Myasthenia gravis focal to the larynx. Report of a case.

Myasthenia gravis, focal to the larynx, should be considered in the differential diagnosis of intermittent breathy dysphonia and aponia. A 20-year-old woman had intermittent breathy dysphonia and aphonia as the sole manifestation of myasthenia gravis. The vocal cords were flaccid, and adducted to the paramedian position for phonation. Improvement of laryngeal function was demonstrated with edrophonium and neostigmine bromide. Therapy with pyridostigmine bromide (Mestinon) maintained normal phonation.