Serologic and electrophysiologic evaluation of patients with Myasthenia gravis

Myasthenia gravis is an autoimmune disorder mainly caused by antibodies to the muscle acetylcholine receptors (AChR-Ab) at the neuromuscular junction. Loss of these receptors leads to a defect in neuromuscular transmission with muscle weakness and fatigue. This antibody is not detected in all the patients and electrophysiologic study is necessary in some patients as a diagnostic tool. The serologic and electrophysiologic tests in Myasthenia gravis are evaluated in this study. One hundred twelve patients entered in a cross-sectional study. Serum AChR-Ab was measured and Repetitive nerve stimulation (RNS) was done. The frequency of positive AChR-Ab and abnormal RNS and the relationship between them were determined. Thirty (26. 8%) patients were males and 82 (73. 2%) were females. Mean of age was 37. 6±15. 4 years. AChR-Ab was positive in 71 (63. 4%) and negative in 41 (36. 6%). RNS was done in 101 patients and was abnormal in 74 (73. 3%) and normal in 27 (26. 7%) patients. Ratio of abnormal RNS was 84. 4% and 53. 7% in seropositive and seronegative patients، respectively (p=0. 001). There is significant relationship between serologic and electrophysiological findings in Myasthenia gravis. Combining electrophysiological and serological tests could increase the accuracy of Myasthenia gravis diagnosis.