Vestibular end-organ dysfunction in children with sensorineural hearing loss and cochlear implants: an expanded cohort and etiologic assessment.
BACKGROUND
Similarities between the peripheral auditory and vestibular systems suggest that children with sensorineural hearing loss (SNHL) may demonstrate associated vestibular impairments. The current study examines vestibular function in a previously reported cohort (n = 40) augmented by 113 children with profound SNHL.


METHODS
The current study is prospective and cross-sectional with repeated measures. Horizontal canal function was assessed in response to caloric and rotational stimuli. Saccular function was examined using vestibular evoked myogenic potentials (VEMP). One hundred fifty-three children were tested; 119 had unilateral cochlear implants (CIs) at time of testing, and 34 were evaluated before CI.


RESULTS
Horizontal semicircular canal function was abnormal in response to caloric stimuli in 50% (69/139), with a proportion (18/69, 26%) reflecting mild to moderate unilateral abnormalities. Severe hypofunction or areflexia occurred in 37% (51/139). Horizontal semicircular canal function in response to rotation was abnormal in 47% (64/139). Bilateral reduction in VOR gain was seen across frequencies in 29% (40/139) and 13% (18/139) demonstrated isolated high-frequency (≥ 2 Hz) loss. Saccular function was absent bilaterally in 21% (32/135) and unilaterally in 30% (40/135). All children with meningitis (n = 11) and 46% with radiologic cochleovestibular anomalies (n = 31) had horizontal canal dysfunction, whereas 45% and 46%, respectively, displayed saccular dysfunction. Unilateral dysfunction of the horizontal canal or the saccule was equally distributed between the implanted and nonimplanted ear (14:9 and 22:18, respectively), and the differences in proportions were not statistically significant.


CONCLUSIONS
Vestibular end organ dysfunction occurred in half of all children with profound SNHL. Approximately one-third of the subjects displayed severe abnormalities(bilateral and/or severe loss). The likelihood of vestibular end-organ dysfunction is highly dependent on etiology, with meningitis and cochleovestibular anomalies having the highest rates of severe dysfunction.
Department of Otolaryngology Head and Neck Surgery, Hospital for Sick Children, 555 University Avenue, Toronto, ON Canada. s.cushing@utoronto.ca
Sharon L
SL
Cushing
Karen A
KA
Gordon
John A
JA
Rutka
Adrian L
AL
James
Blake C
BC
Papsin
D019929:Cochlear Implantation / Q000009:adverse effects*; D003054:Cochlear Implants / Q000009:adverse effects*; D003430:Cross-Sectional Studies; D006319:Hearing Loss, Sensorineural / Q000150:complications / Q000503:physiopathology* / Q000601:surgery; D006801:Humans; D011446:Prospective Studies; D012665:Semicircular Canals / Q000503:physiopathology*; D015837:Vestibular Diseases / Q000150:complications* / Q000503:physiopathology; D058585:Vestibular Evoked Myogenic Potentials; D014724:Vestibular Function Tests