RESUMEN
Introduction: Single fiber electromyography [SFEMG] is the most efficient way of neuromuscular junction disorders diagnosis. By this method action potentials of two adjacent fibers from the same motor unit can be recorded by using a bipolar electrode after voluntary activation or electrical stimulation of the nerve. The variability of the interpotential interval [IPI] between two single muscle fiber action potentials belonging to the same motor unit during successive discharge is referred to JITTER, that is expressed by the mean value of consecutive difference [MCD] quantity. The fiber density of each motor unit is also measure by same electrode
Material and Method: In this study that was carried out on 25 patients referred to mashhad ghaem Hospital with suspected diagnosis of myasthenia gravis [MG], SFEMG Test accomplished by voluntary contraction of extensor digitorum communis [EDC] and frontalis muscles, tensilon test and repetetive stimulation test [RST] was done simultaneously
Result:10 patients [40%] had generalized, 5 patients [20%] had bulbar and 10 patients [40%] had ocular symptoms of myasthenia gravis. SFEMG results in 3 patients suspected to ocular form, was negative. In these patients, myasthenia was also excluded in later evaluationes. SFEMG test was positive in the other patients [100%]
Conclusion: These results suggest that SFEMG for the diagnosis of myasthenia gravis, especially ocular type has more sensitivity and higher reliability than the other diagnostic methodes. It has not yet been feasible to use SFEMG as routine test for diagnosis of myasthenia gravis disease when other diagnostic tests were positive specially in generalized form, considering it is time consuming,costly and not having enough experience