yeungnam Medical Science
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• v.18 no.2
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• pp.277-286
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• 2001

Background: This study was undertaken to evaluate the diagnostic sensitivity of several muscles in repetitive nerve stimulation test (RNST) for myasthenia gravis (MG) patients. Materials and Methods: The study population consisted of 39 MG patients classified by modified Ossermann's classification. Using Stalberg's method, RNST was systematically performed in facial (orbicularis oculi and nasalis) and upper extremity (flexor carpi ulnaris, abductor digiti quinti and anconeus) muscles. Results: The significant electrodecremental response of RNST were noted in orbicularis oculi(58.9%), nasalis (51.3%), flexor carpi ulnaris(42%), anconeus(41%) and abductor digiti quinti muscles(27%). Among the 3 muscles of upper extremity(abductor digiti quinti, flexor carpi ulnaris and anconeus), the positive electrodecremental response of anconeus muscles was significantly higher than other two muscles(p<0.05) in type IIa, IIb and there were no statistical differences of the positive electrodecremental response between orbicularis oculi and nasalis muscles. The facial muscles showed more prominent decremental responses than upper extremity muscles in type I MG(p<0.05). In type IIa MG patients, there were no significant statistical differences between facial and upper extremity muscles but significant statistical differences among upper extremity muscles. In type IIb MG patients, there were no significant statistical differences in all tested muscles in spite of the increased positive electrodecremental response of RNST. Conclusion: On the basis of this study, RNST would be initially performed for the orbicularis or nasalis in type I MG and for the anconeus in type IIa or IIb MG.

• Journal of Yeungnam Medical Science
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• v.15 no.1
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• pp.125-134
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• 1998

Purpose: This study was undertaken to evaluate the clinical usefulness of Tensilon test, repetitive nerve stimulation test(RNST), single fiber EMG(SFEMG) test and acetylcholine receptor antibody(AchR Ab) assay for making diagnosis of myasthenia gravis(MG). Method: These tests were performed in 21 MG patients which were classified into 11 ocular, 5 mild generalized, 4 moderate generalized, and 1 chronic severe MG. Result: The overall positivity of Tensilon test, SFEMG and AchR Ab was 95%, 87%, and 76% respectively. The overall positivity of RNST was 67%; 38% on flexor carpi ulnaris, 43% on adductor digiti quinti and 62% on orbicularis oculi muscles. The positivity of each test was higher in generalized MG group than in ocular MG group. But we could observe the statistically significant difference only in the RNST(p<0.05). Conclusion: Tensilon test showed the highest positivity in all MG groups. So we would like to recommend the, Tensilon test for the diagnosis of MG at first, followed by RNST and AchR Ab assay, and SFEMG would be indicated to MG group which showed relatively low postivity in other tests.