[Ocular myasthenia: an etiology to consider in unexplained oculomotor paralysis]

Three cases of ocular myasthenia gravis were observed. The first patient, a 74-year-old man was found to have complete left ophthalmoplegia and ptosis unchanged at examination on month after onset. The second patient, a 42-year-old man, developed incomplete right ophthalmoplegia with pseudoanterior internuclearis ophthalmoplegia, then ptosis two days later. The third patient, a 70-year-old man, presented with sudden onset complete right palsy of the third nerve. Diabetes mellitus or intra-cranial lesions were suspected in all three patients although laboratory tests, tomodensitometry, nuclear magnetic resonance imaging, or arteriography gave no confirmation. Ptosis was relieved and eye movement was improved after the intravenous edrophonium test, but electromyography was negative. The three patients were treated with anticholinesterase agents and showed unequivocal improvement. The second patient underwent thymectomy. Clinicians should inform patients of the contraindications of drugs in this disease. The diagnosis of pure oculomotor forms of myasthenia gravis is sometimes difficult to establish and should be suspected in cases of unexplained oculomotor palsy.