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Results for “Retrocochlear Diseases”

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PubMed1994

Auditory temporal resolution in multiple sclerosis.

Disturbances of hearing in multiple sclerosis patients have been variably reported, likely because standard audiologic testing emphasizes assessment of peripheral, rather than central, auditory function. This study investigated a group of patients with multiple sclerosis (MS), prospectively selected on the basis of magnetic resonance imaging (MRI) scans. Five of these patients had demyelinating lesions that included the rostral auditory fibre tracts, while another seven patients had lesions restricted to brainstem auditory sites. A further four had no lesions in the distribution of their auditory pathways. A comprehensive battery of audiometric tests, including standard audiometry and retrocochlear testing, was performed. In addition, their findings on electrophysiologic testing, including auditory brainstem responses (ABR) and middle latency responses (MLR), were studied. Finally, their performances in gap detection and speech recognition in continuous and interrupted background noise were examined to assess their auditory temporal resolution. The MS patients were found to be selectively impaired under the interrupted masker of this speech-in-noise paradigm, confirming a temporal processing defect. Furthermore, these patients' performances suggested a predominant role of forebrain pathways in mediating auditory temporal resolution.

Adult↗

PubMedDate not supplied

Brainstem auditory evoked potentials following meningitis in children.

The report concerns findings for brainstem auditory evoked potentials (BAEPs) recorded in 116 children, aged between a few days and 7 years, having suffered from bacterial meningitis. 26% of cases occurred between birth and 6 months, 55% between 6 months and 2 years, and 19% after 2 years of age. Hemophilus was the most common bacteria (49%), followed by Pneumococcus (22%) and Meningococcus (15%). Neurological complications were found in 30% of the meningitis cases and accounted for 85% of all complications found. 29% of BAEPs were abnormal, of which 47% revealed transmission, 32% endocochlear and 21% retrocochlear impairment. Transmission impairment mainly occurred before the age of 2 years (88%), most frequently in meningococcus meningitis cases (44%), and independently of neurological complications. Retrocochlear impairment was found in association with neurological complications in 71% of cases. Endocochlear BAEP damage was found in 9.5% of cases, half of which were bilateral and total, representing cophosis: it was found at all ages, and without any particular associated neurological complication. Hemophilus was the commonest bacterial agent in endocochlear cases overall, with Pneumococcus underlying 50% of cophosis cases. The study shows BAEP recording in association with a clinical ear examination is useful following childhood bacterial meningitis, screening for definitive endocochlear and deafness, distinguishing total from partial hearing-loss and indicating suitable treatment.

Age Factors↗

PubMedDate not supplied

Auditory brain stem response results from 255 patients with suspected retrocochlear involvement.

Auditory brain stem response (ABR) evaluations were conducted on 255 patients with suspected retrocochlear involvement. Twenty-six patients (10%) had surgically confirmed tumors, and ABRs were abnormal in 25 (96%) of these cases. The remaining 229 patients had nontumor medical diagnoses, but 25% of these were found to have abnormalities in ABR recordings. The most common ABR abnormality in the nontumor patients was large wave V interaural latency difference, followed by no response or poor waveform resolution and delayed absolute wave V latency. Peripheral hearing loss, including decreased sensitivity at 2000 and 4000 Hz, appears to have influenced waveform morphology and component latency.

Brain Stem↗

PubMed1978

Recovery of eighth nerve function after cerebellopontine angle surgery.

Retrocochlear lesions cause typical patterns of hearing loss as detailed in special audiometric tests. Such losses, however, may be temporary deficits. Indeed, return to near normalcy following severely depressed auditory function is documented in this article. Conservative surgery on lesions influencing eighth nerve function should be considered. This is not to say that neoplasia can be partially removed, but rather that when tumors can be resected while preserving the cochlear nerve, this should be done inasmuch as good hearing levels may be restored.

Auditory Threshold↗

PubMed1989

[Role of evoked oto-acoustic emission as an objective test of cochlear function].

Evaluation of clinical application of evoked oto-acoustic emission (OAE) as an objective cochlear function test was studied in normal hearing subjects, retrocochlear and cochlear deafness cases. In normal hearing subjects, OAE responses showed good reproducibility while the minimum detectable level of OAE varied between subjects. We found that the interaural difference of minimum detectable level of OAE is the best indicator of cochlear damage. As both OAE and ECochG originate from the hair cells, we compared the behavior of OAE and ECochG in cases with retrocochlear deafness. We found that OAE exhibited the same behaviour as CM in ECochG in these cases. In cases of cochlear deafness, in spite of the recovery of the hearing thresholds to within normal levels, the minimum detectable level of OAE remained at an average of about 4. 4dB higher as compared to normal hearing subjects. This demonstrates that a minimal cochlear damage likely to go undetected by pure tone audiometry is detected by OAE measurement. We conclude that OAE must be added to the growing list of tests in the objective assessment of cochlear function.

Adolescent↗

PubMed2001

Progressive sensorineural hearing loss in children with mitochondrial encephalomyopathies.

OBJECTIVE: Mitochondrial disorders are responsible for a variety of neurological syndromes. Specific mitochondrial DNA mutations have been identified recently in some of these rare disorders. Clinical symptoms may occur in different organs to various extent; often they are associated with progressive hearing loss. The aims of this study were to determine incidence, onset, and characteristics of hearing loss in children with mitochondrial encephalomyopathies and to investigate a possible correlation between the degree of hearing loss and neurological symptoms. In addition, we investigated the prognostic value of hearing loss as a predictor of the disease. STUDY DESIGN: From August 1992 to September 1998, 29 patients ranging in age from 5 to 23 years (mean years) were studied. These children were hospitalized for diagnostic purposes in the neuropediatric department. METHODS: The mitochondrial disorder was diagnosed by clinical and laboratory testings, including analysis of the mtDNA. Audiological evaluation consisted of measurements of pure-tone and speech audiometry, tympanometry, and acoustic refle- threshold testing, auditory brainstem response, and evoked as well as distortion-product otoacoustic emissions. RESULTS: A sensorineural hearing loss was identified in 12 children. Three of these were diagnosed as having classic Kearns-Sayre syndrome; five as having multisystem KSS; two as having the syndrome of mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS); one as having KSS-MELAS overlap syndrome; and one as having Friedreich ataxia. Longitudinal testing was performed in seven children, and in all of them a progression of the hearing loss could be demonstrated. Audiological test results in all 12 children suggested cochlear as well as retrocochlear origin of the hearing loss presenting independently from the severity of hearing impairment. No correlation between the characteristics and degrees of hearing loss and the number and severity of clinical neurological symptoms could be found. CONCLUSIONS: The present study demonstrated a high incidence (42%) of sensorineural hearing loss in children with mitochondrial encephalomyopathies. The progressive nature of the hearing impairment was confirmed by a significant correlation between the duration in years and severity of hearing loss in the children. The hearing loss does not have a prognostic value for the progression of the disorder. Based on our findings, we recommend regular audiometric examinations in patients with mitochondrial disorders.

Acoustic Impedance Tests↗

PubMed1992

Tinnitus: imaging algorithms.

The causes of tinnitus can be grouped according to whether the noise is continuous or pulsatile, whether it is subjective or objective and whether there is a retrotympanic mass. Imaging algorithms can be based on these symptoms and signs. For patients with nonpulsatile tinnitus and a normal drum, magnetic resonance imaging is preferred if a retrocochlear lesion is suspected, whereas high-resolution computed tomography (HRCT) is recommended if a cochlear abnormality is likely. If a chronic inflammation in the middle ear is suspected, HRCT is the study of choice to differentiate cholesteatoma from chronic otitis media. If the bruit is objective and the tympanic membrane normal, selective cerebral angiography should be the initial investigation, because most such patients have an acquired vascular abnormality, usually a dural arteriovenous fistula. If there is pulsatile tinnitus and a retrotympanic mass, HRCT should be the first examination because this technique allows differentiation of a vascular variation, such as an aberrant carotid artery or jugular dehiscence, from a paraganglioma.

Algorithms↗

PubMed2002

Sudden deafness and anterior inferior cerebellar artery infarction.

BACKGROUND AND PURPOSE: Acute ischemic stroke in the distribution of the anterior inferior cerebellar artery (AICA) is known to be associated with vertigo, nystagmus, facial weakness, and gait ataxia. Few reports have carefully examined the deafness associated with the AICA infarction. Furthermore, previous neurological reports have not emphasized the inner ear as a localization of sudden deafness. The aim of this study was to investigate the incidence of deafness associated with the AICA infarction and the sites predominantly involved in deafness. METHODS: Over 2 years, we prospectively identified 12 consecutive patients with unilateral AICA infarction diagnosed by brain MRI. Pure-tone audiogram, speech discrimination testing, stapedial reflex testing, and auditory brainstem response were performed to localize the site of lesion in the auditory pathways. Electronystagmography was also performed to evaluate the function of the vestibular system. RESULTS: The most common affected site on brain MRI was the middle cerebellar peduncle (n=11). Four patients had vertigo and/or acute auditory symptoms such as hearing loss or tinnitus as an isolated manifestation from 1 day to 2 months before infarction. Audiological testings confirmed sensorineural hearing loss in 11 patients (92%), predominantly cochlear in 6 patients, retrocochlear in 1 patient, and combined on the affected side cochlear and retrocochlear in 4 patients. Electronystagmography demonstrated no response to caloric stimulation in 10 patients (83%). CONCLUSIONS: In our series, sudden deafness was an important sign for the diagnosis of AICA infarction. Audiological examinations suggest that sudden deafness in AICA infarction is usually due to dysfunction of the cochlea resulting from ischemia to the inner ear.

Adult↗

PubMed1982

ABR in eighth-nerve and brain-stem disorders.

Auditory brain-stem response (ABR) results are reported on three cases of acoustic tumors and two cases with brain-stem lesions. These cases highlight several considerations in the clinical use of ABR. The sensitivity of ABR to retrocochlear involvement in light of normal pure-tone hearing and cochlear hearing loss is shown in the first two cases. The third case shows the advantage of "contralateral" ABR testing and a unique effect of stimulus polarity. The use of an intensity function and high presentation rate procedures are shown to be helpful diagnostic procedures in case four. Case five shows bilateral ABR effects which correlate well with the degree of brain-stem involvement. In addition to the ABR data, audiologic, radiologic, and medical findings on these patients are also discussed.

Adult↗

PubMed1990

Hearing problems and hormonal disturbances in the elderly.

The most frequent hormonal diseases attracting audiological interest are hypothyroidism (myxodema) and diabetes mellitus. For many years these diseases have been considered to cause hearing disorders with the lesion located predominantly in the inner ear and central auditory pathways, resulting in sensorineural hearing loss. However, the causal relationship between hearing loss and hypothyroidism has been questioned, and thus a study was undertaken to elucidate this problem. A sample of hypothyroid patients (n = 15) with a median age of 76 years (range 61-92) underwent audiological examination before and after treatment with L-thyroxine (average 5 months; range 2-12), and re-examination (n = 13) after an observation period of average 40 months (range 32-46). No significant improvement in their hearing thresholds, speech reception thresholds or discrimination scores could be demonstrated, and the hearing ability in the hypothyroid patients did not differ significantly from that found in an age- and sex-matched population. In addition, histological investigation of the temporal bones from an 83-year-old woman with myxoedema showed no morphological changes or deposition of glycosaminoglycans. Audiological examinations in patients with insulin-dependent diabetes mellitus also show contradictory results. Therefore, the cochlear and retrocochlear hearing functions were evaluated in 20 patients with diabetic microangiopathy with a median age of 41 years (range 25-66), and in 19 patients without microangiopathy with a median age of 27 years (range 17-42). No significant differences in hearing thresholds or discrimination scores were present between the two diabetic groups, nor was any difference found between the diabetic patients and an age- and sex-matched population. In the patients with long-term insulin-dependent diabetes mellitus, brainstem audiometry revealed abnormal responses in 40%, indicating the presence of diabetic encephalopathy.

Aged↗

PubMedDate not supplied

The intra-aural muscle reflex in retrocochlear pathology: a model study in the rabbit.

An animal model for the evaluation of the acoustic stapedius reflex is described. The intra-aural muscle reflex in the rabbit can be recorded with a technique identical to that used in man. The validity and reproducibility of the measurements are good. Lesions in the reflex pathway were shown to be followed by changes in reflex properties. The type of alteration depended on the location of the damage. Lesions in the dorsal cochlear nucleus were not followed by reflex changes. Lesions in the ventral cochlear nucleus and/or the eighth nerve were followed by a rise of reflex threshold and often, but not always, by reflex decay. Lesions in the midline of the trapezoid body were followed by specific changes in the crossed reflex, whereas the ipsilateral reflex was unaffected. The advantage of making simultaneous ipsilateral and contraleral reflex recordings was pointed out.

Acoustic Stimulation↗

PubMed1997

Rare lesions of the posterior fossa with initial retrocochlear auditory and vestibular complaints.

OBJECTIVE: To catalog a series of rare lesions of the posterior fossa that appeared with unusual initial retrocochlear symptoms and signs and to make the reader more aware of these unusual lesions with a view to improving initial assessment and treatment planning. STUDY DESIGN: The study was a retrospective case review of seven patients. SETTING: Multidisciplinary team evaluation in a tertiary hospital referral center. PATIENTS: Patients with unusual lesions of the cerebellopontine angle and posterior fossa with initial retrocochlear symptoms and signs were included. INTERVENTIONS: Diagnostic and therapeutic. MAIN OUTCOME MEASURES: Hearing preservation and balance function. RESULTS: The rare lesions presented include two aneurysms of the anterior inferior cerebellar artery, one giant basilar artery aneurysm, and one each of the following neoplasms: endodermal cyst, choroid plexus papilloma, cavernous angioma, and ependymoma. CONCLUSIONS: A close working relationship among the otolaryngologist, neurotologist, neurosurgeon, and neuroradiologist is necessary to accurately evaluate these unusual cerebellopontine angle lesions and effect the best treatment outcome.

Adult↗

PubMed1977

Normal opaque cerebellopontine cisternogram.

An attempt has been made through this study to establish a tumor suspect pool of 100 patients, each one highly suspect because of a single or usually several strong clinical indicators of a retrocochlear lesion. In turn each patient has been proven tumor negative by virtue of a normal opaque cerebellopontine cisternogram. This has given us a unique opportunity to critically reassess the clinical indications of VIIIth nerve tumor from a reverse or negative viewpoint. All data from these patients has been carefully analyzed in relation to indication for opaque cisternography, clinical symptomatology, vestibular function, final etiologic diagnosis, and the associated special auditory tests, tomograph of the internal auditory canal, the associated vestibular aqueduct findings. This paper parallels our earlier study of 121 surgically proven schwannomas providing a total tumor suspect pool of 221 patients with a comparable tumor positive-tumor negative distribution.

Audiometry↗

PubMed1976

[Electrocochleography as a neurootological tool (author's transl)].

A series of 13 patients where surgery confirmed retrocochlear lesions in the cerebellopontine angle was tested preoperatively by electro-cochleography. The following conclusions can be drawn: 1. Compound action potentials (CAP) of the acoustic nerve could be registered by electro-cochleography in all patients regardless of the fact whether hearing on the side of the lesion could be demonstrated in pure tone audiometry or not. 2. The threshold latency for the 2 kHz sinustone-burst elicited compound action potential was within the normal range if hearing on the side of the lesion could be shown in pure tone audiometry. Threshold latency for 2 kHz CAP was shortened pathologically when hearing on the side of the lesion was absent in pure tone audiometry.

Action Potentials↗

PubMed2003

[Interaction between noise and ototoxic agents in the work environment].

There is a large number of well known substances, which exert an ototoxic effect in industrial settings. Ototoxic agents may be involved in many interactions with noise, the main factor responsible for the development of occupational hearing loss. Owing to the complexity of these relationships, their assessment is easier if controlled trials are carried out on animals. However, the results of experimental studies apply to high exposure levels, which are very rarely observed in industrial conditions. Data useful in estimating risks of hearing loss induced by industrial exposure are scarce. Until quite recently, the studies have focused on the combined effects of noise and chemicals of such groups as organic solvents, carbon monoxide or heavy metals. In the former group, a synergistic effects of noise and carbon disulfide as well as noise and toluene have been revealed at the cochlear level. Interactions between these chemicals and noise at the higher levels of the auditory system are most likely of an additive nature. Synergistic effect of carbon monoxide and noise may occur only at high concentrations of this substance. It is believed that the mechanism responsible for the interaction between carbon monoxide and noise depends on the hypoxemic effect of the former. A diminished access to oxygen exacerbates noise-induced metabolic disorders. However, it should be stressed that the nature of an interaction may be rather complex, because carbon monoxide (contrary to noise) also induces retrocochlear damage. As to the combined exposure to heavy metals and noise (range, 68-72 dB), the occurrence of cardiotoxic effects, not observed in single exposure to those agents, has been found in experimental studies. This may evidence a potentially wider range of possible interactions between toxic agents and noise not only in respect of the hearing organ. In further studies it seems essential to find out to what extent the effect of ototoxic agents should be taken into account in assessing the risk of hearing loss in industrial settings. If the effects of these agents in the work environment are taken into account then it will be necessary to verify the medical prevention criteria and hygiene norms regarding noise exposure.

Environment↗

PubMed1979

Audiologic evaluation of patients with localized intracranial lesions.

A battery of audiological tests for retrocochlear disorders was performed of 79 cases with localized intracranial lesions confirmed surgically or neurologically. The Type III trace of Békésy audiometry was found to originate from pathologies in the brainstem and the Type IV from abnormalities in the first neuron of the VIIIth nerve or in the brainstem. It was suggested that an unusually large amplitude peak in the Békésy tracing indicates a lesion in the temporal lobe. Large values of differential limen for short increment (DLSI) were found in patients with brainstem lesions. A good speech discrimination with a poor filtered speech discrimination apparently indicated supratentorial lesions. The binaural separation test using dichotically presented digit sounds was found to be helpful for differential diagnosis between the supratentorial and subtentorial lesions.

Adult↗

PubMed2000

[Assessment of the hearing system in workers chronically exposed to carbon disulfide and noise].

Epidemiological studies carried out in the years 1984-1993 revealed carbon disulfide (CS2) to be one of the major chemical occupational hazards. Whereas among physical factors, noise was found to be the most common threat. Industrial workers very often face a combined exposure of two or more factors, like CS2 and noise, responsible for significant biological risk to the human health, although health effects of such an exposure have not as yet been thoroughly recognized and explored. The aim of this study was to assess changes in the hearing system in people exposed to toxic effect of CS2, recognized as characteristic of an overall clinical history of chronic poisoning by this solvent, in cases of concomitant exposure to noise exceeding maximum allowable levels. The study covered 80 workers aged 44-65 years (mean = 44.9 +/- 5.1), employed in a spinning mill of viscose fibre for 20.3 years on average (+/- 5.4 years) with clinically observed chronic CS2 poisoning, and a group of 40 people (mean age = 56.8 years) exposed to CS2 but without subjective or objective symptoms indicating chronic poisoning by the solvent. Both groups of subjects at similar age and with almost the same duration of employment were exposed to CS2 in concentrations changing in time between 10 and 35 mg/m3 (mean concentration = 25.8 mg/m3), and to continuous noise with the level ranging from 88 to 92 dB(A) for six hrs per one shift. The control group was composed of 40 workers (mean age = 52.0 +/- 5.3 years) employed in the cotton industry plant, without contact with CS2 or other chemicals and working in the acoustic environment with similar level of exposure to noise (86-93 dB(A)). Audiological and electronystagmographic examinations revealed bilateral retrocochlear hearing impairment associated with symptoms of the central vestibular syndrome in 97.5 subjects with diagnosed chronic CS2 poisoning. In workers free from clinical symptoms of chronic CS2 poisoning, perceptive hearing impairment of various degrees was found, including retrocochlear in 45% of subjects and cochlear in 32.5%, while in 22.5% of those under study normal hearing was observed. In the control group of subjects exposed to noise without contact with CS2, sensorineural cochlear hearing loss, typical of chronic acoustic trauma without concomitant vestibular disorders, was revealed. The results of the study show that in subjects with diagnosed chronic CS2 poisoning and exposed to noise, hearing impairment and vestibular disorders occur in the form of central changes which suggests a dominating CS2 toxic effect on the hearing system. But in some people exposed to both CS2 and noise, the hearing impairment in localised in cochlea like in acoustic trauma damage. This probably depends on individual susceptibility to harmful effect of these factors.

Adult↗

PubMedDate not supplied

Differential facial nerve function in tumors of the internal auditory meatus.

Fifty-five consecutive cases of neoplastic involvement of the internal auditory meatus resulting in ipsilateral retrocochlear auditory dysfunction were reviewed. The majority of these tumors (89%) were solitary schwannomas of the eighth nerve. Eleven percent were other tumors. Preoperative facial paralysis was unusual in eighth nerve schwannomas (6.1%) and much more common in other tumors (66.6%). These data tend to suggest that facial paralysis preoperatively increases the probability that the tumor is other than an eighth nerve schwannoma. Furthermore, facial paralysis resulting from an eighth nerve schwannoma indicates a poorer prognosis for ultimate facial nerve function. The small numbers in this series, though far from conclusive, suggest that normally functioning facial nerves may be infiltrated by eighth nerve schwannomas. Failure of eventual recovery of facial nerve function in the postoperative period may suggest tumor infiltration.

Adult↗