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Partial labyrinthectomy with hearing preservation: Frequency-specific data using tone-burst ABR
P96
Otolaryngology Head and Neck Surgery Scientific Sessions- - Monday
relative to the control group rats, as evidenced by smaller decrements of both DPOAE and ABR threshold shift. P o s t e r 56
Partial Labyrinthectomy with Hearing Preservation: Frequency-Specific Data Using Tone-Burst ABR ERIC E. SMOUHA, MD (presenter), and MASSAYUKI INOUYE, Stony Brook, N.Y.
August 1996
two dichotic tests that are designed to assess auditory pathways of the cerebral cortex. Results found no abnormalities in either brain stem or cortical findings of subjects with spasmodic dysphonia, contradicting findings of previous investigations. Results of this study along with implications of these results on theories of spasmodic dysphonia will be discussed. P o s t e r 58
Surgical approaches to the inner ear with preservation of hearing have valuable implications for neurotologic surgery. In a previous study in guinea pigs, we demonstrated that click-evoked auditory brain stem responses (ABR) were preserved after transection and plugging of one or more semicircular canals but were lost after entering the vestibule. A limitation of that study was that click-evoked ABR might not represent the function of the entire cochlea. In the present study, we used tone-burst ABR to determine thresholds across a broad range of frequencies (2-24 KHz) after surgical entry into the labyrinth at the lateral semicircular canal (LSCC), at the ampulla, and at the vestibule. Serial measurements were made, and a sham surgery group was used as a control. Cochlear hair cell preservation was also studied histologically. The results obtained with tone-burst ABR generally agreed with those previously obtained with click stimuli. Tone-burst ABR threshold levels were similar across most frequencies tested. Transection of the LSCC resulted in preservation of ABR thresholds. Ampullectomy had a variable effect on ABR thresholds. Vestibulotomy usually resulted in hearing loss. We conclude that surgical injury to the membranous labyrinth near the vestibule is the critical factor in hearing preservation after partial labyrinthectomy. We propose ways in which hearing loss might be avoided after surgical entry into the inner ear. P o s t e r 57
Auditory Brain Stem Response and SCAN-A: Evaluation of Patients with Spasmodic Dysphonia KEITH M. WILSON, MD (presenter), MICHELE MIDDLETON, ROBERT W, KEITH, PhD, and DAN KELLY, PhD, Cincinnati, Ohio
Spasmodic dysphonia is a focal laryngeal dystonia characterized by inappropriate contractions of the intrinsic laryngeal musculature. The increased prevalence of associated neurological findings has led to detailed investigation of the central nervous system. Previous research found abnormalities in response latency of the auditory brain stem responses. This study further investigated central auditory findings in patients with spasmodic dysphonia including brain stem and cortical function. Fifteen patients with normal hearing were tested using the auditory brain stem response and SCAN-A test for auditory processing disorders. To stress the auditory system, two click rates were utilized in ABR testing. The SCAN-A subtests included filtered words, auditory figure ground, and
Effect of Presbyacusis on Linguistic Interference Effects WILLARD HARRILL, MD (presenter), HENRY L. LEW, MD, PhD, ROSE C, HARDCASTLE, MS, SUSAN W. JERGER, PhD, and JAMES JERGER, PhD, Houston, Tex., and Durham, N.C.
In young adults, linguistic interference can be demonstrated in both the peak amplitude and the offset slope of the P30o event-related potential (ERP). The purpose of the present project was threefold: first, to examine characteristics of the P300 ERP to linguistic interference in elderly persons with presbyacusic hearing loss; second, to compare the P30o responses of young and elderly persons; and third, to compare the responses of elderly persons with and without evidence of central auditory processing disorder. Data from 24 elderly males were compared with similar data previously obtained from 30 young adult males in this laboratory. Two paradigms were used to study linguistic interference in the auditory domain, Stroop and Garner interference. In the Stroop interference paradigm, the ERPs to congruent and conflicting types of targets were compared. In the Garner interference paradigm, ERPs to control and orthogonal types of conditions were compared. Results suggested three conclusions: (1) Elderly males with presbyacusic hearing loss demonstrate less linguistic interference in the P3~x~ERP than young adults; (2) both paradigms of linguistic interference relected significantly smaller peak amplitudes and longer latencies in elderly males than in young adult males; (3) the P3c~waveforms of elderly persons with evidence of central auditory processing disorder differed from the waveforms of elderly persons without such deficits. In the former group, the offset characteristic after the P3c~)peak reflected a more rapid return to baseline than in the latter group. Poster 59
Surgical Ablation of the Vestibular Nerves Abolishes the Effects of Contralateral Acoustic Stimulation on Transient Evoked Otoacoustlc Emissions PATRICK J. FITZGERALD, MD (presenter), JOSEPH B. ROBERSON, Jr., MD, and BRAD A. STACH, PhD, Stanford and Palo Alto, Calif.
In humans, it is generally accepted that efferent innervation to the cochlea travels via the inferior division of the vestibular nerve. After leaving the inferior vestibular nerve, it enters the cochlea via the vestibulocochlear anastomosis. Activation of this efferent pathway by acoustic stimulation produces an inhibitory effect on transient evoked otoacoustic
Otolaryngology Head and Neck Surgery Scientific Sessions- - Monday
relative to the control group rats, as evidenced by smaller decrements of both DPOAE and ABR threshold shift. P o s t e r 56
Partial Labyrinthectomy with Hearing Preservation: Frequency-Specific Data Using Tone-Burst ABR ERIC E. SMOUHA, MD (presenter), and MASSAYUKI INOUYE, Stony Brook, N.Y.
August 1996
two dichotic tests that are designed to assess auditory pathways of the cerebral cortex. Results found no abnormalities in either brain stem or cortical findings of subjects with spasmodic dysphonia, contradicting findings of previous investigations. Results of this study along with implications of these results on theories of spasmodic dysphonia will be discussed. P o s t e r 58
Surgical approaches to the inner ear with preservation of hearing have valuable implications for neurotologic surgery. In a previous study in guinea pigs, we demonstrated that click-evoked auditory brain stem responses (ABR) were preserved after transection and plugging of one or more semicircular canals but were lost after entering the vestibule. A limitation of that study was that click-evoked ABR might not represent the function of the entire cochlea. In the present study, we used tone-burst ABR to determine thresholds across a broad range of frequencies (2-24 KHz) after surgical entry into the labyrinth at the lateral semicircular canal (LSCC), at the ampulla, and at the vestibule. Serial measurements were made, and a sham surgery group was used as a control. Cochlear hair cell preservation was also studied histologically. The results obtained with tone-burst ABR generally agreed with those previously obtained with click stimuli. Tone-burst ABR threshold levels were similar across most frequencies tested. Transection of the LSCC resulted in preservation of ABR thresholds. Ampullectomy had a variable effect on ABR thresholds. Vestibulotomy usually resulted in hearing loss. We conclude that surgical injury to the membranous labyrinth near the vestibule is the critical factor in hearing preservation after partial labyrinthectomy. We propose ways in which hearing loss might be avoided after surgical entry into the inner ear. P o s t e r 57
Auditory Brain Stem Response and SCAN-A: Evaluation of Patients with Spasmodic Dysphonia KEITH M. WILSON, MD (presenter), MICHELE MIDDLETON, ROBERT W, KEITH, PhD, and DAN KELLY, PhD, Cincinnati, Ohio
Spasmodic dysphonia is a focal laryngeal dystonia characterized by inappropriate contractions of the intrinsic laryngeal musculature. The increased prevalence of associated neurological findings has led to detailed investigation of the central nervous system. Previous research found abnormalities in response latency of the auditory brain stem responses. This study further investigated central auditory findings in patients with spasmodic dysphonia including brain stem and cortical function. Fifteen patients with normal hearing were tested using the auditory brain stem response and SCAN-A test for auditory processing disorders. To stress the auditory system, two click rates were utilized in ABR testing. The SCAN-A subtests included filtered words, auditory figure ground, and
Effect of Presbyacusis on Linguistic Interference Effects WILLARD HARRILL, MD (presenter), HENRY L. LEW, MD, PhD, ROSE C, HARDCASTLE, MS, SUSAN W. JERGER, PhD, and JAMES JERGER, PhD, Houston, Tex., and Durham, N.C.
In young adults, linguistic interference can be demonstrated in both the peak amplitude and the offset slope of the P30o event-related potential (ERP). The purpose of the present project was threefold: first, to examine characteristics of the P300 ERP to linguistic interference in elderly persons with presbyacusic hearing loss; second, to compare the P30o responses of young and elderly persons; and third, to compare the responses of elderly persons with and without evidence of central auditory processing disorder. Data from 24 elderly males were compared with similar data previously obtained from 30 young adult males in this laboratory. Two paradigms were used to study linguistic interference in the auditory domain, Stroop and Garner interference. In the Stroop interference paradigm, the ERPs to congruent and conflicting types of targets were compared. In the Garner interference paradigm, ERPs to control and orthogonal types of conditions were compared. Results suggested three conclusions: (1) Elderly males with presbyacusic hearing loss demonstrate less linguistic interference in the P3~x~ERP than young adults; (2) both paradigms of linguistic interference relected significantly smaller peak amplitudes and longer latencies in elderly males than in young adult males; (3) the P3c~waveforms of elderly persons with evidence of central auditory processing disorder differed from the waveforms of elderly persons without such deficits. In the former group, the offset characteristic after the P3c~)peak reflected a more rapid return to baseline than in the latter group. Poster 59
Surgical Ablation of the Vestibular Nerves Abolishes the Effects of Contralateral Acoustic Stimulation on Transient Evoked Otoacoustlc Emissions PATRICK J. FITZGERALD, MD (presenter), JOSEPH B. ROBERSON, Jr., MD, and BRAD A. STACH, PhD, Stanford and Palo Alto, Calif.
In humans, it is generally accepted that efferent innervation to the cochlea travels via the inferior division of the vestibular nerve. After leaving the inferior vestibular nerve, it enters the cochlea via the vestibulocochlear anastomosis. Activation of this efferent pathway by acoustic stimulation produces an inhibitory effect on transient evoked otoacoustic