[Myasthenia in the aged: a case with unusually late onset]

Myasthenia is an uncommon autoimmune condition that can occur at any age. Peak frequency is seen around the age of 65 years. We report a case with a particularly late onset and discuss the particular conditions of myasthenia in the elderly subject.

A 97-year-old patient was hospitalized for dysphonia and dysphagia associated with exercise-induced dyspnea. The general picture suggested generalized myasthenia confirmed by the electromyography exploration and a positive anticholinesterase test. Treatment with acetylcholinesterase inhibitor was effective although cure was incomplete. Further improvement was obtained with immunosuppressor therapy using azathioprine.

The clinical presentation of very late onset myasthenia differs little from that in younger subjects excepting the very high frequency of brain stem involvement in the initial presentation. Diagnosis may however be more difficult as other conditions are more easily taken to be the causal element. Thus, for the elderly patient, the real problem is to envisage the diagnosis of myasthenia. Positive diagnosis is based on the same criteria as in younger subjects. Clinicians should be aware of the possibility of myasthenia in the geriatric population as specific treatment can improve functional prognosis with satisfactory efficacy.