Effects of Tympanomeatal Angle Blunting on Sound Transfer
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LED light source. Contralateral ears, serving as controls, re- ceived daily intratympanic saline injections. Outcome Mea- surements: Auditory brainstem response (ABR) thresholds were determined pre- and one-day-post-treatment using 4 ms pure-tone bursts between 8 and 32 kHz. Statistical compari- sons were completed using student’s two-tailed t-test. RESULTS: Pre-injection mean (SEM) ABR threshold in sa- line-treated ears was 44.6 dB (1.74) versus 44.1 dB (1.81) in M-ALA-treated ears (p 0.42). Post-injection mean (SEM) ABR thresholds were 45.3 (1.60) for saline-treated ears and 45.6 (1.71) for M-ALA-treated ears (p 0.38). Comparison of pre- to post-injection ABR thresholds showed no statistical difference within saline-treated (p 0.47) or M-ALA-treated ears (p 0.60). All ears displayed minimal granulation around tympanic membrane injection sites, although M-ALA treated ears showed slightly delayed development of minimal granu- lation compared to saline ears. Tympanic membranes of both groups showed no difference by 1 week after treatment, with healing perforations and decreasing granulation. CONCLUSION: Intratympanic application of methyl delta- aminolevulinic acid over a 7 day course in a murine model does not produce measurable acute ototoxicity and is well tolerated. Effect of Mastoid Drilling on Hearing of Contralateral Ear Ashish Vashishth, MBBS, MS (presenter); Arun Goyal, MBBS, MS; P P Singh, MBBS, MS OBJECTIVE: 1) Understanding the effect of otologic drilling during surgery on the hearing of contralateral normal ear. This drill produces a high intensity noise and vibration which can affect the hearing of the other ear. 2) To find the nature of hearing loss, if any, whether temporary or persistent. 3. Detect correlation between hearing loss and various drill parameters used. METHOD: A prospective clinical study was carried out at a tertiary referral center during 2008-2009. Thirty patients with unilateral cholesteatoma and otoscopically and audiologically normal contralateral ear admitted for mastoid surgery were included. Patients were evaluated preoperatively and for five days following mastoid surgery, using high frequency pure tone audiometry and low/high frequency range transient evoked and distortion product otoacoustic emission (TEOAE & DPOAE). The pre and postoperative data was analyzed using repeated measures ANOVA and COCHRAN test. RESULTS: On analyzing otoacoustic emission (OAE), statis- tically significant changes were observed in DPOAE at high frequency (p0.016) and TEOAE in both low and high fre- quency ranges (p0.035 & 0.021 respectively). High fre- quency pure tone audiometric results showed significant changes in air conduction thresholds. OAE changes showed higher statistical correlation with cutting drill as compared to diamond drill. However, no correlation with drill speed was observed. CONCLUSION: Drilling during mastoid surgery poses a threat to the hearing of contralateral normal ear due to the noise and vibration conducted transcranially. This hearing deficit though temporary in most cases can be persistent in certain ears. Cutting burr poses more threat than diamond burr. Effects of Tympanomeatal Angle Blunting on Sound Transfer Sam Turner (presenter); Xianxi Ge, MD; Ronald Jackson, PhD; Jianzhong Liu, MD OBJECTIVE: 1) Measure the peak to peak displacement of the round window membrane prior to blunting procedure. 2) Evaluate the impact of blunting the anterior tympanomeatal angle on middle ear sound transfer function. METHOD: Six fresh human temporal bones were prepared using a mastoidectomy and facial recess approach. Baseline RWM peak to peak displacements were obtained by single point laser Doppler Vibrometry (LDV) at 90 dB SPL over a spectrum of 250 8,000 Hz. The temporalis muscle was har- vested, then fashioned into ATA for each temporal bone mim- icking ATA blunting. RWM displacement responses with the blunted ATA were measured using the LDV. RESULTS: For each of the six temporal bones, the average displacement decreased across all sound frequencies with the ATA blunting when compared to baseline (no blunting). Base- line velocity measurements for the sound signal between 500 to 2,000 Hz averaged 0.0163; 0.0064 (mean SD) dB mm/sec and while measurements averaged 0.0072 0.0021 dB mm/sec with blunting of the ATA (P0.05). This decrement correlates to a loss of approximately 10 dB SPL. CONCLUSION: Blunting of the ATA decreases the sound transfer function of the tympanic membrane and middle ear. Prevention of blunting at the ATA during tympanoplasty must be emphasized. Epidemiology and Natural History of Vestibular Schwannoma Sven Eric Stangerup, MD (presenter) OBJECTIVE: To describe the epidemiology and natural his- tory of vestibular schwannomas with special focus on inci- dence, tumor size, age at diagnosis, growth of tumor and change in hearing during wait and scan. METHOD: In Denmark, all patients with vestibular schwan- noma have been referred to one center since 1976. During the last 34 years, all the data have been entered prospectively into a national database. In total 2444 patients are included in the study. Half of the patients were initially operated during the beginning of the period. During the last part of the period 90% of patients with tumors 20 mm extrameatally or smaller were allocated to wait & scan with repetitive MR scans. P92 Otolaryngology-Head and Neck Surgery, Vol 143, No 2S2, August 2010
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Transcript of Effects of Tympanomeatal Angle Blunting on Sound Transfer
LED light source. Contralateral ears, serving as controls, re-ceived daily intratympanic saline injections. Outcome Mea-surements: Auditory brainstem response (ABR) thresholdswere determined pre- and one-day-post-treatment using 4 mspure-tone bursts between 8 and 32 kHz. Statistical compari-sons were completed using student’s two-tailed t-test.
RESULTS: Pre-injection mean (SEM) ABR threshold in sa-line-treated ears was 44.6 dB (1.74) versus 44.1 dB (1.81) inM-ALA-treated ears (p � 0.42). Post-injection mean (SEM)ABR thresholds were 45.3 (1.60) for saline-treated ears and45.6 (1.71) for M-ALA-treated ears (p � 0.38). Comparison ofpre- to post-injection ABR thresholds showed no statisticaldifference within saline-treated (p � 0.47) or M-ALA-treatedears (p � 0.60). All ears displayed minimal granulation aroundtympanic membrane injection sites, although M-ALA treatedears showed slightly delayed development of minimal granu-lation compared to saline ears. Tympanic membranes of bothgroups showed no difference by 1 week after treatment, withhealing perforations and decreasing granulation.
CONCLUSION: Intratympanic application of methyl delta-aminolevulinic acid over a 7 day course in a murine modeldoes not produce measurable acute ototoxicity and is welltolerated.
Effect of Mastoid Drilling on Hearing of
Contralateral Ear
Ashish Vashishth, MBBS, MS (presenter); ArunGoyal, MBBS, MS; P P Singh, MBBS, MS
OBJECTIVE: 1) Understanding the effect of otologic drillingduring surgery on the hearing of contralateral normal ear. Thisdrill produces a high intensity noise and vibration which canaffect the hearing of the other ear. 2) To find the nature ofhearing loss, if any, whether temporary or persistent. 3. Detectcorrelation between hearing loss and various drill parametersused.
METHOD: A prospective clinical study was carried out at atertiary referral center during 2008-2009. Thirty patients withunilateral cholesteatoma and otoscopically and audiologicallynormal contralateral ear admitted for mastoid surgery wereincluded. Patients were evaluated preoperatively and for fivedays following mastoid surgery, using high frequency puretone audiometry and low/high frequency range transientevoked and distortion product otoacoustic emission (TEOAE& DPOAE). The pre and postoperative data was analyzedusing repeated measures ANOVA and COCHRAN test.
RESULTS: On analyzing otoacoustic emission (OAE), statis-tically significant changes were observed in DPOAE at highfrequency (p�0.016) and TEOAE in both low and high fre-quency ranges (p�0.035 & 0.021 respectively). High fre-quency pure tone audiometric results showed significantchanges in air conduction thresholds. OAE changes showedhigher statistical correlation with cutting drill as compared to
diamond drill. However, no correlation with drill speed wasobserved.CONCLUSION: Drilling during mastoid surgery poses athreat to the hearing of contralateral normal ear due to the noiseand vibration conducted transcranially. This hearing deficitthough temporary in most cases can be persistent in certainears. Cutting burr poses more threat than diamond burr.
Effects of Tympanomeatal Angle Blunting on
Sound Transfer
Sam Turner (presenter); Xianxi Ge, MD; RonaldJackson, PhD; Jianzhong Liu, MD
OBJECTIVE: 1) Measure the peak to peak displacement ofthe round window membrane prior to blunting procedure. 2)Evaluate the impact of blunting the anterior tympanomeatalangle on middle ear sound transfer function.METHOD: Six fresh human temporal bones were preparedusing a mastoidectomy and facial recess approach. BaselineRWM peak to peak displacements were obtained by singlepoint laser Doppler Vibrometry (LDV) at 90 dB SPL over aspectrum of 250 8,000 Hz. The temporalis muscle was har-vested, then fashioned into ATA for each temporal bone mim-icking ATA blunting. RWM displacement responses with theblunted ATA were measured using the LDV.RESULTS: For each of the six temporal bones, the averagedisplacement decreased across all sound frequencies with theATA blunting when compared to baseline (no blunting). Base-line velocity measurements for the sound signal between 500to 2,000 Hz averaged 0.0163; 0.0064 (mean SD) dB mm/secand while measurements averaged 0.0072 0.0021 dB mm/secwith blunting of the ATA (P�0.05). This decrement correlatesto a loss of approximately 10 dB SPL.CONCLUSION: Blunting of the ATA decreases the soundtransfer function of the tympanic membrane and middle ear.Prevention of blunting at the ATA during tympanoplasty mustbe emphasized.
Epidemiology and Natural History of Vestibular
Schwannoma
Sven Eric Stangerup, MD (presenter)
OBJECTIVE: To describe the epidemiology and natural his-tory of vestibular schwannomas with special focus on inci-dence, tumor size, age at diagnosis, growth of tumor andchange in hearing during wait and scan.METHOD: In Denmark, all patients with vestibular schwan-noma have been referred to one center since 1976. During thelast 34 years, all the data have been entered prospectively intoa national database. In total 2444 patients are included in thestudy. Half of the patients were initially operated during thebeginning of the period. During the last part of the period 90%of patients with tumors 20 mm extrameatally or smaller wereallocated to wait & scan with repetitive MR scans.
P92 Otolaryngology-Head and Neck Surgery, Vol 143, No 2S2, August 2010
