Longitudinal audiological findings in mild to moderate Mucopolysaccharidosis type II and potential impact of inner ear dysfunction following blood-brain barrier-penetrating enzyme therapy.

BACKGROUND

Mucopolysaccharidosis type II (MPS II) is caused by a deficiency of the lysosomal enzyme iduronate-2-sulfatase. This study aimed to evaluate audiological characteristics and longitudinal hearing changes in patients with MPS II.

METHODS

We retrospectively reviewed 17 patients with MPS II whose hearing thresholds could be examined using pure-tone audiometry (PTA) at our institution for at least two years. Hearing was evaluated using auditory brainstem responses (ABR) and PTA. Longitudinal changes in hearing were analyzed to assess hearing progression and explore treatment-related effects.

RESULTS

Seventeen patients (34 ears) met the inclusion criteria for longitudinal analysis. All patients demonstrated at least mild sensorineural hearing loss at initial or during follow-up. Air conduction thresholds (AC) and bone conduction thresholds (BC) were significantly higher at the final assessment than at the initial visit. The mean annual rates of change in AC and BC were 1.36 dB HL/year (95% CI, 0.96-1.76; P < 0.0001) and 1.29 dB HL/year (95% CI, 0.82-1.75; P < 0.0001), respectively. During follow-up, 4 patients (8 ears) received pabinafusp alfa. Improvement in AC deterioration was observed in 5 of 8 ears (62.5%) and improvement in BC deterioration in 6 of 8 ears (75.0%).

CONCLUSIONS

Hearing impairment in both AC and BC was highly prevalent and progressive in patients with MPS II. The exploratory findings suggest a possible attenuation of hearing deterioration after pabinafusp alfa treatment; however, the small sample size and lack of statistical significance preclude definitive conclusions.