Reversible deafness caused by biotinidase deficiency

We present a child with complete biotinidase deficiency who developed bilat eral sensorineural deafness without a response to a maximal stimulus of 90 dB in brainstem acoustic-evoked response. After treatment with 20 mg biotin daily, a repeated brainstem acoustic-evoked response demonstrated an impro ved hearing threshold of 65 dB, and the child began to talk. The case is a rare example of reversible hearing loss caused by to biotinidase deficiency and highlights the need for immediate replacement therapy once the diagnos is is established. (C) 2000 by Elsevier Science Inc. All rights reserved.