Involvement Of Auditory Pathways Research Articles

Involvement of the Auditory Pathway in Spinocerebellar Ataxia Type 7

Background: Spinocerebellar ataxia type 7 (SCA7) is an autosomal dominant disorder caused by a mutation in the ATXN7 gene. The involvement of the brainstem auditory pathway in pathogenesis of this disease has not been systematically assessed. Aim: To determine involvement of the brainstem auditory pathway in SCA7 patients and its relationship to clinical features of the disease. Methods: In this case-control study, brainstem auditory-evoked potentials (BAEPs) were assessed in 12 SCA7 patients with clinical and molecular diagnosis, compared to 2 control groups of 16 SCA2 patients and 16 healthy controls. Results: SCA7 patients exhibited significant prolongation of I-wave and III-wave latencies, whereas SCA2 patients showed increased latencies for III and V waves and I–III interpeak interval. SCA7 patients with larger I-wave latencies exhibited larger CAG repeats, earlier onset age, and higher SARA scores, but in SCA2 cases, these were not observed. Conclusions: BAEP tests revealed functional involvement of the auditory pathway in SCA7 (mainly at) peripheral portions, which gave new insights into the disease physiopathology different from SCA2 and may unravel distinct pathoanatomical effects of polyQ expansions in the central nervous system. Significance: These findings offer important insights into the distinctive disease mechanisms in SCA7 and SCA2, which could be useful for differential diagnosis and designing specific precision medicine approaches for both conditions.

Oto-acoustic emissions and brainstem evoked response audiometry in patients of tinnitus with normal hearing.

Tinnitus is defined as the perception of sound that results completely from activity within the nervous system without any corresponding mechanical, vibratory activity within the cochlea, and not related to external stimulation of any kind. It disrupts the daily life of 1 out of every 200 adults. The source of tinnitus generation is not limited to the peripheral auditory system. However, there are abnormalities seen in BERA in tinnitus patients depicting auditory pathway involvement. Oto-acoustic emissions are mechanical vibrations generated in the cochlea, which are evaluated by TEOAE and DPOAE whereas BERA evaluates both cochlea and brainstem auditory pathway for any conduction abnormalities. The aim of the study is to analyze the changes in OAE and BERA in patients suffering from tinnitus with normal hearing, which may help us to understand the patho-physiology of tinnitus. This is a prospective study conducted in a tertiary care hospital in Northern India between 1st December 2015 to 31st July 2017. All patients of tinnitus with normal hearing were included in the study group, whereas Individuals with normal hearing with no other ear complaints were included in control group. Total 160 Ears were evaluated with 80 ears in both study and control group each. Patients with PTA >25dB, age >55 years or any chronic medical illness were excluded from the study. 80 individuals (46 Males and 34 Females) were divided into study and control Group (80 Ears each). Tinnitus was bilateral in 28 subjects (53.84%) and unilateral in 24 subjects (46.16%). Both control and study group showed significant difference in TEOAE and DPOAE study. In TEOAE, 8 (10%) ears in control group and 30 ears (37.5%) in study group showed test result as REFER whereas in DPOAE 10 (12.5%) ears in control group and 35 (43.8%) ears showed test result as REFER. All these result were statistically significant. In BERA the latency of wave I was significantly prolonged in study group as compared to control group, while difference between all other parameters between the two groups was insignificant. There were various significant abnormalities seen in parameters of Oto-Acoustic Emissions (OAE) and Brainstem Evoked Response Audiometry (BERA). So these tests should be included in the test battery for the screening of patients complaining of tinnitus even with normal hearing.

Brainstem auditory responses in type-2 diabetes mellitus

<p class="abstract"><strong>Background:</strong> Diabetes mellitus causes pathophysiological changes at multiple organs. Brainstem Evoked Response Auditory (BERA) represents a non-invasive tool to detect diabetes related sensorineural hearing loss. The aim was to assess diabetes related central auditory pathway involvement using BERA.</p><p class="abstract"><strong>Methods:</strong> The study comprises two groups, (i) Diabetic group (n=15), (ii) Control group (n=15). The controls were matched for age and sex with the study group. BERA was done for all these patients after detailed clinical examination and relevant blood investigations. </p><p class="abstract"><strong>Results:</strong> There was significant latency differences found in wave III, V and interpeak latencies I-III, III-V and I-V between control and study groups at 70 dBnHL and 80 dBnHL. At 90 dBnHL the diabetic group demonstrated significant latency differences in waves I, III and V and interpeak I-III, III-V and I-V compared to controls. The duration of DM was 5-10 years in 8 patients (53.3%) out of which 7 subjects (87.5%) had prolonged BERA. 7 patients (46.6%) were diabetic for more than 10 years of which all patients (100%) had prolonged latencies.</p><p><strong>Conclusions:</strong> The wave I latency was found non significant which suggests that the pathway from 8<sup>th</sup> nerve to cochlear nucleus is not affected in diabetic patients. The delay in latencies III and V and interpeak latencies I-III, III-V and I-V in diabetic patients compared to the controls suggests brainstem and midbrain involvement. So the study suggests that BERA helps in early detection of central neuronal axis involvement in type-2 diabetes mellitus. </p>

Auditory spatial deficits in brainstem disorders

PurposeBrainstem disorders seem to negatively influence the central auditory system, causing spatial hearing deficits. Material and methodsWe tested 11 patients with brainstem lesions due to ischemic stroke (IS), multiple sclerosis (MS), or cerebellopontine angle tumor (CPAT) together with 50 age- and sex-matched healthy volunteers. We used pure tone audiometry (PTAud), brainstem auditory evoked potentials (BAEPs) and the horizontal minimum audible angle test (HMAAT) for 8 azimuths with binaural stimulation. ResultsThe chosen patients and the controls had normal or near normal hearing in PTAud. BAEPs interaural wave I–V latency difference was over 7 times longer in the patients group compared to the controls. Additionally, 9 of the 11 patients (81.1%) had abnormal HMAAT results. The biggest quantitative disturbances in HMAAT were present in the CPAT and the MS patients. The sound localization ability in HMAAT was significantly worse in the patients in 0° azimuth in comparison with the controls, and in 45° and 90° azimuth in patients with auditory pathway involvement compared with the ones without the involvement. ConclusionsOur study confirms the strong relationship between various brainstem pathologies and sound localization disability and sheds some light on the complexity of the relationship.

Auditory findings and electrophysiologics in individuals with G/BBB syndrome

AbstractThe G/BBB syndrome is a rare condition characterized by hypertelorism, cleft lip and palate, and hypospadias. No studies were found on the hearing of individuals with this syndrome. AimTo investigate the auditory function in patients with G/BBB syndrome, such as the occurrence of hearing loss, and central and peripheral auditory nerve conduction. MethodsFourteen male patients aged 7-34 years with the G/BBB syndrome were assessed by otoscopy, audiometry, tympanometry and evoked auditory brainstem response (ABR). Model: A retrospective clinical series study. ResultsAudiometric thresholds were normal in 12 (66.7%) of the sample and altered in two (33.3%), one with conductive and one with sensorineural loss. ABR resuts were: all patients had normal absolute wave I latencies; absolute wave III and V latencies were increased in two and six patients, respectively; interpeak latencies I-III, IV and V interpeak latencies were increased in four, three and eight patients respectively. ConclusionHearing loss can occur in the G/BBB syndrome. There is evidence of central auditory pathway involvement in the brainstem. Imaging studies are needed to clarify the clinical findings.

Is It CAPD or ADHD?

Is It CAPD or ADHD?

Evaluation of hearing in middle-aged patients with diabetes mellitus type 2

Introduction: Involvement of auditory pathway is one of the examples of central neuropathy in diabetics. The purpose of this study is to compare the auditory function of patients with type 2 diabetes mellitus with healthy subjects. Methodology: 30 diabetic and 30 healthy subjects participated in this study. For all participants conventional pure-tone audiometry (PTA) and Auditory Brainstem Evoked Responses (ABER) study were performed. Results: In PTA Hearing threshold only at 2, 4, 8 KHz frequencies were significantly higher than healthy subjects but were in normal range in patients with diabetes. ABER revealed that absolute latencies of waves I, III, V and inter wave latencies of III-V, I-V, I-III were significantly prolonged in diabetics. Conclusion: In this study, 50% of diabetic patients had hearing defects in ABER test despite normal hearing threshold and good meta-bolic control. Prolonged inter wave latencies of I-III, III-V, I-V explains retrocochlear and brain stem involvement.

Case Study of Central Auditory Processing in Patients with Stroke

This study aimed to investigate central auditory processing dysfunction in patients with stroke. Three patients who had suffered strokes with confirmed auditory pathway involvement, participated. All subjects had normal hearing bilaterally, and were right-handed. All subjects completed K-MMSE (Korean version of Mini-Mental State Exam) and K-WAB (Korean version-the Western Aphasia Battery), and performed Korean Central Auditory Processing Assessment (CAPA-K) battery, including Frequency Pattern test, Dichotic Digit test, Filtered Word test, Compressed Speech test, Speech in Noise test, and Binaural Fusion test. The scores for the each test were evaluated by comparing the normative data in young adult population for the standardization of CAPA-K battery. The results of the study revealed that all three subjects had difficulties in central auditory processing. S1 (male, 17 years, Rt. middle cerebral artery infarction including Rt. insula and basal ganglia) showed poor performance in contralateral ear to the lesion in all speech recognition tests. Contralateral ear suppression was also seen in dichotic testing. Furthermore, frequency pattern recognition was poorer in the linguistic labeling condition than in the humming condition in both ears. S2 (female, 46 years, both pontine infarction including lateral lemniscus and superior olivary complex) demonstrated difficulties through the entire tests whereas S3 (male, 51 years, Lt. pontine infarction including lateral lemniscus) showed normal performance in speech recognition test and monaural-low redundancy speech tests in both ears. Regardless of side of lesion, temporal processing difficulties in both ears were found in patients associated with pontine infarction. In these cases, auditory dysfunction resulting from stroke varied with the location and extent of auditory pathway infarction. Therefore, more cases are needed to identify the central auditory dysfunction in patients with stroke.

Distortion-Product Otoacoustic Emissions: A Useful Test for Monitoring Ototoxicity Induced by Pegylated Interferon and Ribavirin Treatment in Patients with Chronic Hepatitis C

Pegylated-interferon (peg-IFN) and ribavirin combination therapy for the treatment of hepatitis C virus (HCV) infection is well known to be associated with significant adverse effects. Several studies have investigated a possible auditory pathway involvement during IFN therapy, but a method to monitor the potential auditory involvement during treatment has not yet been described. The aim of this study is to evaluate possible modifications of the outer hair cell (OHC) function in HCV patients receiving peg-IFN and ribavirin combination therapy. Thirteen adult HCV patients (8 F/5 M, mean age 52∓12 years) treated with peg-IFN and ribavirin combination therapy underwent Pure Tone Audiogram and Distortion Product Otoacoustic Emission (DPOAE) tests. We compared mean auditory thresholds (PTA) and mean DPOAE amplitude before, at month 3 during, and at the end of treatment (T0, T3, and Tend, respectively), and 3 months after treatment discontinuation (Tfu). No significant differences were found in hearing levels at the different time points analyzed. During treatment, three patients developed tinnitus, which in 2 cases resolved spontaneously after the end of therapy. Compared to T0 (19.5±0.83), a statistically significant DPOAE increase at T3 (30±1,26) and Tend (28.6±2.16) was found (p<0.05 at both time points), while DPOAEs returned to pre-treatment levels at Tfu (19.3±1.3). In our group, none of the patients reported a permanent auditory impairment, excluding one patient with persistent tinnitus. Peg-IFN could produce an increase of motility of the OHCs by means of intracellular pathways. DPOAE test could be considered a new method for monitoring ototoxicity induced by IFN. On the basis of recent literature and our audiological results, physicians should be aware of the possible ototoxic effects of peg-IFN, requiring appropriate surveillance, and the patient should be informed of the potential side effects of IFN therapy on the auditory pathway.

Electrophysiological characterisation in hereditary spastic paraplegia type 5

Objective To assess in SPG5 hereditary spastic paraparesis (HSP) the involvement of the central (CNS) and the peripheral (PNS) nervous system by a multimodal electrophysiological approach. Methods Four patients belonging to three HSP families, with a molecular diagnosis of SPG5, underwent electrophysiological evaluation including electromyography (EMG) and nerve conduction study (NCS), motor-evoked potentials (MEPs) by transcranial magnetic stimulation (TMS) and somatosensory evoked potentials (SEPs) at upper and lower limbs, visual (VEPs) and brainstem auditory evoked potentials (BAEPs). In one patient, electrophysiological evaluation was performed twice at the age of 12 and 31 years. Results EMG and NCS were normal. MEPs and SEPs were abnormal in all patients along the central pathway for upper and/or lower limbs. VEPs revealed a damage of visual pathway and BAEPs showed the involvement of auditory pathway within the brainstem. In the patient who underwent electrophysiological follow-up, MEP and SEP findings were unmodified, whereas VEPs showed no reproducible responses. Conclusions We report an extensive electrophysiological evaluation of SPG5 and we confirm that the SPG5 phenotype may be broader than pure presentation. Significance Electrophysiological evaluation, showing diffuse CNS involvement with PNS sparing, could be very useful to address the molecular diagnosis and to follow-up a hypothetical treatment.

Brainstem evoked response in bus drivers with noise-induced hearing loss

Studies carried out by Brainstem Evoked Auditory Potentials (BEAP) in Noise-Induced Hearing Loss (NIHL) workers show different results in relation to neuronal involvement, not involving bus drivers as study object. AIM: to use BEAP in a prospective case/control clinical study to check whether or not there is neural auditory pathway involvement in bus drivers with NIHL. MATERIALS AND METHODS: we selected 50 bus drivers between 27 and 40 years with mild to moderate NIHL, and 20 individuals between 29 and 40 years with normal hearing and without prior history of noise exposure. BEAP tests were carried out and the traces were analyzed. RESULTS: in the NIHL group, the auditory thresholds in 3, 4 and 6 kHz were significantly higher in the left ear. In the NIHL group, potentials PI, PIII and/or PV were not present in a small number of the individuals; we observed a statistically significant increase in PI, PIII and PV absolute latencies, (LIP) LIP I-III interpeak latencies, bilaterally and LIP I-V in the left ear. CONCLUSION: in the NIHL group, besides sensorial injury, changes in BEAP latencies suggest an early functional injury of the first auditory pathway afferent neuron.

Brainstem evoked response in bus drivers with noise-induced hearing loss

SummaryStudies carried out by Brainstem Evoked Auditory Potentials (BEAP) in Noise-Induced Hearing Loss (NIHL) workers show different results in relation to neuronal involvement, not involving bus drivers as study object.Aimto use BEAP in a prospective case/control clinical study to check whether or not there is neural auditory pathway involvement in bus drivers with NIHL.Materials and Methodswe selected 50 bus drivers between 27 and 40 years with mild to moderate NIHL, and 20 individuals between 29 and 40 years with normal hearing and without prior history of noise exposure. BEAP tests were carried out and the traces were analyzed.Resultsin the NIHL group, the auditory thresholds in 3, 4 and 6 kHz were significantly higher in the left ear. In the NIHL group, potentials PI, PIII and/or PV were not present in a small number of the individuals; we observed a statistically significant increase in PI, PIII and PV absolute latencies, (LIP) LIP I-III interpeak latencies, bilaterally and LIP I-V in the left ear.Conclusionin the NIHL group, besides sensorial injury, changes in BEAP latencies suggest an early functional injury of the first auditory pathway afferent neuron.

Chromosome 10p deletion in a patient with hypoparathyroidism, severe mental retardation, autism and basal ganglia calcifications

Chromosome 10p terminal deletions have been associated with a DiGeorge like phenotype. Haploinsufficiency of the region 10p14-pter, results in hypoparathyroidism, sensorineural deafness, renal anomaly, that is the triad that features the HDR syndrome. Van Esch (2000) identified in a HDR patient, within a 200 kb critical region, the GATA3 gene, a transcription factor involved in the embryonic development of the parathyroids, auditory system and kidneys. We describe a new male patient, 33-year-old, with 10p partial deletion affected by hypocalcemia, basal ganglia calcifications and a severe autistic syndrome associated with mental retardation. Neurologically he presented severe impairment of language, hypotonia, clumsiness and a postural dystonic attitude. A peripheral involvement of auditory pathways was documented by auditory evoked potentials alterations. CT scan documented basal ganglia calcifications. Hyperintensity of the lentiform nuclei was evident at the MRI examination. Renal ultrasound scan was normal. Haploinsufficiency for GATA3 gene was documented with FISH analysis using cosmid clone 1.2. Phenotypic spectrum observed in del (10p) is more severe than the classical DGS spectrum. GATA3 has been found to regulate the development of serotoninergic neurons. A serotoninergic dysfunction may be linked with autism in this patient.

A NOVEL MUTATION OF CONNEXIN‐32 GENE IN A CMTX ITALIAN FAMILY

X‐linked Charcot‐Marie‐Tooth is an inherited motor and sensory neuropathy associated with mutations in GJB1, a gene on chromosome X coding for the gap junction protein “connexin 32” (Cx32). Cx 32 gene is expressed in both peripheral and central nervous system myelin.We describe a family affected by X‐linked CMT neuropathy with a novel point mutation in Cx32 gene, in which the mother, the putative carrier, and three affected sons were examined. The affected sons (32, 35, 38 yrs) presented a motor‐sensory slowly progressive neuropathy mainly involving lower limbs. Nerve conduction study showed both axonal and demyelinating pattern of denervation. Evoked potentials indicated visual and brainstem auditory pathway involvement. The mother showed subclinical electrophysiological abnormalities in nerve conduction velocities.By mutational analysis of GJB1 using SSCP and sequencing of candidate regions, a previously undescribed missense mutation in the exon 2, codon 151, was found. This mutation was due to a transversion (TAT‐&gt; TCT) leading to a Tyr‐&gt;Ser substitution in the 2nd extracellular domain.Our findings further stress the wide variability in the spectrum of Cx32 mutations associated to CMTX, making it worthwhile to deepen knowledge about genotypic–phenotypic interrelationship in this disease.

Effects of occupational exposure to organic solvents and noise on hearing.

This study explored the effects of occupational exposure to solvents and noise on hearing. Interviews and hearing tests were conducted for printing and paint manufacturing workers. The experimental groups included unexposed (N = 50) workers and workers exposed to noise (N = 50), noise and toluene (N = 51), or an organic solvent mixture (N = 39). The risk of hearing loss was greater for the exposed groups than for the unexposed group. The adjusted relative risk estimates were four times greater [95% confidence interval (95% CI) 1.4-12.2] for the noise group, 11 times greater (95% CI 4.1-28.9) for the noise and toluene group, and five times greater (95% CI 1.4-17.5) for the solvent-mixture group. The findings suggest that exposure to the studied solvents had a toxic effect on the auditory system and that an interaction between noise and toluene took place. The audiological results of the noise and toluene group suggest a central auditory pathway involvement in the hearing losses observed.

Auditory evoked potentials in preterm infants: Neurodevelopmental outcome at 5 years : J.W. Pasman, J.J. Rotteveel, B. Maassen. University of Nijmegen, The Netherlands

Brain-stem and middle latency auditory evoked potentials (BAEPs and MLAEPs) have been studied in 34 multiple sclerosis (MS) patients.We were able to detect a central nervous system auditory pathway involvement in 17 (50%) of the patients: 38% by BAEPs alone (I–V inter-peak latency) and 47% by MLAEPs alone (Na and Pa peak latency). Five patients had abnormal MLAEPs with normal BAEPs whereas the opposite was detectable in only 1 patient. In addition, most MLAEP parameters in the MS group statistically differed from those obtained in the control group. Therefore, our results demonstrated that the auditory pathway impairment could frequently be located at a rostral level along the auditory radiation. In conclusion, even if only Na and Pa components were considered, MLAEPs succeeded in improving the sensitivity of the auditory evoked potential examination without increasing the false positive rate.

Middle latency auditory evoked potentials improve the detection of abnormalities along auditory pathways in multiple sclerosis patients

Brain-stem and middle latency auditory evoked potentials (BAEPs and MLAEPs) have been studied in 34 multiple sclerosis (MS) patients.We were able to detect a central nervous system auditory pathway involvement in 17 (50%) of the patients: 38% by BAEPs alone (I–V inter-peak latency) and 47% by MLAEPs alone (Na and Pa peak latency). Five patients had abnormal MLAEPs with normal BAEPs whereas the opposite was detectable in only 1 patient. In addition, most MLAEP parameters in the MS group statistically differed from those obtained in the control group. Therefore, our results demonstrated that the auditory pathway impairment could frequently be located at a rostral level along the auditory radiation. In conclusion, even if only Na and Pa components were considered, MLAEPs succeeded in improving the sensitivity of the auditory evoked potential examination without increasing the false positive rate.