Comparison of the prevalence and features of inner ear malformations in congenital unilateral and bilateral hearing loss.
OBJECTIVES
The aim of the study was to clarify differences in the prevalence and features of bony malformations in inner ear between congenital unilateral sensorineural hearing loss (USNHL) and congenital bilateral sensorineural hearing loss (BSNHL).


METHODS
We conducted a retrospective study of 378 consecutive infants referred from routine newborn hearing screening in the past 18 years. Clinical background, audiological data, and temporal bone computed tomography (CT) findings were analyzed. The prevalence of malformations between USNHL and BSNHL groups were compared using the Chi-square test.


RESULTS
The proportion of family history of hearing loss was significantly higher in infants with BSNHL than in those with USNHL (26/107 [24.3%] vs. 4/105 [3.7%]; p = 0.0001). Temporal bone CT scanning revealed significantly a higher prevalence of inner ear malformations in infants with USNHL than in those with BSNHL (93/109 [85.3%] vs. 4/107 [3.7%]; p < 0.0001). The most frequent anomaly in USNHL was cochlear nerve canal stenosis (69.7%), followed by cochlear malformations (20.2%), and narrow internal auditory canal (17.4%). Four infants with BSNHL accompanied by inner ear anomaly had complications such as Down's syndrome, developmental delay, or epilepsy.


CONCLUSIONS
The prevalence of bony malformations in inner ear and/or IAC was markedly higher in infants with congenital USNHL than in infants with BSNHL. Temporal bone CT scanning may help to clarify the etiology of congenital hearing loss, especially in USNHL.
['Masuda|Sawako|S|', 'Usui|Satoko|S|']
D007758:Ear, Inner D005260:Female D020022:Genetic Predisposition to Disease D006312:Hearing Loss, Bilateral D006319:Hearing Loss, Sensorineural D046088:Hearing Loss, Unilateral D006801:Humans D007223:Infant D007231:Infant, Newborn D008297:Male D015995:Prevalence D012189:Retrospective Studies D013701:Temporal Bone D014057:Tomography, X-Ray Computed
Inner ear Bilateral hearing loss Infants Etiology Congenital abnormalities Unilateral hearing loss