|Year : 2015 | Volume
| Issue : 2 | Page : 88-91
Audiological profile in cases with cerebrovascular accidents
Matlapudi Venkata Subbarao1, Prema Devi2, Venkat Raman Prusty3, Srihimaja Nandamudi4
1 Department of ENT, MediCiti Institute of Medical Sciences, Ghanpur, RR District, Hyderabad, Telangana, India
2 Department of BASLP, and Department of ENT, Dr. BRAM Hospital, Raipur, Chhattisgarh, India
3 Department of ENT, Central Hospital, South Eastern Railway, Gardern Reach, Kolkata, West Bengal, India
4 Department of Speech Science, Bowling Green State University, Bowling Green, Ohio, USA
|Date of Web Publication||20-Apr-2015|
Near Children Park, Red Cross Road, Bhanjanagar, Ganjam, Odisha
Source of Support: None, Conflict of Interest: None
Background: Over the past decades there has been increase demand of audiological complaints coinciding with neurological impairments due to cerebrovascular accidents (CVAs). Most of the cases represent inconsistent responses to acoustic stimuli or total lack of response to sound, documented as auditory agnosia. Aim: The present investigation aims at understanding of potential anatomical co-relates to the involvement of the cortical structure and the processing of auditory stimuli. Materials and Methods: A case series with convenient sampling method included eight cases (six male and two female) with age range 45-55 years with CVA, were taken for this study. Of them two cases were found with lesion in right middle cerebral artery, four cases with left middle cerebral artery and two cases with left posterior cerebral artery lesion confirmed from magnetic resonance imaging scan. Audiological test battery including otoscopy, tuning fork test, pure tone audiometry, speech audiometry, immittance audiometry, dichotic-diotic listening test, auditory brainstem responses, otoacoustic emissions and gap detection tests were carried out including routine ENT evaluation. Results and Conclusion: Result suggests; there is a significant difference in hearing threshold and speech perception in all the eight subjects. The findings and compromised vascular anatomy in all these cases were discussed in this article.
Keywords: Cerebrovascular accidents, Dichotic and diotic, Gap detection test, Hearing profile-auditory brainstem responses, Otoacoustic emissions
|How to cite this article:|
Subbarao MV, Devi P, Prusty VR, Nandamudi S. Audiological profile in cases with cerebrovascular accidents. Indian J Otol 2015;21:88-91
| Introduction|| |
Cerebrovascular disorders are pathologic condition of the blood vessels in the brain (Smith-1983). Epidemiology originally signified the study of epidemics, but it is now used more broadly for the study of groups: Epi = among; demos = people; logos = study. India is a vast country with diverse geographic variation. It would be interesting and highly educative to study the epidemiology of stroke in such a diverse group.
Unfortunately in India, epidemiological information on annual incidence, prevalence rates, morbidity and mortality trends in well-defined populations is not available. Most of the data published is from a retrospective analysis of subjects admitted to urban medical hospitals though the majority of Indian population lives in small towns and villages. Some of the studies lack proper stroke terminology and baseline investigations.
Despite these limitations, analysis of data collected from major urban hospitals suggests that nearly 2% of all hospital admissions; 4-5% of medical and 20% of neurological admission have cardiovascular disease (CVD). The incidence of stroke in the young (<40 years of age) is high (13-32%) when compared to similar data from the west. Many studies on the epidemiology of stroke in India are deficient with respect to randomization of data, making comparison difficult between them. Data show prevalence of CVD in the range of 52-843/100,000 population. Only data from the Paris Community (Bombay), (843/100,000) comes somewhere near the expected rate of 900/100,000 in the oriental population. Lower rate reported in other studies may be due to several factors.
Current trends in healthcare have prompted an attempt to improve accuracy and efficiency in audiological diagnoses. In particular, identification of the sources of variability and errors in the auditory processing, as well as of possible solutions for reducing or eliminating such errors, has become paramount in quality assurance efforts in the field of audiology.
As one would suspect, the incidence of cerebrovascular disease is age dependent, that is, about 840/100,000 for individuals with in the age range of 65-74 years. According to Toole's statistics in 1979, the incidence of vascular occlusion is as high as 41% as compared to cerebral and subarachnoid hemorrhage. The symptoms and signs of cerebrovascular disease are dependent on the location and number of vessels involved. The primary symptoms as headache, confusion, drowsiness, paresthesia, hemiplegia, various sensory deficits (including hearing) and aphasia can be seen in resulting from cerebrovascular problems (McLeod and Lance, 1989). , When blood supply to the brain is disrupted for 30 s, it develops ischemic and about 5 min deprivation causes tissue anoxia causing infraction (Toole, 1979).
From an audiological standpoint, there are two main vascular systems to consider. The vertebral system which forms basilar artery is the vascular supply to auditory periphery and auditory structure at the pons, and the internal carotid artery giver rise to the middle cerebral artery (MCA) in turn supplies to the auditory structures of the cortex. This review considers patients with CVD has disorders of processing of stimuli with particular acoustic structures, may be at a higher level as an apparent cognitive deficit, such as pure word deafness, amusia or environmental sound agnosia, which depends on the affected cortical domine.
The recent audiological trend faces many challenges in the area of auditory deficits either with central or peripheral lesion with underlying and unknown secondary vascular lesion. The audiologist should be involved in the workup of aphasic patient to get an insight into the status of the periphery and central auditory reception ability of patient and for the rehabilitative measures as this population has major clinical impact in communication trend.
Impact of cerebrovascular accident on auditory processing
Most population with cerebrovascular accident (CVA) had central deafness with preserved peripheral auditory function. The result on audiological findings shows inconsistent response to acoustic stimuli, total lack or response to sound and in some cases reversible hearing threshold. Closed head injured and stroke patients demonstrated a significant effect on sentence comprehension and the patterns of breakdown in the ability to assign thematic roles and co-index referentially dependent noun phrases. Findings suggest that syntactic comprehension disturbances are similar following left cerebral hemisphere infarction and closed head injury (Butler-Hinz et al., 1990). , Some other audiological disorders were shown as fragility in the perception of brief sound stimuli, difficulties to apprehending prolonged series of stimuli (rhythms), defective sound localization, and an increase in the homolateral and in the contralateral effects of masking sounds. On the other hand, differential thresholds for frequency and for intensity, as well as fusion thresholds, were little affected, or unaffected. Besides this, some cases with CVA also had intermingling signs of tinnitus and vertigo, although the lesion don't correlate to vestibule-cochlear nerve, studies suggest there is underlying impairment in the basal ganglionic structure (Berlin and Heidelberg 1983). , There is a wide variability in auditory responses in cases of CVA due to the lack of considerable variability in nature and extent of auditory deficit and lack of consistent assessment protocol used across the investigations (Baran and Zaidan, 2003).
Aim of the study
- Ruling out the auditory impairment or hearing issues in cases with CVA
- To give a trend to the audiologist for correlating the neuroimaging with audiological findings
- Management issues in cases with CVA for their auditory perceptual status.
| Materials and Methods|| |
The present study aims to represent audiological findings of cases following CVAs and their computed tomography/magnetic resonance imaging (CT/MRI) correlations with the audiological findings. The study included eight cases following CVA. The selection of subjects done based on the following criteria.
- Subjects underlying stroke complaint
- Hearing issues following stroke
- Age limit >45-<70 years
- Minimum, effective communication following stroke
- Communication skills premorbid to stroke in English (L2-English).
- Cases with complaint of associated health issues prior to stroke
- Subjects with epileptic or controlled epileptic issues
- Trauma including acoustic neuroma, ototoxication, multiple sclerosis
- Surgical issues as ear discharge, respiratory infections, radiotherapy/chemotherapy
- Psychotic behavior.
Demographic and medical history of all the subjects was documented.
All the subjects were undergone serial audiometric test procedure, that is, otoscopic examination, impedance audiometry, pure tone audiometry, speech audiometry, dichotic listening test, otoacoustic emission (OAE), auditory brainstem response (ABR), gap detection test (GDT) (dual channel audiometer). All the instruments were calibrated as per ANSI S.3.6, 1996 standards.
All the eight subjects had a consent form signed prior to the test conducted. Subjects and family members were oriented about the test procedure in an effective way, and console to share the test result following analysis. Subjects were tested individually in a relatively quiet room, and their demographic data taken including age of onset of the problem, habits, associated problems and problems following strokes. Subject's CT/MRI scan details were noted down. Prior to the audiometric test protocol, the examiner provided all the required information and instructions. Subjects and their family members were assured about confidentiality of their responses.
Initial step was carried out by the visual inspections of external ear canal and tympanic membrane using handheld otoscope to rule out presence of excessive wax, perforation of tympanic membrane or any discharge/foreign body in external auditory canal. Objective assessment of middle ear was done to rule out any middle ear issues. Tympanometry done and reflexes were noted for 500 Hz, 1 kHz, 2 kHz, and 4 kHz. Pure tone audiometry done in double room setup using Orbiter 922 and sum of all frequencies, that is, 250 Hz to 8 kHz were taken for mean hearing loss. Speech audiometry carried out to find speech awareness threshold using questions for conversations to correlate with pure tone average (PTA) threshold. Speech recognition threshold and sine-wave speech calculated using spondee and phonetically balanced word list in English, respectively. Subjects were then instructed to keep quite while OAE measurements, then dichotic listening test and GDT test carried out. GDT includes filterer word test, auditory figure ground, competing word and sentence test. ABR done with natural sleep using click stimuli as 11 rates/s. All tests were carried out observing clients relaxation and comfortability stage. ENT examination done with case's requirements.
| Results|| |
The findings of all the eight subjects were subjectively and objectively varied depending on the site and extent of the lesion. The otoscopy findings showed normal tympanic membrane with presence of cone of light. The audiometric findings for PTA threshold ranged from mild to severe degree. Speech audiometric findings were correlating with PTA in few cases where as varying in MCA occlusion. Tympanometry suggests normal pressure, compliance and shape bilaterally in all cases. However, reflexometry were noted with slightly elevated hearing levels at low frequency, that is, at 500 Hz. Distortion product OAE (DPOAE) for all the ears were essentially with in normal range for absolute amplitude level (in dB sound-pressure level) at 1 kHz to 4 kHz. Noise floor were elevated in two subjects, that is, recording falling at ratio <10 dB at 1 kHz level, probably due to nervousness. Dichotic test result showed better responses in left posterior cerebral artery (Lt PCA) impaired cases. The ABR and interwave latencies for all the ears fell with in normal range. GDT (competing word and messages) are varied from 2 to 6 ms. [Table 1] shows the demographic details and summary of audiological findings of all 8 cases included in this study.
| Discussion|| |
Cases with CVA show varying audiological configurations. This present study aimed at correlation of auditory processing and anatomical information in terms of audiological findings. Based on the review of vascular anatomy presented by Waddington (1974), the MCA occlusion leads to more auditory issues as posterior temporal and its branches derived from this.
Similar findings were obtained from the study done by Rosati and Artioli, who reported of severe agnosia for verbal and nonverbal sounds without associated aphasic disorder. A CT scan revealed bilateral, temporal lobe lesions from two ischemic accidents that had occurred 9 months apart. The search for subtle deficits in the patient showed normal sensitivity to changes in the intensity and frequency of simple sounds; in contrast, the ability to discriminate sound duration, and musical note sequences were severely impaired. The simultaneous recording of the whole auditory-evoked response pattern revealed no abnormality in the early components, which reflect the activation of the auditory nuclei and pathways of the brainstem. However, the middle and late components were delayed and slowed. These results and others in the literature suggest that the neocortex in man, as in other mammals, plays an essential role in the temporal aspects of hearing. Furthermore, the two main ingredients commonly recognized in auditory agnosia, that is, word deafness and the inability to interpret nonverbal sounds, are caused by the disruption of elementary, bilaterally represented cortical functions which start the processing of every kind of auditory information.
Auditory agnosia was also reported by Rochelle, Loth, Chain (2004) in a case report, in which a patient was become unable to identify all kinds of auditory material, including speech, despite only subnormal audiometric thresholds (i.e., "auditory agnosia"). The audiological disorders were fragility in the perception of brief sound stimuli, difficulties to apprehending prolonged series of stimuli (rhythms), defective sound localization, an increase in the homolateral and in the contralateral effects of masking sounds. On the other hand, differential thresholds for frequency and for intensity, as well as fusion thresholds, were little affected, or unaffected. A complete dissociation appeared between the auditory evoked potentials and the audiometric thresholds. Following a year the first examination, the auditory potentials were largely reduced, or even have elapsed for one ear while the audiometric thresholds seem to remain nearly the same.
Another study by Musiek et al., Pollak, Baran and Zaidan et al. (2007) ,,,, reported a case with bilateral CVA compromising Hescle's gyrus, following 18 months post-CVA the audiological findings revealed bilateral profound hearing loss, speech awareness present but rarely recognized with OAE present, bilateral acoustic reflex and ABRs were within normal limit, however, middle and late responses were yielding complex modification of wave forms, however, GDT is also compromised in this case.
Even, there are sudden onsets of sensorineural hearing loss with vertigo, reported to be due to arterial occlusion. The hearing loss in these cases vary from mild (a minimum of 30 dB of hearing deficiency at three adjacent frequencies) to severe (>80 dB), without any history of hearing fluctuation and with predominantly sensorial characteristics. It may be associated with vestibular symptoms.
The audiological findings vary in the cases of CVA and diagnosis of these occlusive cerebrovascular diseases can be made with the discussion with hemodynamic team. There is an increase demand in the field of audiology to meet with the need of cases with CVA and other neurological impairment cases, irrespective of nature of the problem as hearing loss, processing difficulty, comprehension deficit, etc. Many clients don't show pathological hearing loss, but present with hearing loss physiologically due to processing impairments. The cases with CVA may represent normal hearing threshold for environmental signal or nonspeech sound may significantly affect the communication. The raising audiological issues in managing the associated sensory impairments of clients with CVA guide the researcher to conduct this study.
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