Proportion of bony cochlear nerve canal anomalies in unilateral sensorineural hearing loss in children.
OBJECTIVE
The aim of this study was to characterize the various bony anomalies of the inner ear in patients with unilateral sensorineural hearing loss using high-resolution temporal bone computed tomography and establish the relationship between hearing and the diameter of the bony cochlear nerve canal.


METHODS
We performed a retrospective review of 51 patients (mean age 11 years, range 0-20 years, 27 boys, 24 girls) who were diagnosed with unilateral sensorineural hearing loss with an audiogram. Coronal and axial diameter of the inner ear structures, including the internal auditory canal, bony cochlear nerve canal, and each turn of the cochlea and semicircular canals, were measured with high-resolution temporal bone computed tomography. The mean values (± 2 standard deviations) were calculated and compared between sensorineural hearing loss and normal ears, and between narrow bony cochlear nerve canal and normal bony cochlear nerve canal ears. Bony cochlear nerve canal atresia/stenosis was defined as a value less than 1.4mm in axial images.


RESULTS
The diameter of the bony cochlear nerve canal was significantly smaller in sensorineural hearing loss ears than in normal ears (p<.05). Associated inner ear anomalies, such as IAC stenosis (24%), cochlear hypoplasia (7-17%), and narrow semicircular canal bony island (8%) were only observed in the narrow bony cochlear nerve canal group. This group also showed statistically significant, severe to profound hearing loss compared to the normal bony cochlear nerve canal group (p<.05, R(2)=12.8%).


CONCLUSIONS
Most (57%) of the unilateral sensorineural hearing loss ears had bony cochlear nerve canal stenosis/atresia and this group showed associated inner ear anomalies. When the diameter of the bony cochlear nerve canal was less than 1.4mm, pure tone audio averages were more than 70 dB HL in most ears.
Department of Otolaryngology, Asan Medical Center, University of Ulsan College of Medicine, Asanbyeongwon-gil 86, Songpa-gu, Seoul 138-736, Republic of Korea.
Jong Sook
JS
Yi
Hyun Woo
HW
Lim
Byung Chul
BC
Kang
Sun-Young
SY
Park
Hong Ju
HJ
Park
Kwang-Sun
KS
Lee
D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D003051:Cochlea / Q000002:abnormalities* / Q000000981:diagnostic imaging; D003056:Cochlear Nerve / Q000002:abnormalities* / Q000000981:diagnostic imaging; D007758:Ear, Inner / Q000002:abnormalities* / Q000000981:diagnostic imaging; D005260:Female; D006319:Hearing Loss, Sensorineural / Q000175:diagnosis* / Q000000981:diagnostic imaging; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D011859:Radiography; D012189:Retrospective Studies; D013701:Temporal Bone / Q000002:abnormalities* / Q000000981:diagnostic imaging; D055815:Young Adult