TY - JOUR
T1 - Air-bone gap component of inner-ear origin in audiograms of cochlear implant candidates
AU - Attias, Joseph
AU - Ulanovski, David
AU - Shemesh, Rafael
AU - Kornreich, Liora
AU - Nageris, Benny
AU - Preis, Michal
AU - Peled, Miriam
AU - Efrati, Michal
AU - Raveh, Eyal
PY - 2012/6
Y1 - 2012/6
N2 - BACKGROUND: Experimental studies have shown that creating a window in the bony cover of the cochlea and vestibular parts of the inner ear, with preservation of membranous and middle-ear functions, induces an air-bone gap (ABG). This study sought to determine if a similar mechanism explains the ABG frequently observed in audiograms of cochlear implant candidates. METHOD: The study group included 47 candidates for a cochlear implant (94 ears) attending a university-affiliated tertiary medical center who had an ABG component in the audiogram in the absence of external or middle-ear abnormalities. Air- and bone-conduction thresholds on pure-tone audiometry were analyzed for 250 to 8,000 Hz and 250 to 4,000 Hz, respectively. In the 25 patients operated on during the study period, differences in the ABG and in cerebrospinal fluid (CSF) leak were compared between those with and without anomalies on computed tomography. RESULTS: Imaging revealed an abnormal inner-ear structure in 46% of cases, mostly a large vestibular aqueduct, alone or combined with other cochlear or vestibular malformations. ABG was evident over high and low frequencies and was significantly larger at low frequencies and in ears with structural anomalies. A high rate of CSF leak was observed in patients with an ABG and structural anomalies imaging as well as in those with an ABG and normal imaging findings. CONCLUSION: In cochlear implant candidates, the presence of a third window could cause an ABG because of stapes motion-induced shunting of acoustic energy outside the cochlear duct in response to air-conducted stimuli while bone conduction is preserved.
AB - BACKGROUND: Experimental studies have shown that creating a window in the bony cover of the cochlea and vestibular parts of the inner ear, with preservation of membranous and middle-ear functions, induces an air-bone gap (ABG). This study sought to determine if a similar mechanism explains the ABG frequently observed in audiograms of cochlear implant candidates. METHOD: The study group included 47 candidates for a cochlear implant (94 ears) attending a university-affiliated tertiary medical center who had an ABG component in the audiogram in the absence of external or middle-ear abnormalities. Air- and bone-conduction thresholds on pure-tone audiometry were analyzed for 250 to 8,000 Hz and 250 to 4,000 Hz, respectively. In the 25 patients operated on during the study period, differences in the ABG and in cerebrospinal fluid (CSF) leak were compared between those with and without anomalies on computed tomography. RESULTS: Imaging revealed an abnormal inner-ear structure in 46% of cases, mostly a large vestibular aqueduct, alone or combined with other cochlear or vestibular malformations. ABG was evident over high and low frequencies and was significantly larger at low frequencies and in ears with structural anomalies. A high rate of CSF leak was observed in patients with an ABG and structural anomalies imaging as well as in those with an ABG and normal imaging findings. CONCLUSION: In cochlear implant candidates, the presence of a third window could cause an ABG because of stapes motion-induced shunting of acoustic energy outside the cochlear duct in response to air-conducted stimuli while bone conduction is preserved.
KW - Air-bone gaps
KW - Cerebrospinal fluid leak
KW - Cochlear implant
KW - Inner ear anomalies
KW - Third window
UR - http://www.scopus.com/inward/record.url?scp=84861335621&partnerID=8YFLogxK
U2 - 10.1097/MAO.0b013e3182544cba
DO - 10.1097/MAO.0b013e3182544cba
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C2 - 22525217
AN - SCOPUS:84861335621
SN - 1531-7129
VL - 33
SP - 512
EP - 517
JO - Otology and Neurotology
JF - Otology and Neurotology
IS - 4
ER -