A comparative study of ocular and generalized myasthenia gravis

We compared the relations and therapeutic outcomes of ocular and generalized types of myasthenia gravis (MG) and used retrospective analysis for 65 patients with myasthenia gravis during a mean follow-up time of 30.4 months. There were 35 ocular and 30 generalized MG patients. Items of comparison included sex, age, clinical presentations, serum antibody titer, the association with thymus status, and therapeutic outcome. Of the patients with generalized MG, males were significantly older than females. Ptosis and diplopia were the most common symptoms in patients with MG, but there were no significant differences between the two types of MG. The eyelid levator muscle and lateral rectus muscle were the most commonly involved extraocular muscles in patients with MG. The associations with thymoma or thymus hyperplasia were more common in generalized MG than in ocular MG, and more common in younger than in older patients. The result of positive neostigmine test was 93.8% in all patients, but there were no significant differences between the two types of MG. Acetylcholine receptor antibody (AchRAb) presented an 81.1% positive rate and was significantly higher in generalized MG than that in ocular MG (96.2% vs 66.7%). There were no significant differences between the two types of MG regarding successful treatment strategies in both initial therapy and maintenance therapy. Only two of 16 patients had complete remissions after thymectomy. From the viewpoint of clinical presentations or from the therapeutic strategy outcome, the boundary between both types of MG seems to be vague. Both types of MG probably share the same entity in nature and the difference is just a matter of degree of severity. The benefit of thymectomy in treatment of MG needs further investigation.