Superficial siderosis of the central nervous system. A case report on examination by ECoG and DPOAE.

This is a case of superficial siderosis of the central nervous system (SSCN). The diagnosis of SSCN was based on the result of T2-weighted magnetic resonance imaging and on suggestive clinical manifestations. The pure-tone audiogram showed bilateral progressive sensorineural hearing loss with a poor speech discrimination score and Jerger type IV. The remarkable elevation of the detective threshold of cochlear microphonics on electrocochleography was found and distortion product otoacoustic emission (DPOAE) showed no response: These electrophysiologic examinations, including electrocochleography and DPOAE, revealed that the progressive sensorineural hearing loss in this case was caused by both retrocochlear and cochlear damages.