Coexistence of Parkinson's disease and myasthenia gravis: A case report and literature review.

The coexistence of Parkinson's disease (PD) and myasthenia gravis (MG) is rare. When similar symptoms of both diseases overlap, it is challenging to make a concomitant diagnosis of PD and MG. The present study describes the case of a patient with concomitant PD and MG. In addition, a systematic literature review was conducted by searching PubMed and Embase for reports on all patients with concomitant PD and MG, which were then grouped and compared according to different preexisting diseases. Finally, a total of 47 cases of concomitant PD and MG (35 men; 12 women), including the present case, were analyzed. The median age of the patients at first diagnosis was 66.59±9.91 years. The interval between the two diseases varied from 2 months to 22 years. Based on the sequential occurrence of these two diseases, the patients were categorized into three groups: The prePD-MG (30 cases), preMG-PD (12 cases), and coPD-MG (5 cases) groups. In the prePD-MG group, the onset age of MG was older and head drop was more common. In the preMG-PD group, the patients were more likely to have comorbid immune diseases.