Ocular versus generalized myasthenia gravis: A continuum associated with acetylcholine receptor antibody titers

The aim of this study was to evaluate clinical and serological differences between the ocular Myasthenia Gravis (oMG) and generalized MG (gMG). This study is a retrospective chart review, in which data was collected from patients fulfilling 2 of 3 diagnostic MG criteria (positive antibodies, evidence of neuromuscular transmission defect on neurophysiological examination, positive effect of pyridostigmine treatment). 350 patients were included and data concerning demographics and MG medical history were collected. Patients with oMG accounted for 15.7% of the included patients. The two subgroups differed significantly in oMG having a later age at onset, lower AChR antibody-titers, longer doctor-to-diagnosis delay and less intensive MG treatment. Additionally, patients with oMG were faster at reaching a well-controlled disease state. Thymus pathology, number of antibody-positive (95.9% of gMG and 94.5% of oMG), sex, number of other autoimmune diseases and delay before drug stability did not differ between oMG and gMG. In conclusion oMG is presumably a milder form of gMG characterized by lower AChR antibody-titers, a milder phenotype, and a quicker response to a less aggressive treatment. But otherwise, oMG and gMG show very similar characteristics, including the same frequency of positive AChR antibodies, which seems new compared to previous reports.