Progress of hearing loss in neurofibromatosis type 2: implications for future management

The objective of this study was to describe changes in hearing over time in patients with neurofibromatosis type 2 (NF2) treated conservatively. A retrospective case review was conducted in a tertiary referral centre. Pure tone audiometry, speech discrimination scores, serviceable hearing (American Academy of Otolaryngology class A or B) and measurement of vestibular schwannoma (VS) size on magnetic resonance imaging were evaluated in 56 patients (89 ears) with NF2 with at least one conservatively managed VS. Over a mean follow-up period of 7 years (range 0.8-21 years) pure tone average thresholds increased gradually with a mean annual rate of 1.3 dB for the right ear (p = 0.0003) and 2 dB for the left ear (p = 0.0009). Speech discrimination scores dropped with an average annual rate of 1.3 and 0.34 % in the right and left ear, respectively. Patients maintained serviceable hearing for an average of 7.6 years (range 2.7-19.3 years). The average annual VS growth was 0.4 mm without any correlation with hearing loss. There was a correlation between patients' age and pure tone threshold increase (p < 0.05 for both ears). In this selected population of patients with NF2, hearing threshold increases were very slow. In NF2 patients with indolently behaving tumours, serviceable hearing can be maintained for a significant length of time, making conservative management an attractive option.