Progressive bilateral sensorineural hearing loss induced by an antithyroid drug

We report a patient with antithyroid drug-induced progressive bilateral sensorineural hearing loss associated with myeloperoxidase-antineutrophil cytoplasmic antibodies (MPO-ANCA). While antithyroid drugs have been linked to MPO-ANCA-associated small-vessel vasculitis, sensorineural hearing loss rarely was noted. A 36-year-old man treated for hyperthyroidism with propylthiouracil (PTU) developed progressive bilateral sensorineural hearing loss accompanied by fever and arthritis. MPO-ANCA were demonstrated in serum. Distortion product otoacoustic emissions test results suggested dysfunction of outer hair cells of the organ of Corti. Inner ear blood flow impairment from ANCA-associated small-vessel vasculitis presumably caused cochlear dysfunction. PTU withdrawal and high-dose methylprednisolone administration greatly improved hearing on both sides.