Objective To examine the association between cochlear nerve canal (CNC) dimensions and sensorineural hearing loss (SNHL).
Design Retrospective review.
Setting Tertiary pediatric hospital.
Patients Children with SNHL and CNC stenosis.
Intervention The CNCs measured in axial and 45° oblique planes on temporal bone computed tomography (TBCT) in children with SNHL were compared with TBCT from children with normal hearing and 100 normal temporal bone specimens. Additional inner ear abnormalities were recorded. Hearing was measured using 4 frequency pure-tone averages (PTAs).
Main Outcome Measure The degree of CNC stenosis related to the degree of SNHL.
Results Fifty-three patients (32 female) with SNHL had CNC stenosis in 85 ears (32 bilateral, 21 unilateral). The mean (SD) axial CNC measurement for 85 ears was 0.98 (0.57) mm (range, 0-1.75 mm). The mean (SD) Poschl CNC measurement was 1.30 (0.69) mm (range, 0-2.80 mm). Of 85 ears, 64 had at least 1 additional inner ear abnormality. The mean (SD) PTA was 56.2 (40.8) dB. For each ear separately axial and Poschl plane CNC measurements were highly correlated (P < .001). The degree of CNC stenosis was significantly (P = .02) related to degree of hearing loss, and PTA decreased in the CNC stenosis population by 1.4 dB per year (P = .054). In addition, PTA and additional inner ear abnormalities were found to be significantly correlated (P = .002).
Conclusions Cochlear nerve canal stenosis is associated with SNHL, and the degree of stenosis predicted the degree of SNHL. In addition, the presence of CNC stenosis with additional inner ear abnormalities may affect the severity of SNHL.