[Hypothyroidism and myasthenia: a case study].

Several disorders of immunological origin, in particular thyroid disorders have been reported in patients with myasthenia. This relationship has been little elucidated but in patients with myasthenia and Graves' disease was found an immunological cross-reaction between the neuromuscular junction and thyroid components. It is generally accepted that the association between hyperthyroidism and myasthenia is much more common than between myasthenia and hypothyroidism. However, there has been no clear explanation for this difference. We here report the case of a 53-year old patient treated for hypothyroidism due to suspected Hashimoto's disease well balanced under replacement therapy and whose evolution was marked by the detection of myasthenia during the follow up period. Myasthenia responded well to treatment based on neostigmine.