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At least 19 recordsLinked to original sources

Clinical psychoacoustics in Alzheimer's disease central auditory processing disorders and speech deterioration.

BACKGROUND: Difficulty in speech understanding in the presence of background noise or competing auditory signals is typically present in central auditory processing disorders. These disorders may be diagnosed in Alzheimer's disease as a result of degeneration in the central auditory system. In addition perception and processing of speech may be affected. MATERIAL AND METHODS: A MEDLINE research was conducted in order to answer the question whether there is a central auditory processing disorder involved in Alzheimer's disease. A second question to be investigated was what, if any is the connection, between central auditory processing disorders and speech deterioration?Articles were retrieved from the Medline to find relevance of Alzheimer's dis ease with central auditory processing disorders, they summed up to 34. Twelve papers were studied that contained testing for CAPD through psychoacoustic investigation. An additional search using the keywords 'speech production' and 'AD' produced a result of 33 articles, of them 14 are thoroughly discussed in this review as they have references concerning CAPD. The rest do not contain any relavent information on the central auditory system. RESULTS: Psychoacoustic tests reveal significantly lower scores in patients with Alzheimer's disease compared with normal subjects. Tests concerning sound localization and perception of tones as well as phoneme discrimination and tonal memory reveal deficits in Alzheimer's disease. Central auditory processing disorders may exist several years before the onset of clinical diagnosis of Alzheimer's disease. Segmental characteristics of speech are normal. Deficits exist concerning the supra-segmental components of speech. CONCLUSIONS: Central auditory processing disorders have been found in many cases when patients with Alzheimer's disease are tested. They may present as an early manifestation of Alzheimer's disease, preceding the disease by a minimum of 5 and a maximum of 10 years. During these years changes in the central auditory system, starting in the temporal lobe, may produce deficits in speech processing and production as hearing and speech are highly connected human functions. Another theory may be that spread of degeneration of the central nervous system has as a consequence, speech deterioration. Further research and central auditory processing disorders testing in the elderly population are needed to validate one theory over the other.

Journal Article↗

Central auditory function in Alzheimer's disease.

The central auditory (dichotic) function of 38 patients with Alzheimer's disease was found to be significantly impaired when compared with a control group. Significant relationships were observed between dichotic scores and intelligence quotient, cortical atrophy in the temporal lobes, and cerebral glucose metabolism in the left temporal lobe. Comparing atrophy and glucose metabolism in the temporal lobes, we observed contralateral ear effects in dichotic performance as well as an interaction of asymmetry of atrophy with dichotic performance, consistent with previous models of dichotic listening in other forms of temporal lobe pathology.

Adult↗

The anatomy and pathology of the central auditory pathways.

The anatomy of the central auditory pathways from the cochlear nucleus to the auditory cortex is reviewed. The common pathologies affecting these pathways are described and the neurological, ophthalmological and vestibular symptoms and signs, which are valuable in diagnosing and siting the level of these lesions are discussed.

Auditory Cortex↗

Lesion site in sudden deafness: study with electrocochleography and transiently evoked otoacoustic emission.

We examined electrocochleogram (ECochG) and transiently evoked otoacoustic emission (TEOAE) on five cases of sudden sensorineural hearing loss which had no abnormalities detected on diagnostic imagings and showed complete recovery of hearing. At the initial examination, three cases showed a broadened wave 1 with prolonged latency in the auditory brainstem response (ABR) at 90 dB HL. The ECochG AP showed a broad waveform, low amplitude, and high threshold. CM threshold, although increased, was relatively well preserved compared with hearing threshold measured with conventional pure-tone audiometry. The thresholds in TEOAE examination were similar to those for CM and preserved better when compared with pure-tone audiometric thresholds. These findings suggest that the location of the disorder in these three cases involved not only the cochlea but also the retrocochlear auditory pathway. The other two cases showed normal ABR waveforms at 90 dB HL at the initial examinations. ECochG examination showed that a normal AP in one case and a smaller amplitude AP, an elevated threshold, and normal waveform of AP in the other ear. CM thresholds coincided with the conventional audiometry thresholds. These findings suggest that hearing loss in these two cases involved primarily the sensory hair cells.

Acoustic Stimulation↗

Pure-tone audiometry of patients with auditory brainstem response abnormalities.

To determine the pure-tone thresholds of patients with brainstem disorders, pure-tone audiometry was done on 22 patients with partial auditory brainstem response wave disappearance (including wave I response, wave I-III response, and wave I-IV response). This group of patients was selected since partial wave disappearance indicates pathology of the auditory nerve and/or the brainstem auditory pathway. The pure-tone threshold of these patients was essentially normal or very mildly impaired, except for patients with an acoustic tumor or an other cerebellopontine angle tumor.

Audiometry↗

The value of combining auditory brainstem responses and acoustic reflex threshold measurements in neuro-otological diagnosis.

Acoustic reflex thresholds (ART) and auditory brainstem responses (ABR) were measured in 69 patients referred to the Neuro-otological clinic on the suspicion of a retrocochlear lesion. The pure-tone selection criterion was an average hearing loss of less than 60 dB at 0.5, 1, 2, and 4 kHz, with no thresholds exceeding 70 dB and only one threshold exceeding 60 dB. Both tests proved independently to be most effective in the diagnosis of cerebello-pontine angle (CPA) tumours and to a lesser extent for brainstem lesions. The ABR was positive in 100% of CPA group and 90% in the brainstem group compared with 93% and 70% respectively for the ART. The combination of the two tests provides patterns of abnormality which are more disease specific. In the CPA cases the most common and consistent patterns of abnormality were the unilateral delay of Wave V or III and V of the ABR associated with a vertical ART pattern indicative of an abnormality of the ipsi and contralateral reflexes on stimulating the affected side. Intrinsic brainstem lesions most commonly resulted in bilateral ABR abnormalities combined with the full-house ART pattern indicative of bilateral abnormalities of both ipsi and contralateral reflexes.

Adolescent↗

Aetiology and clinical presentations of auditory processing disorders--a review.

Auditory processing disorders may have detrimental consequences on a child's life, if undiagnosed and untreated. We review causes of auditory processing disorders in order to raise clinical awareness. Auditory processing disorders may present against a background of neurological disease or developmental disorders, as well as in isolation. Clinicians need to be aware of potential causes and implications of auditory processing disorders.

Auditory Diseases, Central↗

Pediatric central auditory dysfunction. Comparison of children with confirmed lesions versus suspected processing disorders.

This study compared and contrasted results on pure tone audiometry, acoustic reflexes, and the Pediatric Speech Intelligibility Test in children with either documented or suspected central auditory dysfunction. Ages ranged from 3 years, 2 months, to 8 years, 4 months. In children with confirmed CNS lesions, results were consistently normal for children with lesions in nonauditory areas of the brain and consistently abnormal for children with lesions in areas of the brain important for auditory perceptual function. The patterns of abnormality were consistent with previous findings in adults. In children with suspected central auditory processing disorders (CAPDs), audiometric findings typically showed normal hearing sensitivity, abnormal (rising) audiometric contours, normal acoustic reflexes, normal degraded monotic speech perception, and abnormal dichotic speech perception. This pattern of results was similar to findings in children with confirmed temporal lobe lesions. Overall, results supported an auditory perceptual, rather than a linguistic, basis for CAPDs.

Auditory Diseases, Central↗

Central auditory dysfunction among chronic alcoholics.

The relationship between chronic alcoholism and auditory processing problems was examined using a central auditory test battery. Fifteen carefully selected alcoholic subjects and 15 age-matched nonalcoholic control subjects were evaluated using pure-tone thresholds, spondee thresholds, speech discrimination, acoustic reflex thresholds, performance-intensity function, Staggered Spondaic Word (SSW) test, Synthetic Sentence Identification (SSI), and temporal summation. Significant differences between the groups were obtained for acoustic reflex measurement, SSW, and SSI. A significant subject-related interaction was obtained for temporal summation measurement. Approximately half of the alcoholics yielded results consistent with brainstem pathologic features.

Adult↗

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↗

High-resolution MR imaging of the auditory pathway.

MR imaging is a valuable tool in the evaluation of the auditory pathway. The current techniques in high-resolution MR imaging of the temporal bone are presented followed by a review of normal anatomy. Several diseases involving the middle ear, inner ear, internal auditory canal, and cerebellopontine angle are then presented. A radiologic-pathologic approach is used to illustrate the nature of these diseases and their appearance on MR imaging.

Auditory Diseases, Central↗

Regeneration and recovery of the hearing function of the central auditory pathway by transplants of embryonic brain tissue in adult rats.

The present study is the first report of successful regeneration and recovery of hearing function of the central auditory pathway after transection in the adult rat. The ventral cochlear tract in the brain stem to pons was transected on one side in adult rats. Tissue from embryos (E14 to E16) was used to cover the lesion site. In 30% of the rats examined, the axons regrew beyond the transected site and regenerated into the denervated side and terminated at the normal targets. The hearing function of rats was elucidated by recording the auditory brain stem response (ABR). Rats with successful regeneration showed nearly normal ABR. In rats receiving simple transection without covering embryonic tissue, there was no regeneration and hearing function did not recover. Thus, the present findings contradict the widely held view that the adult mammalian central auditory system cannot be restored following damage.

Animals↗

Reversible neuroaudiologic findings in a case of right frontal lobe abscess with recovery.

A patient with a large right frontal lobe abscess was administered a battery of audiologic and neuroaudiologic tests. Results indicated a definite central auditory processing deficit with essentially normal peripheral hearing. The same test battery was given three months later, after the abscess had completely resolved. The neuroaudiological results on retest were essentially normal for the entire test battery. The specific central auditory processing deficit noted in this case is discussed, along with details of the neuroaudiologic assessment.

Auditory Diseases, Central↗

Indices of hearing in patients with central auditory pathology. I. Detection and discrimination.

This paper describes the effect of site of lesion on auditory detection, discrimination and speech processing. Three groups of ten patients with confirmed pathology of the eighth nerve and right and left temporal cortex and two normal-hearing control groups, differing with respect to hospitalization, participated. In each of the fifty subjects, measurements were made of detection thresholds, and difference limens for frequency and duration for 50 and 300 ms pure tones of 500 Hz and 2000 Hz. Consonant discrimination was assessed using the Four Alternative Auditory Feature Test (Foster & Haggard, 1979), presented in quiet. Subjects with left temporal pathology had the largest frequency and duration difference limens. Those with either left temporal or eighth nerve pathology had significantly lower speech intelligibility scores that were correlated with the duration difference limen for short stimuli and detection thresholds, respectively. These findings challenge traditional views of cortical processing and highlight differences between peripheral and central mediators of speech processing.

Adult↗