Two cases of myasthenia gravis with closing movement disturbance

Myasthenia gravis (MG) is an autoimmune disorder characterized clinically by proximal weakness and bulbar symptoms and pathologically by damage to the post-synaptic membrane at the neuromuscular junction. We report 2 patients with MG who were given the diagnosis on the basis of jaw closing dysfunction.An 87-year-old woman and a 66-year-old woman had not been given a diagnosis of MG, despite the presence of ptosis. Masticatory muscle electromyograms (EMGs) clearly showed that the masseter and temporal muscles had markedly decreased voltage during closing movements. In contrast, the digastric muscle showed minimal voltage on either closing or opening the jaw. Bulbar symptoms and high titers of antibodies against acetylcholine receptor were also noted in both patients. Finally, they were given a diagnosis of MG by a neurologist on the basis of the Tensilon test.Oral surgeons have to consider MG in patients who have masticatory dysfunction with ocular symptoms.