Auditory phenotype in Stickler syndrome: results of audiometric analysis in 20 patients

Hearing loss in Stickler syndrome has received little attention due to the often more disabling ocular, orofacial and skeletal manifestations. Estimates suggest a global prevalence of sensorineural hearing loss (SNHL) ranging from 50 % to about 100 % though, depending on the underlying Stickler genotype. By performing extensive audiometric analysis in Stickler patients, we aimed to further elucidate the auditory phenotype. Twenty molecularly confirmed Stickler patients (age 10–62 year), of whom sixteen with type 1 Stickler syndrome (COL2A1 mutation) and four with type 2 Stickler syndrome (COL11A1 mutation) underwent an otological questionnaire, clinical examination, pure tone and speech audiometry, tympanometry and otoacoustic emission testing. Cross-sectional and longitudinal regression analysis of the audiograms was performed to assess progression. In type 1 Stickler syndrome, 75 % demonstrated hearing loss, predominantly in the high frequencies. No significant progression beyond presbyacusis was observed. All type 2 Stickler patients exhibited mild-to-moderate low- and mid-frequency SNHL and moderate-to-severe high-frequency SNHL. In both types, hearing loss was observed in childhood. Otoacoustic emissions were only detectable in 7/40 ears and had very low amplitudes, even in frequency bands with normal hearing on pure tone audiometry. Type 1 Stickler syndrome is characterized by a mild high-frequency SNHL, emerging in childhood and non-progressive. Absent otoacoustic emissions are a frequent finding. Patients with type 2 Stickler syndrome exhibit early-onset moderate SNHL affecting all frequencies with a sloping audiogram. Taking into account the visual impairment in many patients, we recommend regular auditory follow-up in patients with Stickler syndrome, especially in childhood.