degrees, and over time, the absolute deviated degrees of SVVtilts decreases. We investigated SVV values in patients withvestibular neuritis (VN) during eccentric rotation, the methodused to assess utricular function during stimulation of onelabyrinth.METHOD: Prospectively, we performed SVV during eccen-tric rotation in 17 patients with VN and 20 normal subjects. Wecompared the SVV values of patients with normal control.RESULTS: No difference in the resting state SVV valueswere observed between the VN patients and the control group,but there were significant differences in SVV values betweenthese two groups during eccentric rotation.CONCLUSION: SVV during eccentric rotation allowed us toobtain information about unilateral vestibular loss that couldnot be found by conventional SVV in patients with VN. Thus,SVV during eccentric rotation might be a good tool to diag-nose unilateral vestibular loss.

Synergistic Effects of HIV in Aminoglycoside

Ototoxicity

Johannes Fagan, MB, ChB, MMed (presenter);Soraya Bardien, PhD

OBJECTIVE: The aim of the study was to determine whetherHIV positive patients are more likely to develop ototoxicitywhen exposed to long term aminoglycoside use than HIVnegative patients.METHOD: Baseline high frequency pure tone audiometry isperformed on all MDR-TB patients on admission to BrooklynChest TB Hospital. A prospective cohort study was done on163 such patients with normal hearing who received amino-glycoside therapy. High frequency pure tone audiometry wasperformed monthly for three months. HIV testing was done onall patients unless HIV status was already known. Geneticscreening was done on 115 patients using the SNaPshot tech-nique to screen for five mutations in the MT-RNR1 gene:A1555G, C1494T, T1095C, 961delT�C(n) and A827G.RESULTS: Fifty-three percent of the patients were HIV pos-itive; 47% were HIV negative. All HIV positive patients wereon antiretroviral drugs. The overall incidence of high fre-quency hearing loss was 53% (87/163). Of the patients whohad hearing loss, 69% (60/87) were HIV positive and 31%were HIV negative. HIV positive patients were more likely todevelop aminoglycoside induced hearing loss than HIV nega-tive patients (odds ratio [OR] 4.2, 95% confidence interval CI4.2-8.2). One patient with ototoxicity had a mitochondrialmutation (962 del C variant).CONCLUSION: HIV patients are at greater risk of hearingloss when exposed to aminoglycosides than HIV negativepatients. One of the reasons may be concomitant administra-tion of antiretroviral drugs. Further studies are needed to eval-uate the effect of antiretroviral drugs on the hearing status ofHIV positive individuals especially when they are exposed toaminoglycosides.

Systematic Screening for KCNE1 Mutations in

Chronic Tinnitus

Berthold Langguth, MD (presenter); AlexanderLuettich, BSc; Philip Sand, MD

OBJECTIVE: Chronic tinnitus is a highly prevalent and oftenincapacitating condition frequently associated with sensorineu-ral hearing loss. While its etiology remains poorly understood,there is growing awareness of genetic factors that predisposeto, or aggravate, chronic tinnitus. Among candidate genes forthe disorder counts KCNE1, a potassium channel subunit genethat has been implicated in maturation defects of central ves-tibular neurons, in Meniere’s disease, and in noise-inducedhearing loss.METHOD: 201 Caucasian outpatients with a diagnosis ofchronic tinnitus were systematically screened for mutations inthe KCNE1 open reading frame and in the adjacent sequenceby direct sequencing.RESULTS: Allele frequencies were determined for 46 knownvariants, plus two novel KCNE1 mutations. These comprisedone missense substitution (V47I) in the highly conserved re-gion encoding the KCNE1 transmembrane domain, and onerare variant in the gene’s 3’UTR. When genotypes weregrouped assuming dominance of the minor alleles, no signifi-cant genotype or compound genotype effects were observed ontinnitus severity.CONCLUSION: The newly identified V47I substitution in acase of extreme tinnitus argues in favor of an enlarged spec-trum of mutations in hearing disorders. However, with regardto allele frequencies in healthy control populations from earlierstudies, more common KCNE1 variants are unlikely to play amajor role in chronic tinnitus. Further investigations are invitedto address variation in additional channel subunits as possiblerisk factors in tinnitus.

Tension Pneumocele

David Eisenman, MD (presenter)

OBJECTIVE: The translabyrinthine approach to the posteriorfossa was pioneered by House in the 1960s, and has sincegained increasing popularity amongst Neurotologists. The sur-gical defect is typically repaired with a free adipose tissuegraft. The long-term viability of such grafts is good, but re-sorption can occur, with potential for complications. We de-scribe a subacute presentation of a tension pneumocele 23years after translabyrinthine resection of a large vestibularschwannoma.METHOD: Case report. Setting: Tertiary care, academic med-ical center.RESULTS: A 64 year-old woman with a 2 week history ofrapidly progressive ataxia and right-sided headache, 23 yearsafter right, translabyrinthine resection of a 4 cm vestibularschwannoma. A large, bilobed, mastoid-posterior fossa tensionpneumocele was seen on CT, and treated with urgent surgical

P248 Otolaryngology-Head and Neck Surgery, Vol 143, No 2S2, August 2010

decompression, dural repair and mastoid reobliteration withfree abdominal adipose graft. The symptoms were immedi-ately relieved post-operatively, and repeat imaging confirmedresolution of the pneumocele.CONCLUSION: Ultra-delayed complications of translabyrin-thine surgery have not been described. With the passing oftime since popularization of this approach, more such uncom-mon complications may be seen. Neurotologists should beaware of the possibility of their occurrence and approaches totreatment.

The 10-year Recurrence Rate of Attic

Cholesteatoma

Masafumi Sakagami, MD, PhD (presenter); OsamuAdachi, MD

OBJECTIVE: 1) Investigate the 10-year recurrence rate ofattic cholesteatoma using Kaplan-Meier survival analysis. 2)Show the Japan Otological Society (JOS) attic cholesteatomastaging systemMETHOD: Retrospective study. Setting: Tertiary referral andacademic center. Patients: Eighty-six patients with attic cho-lesteatoma who underwent surgical treatments performed by asingle surgeon from January 1, 1994, through December 31,1999. Intervention: Therapeutic Main outcome measures: The10-year recurrence rate of attic cholesteatoma based on JOSattic cholesteatoma staging system was calculated usingKaplan-Meier survival analysis. JOS attic cholesteatoma stag-ing system is defined as follows: 1) Stage I indicates atticcholesteatoma not extending beyond the attic. 2) Stage IIindicates attic cholesteatoma extending beyond the attic. 3)Stage III indicates any attic cholesteatoma showing one of thefollowing complications; facial palsy, intracranial complica-tion, labyrinthine fistulae, total atelectasis, profound sensori-neural hearing loss, large defect of the bony canal.RESULTS: The 10-year recurrence rate was 17.0% overall,0% in Stage I, 22.4% in Stage II and 9.1% in Stage III.CONCLUSION: Intact canal wall tympanoplasty or atticot-omy and scutumplasty are well indicated for Stage I, whilecanal wall down tympanoplasty is indicated for Stage III.However, the surgical method for Stage II should be selectedflexibly, based on not only the staging system but also Eusta-chian tube function, age and hearing level.

The Effects of GABAergic Inhibition on Gap

Responses

Kaiming Su, MD, PhD (presenter); Shankai Yin, MD,PhD; Jian Wang, MD, PhD

OBJECTIVE: Gap-detection paradigm has been utilized tomeasure the temporal acuity in the auditory system. However,the mechanism for the neuronal encoding of gaps has not beenwell established. Specifically, the role of central auditory inhi-

bition has been predicted but never confirmed. To address thisissue, the present study observed the effects of bicuculline(GABAA receptor antagonist) on the gap response of inferiorcolliculus neurons in guinea pigs.METHOD: Five-barrel glass micropipettes were used for therecording of both neural spikes and iontophoresis of bicucul-line. The neurons responses to gaps were recorded to a seriesof silent gaps of different widths marked by 100 ms pre-gapand 50-ms post-gap bursts of broad-band noise (NB1 andNB2).RESULTS: From a total of 121 units with sufficient data, wefound that bicuculline changed the minimal gap threshold(MGT) deferentially with a dependence on the temporal re-sponse patterns of neurons: it decreased MGT in phasic neu-rons but increased MGT in tonic neurons. The decrease ofMGT in phasic neurons was consistent with the change inrecovery function as gap width. Consistent with previous re-ports, bicuculline application resulted in an overall increase inresponses and shifting of the temporal response pattern fromphasic to tonic pattern. Furthermore, a shortened latency wasalso found in responses to both NB1 and NB2 when bicucul-line was applied.CONCLUSION: GABAergic inhibition may make a potentialrole in the gap response of inferior colliculus neurons in guineapigs.

The Molecular Mechanism of Autophagy in

Auditory Cells

Ken Hayashi, MD, PhD (presenter)

OBJECTIVE: Oxidative stress may play a crucial role in thepathogenesis of a variety of inner ear diseases, such as noise-induced hearing loss, ischemic impairment and age-relatedhearing loss. On the other hand, oxidative stress is known tostimulate autophagy, and autophagy may act as either a celldeath or cell survival mechanism. However, the exact mecha-nism by which oxidative stress regulates autophagy in auditorycells is still poorly understood. Thus, the purposes of this studywere to elucidate how H2O2 exerts its cytotoxic effects onauditory cell line (HEI-OC1) and to uncover the molecularmechanism that might be involved. Finally, we demonstratethat autophagy plays a cytoprotecive role in H2O2-inducednecrotic cell death.METHOD: We used auditory cell line (HEI-OC1) in thisstudy. The viability of HEI-OC1 was determined by cell via-bility assays. The samples after treatment of HEI-OC1 wereanalyzed by a FAC scan flow cytometer. Electron microscopyand morphometric analysis were performed at x6000. Immu-nofluorescent confocal laser microscopy was used. For proteinanalysis, western blot was performed.RESULTS: HEI-OC1 treated with different concentrations ofH2O2 for 0.5 h and 1 h exhibited the dose- and time-dependentcell death. After H2O2 treatment, not apoptotic cell but ne-

P249Poster Presentations

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