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PubMed1991

The choice of ABR click polarity and amplitude variables in multiple sclerosis patients.

Evoked brainstem responses (ABR) to 75 dB nHL condensation (C), rarefaction (R), and alternating (A = C+R) clicks were investigated in healthy subjects and in patients with multiple sclerosis. A new wave IV-V 'shape ratio' (SR IV-V) was most sensitive. SR IV-V correlated most strongly with clinical MS classification, and seemed to be rather specific for retrocochlear dysfunction. Wave IV-V amplitude was also more sensitive than the common IV-V amplitude ratio. The variability of latencies and interpeak latencies was lower in ABR to A clicks than in ABR to either R or to C clicks. In patients, fewer subcomponents were found in ABR to A than in ABR to R and C clicks. ABR to A clicks were on the average slightly more sensitive than either C or R click ABR. Our results suggest that both A-mode ABR and the 'dispersion' variable SR IV-V can be used without significant problems in the diagnosis of brainstem demyelination. A test protocol which requires ABR to both C and R clicks to be abnormal, will, however, be less sensitive, though probably more specific.

Acoustic Stimulation↗

PubMed1987

Sensitivity and specificity of brain stem potentials as a means of differentiating cochlear and retrocochlear disorders (acoustic neuromas).

Between 1980 and 1985 we examined a fairly large group of patients for retrocochlear disorders. Every patient was examined by at least two procedures, registration of brain stem potentials and CT; we had also magnetic resonance images taken of some of these patients. We diagnosed a total of 37 acoustic neuromas in 34 of the patients examined. From our study a conclusion can be drawn about the sensitivity and specificity of brain stem potentials as evidence of an acoustic neuroma. The rate of false negative diagnoses is about 6%. The false positive rate is considerably higher, and it is discussed in detail. The clinical utility of brain stem potentials is illustrated with two case histories. Because of the method's low false negative rate, cochlear disorders diagnosed by registering brain stem potentials need not as a rule be confirmed by modern imaging procedures.

Adult↗

PubMed2006

Molecular bases of hearing loss in multi-systemic mitochondrial cytopathy.

PURPOSE: Hearing loss is a common clinical feature in classic mitochondrial syndromes. The purpose of this study was to evaluate the diverse molecular etiologies and natural history of hearing loss in multi-systemic mitochondrial cytopathies and the possible correlation between degree of hearing loss and neurological phenotype. METHODS: In this retrospective study we evaluated the clinical features and molecular bases of hearing loss associated with multi-systemic mitochondrial cytopathy. Forty-five patients with sensorineural hearing loss and definite diagnosis of mitochondrial cytopathy according to the published diagnostic criteria were studied. RESULTS: The sensorineural hearing loss was progressive and for the most part symmetrical with involvement of the higher frequencies. Both cochlear and retrocochlear involvement were found in this cohort. No correlation was found between the degree of hearing loss and the number and severity of neurological manifestations. Deleterious mtDNA point mutations of undisputed pathogenicity were identified in 18 patients. The A3243G mutation was the most frequently encountered among this group. MtDNA depletion, over-replication, and multiple deletions were found in further 11 cases. CONCLUSION: This study reveals an expanding spectrum of mtDNA abnormalities associated with hearing loss. No correlation was found between the degrees of hearing loss and the severity of neurological manifestations.

Adolescent↗

PubMed1992

Cochlear and neural dysfunction in acoustic neuroma: can they be separately revealed by auditory brain-stem wave V latency?

Cochlear and retrocochlear lesions may be differentiated by a diagnostic index (D5), which is derived from the patient's auditory brain-stem wave V latency and pure-tone hearing threshold at 2 to 4 kHz. The D5 values obtained from 49 cases of acoustic neuroma (AN) have been shown to share some properties with D5 values of patients with cochlear hearing loss (280 cases), indicating a lesser prolongation of wave V latency in cases with pronounced hearing loss. Assuming this finding is indicative of some degree of cochlear impairment concomitant to the neural dysfunction, AN data were corrected in an attempt to remove the effects of cochlear impairment. The resulting D5 values could reflect the delay in wave V solely due to the neural dysfunction. A significant relationship between these D5 values and tumour size seems to support this hypothesis.

Adult↗

PubMed1984

Considerations in the differentiation between brainstem lesions and sensori-neural hearing loss using auditory nerve-brainstem evoked responses.

When auditory nerve-brainstem evoked responses are used in neurological diagnosis, an important response parameter to be evaluated is brainstem transmission time - the time interval between the auditory nerve response (wave 1) and the response from the rostal brainstem (wave P4). Occasionally the only response wave present is wave P4 and its latency is prolonged. This can be compatible with a conductive or a sensorineural hearing loss (SNHL), or a neurological (brain stem) lesion such as a retrocochlear hearing loss (RCHL). A conductive hearing loss can be excluded by otoscopic, audiometric and tympanometric examination. In order to differentiate between SNHL and RCHL, several techniques have been suggested in order to enhance the visibility of wave 1, but these are not always applicable or successful. In this study, P4 latency was plotted as a function of the audiometric hearing loss at 4 kHz for 26 ears with SNHL only. From this, the correlation coefficient (r = 0.71) was calculated along with the linear regression equation and the standard error of the prediction. This gave an estimation of the range of P4 latency to be expected for a given SNHL for comparison with the actual latency obtained in patients with neurological complaints. An actual latency greater than the expected latency range would be considered corroboratory of a RCHL. Several clinical examples are presented. These considerations also point out the need to bear in mind the otological context of these evoked responses even when used in neurological diagnosis.

Audiometry↗

PubMed1993

The effect of hearing loss on ABR interpretation: use of a correction factor.

Patients suspected of retrocochlear disorders often have abnormal ABRs in the presence of high-frequency hearing loss, making clinical decisions difficult. In a retrospective study of the ABR test results of 1539 patients, the false-positive and false-negative rates for ABR are presented as a function of hearing loss at 4000 Hz, both before and after using Selters and Brackmann's correction factor for hearing loss. For patients with more than 50 db HL at 4000 Hz the false-positive and false-negative rates, uncorrected for hearing loss, were 25.0% and 2.9% respectively, and when the correction factor was used were 12.5% and 5.8%. When hearing loss at 4000 Hz was over 90 dB the ABR was abnormal in 75% of nontumor patients. Conclusions are that a correction factor for hearing loss is helpful with reservations, and that ABR is not a useful test when 4000 Hz hearing loss is greater than 90 dB HL and 2000 Hz is greater than 75 dB HL.

Adolescent↗

PubMed2007

Potential ototoxicity of aluminum in hemodialysis patients.

OBJECTIVES/HYPOTHESIS: Aluminum (Al) is a neurotoxin in both human and animal models. Al accumulation is usually observed in patients with end-stage renal disease (ESRD). To clarify whether Al also exhibits toxic effects on the specified neural organ of inner ear, we recruited hemodialysis (HD) patients to investigate the effect of serum Al level on the auditory physiology. STUDY DESIGN: Forty patients in maintenance HD as well as 40 age-matched healthy subjects without hearing complaints were enrolled. The auditory function tests, including pure-tone audiometry (PTA), distortion-product otoacoustic emissions (DPOAEs), and auditory brainstem response (ABR) were performed in all subjects. The serum Al levels determined within 3 months of auditory tests were used for analysis. RESULTS: High-frequency hearing impairment was the predominant auditory dysfunction in HD patients who showed worse high-tone hearing level on PTA and diminished amplitudes of DPOAEs at 3 K and 4 K as compared with the controls (P < .001). Age was a significant factor determining the auditory dysfunction in both HD patients and control subjects. After age correction, serum Al level correlated reversely with the amplitude of DPOAEs-2 K (P = .002), but not with amplitudes of DPOAEs-3 K, -4 K, hearing levels on PTA, or wave latencies on ABR. CONCLUSION: High-frequency hearing impairment is a common presentation in HD patients. Serum Al level correlates reversely with the amplitude of DPOAEs-2 K but not those of DPOAEs-3 K, -4 K, hearing levels on PTA, and wave latencies on ABR. Possibly, the correlation between the Al level and the high-frequency OAE results was obscured by the significantly diminished amplitudes of DPOAEs-3 K, -4 K in ESRD patients. These results implicate that the effect of Al is mainly of cochlear origin rather than of retrocochlear origin.

Adult↗

PubMed2002

[The status of auditory function in auditory neuropathy].

OBJECTIVE: To study the status of auditory function and the site of lesion in auditory neuropathy. METHOD: The data of 65 patients were analyzed including the clinic signs, pure tone audiometry, auditory brainstem response(ABR), 40 Hz auditory event related potential(40 Hz AERP) and otoacoustic emissions (OAEs). RESULT: The low frequency hearing loss in auditory neuropathy arose from the lesion of retrocochlear auditory afferent and efferent nerve and auditory brainstem, presented at the abnormality of acoustic reflex, efferent suppreSsion, ABR and the unparallel relationship between evoked OAE amplitude and pure tone threshold. To corresponding, the outer hair cells in low frequency region were out of suppression, presented at the strong response of SOAE, TEOAE and DPOAE in low frequency region. The high frequency hearing loss in auditory neuropathy arose from the lesion of cochlear outer hair cells, presented at the parallel relationship between DPOAE amplitude and pure tone threshold in high frequency region. The intermediate frequency hearing loss in auditory neuropathy was damaged gently or close to normal, presented at both pure tone threshold and DPOAE amplitude nearby 2 kHz were close to normal. CONCLUSION: The dysfunction in differ degree lied in the afferent and efferent nervous systems and cochlear level in auditory neuropathy, the main site of lesion was in the cochlear afferent and efferent nerve, up to the brainstem and down to the cochlea.

Adolescent↗

PubMed2002

Management of cholesterol granulomas of the petrous apex based on clinical and radiologic evaluation.

OBJECTIVE: The purpose of this study was to analyze the imaging characteristics of 12 cholesterol granulomas as a function of their clinical symptoms. The results of the different surgical approaches and the management of these lesions are discussed. STUDY DESIGN: Retrospective case review. SETTING: Five tertiary referral centers. PATIENTS: Twelve patients managed for a cholesterol granuloma of the petrous apex. INTERVENTIONS: All patients were evaluated via computed tomography and magnetic resonance imaging. Eight patients required surgical drainage: through a conservative approach in seven patients (infralabyrinthine, n = 5; infracochlear, n = 2) and a transotic approach in one patient. Clinical and radiologic follow-up without surgery was the mode of treatment for four patients. The mean follow-up period was 18 months for patients who underwent operations and ranged from 6 months to 10 years for patients without operations. RESULTS: Four patterns of clinical symptoms were noted: retrocochlear signs by an involvement of the internal auditory meatus (n = 8), headaches by a traction of the dura (n = 4), serous otitis media by a compression of the eustachian tube (n = 2), and asymptomatic lesions with no involvement of the adjacent structures (n = 2). Hearing and facial functions were preserved in all the cases treated by a noninvasive procedure. No recurrence or complication was reported in the patients who underwent operations. None of the noninvasively treated patients with cholesterol granulomas showed significant enlargement on follow-up imaging. CONCLUSION: Clinical manifestations of cholesterol granulomas depend on their anatomic location and the involvement of the adjacent structures. Aggressive lesions in patients with residual hearing can be drained via an infralabyrinthine or an infracochlear approach with minimal morbidity. Follow-up must be preferred for patients with nonaggressive lesions. Although magnetic resonance imaging provides a specific diagnosis tool for cholesterol granulomas, computed tomography is essential for an accurate evaluation of the location of the cyst and choice of the surgical procedure.

Adolescent↗

PubMed2003

Transmeatal cochlear laser (TCL) treatment of cochlear dysfunction: a feasibility study for chronic tinnitus.

Low-level-laser-therapy (LLLT) targeting the inner ear has been discussed as a therapeutic procedure for cochlear dysfunction such as chronic cochlear tinnitus or sensorineural hearing loss. Former studies demonstrate dose-dependent biological and physiological effects of LLLT such as enhanced recovery of peripheral nerve injuries, which could be of therapeutic interest in cochlear dysfunction. To date, in patients with chronic tinnitus mastoidal and transmeatal irradiation has been performed without systematic dosimetric assessment. However, light-dosimetric studies on human temporal bones demonstrated that controlled application of laserlight to the human cochlea depends on defined radiator position within the external auditory meatus. This feasibility study first presents a laser application system enabling dose-controlled transmeatal cochlear laser-irradiation (TCL), as well as preliminary clinical results in patients with chronic cochlear tinnitus. The novel laser TCL-system, consisting of four diode lasers (lambda=635 nm-830 nm) and a new specific head-set applicator, was developed on the basis of dosimetric data from a former light-dosimetric study. In a preliminary clinical study, the TCL-system was applied to 35 patients with chronic tinnitus and sensorineural hearing loss. The chronic symptoms persisted after standard therapeutic procedures for at least six months, while retrocochlear or middle-ear pathologies have been ruled out. The patients were randomised and received five single diode laser treatments (lambda=635 nm, 7.8 mW cw, n=17 and lambda=830 nm, 20 mW cw, n=18) with a space irradiation of 4 J/cm2 site of maximal cochlear injury. For evaluation of laser-induced effects complete otolaryngologic examinations with audiometry, tinnitus masking and matching, and a tinnitus-self-assessment were performed before, during and after the laser-irradiation. The first clinical use of the TCL-system has been well tolerated without side-effects and produced no observable damage to the external, middle or inner ear. Changes of tinnitus loudness and tinnitus matching have been described. After a follow-up period of six months tinnitus loudness was attenuated in 13 of 35 irradiated patients, while two of 35 patients reported their tinnitus as totally absent. Hearing threshold levels and middle ear function remained unchanged. Further investigations by large double-blind placebo-controlled studies are mandatory for clinical evaluation of the presented TCL-system and its therapeutic effectiveness in acute and chronic cochlear dysfunction.

Chronic Disease↗

PubMed1993

[Giant mucocele of the paranasal sinuses with extension to the contralateral posterior cranial fossa and reversible retrocochlear deafness].

Report on a huge mucocele of the right maxillary sinus extending into the ethmoid and sphenoid sinuses, and protruding into the contralateral left posterior cranial fossa. The patient, a 45-year old male, had no history of paranasal sinus energy, nasal or paranasal symptoms. He went to his physician because of a slowly developing deafness in his left ear and because of episodes of loss of consciousness when blowing his nose. A reversible episode of vertigo and reversible paresis of the left abducent nerve 17 years previously, were later assumed to have been the first symptoms of endocranial extension of the mucocele. The diagnosis of a mucocele was made by MRI. MRI in T2 weighted spin-echo sequences is the best imaging technique for diagnosing a mucocele. The mucocele was treated primarily with endonasal surgery of the paranasal sinuses, using telescopes and an operating microscope. After opening the right maxillary sinus via the middle meatus liquid contents of the mucocele poured into the nasal cavity. The sack of the mucocele was removed partially. Three months later the patient was reoperated with a combined transfacial and endonasal approach, because of progression from partial hearing loss to total deafness. Postoperatively hearing improved nearly completely and compression of the pons and the posterior fossa had disappeared on MRI. It is concluded that in mucoceles no longer the extirpation of the sack, but endonasal marsupialization, using the operating microscope and telescopes, is the therapy of choice.

Audiometry, Evoked Response↗

PubMed1999

Safety and clinical performance of acoustic reflex tests.

OBJECTIVE: Safety and effectiveness of acoustic reflex tests are important issues because these tests are widely applied to screen for retrocochlear pathology. Previous studies have reported moderately high sensitivity and specificity for detection of acoustic neuroma. However, there have been reports of possible iatrogenic hearing loss resulting from acoustic reflex threshold (ART) and decay (ARD) tests. This study assessed safety and clinical performance of ART tests for detection of acoustic neuroma. DESIGN: We report a case in which ARD testing resulted in a significant bilateral permanent threshold shift. This case was the impetus for us to investigate the clinical utility of ART and ARD tests. We analyzed sensitivity and specificity of ART, as well as asymmetry in pure-tone thresholds (PTT) for detection of acoustic neuroma in 56 tumor and 108 non-tumor ears. RESULTS AND CONCLUSIONS: Sensitivity and specificity were higher for PTT asymmetry than for ART. Ipsilateral ART at 1000 Hz had poor sensitivity and specificity for detection of acoustic neuroma, and involves some potential risk to residual hearing for presentation levels higher than 115 dB SPL. Approximately half of the acoustic neuroma group had ipsilateral ARTs that would require administration of ARD tests at levels exceeding 115 dB SPL. Therefore, we conclude that PTT asymmetry is a more effective test for detection of acoustic neuroma, and involves no risk to residual hearing. Future studies of contralateral reflex threshold and ARD in combination with PTT asymmetry are recommended.

Adult↗

PubMed1992

Effects of aircraft noise on hearing and auditory pathway function of airport employees.

The effects of aircraft noise on hearing and auditory pathway function were studied in 112 airport employees, both by audiometry and brainstem auditory evoked potentials (BAEPs) to evaluate cochlear function and to verify the possibility of retrocochlear involvement. Employees were divided into five groups according to their daily jobs. Group A was made up of 23 maintenance workers, Group B of 20 firemen, Group C of 24 policemen, Group D of 34 airline ground staff, and Group E of 14 civil servants. The typical audiogram pattern of noise-induced hearing loss (NIHL) was a dip at 3 or 4 kHz and moderate hearing loss in the frequency range of 6 to 8 kHz. The results of audiograms in this study revealed the prevalence rate of high-frequency loss in all employees was 41.9%. The incidences of NIHL were highest in the groups of maintenance workers (65.2%) and firemen (55.0%), who are almost continuously exposed to aircraft noise. As for the BAEPs, both click threshold and latencies showed that the impairment was most severe in the groups of maintenance workers and firemen. There was prolongation in central conduction time, shown mainly in intervals of I-V and III-V. This suggests that involvement of the central auditory pathway, especially between the pons and midbrain, is present. In summary, the degree of auditory damage coincided with job patterns. Furthermore, damage of both peripheral cochlear organs and the central auditory pathway by high-frequency aircraft noise exposure was confirmed.

Adult↗

PubMed1981

On the use of click-evoked electric brainstem responses in audiological diagnosis. III. Latencies in cochlear hearing loss.

The basis for the use of click-evoked BSER in neurotologic differential diagnosis would seem to be its sensitivity to retrocochlear but relative resistivity to cochlear lesions. The present study was performed in order to investigate the presumed robustness of BSER in cochlear hearing loss by recording BSER in 110 consecutive cochlear ears with click thresholds not in excess of 60 dB HL. There were eleven ears with rising, twenty-two ears with flat, and 77 ears with sloping audiograms. Click intensities were 80 dB HL and 60 dB SL, and the BSERs were observed for replicability and latencies of waves I, III and V, as well as for I-V and III-V interpeak intervals. Wave V latency increments (relative to normal values) were related to hearing thresholds at 4 kHz. Wave V was identifiable in all of the ears at 80 dB HL and/or 60 dB SL, whereas waves I and III often failed to appear at 80 dB HL and occasionally at 60 dB SL. At 80 dB HL click level, the wave V latency increment was related to the 4 kHz hearing loss (statistically significant at level 0.05 in the HF loss group), increasing by approximately 0.1 ms for each 10 dB, starting at 30 dB HL. Increasing click intensity to 60 dB SL tended to bring waves I and III into appearance and to offset the V latency increase (even inverting it in highly recruiting flat loss ears). Interpeak intervals were not significantly affected by cochlear hearing loss. Unfiltered alternating clicks were used after two initial experiments had shown that nothing would be gained in this study from using filtered clicks or uniphase unfiltered clicks.

Adolescent↗