Sensitivity of Diagnostic Tests and Therapeutic Outcome in Ocular Myasthenia Gravis

Purpose : To compare the sensitivity of various diagnostic tests, and to assess the efficacy of therapy in the management of myasthenia gravis (MG). Methods : Thirty-two patients with ocular findings with MG were examined by Stimulated Single Fiber Electromyograhy (SFEMG), Repetitive Nerve Stimulation (RNS) test, Edrophonium (Tensilon) test, antiacethylcholine receptor antibody titer. We also studied retrospectively clinical characteristics and efficacy of therapy. Results : Mean age of patients was 32 years (range 1 to 63 years). Twenty (62.5%) were females and 12 (37.5%) were males. Mean duration of symptoms was 17 months (range 5 months to 10 years). Associated ocular findings were ptosis 31 eyes (97%), diplopia 20 eyes (63%), and ocular limitation 19 eyes (59%). The value of diagnostic sensitivity was 97% in SFEMG, 94% in tensilon test, 75% in RNS test, and 69% in anti-acetylcholine receptor antibody assay. Nine of 10 cases who were treated with thymectomy and pyridostigmine were markedly improved. Eight cases (25%) subsequently developed generalized type of myasthenia gravis. Conclusions : Ptosis and diplopia were most frequently associated with ocular myasthenia gravis. For diagnosis of ocular myasthenia gravis, SFEMG or tensilon test was the most sensitive test. Thymectomy combined with pyridostigmine bromide seemed to be an effective therapeutic modality.