Facial Muscular Atrophy in a Myasthenia Gravis Patient

抄録

A 56-year-old man with anti-acetylcholine receptor antibody-mediated myasthenia gravis had bilateral facial muscular atrophy and had noticed blepharoptosis 15 years earlier. From 45 to 51 years of age, 5-10 mg prednisolone and 180 mg pyridostigmine daily relieved his symptoms. Subsequently, these treatments no longer improved the facial weakness, though blepharoptosis was absent. At 56 years of age, the edrophonium test and repetitive supramaximal stimulation testing of the orbicularis oris were negative. Frontalis muscle needle electromyography showed low amplitude polyphasic units and an incomplete interference pattern. Facial muscle atrophy, caused by disuse atrophy from neuromuscular junction depletion, contributed to this patient's facial weakness.