Auditory Characteristics in Patients With Mucopolysaccharidosis

The purpose of the study was to evaluate audiologic findings according to mucopolysaccharidosis (MPS) subtypes and to estimate hearing changes as the disease progressed, as well as the therapeutic effect of enzyme replacement therapy on the hearing apparatus.

A total of 124 patients who were diagnosed with MPS between September 1994 and December 2016 were retrospectively analyzed. Play audiometry or pure-tone audiometry was performed for hearing assessment, and auditory brainstem response was conducted in patients with poor compliance.

In total 124 patients were identified, ranging in age at diagnosis from 0 to 33 years. Fourteen of the patients had been diagnosed with type I, while 91 had type II, 2 had type III, 14 had type IV, and 3 had type VI. Mean bone conduction and air conduction for the better ear were 26.13±16.95 dB and 34.77 ± 20.00 dB in all patients, and 34.20±7.64 dB and 40.70±9.67 dB in patients with MPS II. The average auditory brainstem response threshold was 68.96 ±21.93 dB nHL. The most common type of hearing loss was pure sensorineural hearing loss in all subtypes, and the degree of hearing loss was variable mostly within the mild to severe range. The increase in the hearing threshold was also significantly correlated with the disease duration. However, the change in hearing level was not correlated with the duration of enzyme replacement therapy.

Hearing impairment in MPS patients is common and is aggravated as the disease progresses. Thus, adequate intervention and hearing rehabilitation might play an important role in managing hearing disabilities in MPS patients.