[Ptosis and mastication disorders revealing concurrent myasthenia gravis and chronic polyradiculoneuritis]

Although myasthenia gravis (MG) has frequently been associated with other autoimmune disorders, it has only rarely been reported in conjunction with diseases of the nervous system. A 74-year-old patient with hypertension suddenly presented left unilateral ptosis and mastication disorders. Clinical examination showed a concomitant loss of strength distally and reduced deep tendon reflex. Electrophysiologic data indicated a diagnosis of MG and chronic inflammatory demyelinating polyneuropathy; acetylcholine receptor antibody was elevated at 4.1 nmol/L (normal < 2 nmol/L). Improvement was rapid after initiation of pyridostigmine in association with corticosteroid (1 mg/kg/day). One month later, the cranial nerve deficit disappeared and strength was normal. It is likely that a basic abnormality of immune regulation was responsible for the emergence of diseases with different clinical presentations, but similar immunopathogenesis. Corticosteroid seemed to be the most effective treatment.