Etiology of Unilateral Neural Hearing Loss in Children

A new study published in the International Journal of Pediatric Otorhinolaryngology (available online 19 January 2009, doi:10.1016/j.ijporl.2008.11.012) reviewed unilateral hearing loss in 480 children to better understand its etiology and audiologic features. The abstract is provided here;for a copy of the full article or a subscription to the journal, visit: www.sciencedirect.com/science/journal/01655876

Authors: Adrienne M Laury, Sarah Casey, Sarah McKay, and John A Germiller Division of Pediatric Otolaryngology, The Children's Hospital of Philadelphia, Philadelphia, PA, United States;Department of Otorhinolaryngology, University of Pennsylvania, Philadelphia, PA, United States.

Objective: Unilateral sensorineural hearing loss (SNHL) can be caused by a variety of lesions of the inner ear and central nervous system. An inner hair cell or neural site of pathology must be suspected when otoacoustic emissions (OAEs) are present, and inconsistent with audiologic data. We reviewed unilateral neural hearing loss (UNHL) in children, to better understand its etiology, clinical and audiologic features.

Design: Retrospective series

Setting: Tertiary pediatric center

Methods: From a database of 480 children with unilateral SNHL, 148 had OAE data. Patients with a neural pattern (present OAEs in the affected ear) were reviewed. OUTCOME MEASURES: Clinical course, audiologic data, imaging findings.

Results: Of 148 patients with OAE data, 11 (7.4%) had the unilateral neural phenotype. Most had stable, severe-to-profound loss in the affected ear. MRI determined an etiology in all 10 patients who received it. Absent cochlear nerves were remarkably common, being found in eight patients (73%). Tumors, previously unsuspected, were identified in the other two patients who received MRI.

Conclusions: Cochlear nerve aplasia appears by far the most common cause of UNHL in children. As in adults, mass lesions must also be considered in children with unilateral SNHL with a neural pattern. As both lesions elude diagnosis on CT, MRI is the better modality for evaluating this condition.