Improvements in sensorineural hearing loss after cord blood transplant in patients with mucopolysaccharidosis

Objective: To objectively determine changes in sensorineural hearing in children with mucopolysaccharidosis (MPS) by comparing audiological data before and after hematopoietic stem cell transplantation (HSCT). Design: Retrospective medical chart analysis. Setting: Tertiary referral hospital. Patients: Thirty pediatric patients with the diagnosis of MPS who underwent HSCT and had audiological data before and after HSCT. Data were extracted from medical charts for patients seen at our institution from January 1, 1999, to December 1, 2009. Main Outcomes Measures: Hearing was assessed using behavioral audiometry testing and auditory brainstem responses (ABR) before and after HSCT. Patient demographics, diagnosis, and age at HSCT were also evaluated. Results: Thirty patients with MPS were included. Four (13%) had MPS type 3a, 2 (7%) had MPS type 2, and 24 (80%) had MPS type 1. The average age at HSCT was 19 months (range, 5-44 months). Hearing improvement was evaluated by audiogram (20 patients), ABR (8 patients), and qualitative measures (30 patients). On average, patients did not show improvement on audiogram (P=.28; paired t test). The ABR click threshold improved 19 dB on average (P<.001). Qualitatively, 3 patients had normal hearing before and after HSCT. Of the remaining 27 patients, 20 (67%) showed improvement in sensorineural hearing (P<.001). Five (17%) had hearing loss and did not improve. Two (7%) had worsening hearing. Hematopoietic stem cell transplantation at the age of 25 months or younger was significantly correlated with hearing improvement (P=.03). Conclusions: Hematopoietic stem cell transplantation may provide improvement in MPS-associated sensorineural hearing loss. Hearing improvement is more likely to occur in patients who undergo transplantation at 25 months or younger.