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Fred F Telischi

Publications and source records attributed to Fred F Telischi.

At least 19 recordsLinked to original sources
PubMed2006

A model of real time monitoring of the cochlear function during an induced local ischemia.

The aim of this study was to investigate the utility of distortion product otoacoustic emissions (DPOAEs) in intraoperative monitoring (IM) of cochlear ischemic episodes in animals during internal auditory artery (IAA) compression. The IAA was exposed using the posterior fossa approach and then compressed for 3 and 5 min intervals to effect ischemia. DPOAE amplitudes and phases were measured at 4, 8, and 12 kHz geometric mean frequency (GMF). In each monitored ear, laser-Doppler cochlear blood flow (CBF) was measured. All IAA compressions resulted in rapid decrease of DPOAE amplitude and CBF, with simultaneous DPOAE phase increase. DPOAE phase changes were found to increase consistently within several seconds of IAA compression, while corresponding DPOAE amplitudes changed more slowly, with up to 30-40 s delays. Following IAA release, DPOAEs at 12 kHz GMF were characterized by longer delays in returning to baseline than those measured at lower frequencies. In some cases, CBF did not return to baseline. In this animal model, DPOAEs were found to be sensitive measures of cochlear function during transient cochlear ischemic episodes, suggesting the utility of DPOAE monitoring of auditory function during surgery of cerebello-pontine angle tumors.

Animals↗
PubMed2006

Conservation of residual acoustic hearing after cochlear implantation.

OBJECTIVE: This study was designed to test the hypothesis that partial hearing conservation is attainable after cochlear implantation with a long perimodiolar electrode. Surgical strategies for hearing conservation during cochlear implantation are described. STUDY DESIGN: Prospective, single-subject, repeated-measures design. SETTING: Academic tertiary care center. PATIENTS: Twenty-eight severely to profoundly hearing-impaired adult cochlear implant recipients who had some measurable hearing preoperatively. INTERVENTION: Cochlear implantation using Nucleus Freedom Contour Advance electrode. MAIN OUTCOME MEASURES: Preimplant and postimplant pure-tone thresholds and speech recognition scores were obtained to determine the incidence and degree of conserved hearing at a mean interval of 9 (+/-3.9) months. RESULTS: Thirty-two percent of subjects experienced complete conservation of hearing (0- to 10-dB loss), and 57% experienced partial conservation of hearing (>11 dB) after implantation. However, open-set speech recognition was partially conserved in only one subject. Cochlear implant performance was not better in patients with conservation of residual hearing. CONCLUSION: Conservation of pure-tone hearing was possible in 89% of implanted patients; however, residual speech perception was not conserved with this long perimodiolar electrode. A ceiling effect tends to inflate the prevalence of hearing conservation in implantation studies of severely to profoundly hearing-impaired patients.

Adult↗
PubMed2006

Use of neural response telemetry measures to objectively set the comfort levels in the Nucleus 24 cochlear implant.

Cochlear implant programming necessitates accurate setting of programming levels, including maximum stimulation levels, of all active electrodes. Frequently, clinical techniques are adequate for setting these levels; however, they are sometimes insufficient (e.g., very young children). In the Nucleus 24, several methods have been suggested for estimation of comfort levels (C levels) from neural response telemetry (NRT); however, many require co-application of clinical measurements. Data was obtained from 21 adult Nucleus 24 recipients to develop reliable predictions of C levels. Multiple regression analysis was performed on NRT threshold, slope of the NRT growth function, age, length of deafness, length of cochlear implant use and electrode impedance to examine predictive ability. Only the NRT threshold and slope of the growth function measures were significant predictors yielding R2 values from 0.391 to 0.769. Results demonstrated that these measures may provide an alternative means of estimating C levels when other clinical measures are unavailable.

Adult↗
PubMed2005

Simultaneous measurement of electrocochleography and cochlear blood flow during cochlear hypoxia in rabbits.

In this study, a new monitoring system is developed to measure cochlear blood flow (CBF) and electrocochleography (ECochG) during transient ischemic episodes of the cochlea. A newly designed otic probe was used for the simultaneous recordings of laser-Doppler CBF and ECochG directly from the round window (RW). The probe enabled the recording of high amplitude compound action potentials (CAP) and cochlear microphonics (CM) with few averages. Experiments were conducted on rabbits to generate episodes of cochlear ischemia by using timed compressions of the internal auditory artery (IAA). The computer monitoring system extracted and measured CAP and CM components from ECochG in real-time. Results indicate that CM and CAP generally followed CBF during compressions and releases of IAA. Both CBF values and CAP amplitudes showed an overshoot following the reperfusion. CAP amplitude measures were found to be very sensitive to ischemia showing very rapid amplitude, latency and morphological changes. CM amplitude decreased more slowly than the CAP and CBF. Simultaneous recordings of CBF and ECochG using the otic probe provide a valuable neuromonitoring tool to investigate the dynamic behavior of the cochlea during ischemia.

Acoustic Stimulation↗
PubMed2005

Neuromonitoring of cochlea and auditory nerve with multiple extracted parameters during induced hypoxia and nerve manipulation.

A system capable of comprehensive and detailed monitoring of the cochlea and the auditory nerve during intraoperative surgery was developed. The cochlear blood flow (CBF) and the electrocochleogram (ECochGm) were recorded at the round window (RW) niche using a specially designed otic probe. The ECochGm was further processed to obtain cochlear microphonics (CM) and compound action potentials (CAP). The amplitude and phase of the CM were used to quantify the activity of outer hair cells (OHC); CAP amplitude and latency were used to describe the auditory nerve and the synaptic activity of the inner hair cells (IHC). In addition, concurrent monitoring with a second electrophysiological channel was achieved by recording compound nerve action potential (CNAP) obtained directly from the auditory nerve. Stimulation paradigms, instrumentation and signal processing methods were developed to extract and differentiate the activity of the OHC and the IHC in response to three different frequencies. Narrow band acoustical stimuli elicited CM signals indicating mainly nonlinear operation of the mechano-electrical transduction of the OHCs. Special envelope detectors were developed and applied to the ECochGm to extract the CM fundamental component and its harmonics in real time. The system was extensively validated in experimental animal surgeries by performing nerve compressions and manipulations.

Action Potentials↗
PubMed2005

Audiological features of GJB2 (connexin 26) deafness.

OBJECTIVE: The aim of the present study was to characterize audiological profiles in patients with GJB2 deafness DESIGN: We screened DNA from 399 individuals with nonsyndromic deafness for mutations in the connexin 26 gene (GJB2) by sequence analysis. A total of 77 (19%) of these deaf individuals were biallelic GJB2 mutations (either homozygous or compound heterozygous mutations) (GJB2 deafness). Using the audiological classification criteria of genetic deafness proposed by the European Workshop on Genetic Hearing Loss, we analyzed audiograms of these patients to characterize audiological features of the GJB2 deafness. In addition, we reviewed audiological data of 411 deafness cases from the literature providing details of audiological data (including 157 with GJB2 deafness). RESULTS: All categories of hearing loss severity were found, with significant differences in the findings from GJB2 cases: 1 (4.5%) of 22 individuals with mild hearing loss, 10 (13.3%) of 75 with moderate loss, 14 (14.9%) of 94 with severe loss, and 52 (25%) of 208 with profound deafness (Chi-square test, 3 df, p = 0.016). 81.6% of patients with GJB2 mutations had severe to profound loss, 18.4% with mild to moderate loss (Chi-square test, p = 0.014). The 235delC mutation was always associated with profound deafness. The main audiogram shapes found were residual/sloping (72.7%) and flat (23.4%). There were no differences in the severity and audiogram shapes of the hearing impairment between homozygous and compound heterozygous GJB2 deafness (Chi-square test, p > 0.05). CONCLUSIONS: Our study shows that the probability of finding biallelic GJB2 mutations increases with the severity of hearing loss. Audiograms associated with GJB2 deafness were usually nonspecific. Patients with unknown causes of severe or profound hearing loss should be routinely tested for GJB2 mutations, but due to the variability in hearing loss, individuals with lesser degrees of hearing loss should not be precluded from testing.

Adolescent↗
PubMed2005

Pattern of hearing loss in a rat model of cochlear implantation trauma.

HYPOTHESIS: Trauma caused by cochlear implant electrode insertion is attributable to the combination of direct physical trauma and the delayed cell death of oxidative stress-injured auditory sensory cells. BACKGROUND: Histologic evaluation of cochlear implant electrode trauma has demonstrated that the extent of sensory cell losses is proportional to the degree of injury. However, the impact of delayed oxidative stress within injured cochlear tissues and the progressive loss of injured hair cells by way of apoptosis are at present unknown. METHODS: Laboratory rats were evaluated for hearing acuity before and after electrode insertion, before and after round window membrane incision only. Hearing was measured before trauma or incision and over the next 7 days. Objective measurements of hearing function were distortion products of otoacoustic emissions (DPOAEs) in the frequency range of 2 to 32 kHz and tone-burst (i.e., 4-32 kHz) evoked auditory brain stem responses (ABRs). RESULTS: For the experimental cochleae, there were progressive increases in ABR thresholds and decreases in ABR amplitudes. The amplitude of the DPOAEs in the experimental cochleae also showed progressive decreases. For the contralateral control and round window membrane surgical control ears, there were no significant changes in either DPOAE or ABR thresholds. CONCLUSION: These results document a progressive loss of hearing acuity postimplantation and strongly suggest that electrode insertion trauma generated oxidative stress within injured cochlear tissues.

Animals↗
PubMed2005

Facial nerve stimulation after cochlear implantation.

OBJECTIVES: This study was designed to compare the incidence and nature of facial nerve stimulation (FNS) in patients receiving cochlear implants (CI) manufactured by Cochlear Corporation, Advanced Bionics Corporation, and MedEl. STUDY DESIGN: Retrospective chart review at a tertiary referral center. METHODS: The charts of 600 patients who received CIs from 1993 to 2003 with at least 1 year of follow-up were reviewed for significant FNS (FNS on at least 1 channel at functional stimulation levels). Data collected included age, sex, etiology of deafness, device type, electrode, FNS onset after initial stimulation, number and location of electrode contacts causing FNS, and loudness level at which FSN occurred. Nucleus straight and perimodiolar electrodes were also compared. RESULTS: Thirty-nine of 600 (6.5%) patients had FNS on at least one channel, (MedEl 3 of 43 [7.0%], Nucleus 29 of 440 [6.6%], and Clarion 7 of 117 [6.0%]). The incidence of FNS in Nucleus perimodiolar electrodes (16 of 250 [6.4%]) was similar to straight electrodes (13 of 190 (6.8%]), as was the mean number of electrodes causing FNS per patient (11 vs. 12). However, straight electrodes caused stimulation at significantly softer perceived loudness levels than perimodiolar electrodes (P < .0001). CONCLUSIONS: In this large series of CI FNS, the overall incidence of FNS is consistent with previous reports. All devices had a similar incidence of FNS, but perimodiolar electrodes produced FNS only at significantly higher loudness levels than straight electrodes, making them preferable for patients at risk for FNS receiving Nucleus devices.

Adolescent↗
PubMed2004

Evaluation of hearing and auditory nerve function by combining ABR, DPOAE and eABR tests into a single recording session.

In this article, we describe an efficient method for testing both auditory receptor and auditory nerve function in a single recording session. Auditory receptor function is tested in response to pure tone, tone burst and click acoustic stimuli (i.e. distortion products of otoacoustic emissions, DPOAE; and auditory-evoked brainstem responses, ABR). The function of the auditory neurons and nerve is measured in response to direct electric current stimulation (i.e. electrically evoked auditory brainstem responses, eABR). All measurements were obtained from anesthetized laboratory rats during single recording sessions using hardware and software stimulation and analysis programs developed by Intelligent Hearing Systems, Miami, FL.

Acoustic Stimulation↗
PubMed2004

Changes in programming over time in postmeningitis cochlear implant users.

OBJECTIVE: Although successful cochlear implantation of patients with deafness following meningitis is expected, long-term stability of electrical current requirements has not been systematically evaluated. This study evaluated changes in programming for patients deafened by bacterial meningitis and stability of auditory performance over time. STUDY DESIGN AND SETTING: In this retrospective descriptive study, cochlear implant (CI) stimulation mode and performance of 14 patients deafened by meningitis were compared with those of an age-matched control group of patients deafened by other causes. RESULTS: There were no significant differences in mean performance between the meningitis group and control group (P > 0.05). However, the postmeningitis group required progressively higher stimulation levels and higher programming modes over time as compared to the control group. CONCLUSIONS: Even with deafness accompanied by labyrinthine ossification attributed to meningitis, neural elements were present and could be stimulated. Because increasing levels of stimulation were required over time, postmeningitic children with CIs, and those with cochlear ossification in particular, may need frequent programming adjustments to maintain performance. SIGNIFICANCE: These patients need close follow-up of stimulation levels and programming modes postoperatively in order to perform optimally with CIs. EBM RATING: B-3.

Adolescent↗
PubMed2004

Vestibular effects of cochlear implantation.

OBJECTIVES/HYPOTHESIS: Cochlear implantation (CI) carries with it the potential risk for vestibular system insult or stimulation with resultant dysfunction. As candidate profiles continue to evolve and with the recent development of bilateral CI, understanding the significance of this risk takes on an increasing importance. STUDY DESIGN: Between 1997 to 2001, a prospective observational study was carried out in a tertiary care medical center to assess the effects of unilateral CI on the vestibular system. METHODS: Assessment was performed using the dizziness handicap inventory (DHI), vestibulo-ocular reflex (VOR) testing using both alternate bithermal caloric irrigations (ENG) and rotational chair-generated sinusoidal harmonic accelerations (SHA), and computerized dynamic platform posturography (CDP) at preoperative, 1-month, 4-month, 1-year and 2-year postimplantation visits. CI was carried out without respect to the preoperative vestibular function test results. RESULTS: Specifically, 86 patients were entered into the study after informed consent. For the group as a whole, pair wise comparisons revealed few significant differences between preoperative and postoperative values for VOR testing (ENG and SHA) at any of the follow-up intervals. Likewise, DHI testing was also unchanged except for significant reductions (improvements) in the emotional subcategory scores at both the 4-month and 1-year intervals. CDP results demonstrated substantial improvements in postural sway in the vestibular conditions (5 and 6) as well as composite scores with the device "off" and "on" at the 1-month, 4-month, 1-year, and 2-year intervals. Device activation appeared to improve postural stability in some conditions. Excluding those patients with preoperative areflexic or hyporeflexic responses in the implanted ear (total [warm + cool] caloric response or=21 deg/s maximum slow phase velocity) in total caloric response were observed for 8 (29%) patients at the 4-month interval. These persisted throughout the study period. These changes were accompanied by significant low frequency phase changes on SHA testing confirming a VOR insult. Of interest, no significant changes were detected in the DHI or CDP, and there were no effects of age, sex, device manufacturer, or etiology of hearing loss (HL) for these patients. CONCLUSIONS: Unilateral CI rarely results in significant adverse effects on the vestibular system as measured by the DHI, ENG, SHA, and CDP. On the contrary, patients that underwent CI experienced significant improvements in the objective measures of postural stability as measured by CDP. Device activation in music appeared to have an additional positive effect on postural stability during CDP testing. Although VOR testing demonstrated some decreases in response, patients did not suffer from disabling vestibular effects following CI. The mechanism underlying these findings remains speculative. These findings should be considered in counseling patients about CI.

Adolescent↗
PubMed2004

Intraoperative monitoring of cochlear function using distortion product otoacoustic emissions (DPOAEs) in patients with cerebellopontine angle tumors.

HYPOTHESIS: Intraoperative monitoring by distortion-product otoacoustic emissions reflects the cochlear function changes in the real-time domain during removal of cerebellopontine angle tumors. BACKGROUND: Cerebellopontine angle tumor surgery is associated with a significant risk of damaging internal auditory canal contents. Although monitoring facial nerve function intraoperatively has already been effectively developed, such efficacious monitoring of auditory function remains to be established. The aim of this study was to investigate the utility of distortion-product otoacoustic emissions for intraoperative monitoring of the cochlear function in humans during removal of cerebellopontine angle tumors. METHODS: Continuous intraoperative monitoring of distortion-product otoacoustic emissions was performed in 20 of 62 patients undergoing surgical removal of cerebellopontine angle tumors. All of these 20 patients, who underwent the retrosigmoid approach, had distortion-product otoacoustic emissions present preoperatively. Depending on the amplitude and frequency band at which distortion-product otoacoustic emissions were present, monitoring was carried out at 2.0 to 6.0 kHz with primary stimulus tone amplitudes of 60 to 70 dB sound pressure level. RESULTS: In patients operated on for cerebellopontine angle tumors, various patterns of distortion-product otoacoustic emission amplitude reductions and recoveries were observed. Distortion-product otoacoustic emissions recorded from the basal part of the cochlea (i.e., high frequencies) changed earlier and more profoundly than those from the middle and apical sections (i.e., lower frequencies). In some cases, cochlear function was affected irreversibly as reflected by loss of distortion-product otoacoustic emissions. Microcoagulation of small vessels, tumor debulking, and compression or stretch of the internal auditory canal contents were found to be procedures affecting distortion-product otoacoustic emissions. The status of distortion-product otoacoustic emissions at the conclusion of tumor dissection correlated with postoperative hearing levels. CONCLUSION: Distortion-product otoacoustic emissions were used to monitor in the real-time domain auditory function during cerebellopontine angle tumor removal operations. The status of distortion-product otoacoustic emissions at the conclusion of the operations was related to postoperative hearing.

Adult↗
PubMed2003

Pediatric tympanoplasty: effect of contralateral ear status on outcomes.

OBJECTIVE: To assess the prognostic value of different variables on the outcome of pediatric type I tympanoplasty. DESIGN: Retrospective review of medical records. SETTING: An otolaryngology department in a large urban tertiary care medical center. PATIENTS: We reviewed 72 ears in 60 patients who had undergone a type I tympanoplasty from 1987 to 2000. Patient ages ranged from 3 to 18 years. INTERVENTIONS: Type I tympanoplasty. MAIN OUTCOME MEASURES: We identified the following 3 criteria for success: (1) healing of the neotympanic graft; (2) healing of the graft with a postoperative air-bone gap of no greater than 20 dB; and (3) healing of the graft with aeration of the middle ear space. RESULTS: Healing occurred in 59 (82%) of the 72 neotympanic grafts; 39 (83%) of the 47 healed ears for which a postoperative audiogram was available had an air-bone gap of no greater than 20 dB; and 49 (83%) of the 59 healed ears had a normally aerated middle ear space. A statistically significant difference in the rate of graft healing was identified for large perforations (76%), as well as for creation of an aerated middle ear space, when there was evidence of ongoing contralateral eustachian tube dysfunction (ie, otitis media with effusion or negative middle ear pressure, but not a perforation). CONCLUSIONS: Pediatric type I tympanoplasty can offer reasonably good chances for postoperative graft healing, serviceable hearing, and creation of an air-containing middle ear space if performed in carefully selected patients. Caution should be exercised in performing tympanoplasty in children with evidence of ongoing eustachian tube dysfunction, as evidenced by otitis media with effusion and negative middle ear pressure, but not perforations, in the contralateral ear.

Adolescent↗
PubMed2003

Role of mannitol in reducing postischemic changes in distortion-product otoacoustic emissions (DPOAEs): a rabbit model.

OBJECTIVES: The aim of this study was to observe the effects of mannitol, administered topically at the round window (RW), on cochlear blood flow (CBF) and distortion-product otoacoustic emission (DPOAE) after repeated episodes of cochlear ischemia. METHODS: Ten young rabbits were used for this study. Reversible ischemic episodes within the cochlea were induced by directly compressing the internal auditory artery (IAA). CBF was measured using a laser-Doppler (LD) probe positioned at the RW niche. DPOAEs were measured at 4, 8, and 12 kHz geometric mean frequency (GMF) using 60 dB sound pressure level (SPL) primary tone stimuli. In five test ears, mannitol was administered topically at the RW for 30 minutes before the IAA compressions. In five control ears, the IAA compressions were undertaken without application of RW medication. Each ear underwent three 5 minute IAA compressions with a 60 minute rest period between compressions. RESULTS: In the control animals, it was observed that a progressive reduction in DPOAE level followed each successive IAA compression at all three test frequencies. The reduction in DPOAE amplitudes was consistently greater at the higher test frequencies. In the test rabbits, the RW administration of mannitol resulted in significantly less reduction in DPOAE level measures after repeated IAA compressions. For example, 30 minutes after reperfusion at 12 kHz GMF, DPOAE levels in the control ears were reduced by 1.5, 6.0, and 16 dB, compared with 1.5, 4.0, and 6.0 dB in the mannitol test ears. CONCLUSIONS: Mannitol appears to exert a protective effect on cochlear function after periods of ischemia. The RW appears to be an efficacious route for topical administration of mannitol into the inner ear.

Acoustic Stimulation↗
PubMed2003

Preventing internal auditory artery vasospasm using topical papaverine: an animal study.

BACKGROUND: Internal auditory artery (IAA) spasm is thought to be one of the causes of postoperative sensory hearing loss after attempted hearing preservation removal of an acoustic neuroma. The use of topical papaverine, a nonspecific vasodilator, to prevent vascular insufficiency to the inner ear and to improve hearing outcomes has been suggested but not proven. MATERIALS AND METHODS: Vasospasm was mechanically induced by compressing the IAA in the control ears of six rabbits after application of topical saline. The subsequent reduction of cochlear blood flow (CBF) was measured using a laser-Doppler (LD) flow-monitoring technique. Functional loss of cochlear activity was verified with distortion product otoacoustic emissions (DPOAE). The contralateral experimental ears were treated with the topical application of papaverine directly to the IAA and cochleovestibular nerve complex. CBF and DPOAE were compared between the control and papaverine treated ears for 3-minute and 5-minute IAA compressions. RESULTS: Every control ear demonstrated some degree of postcompression IAA vasospasm (i.e., reduced CBF) and reduction of DPOAE. Nearly complete recovery of CBF and DPOAE to baseline was observed in all of the papaverine treated ears. CONCLUSIONS: An animal model of IAA vasospasm was described. Mechanically induced vasospasm of the IAA was prevented by the topical application of papaverine. These findings have clinical implications for surgical procedures involving the internal auditory canal/cerebellopontine angle such as acoustic neuroma removal.

Administration, Topical↗
PubMed2002

The prevalence of connexin 26 ( GJB2) mutations in the Chinese population.

Mutations in GJB2, encoding gap junction beta 2 protein (connexin 26), are responsible for the commonest form of non-syndromic recessive deafness in many populations. It has been reported recently that the most common 35delG mutation in GJB2 is exceptionally low in Japanese and Korean populations, but another deletion, 235delC, is relatively frequent. Since the Chinese constitute approximately one fifth of the global population, the frequency of GJB2 mutations in the population has important implications for understanding worldwide causes of genetic deafness. To determine whether GJB2 mutations are an important cause of deafness in Chinese, we conducted mutation screening for GJB2 in 118 deaf Chinese probands, including 60 from simplex and 58 from multiplex families with non-syndromic deafness, and 150 normal hearing Chinese controls. Four mutations, including 235delC, 299-300delAT, V37I, and 35delG, were found in the patients. Thirty-nine percent of the probands had a GJB2mutation. Of the 118 probands, 19 carried two definitely pathogenic mutations: three among the 58 multiplex cases (5.2%) and 16 among the 60 simplex cases (26.7%). Twenty-seven probands (22.9%) were found to carry only single GJB2 mutations. None of them had mutations in exon 1 of GJB2 and or the 342-kb deletion of GJB6. The 235delC mutation was the most prevalent mutation (20.3% of alleles), accounting for 81% of the pathologic alleles in multiplex cases and 67% in simplex cases. Analysis of the affected haplotypes in the patients with the homozygous 235delC mutation yielded evidence for a single origin of the mutation. The carrier frequency of the 235delC mutation in control subjects with normal hearing was 1.3%. The 35delG mutation was only noted as a heterozygous change in two simplex cases (1.2% of alleles). These results indicated that mutations in GJB2 are a major cause of inherited and sporadic congenital deafness in the Chinese population. The 235delC mutation, rather than 35delG, is the most common mutation found in the Chinese deaf population. Our data support the view that specific combinations of GJB2 mutation exist in different populations.

Alleles↗
PubMed2002

Distortion-product otoacoustic emissions in nonacoustic tumors of the cerebellopontine angle.

OBJECTIVES: The goal of the present study was to compare the frequencies of cochlear and non-cochlear patterns of distortion-product otoacoustic emissions (DPOAEs) in patients with nonacoustic (non-AN) tumors of the cerebellopontine angle (CPA)/internal auditory canal with those in patients with acoustic neuroma (AN). STUDY DESIGN AND SETTING: We conducted a prospective study of patients with non-AN internal auditory canal/CPA tumors treated between 1992 and 1999 in a tertiary care setting. We collected data on behavioral pure tone average, speech discrimination score, acoustic immittance tests, DPOAEs, and tumor size. DPOAEs were divided into those with a cochlear or a noncochlear pattern. Comparisons were made with a control group of patients with AN of the CPA. RESULTS: Twenty-four patients were included in the study: 12 patients in the non-AN group and 12 patients in the AN group. In the non-AN group, 5 (42%) patients had a cochlear pattern and 7 (58%) had a noncochlear pattern. In the AN group, 7 (58%) patients had a cochlear pattern and 5 (42%) had a noncochlear pattern. The differences between the non-AN and AN groups were statistically significant. In the non-AN group, patients with a cochlear-pattern DPOAE had significantly smaller tumors (P = 0.03) and a trend (P = 0.07) toward higher speech discrimination score. Age and pure tone average were not significantly different in the non-AN tumor patients. In the AN group, none of the study parameters were significantly related to the pattern of DPOAE. CONCLUSIONS: ANs appear to differ from other tumors of the CPA in their propensity to cause sensory versus neural hearing loss. A larger series of patients would be useful to confirm these preliminary findings.

Adolescent↗