Abstract Otology 2000 B19-1

James R. Cullen MD

Department of Otolaryngology Altnagelvin Area Hospital GB-Londonderry

Idiopathic sudden sensorineural hearing loss (ISSHL) is a perplexing entity of unknown origin. Two widely proposed theories are that it is either a vascular accident akin to myocardial infarction or, that it isthe result of a viral infection. Herpes Simplex Virus type 1 (HSV1) has been suggested as a possible cause of ISSHL. This experiment attempted to produce an animal model of ISSHL. HSV1 was injected into the scala media of a test group of adult guinea pigs. Viral suspension medium only was injected into a control group. The test group were noted to have a statistically significant (p< 0.001) hearing loss at 24 hours compared with the control group. The animals were followed audiologically and histologically over a 2 week period. The hearing loss was measured and the cochlae examined at 1, 2, 4, 7 and 14 days. In a second arm of the experiment 4 groups of 10 animals each were randomly allocated to treatment with dexamethasone and acyclovir given immediately at the time of the HSV1 injection and after 24 hours. These animals had their hearing and histology checked at the same intervals as the untreated group above. Histology showed an intense inflammatory reaction in the basal turn of the scala media at 24 hours. Over the subsequent days this reaction spread to the apex of the cochlea and was noted to affect the scala vestibuli as well. An intense fibrinous exudate was seen within the cochlea which became organised and replaced by fibrous tissue from day 7. New bone formation was noted in the scala tympani beneath the basilar membrane and within the vestibule. Concentric fibrosis was also noted obliterating some scalae. Treatment with dexamethasone and acyclovir either immediately or delayed did not produce any improvement in the histological outcome.

Abstract Otology 2000 B19-2

Hamad Al Muhaimeed Prof., Siraj M. Zakzouk Prof.

Department of ORL King Abdul Aziz Univ. Hospital SA-Riyadh

A survey to identify the aetiology of hearing impairment among Saudi children was carried out. Children were divided into two groups according to presence or absence of laboratory evidence of herpes simplex virus infection 'at risk' and 'at not risk'. Serological tests for herpes simplex virus infection were performed on 1054 children. We found positive IgM antibody against herpes simplex virus, type 1 (HSV1) in the blood of 82 of the 1054 children (8 percent), and positive IgM antibody against herpes simplex virus type 2 (HSV2) in eight of hte 1054 children (0.8 percent) ages ranged between 12 months and 14 years). Forty-six of the eighty-two infected children (56 percent) with HSV1 were found to have a sensoneural hearing loss (16 of 26 children from the 'at risk' group and 30 of 56 from the 'not at risk' group). Only one case of the eight infected children with HSV2 was found to have bilateral sensoneural hearing loss of moderate degree. This case was in the 'not at risk' group. Hearing impairment was bilateral in all 46 cases, profound in seven, moderate to severe in 23 and mild in 16. Known causes of hearing impairment were excluded together with hearing impairment due to multiple TORCH agents. The high prevalence of hearing impairment among children due to herpes simplex virus infection is described.

Abstract Otology 2000 B19-3

Marina Cakar MD, Elena Bogeska MD, V. Ivanovska MD, Lidija Dubrovska MD

Clinic of Otolaryngology Medical Faculty Chef Department of Audiology MAZ-Skopje

The primary purpose of this study was to investigate the potential role of transient evoked otoacoustic emissions (TEOAEs) for screening impairment and middle ear disorders in school children. Thirty children (ages 5-10 years) participated. TEOAEs pure- tone hearing screening, acoustic immitance (single and multi-frequency tympanometry) and an otoscopic examination were done on each child. Correlations between TEOAEs veriables and immitance measures of middle ear were done. The results sugest that TEOAEs test has potential to be incorporated succesfully into hearing screening program for school children.

Abstract Otology 2000 B19-4

Enis Alpin Güneri MD, Bülent Serbetçioglu MD, Ahmet Ömer Ikiz MD, Ataman Güneri MD, Kerim Ceryan MD

Department of Otolaryngology Head and Neck Surgery Dokuz Eylul University TR-Izmir

One of the most serious side effects of Cisplatin (CP) treatment is ototoxicity. The primary target affected by CP ototoxicity is the outer hair cell population whose involvement leads to a disturbance in the mechanoelectrical transduction of sound. In this article, CP induced ototoxicity and the effects of Vitamine B treatment on ototoxicity in guinea pigs was evaluated using Transient Evoked Otoacoustic Emission technique. Our results showed that, Vitamine B preparation injections for 7 days in addition to a single large dose of CP resulted in significantly better TEOAE responses than that obtained after only CP injections (p < 0.01). Based on the results of this study, we think that further clinical investigations are needed to evaluate the preventive effect of Vitamine B preparation injections against CP induced ototoxicity.

Abstract Otology 2000 B19-5

Euan Murugasu MD

California Ear Institute atStanford Dr. Joseph Roberson USA-Palo Alto, CA

The self-mixing effect of a laser diode was used to measure frequency tuning of basilar membrane (BM) displacements in the 15 kHz region of the guinea pig cochlea whilst perfusing the scala tympani with either artificial perilymph or millimolar salicylate solutions. Following perfusion with either 2.5 or 5 mM sodium salicylate, the tips of the tuning curves became reversibly desensitized by up to 45 dB SPL, the best frequency of the tip shifted to lower frequencies by about 2 kHz, the tip became broader, and the tail of the tuning curve became sensitized by about 10 dB. These changes could be explained if salicylate caused a reduction in feedback from the outer hair cells (OHCs). An increase in the compliance of the cochlear partition, by reducing the turgidity of the OHCs, would also cause a desensitization of the tip and a shift to lower frequencies with sensitization of the tail of the tuning curve. From simultaneous measurements made at the round window at frequencies between 1 and 25 kHz, it was concluded that cochlear microphonics and the compound action potential were poor indicators of the action of salicylate on BM displacement and that salicylate probably had an additional action on the response properties of the auditory nerve. Also, the finding that salicylate-induced changes in the mechanical repsonses of the BM could recover before cochlear microphonics was taken to indicate that the OHCs may be continuously adjusting their operating conditions to optimize the sensitivity and frequency selectivity of the cochlea.

Abstract Otology 2000 B19-6

Elena Bogeska MD, Marina Cakar MD, V. Ivanovska MD, Lidija Dubrovska MD

ENT Department University Hospital MAZ-Skopje

The aim of this study was to compare TEOAEs of subjects having same auditory thresholds but different age ranges. It is well known that elevated hearing thresholds are common with increased age because of the deterioration of outer hair cells. It has also been reported that TEOAEs decrease with increased age. We divided the examined patients in two groups depending on their hearing threshold. The age of these two groups was 40-60 years. The control group of adults between 19 and 39 years was divided in the same way. Our results showed that there is not significant reduce of TEOAEs corresponding with age. Other factors such as presence of hearing loss have more influence on TEOAES than the factor of age.

Abstract Otology 2000 B19-7

Iwao Ohtani MD, Yohko Baba MD, Chiaki Suzuki MD

ENT Department Fukushima Medical University J-Fukushima

Wegener's granulomatosis is assigned to a systemic autoimmune disease that consists of three principal lesions: necrotizing granulomatous lesions of the airway, generalized focal necrotizing vasculitis, and necrotizing glomerulitis. In Wegener's granulamatosis the ear is frequently affected, and many published studies describe clinical findings in this disease. However, there have been only a few reports of histopathologic findings in temporal bones on Wegener's granulomatosis. The objective of this study is to describe the temporal bone pathology of two cases of Wegener's granulomatosis in which the initial symptoms were profound hearing loss and facial nerve palsy respectively. The first case, a woman of 44, suffered profound sensorineural hearing loss which was remarkably improved by steroid and cyclophosphamide treatment for a time, and which seemed to be caused by invasion from granulation tissue filled in the tympanic cavity. The second case was a 61-year-old woman presenting with the facial nerve palsy. The bony canal of the horizontal portion of the facial nerve was destroyed due to granulation tissue which filled in the tympanic cavity, and granulomatous involvement was observed in the facial nerve. Pathogenesis of the facial nerve palsy seemed to be related to granulomatous involvement of the facial nerve, because the palsy resolved completely by steroid and cyclophosphamide treatment.

Abstract Otology 2000 B19-8

Franziska M. Häfner MD (1), Thomas Linder MD (1), A.A. Salam MD (2), D. Balmer MD (2), A. Baumer MD (2), A. Schinzel MD (3), Thomas Spillmann MD (1), Suzanne M. Leal Ph.D. (2)

(1) ENT Department University Hospital CH-Zürich
(2) The Rockefeller University USA-New York, NY
(3) Institute of Medical Genetics University of Zürich CH-Zürich

A novel locus for non-syndromic hearing loss has been identified in a Swiss German kindred with congenital bilateral autosomal dominant sensorineural hearing loss. This kindred has a history of hearing loss that dates back to the middle of the 19th Century. Audiometric and DNA samples were obtained on a total of 56 pedigree members. Thirty family members were considered to be affected and 26 unaffected. Affected family members audiograms displayed a mild to profound hearing loss, mainly in the frequencies between 0.5 kHz and 4kHz. The affected members all had sloping audiograms affecting mainly the mid to high frequencies. Hearing impaired individuals with severe to profound hearing loss in the high frequencies also had moderate hearing loss in the mid and low frequencies. The hearing loss appears to be non-progressive with no correlation between severity of hearing loss and current age. No evidence for acquired risk factors predisposing to hearing loss was observed for any affected family members. A total of 387 polymorphic markers have been genotyped across 23 chromosomes. These markers are spaced approximately 10 cM apart. Two point linkage analysis using MLINK of the FASTLINK package was carried out. A maximum two-point lod score of 4.9 was obtained to a marker on 4q. An additional multipoint analysis was done, including flanking markers using LINKMAP of the FASTLINK package. The analysis was carried out using both equal allele frequencies and allele frequencies that were estimated from the founders of this pedigree as well as from additional Swiss German pedigrees. A multipoint maximum lod score of 6.7 was obtained when equal allele frequencies were used and 6.1 when estimated allele frequencies were used. Additional markers within the region of this locus have been selected from the Marshfield marker maps and are currently being genotyped in order to further refine the location of this locus. The next step in this study will be to isolate the gene which is responsible for DFNA24. This work was supported by the NHLBI Mammalian genotyping service, NIH grant DC03594 and the American Hearing Research Foundation.