Hearing loss in Fabry disease: The effect of agalsidase alfa replacement therapy
Summary: The aim of this study was to describe the nature and prevalence of hearing loss in Fabry disease (McKusick 301500), a rare X-linked lysosomal storage disorder, and its response to enzyme replacement therapy with agalsidase alfa. Fifteen hemizygous male Fabry patients (aged 25–49 years) were randomized to receive placebo or enzyme replacement therapy for 6 months; all have received open-label enzyme replacement therapy for an additional 24 months thus far. Pure-tone audiometry, impedance audiometry and otoacoustic emission testing were performed at 0 (baseline), 6, 18 and 30 months. Four patients (27%) had bilateral and 7 (47%) had unilateral high-frequency sensorineural hearing loss (SNHL). Two (13%) had unilateral middle ear effusions with conductive losses persisting beyond 6 months. Only 3 (20%) had normal hearing. High-frequency SNHL deteriorated over the first 6 months in both placebo and active treatment groups by a median 4.3 dB (p=0.002, Wilcoxon matched pairs). This hearing loss subsequently improved above baseline by 2.1 dB at 18 months (p=0.02) and by 4.9 dB at 30 months (p=0.004). In conclusion, significant hearing loss, usually high-frequency SNHL, is a common manifestation of Fabry disease in adults. α-Galactosidase A replacement therapy with agalsidase alfa appears to reverse the hearing deterioration in these patients. This improvement is gradual, however, suggesting the need for long-term enzyme replacement therapy.