OCULAR MYASTHENIA-GRAVIS - RESPONSE TO LONG-TERM IMMUNOSUPPRESSIVE TREATMENT

Objective-Ocular myasthenia gravis is a subtype of myasthenia gravis t hat causes relatively mild disability, but may convert into severe gen eralised muscle weakness. A universal management plan for ocular myast henia gravis has not been established. This study was performed to det ermine the outcome of ocular myasthenia gravis with the currently avai lable therapeutic options. Methods-Retrospective analysis of 78 patien ts with ocular myasthenia gravis with a mean disease duration of 8.3 ( range 0.5-58.3) years. Results-In 54 patients (69%) symptoms and signs remained confined to the extraocular muscles during the observation p eriod. The remaining 24 patients (31%) developed symptoms of generalis ed myasthenia gravis; 50% of them within two years, 75% within four ye ars after onset. A somewhat reduced risk of generalisation was found i n those with mild symptoms, normal repetitive nerve stimulation test, and low or absent antiacetylcholine receptor (AChR) antibodies at the time of diagnosis. Patients receiving immunosuppressive treatment (cor ticosteroids and/or azathioprine) rarely developed generalised myasthe nia gravis (six of 50, 12%). Those without such treatment, usually due to uncertain diagnosis and late referral, converted into generalised myasthenia gravis significantly more often (18 of 28, 64%). Conclusion s-The prognosis of ocular myasthenia gravis is good. A conventional sc heme with short term corticosteroids and long term azathioprine seems adequate to achieve remission in most patients. The proportion of pati ents developing generalised myasthenia gravis was smaller in this popu lation compared with previously published groups (usually 50%-70%). Ea rly immunosuppressive treatment is at least partially responsible for this finding. Thymectomy (performed here in 12 patients with an abnorm al chest CT) also correlated with a good outcome, but had no apparent advantage over medical treatment alone.