Interpeak Latencies Research Articles

Neurophysiologic, audiometric and vestibular function tests in patients with hyperostosis cranialis interna

ObjectiveHyperostosis cranialis interna (HCI) is an autosomal dominant sclerosing bone dysplasia affecting the skull base and the calvaria, characterized by cranial nerve deficits due to stenosis of neuroforamina. The aim of this study is to describe the value of several neurophysiological, audiometric and vestibular tests related to the clinical course of the disorder. MethodsTen affected subjects and 13 unaffected family members were recruited and tested with visual evoked potentials, masseter reflex, blink reflex, pure tone and speech audiometry, stapedial reflexes, otoacoustic emissions, brainstem evoked response audiometry and electronystagmography. ResultsDue to the symmetrical bilateral nature of this disease, the sensitivity of visual evoked potentials (VEPs), masseter reflex and blink reflex is decreased (25–37.5%), therefore reducing the value of single registration. Increased hearing thresholds and increased BERA latency times were found in 60–70%. The inter-peak latency I–V parameter in BERA has the ability to determine nerve encroachment reliably. 50% of the patients had vestibular abnormalities. No patient had disease-related absence of otoacoustic emissions, because the cochlea is not affected. ConclusionIn patients with HCI and similar craniofacial sclerosing bone dysplasias we advise monitoring of vestibulocochlear nerve function with tone and speech audiometry, BERA and vestibular tests. VEPs are important to monitor optic nerve function in combination with radiological and ophthalmologic examination. We do not advise the routine use of blink and masseter reflex.

Analysis of interpeak latencies of brainstem auditory evoked potential waveforms during microvascular decompression of cranial nerve VII for hemifacial spasm

Microvascular decompression (MVD) of the facial nerve is an effective treatment for patients with hemifacial spasm. Intraoperative monitoring of brainstem auditory evoked potentials (BAEPs) during MVD can reduce the incidence of hearing loss. In this study the authors' goal was to evaluate changes in interpeak latencies (IPLs) of Waves I-V, Waves III-V, and Waves I-III of BAEP Waveforms I, III, and V during MVD and correlate them with postoperative hearing loss. To date, no such study has been performed. Hearing loss is defined as nonuseful hearing (Class C/D), which is a pure tone average of more than 50 dB and/or speech discrimination score of less than 50%. The authors performed a retrospective analysis of IPLs of BAEPs in 93 patients who underwent intraoperative BAEP monitoring during MVD. Patients who did not have hearing loss were in Class A/B and those who had hearing loss were in Class C/D. Binary logistic regression analysis of independent IPL variables was performed. A maximum change in IPLs of Waves I-III and Waves I-V and on-skin change in IPLs of Waves I-V increases the odds of hearing loss. However, on adjusting the same variables for loss of response, change in IPLs did not increase the odds of hearing loss. Changes in IPL measurements did not increase the odds of postoperative hearing loss. This information might be helpful in evaluating the value of IPLs as alarm criteria during MVD to prevent hearing loss.

Introduction: Cranial nerve surgery

In this issue of Neurosurgical Focus, we have compiled a group of interesting papers related to anatomy, physiology, pathology, and surgery of the cranial nerves. We were very pleased to receive many more submissions of excellent papers on this topic from which we had the difficult task of having to select, because of limitations in space, only 8 papers. Rodgers and colleagues give an excellent review of the syndrome of short-lasting unilateral neuralgiform headache attacks with conjunctival injection and tearing. In the authors’ case, the syndrome was caused by an epidermoid tumor of the cerebellopontine angle that was clearly compressing the trigeminal nerve. We found this case report interesting because the etiology of this syndrome has not been clear, and this paper suggests that compression of the trigeminal nerve may be one of the causes. We thought that the excellent review of this topic the authors provide to us is important because neurosurgeons are so frequently called upon to treat trigeminal neuralgia, and we must be able to differentiate that condition from this interesting syndrome. Ross and colleagues report on 4 patients with rare facial nerve tumors and use the opportunity to present us with a nice review of the literature on the clinical syndrome, imaging characteristics, and surgical treatment of these tumors. Wang and colleagues from the University of Pittsburgh review their extensive experience with microvascular decompression for hemifacial spasm and conclude that botulinum toxin injections, which many of these patients underwent for treatment of their spasms before microvascular decompression, had no impact on the results of this operation. This finding is important because nowadays most patients have already had this type of palliative treatment before undergoing microvascular decompression. The second paper by this group of authors (Thirumala et al.) is a careful study of neurophysiological monitoring during microvascular decompression for hemifacial spasm; essentially, the authors conclude that changes in interpeak latency of brainstem auditory evoked potentials during surgery do not increase the odds of postoperative hearing loss and should not be used as an “alarm criteria” during microvascular decompression. Kshettry and colleagues present a nice historical review of the early studies of the anatomy of the petroclival region and the contributions of Primo Dorello, an Italian anatomist, after whom the Dorello canal is named. Interestingly, it turns out that the canal now widely known by Dorello’s name had been previously described 50 years earlier by W. Gruber. This paper also contains a nice review of anatomical studies of this region followed by a brief review of clinical implications. Schmidt et al. present a case of a malignant peripheral nerve sheath tumor of the trigeminal nerve, which they used as an opportunity to review the literature and summarize very nicely a total of 36 cases of malignant peripheral nerve sheath tumors of the trigeminal nerve. As expected, these tumors usually present with altered facial sensation and/or facial pain, and it appears that aggressive resection followed by radiation therapy offers the best chance for survival. Sarnthein and colleagues present another interesting paper concerning neurophysiological monitoring of facial nerve function during skull base surgery. In this careful study, the authors find that an intraoperative increase in the threshold for transcranial stimulation necessary to elicit a facial nerve motor evoked response is very specifically correlated with postoperative facial nerve dysfunction, and they suggest that such monitoring should be used in these operations in addition to the widely used direct electrical stimulation of the facial nerve. This issue also contains a very nice review of the neurosurgical options for management of glossopharyngeal neuralgia by Rey-Dios and Cohen-Gadol. The authors conclude that microvascular decompression is an excellent option but that when a convincing neurovascular conflict is not found, section of the glossopharyngeal nerve and the upper rootlets of the vagus nerve is a satisfactory alternative. (http://thejns.org/doi/abs/10.3171/2013.1.FOCUS1322)

Incidence of high-frequency hearing loss after microvascular decompression for hemifacial spasm

The primary aim of this study was to evaluate the incidence and discuss the pathogenesis of high-frequency hearing loss (HFHL) after microvascular decompression (MVD) for hemifacial spasm (HFS). Preoperative and postoperative audiogram data and brainstem auditory evoked potentials (BAEPs) from 94 patients who underwent MVD for HFS were analyzed. Pure tone audiometry at 0.25-2 kHz, 4 kHz, and 8 kHz was calculated for all individuals pre- and postoperatively ipsilateral and contralaterally. Intraoperative neurophysiological data were reviewed independently. An HFHL was defined as a change in pure tone audiometry of more than 10 dB at frequencies of 4 and 8 kHz. The incidence of HFHL was 50.00% and 25.53% ipsilateral and contralateral to the side of surgery, respectively. The incidence of HFHL adjusted for conductive and nonserviceable hearing loss was 26.6% ipsilaterally. The incidence of HFHL at 4 and 8 kHz on the ipsilateral side was 37.23% and 45.74%, respectively, and it was 10.64% and 25.53%, respectively, on the contralateral side. Maximal change in interpeak latency Waves I-V compared with baseline was the only variable significantly different between groups (p < 0.05). Sex, age, and side did not increase the risk of HFHL. Stepwise logistic regression analysis did not find any changes in intraoperative BAEPs to increase the risk of HFHL. High-frequency hearing loss occurs in a significant number of patients following MVD surgery for HFS. Drill-induced noise and transient loss of CSF during surgery may impair hearing in the high-frequency ranges on both the ipsilateral and contralateral sides, with the ipsilateral side being more affected. Changes in intraoperative BAEPs during MVD for HFS were not useful in predicting HFHL. Follow-up studies and repeat audiological examinations may be helpful in evaluating the time course and prognosis of HFHL. Prospective studies focusing on decreasing intraoperative noise exposure, as well as auditory shielding devices, will establish causation and allow the team to intervene appropriately to decrease the risk of HFHL.

Changes in brainstem auditory evoked potentials among North Indian females with Type 2 diabetes mellitus

Background:Diabetes mellitus is a complex metabolic disorder whose detrimental effects on various organ systems, including the nervous system are well known.Aim:This study was conducted to determine the changes in the brainstem auditory evoked potentials (BAEP) in patients with type 2 diabetes mellitus.Materials and Methods:In this case-control study, 116 females with type 2 diabetes and 100 age matched, healthy female volunteers were selected. The brainstem auditory evoked potentials (BAEP) were recorded with RMS EMG EP Marc-II Channel machine. The measures included latencies of waves I, II, III, IV, V and Interpeak latencies (IPL) I-III, III-V and I-V separately for both ears. Data was analysed statistically with SPSS software v13.0.Results:It was found that IPL I-III was significantly delayed (P = 0.028) only in the right ear, while the latency of wave V and IPL I-V showed a significant delay bilaterally (P values for right ear being 0.021 and 0.0381 respectively while those for left ear being 0.028 and 0.016 respectively), in diabetic females. However, no significant difference (P > 0.05) was found between diabetic and control subjects as regards to the latencies of waves I, II, III, IV and IPL III-V bilaterally and IPL I-III unilaterally in the left ear. Also, none of the BAEP latencies were significantly correlated with either the duration of disease or with fasting blood glucose levels in diabetics.Conclusions:Therefore, it could be concluded that diabetes patients have an early involvement of central auditory pathway, which can be detected quite accurately with the help of auditory evoked potential studies.

Type-2 diabetes mellitus and auditory brainstem response

Objective:Diabetes mellitus (DM) causes pathophysiological changes at multiple organ system. With evoked potential techniques, the brain stem auditory response represents a simple procedure to detect both acoustic nerve and central nervous system pathway damage. The objective was to find the evidence of central neuropathy in diabetes patients by analyzing brainstem audiometry electric response obtained by auditory evoked potentials, quantify the characteristic of auditory brain response in long standing diabetes and to study the utility of auditory evoked potential in detecting the type, site, and nature of lesions.Design:A total of 25 Type-2 DM [13 (52%) males and 12 (48%) females] with duration of diabetes over 5 years and aged over 30 years. The brainstem evoked response audiometry (BERA) was performed by universal smart box manual version 2.0 at 70, 80, and 90 dB. The wave latency pattern and interpeak latencies were estimated. This was compared with 25 healthy controls (17 [68%] males and 8 [32%] females).Result:In Type-2 DM, BERA study revealed that wave-III representing superior olivary complex at 80 dB had wave latency of (3.99 ± 0.24) ms P < 0.001, at 90 dB (3.92 ± 0.28) ms P < 0.001 compared with control. The latency of wave III was delayed by 0.39, 0.42, and 0.42 ms at 70, 80, and 90 dB, respectively. The absolute latency of wave V representing inferior colliculus at 70 dB (6.05 ± 0.27) ms P < 0.001, at 80 dB (5.98 ± 0.27) P < 0.001, and at 90 dB (6.02 ± 0.30) ms P < 0.002 compared with control. The latency of wave-V was delayed by 0.48, 0.47, and 0.50 ms at 70, 80, and 90 dB, respectively. Interlatencies I-III at 70 dB (2.33 ± 0.22) ms P < 0.001, at 80 dB (2.39 ± 0.26) ms P < 0.001, while at 90 dB (2.47 ± 0.25) ms P < 0.001 when compared with control. Interlatencies I-V at 70 dB (4.45 ± 0.29) ms P < 0.001 at 80 dB (4.39 ± 0.34) ms P < 0.001, and at 90 dB (4.57 ± 0.31) ms P < 0.001 compared with control. Out of 25 Type-2 DM, 13 (52%) had diabetic neuropathy, of which 12 (92%) showed abnormal BERA. In nonneuropathic [12 (48%)] only 6 (50%) showed abnormal BERA.Conclusion:Delay in absolute latencies and interpeak latencies by BERA demonstrates defect at level of brainstem and midbrain in long standing Type-2 diabetes subjects, which is more pronounced in those with neuropathy.

Establishment of Normative data for Monaural recordings of Auditory Brainstem Response and its Application in screening Patients with Hearing Loss: A Cohort Study

To establish normative data required for recording Auditory Brainstem Response (ABR) using monaural stimulations in children with normal hearing. This study was conducted on 40 apparently healthy children. Database was collected after assessing with otological questionnaire, otoscopic examination and audiometric evaluation. Brainstem Evoked Response Audiometry (BERA) was used as a tool for establishment of normative data. ABR recordings by monaural presentation were obtained by following the standard test protocol given by Hall. ABR parameters like Absolute latencies, amplitudes, amplitude ratios, Inter- peak latencies and thresholds were assessed for their normative values which are required to establish a baseline data. The Interaural latency difference was less than 0.2 ms (milliseconds) and was found to be normal limit. Mean values of absolute latencies for left ear were1.66 ms 3.68 ms and 5.64 ms respectively and for right ear these were 1.66 ms, 3.65 ms and 5.59 ms respectively. Mean values for amplitude of wave I and V for left ear were 0.32 uV and 0.41 uV respectively. For right values were 0.31 uV and 0.36 uV respectively. Mean values of amplitude ratio (V/I) for left and right ears were 1.81 and 1.74 respectively. Mean values of interpeak latencies of wave I-III, III-V, I-V were 2.02 ms, 2.02 ms and 3.92 ms respectively for left ear and for right ear values were 2.04 ms, 1.98 ms and 4.03 ms respectively. Mean values for left and right ear hearing threshold was 25.25 dBnHL. ABR parameters shows variation in values depending upon age, myelination process, maturation of auditory pathway, environmental factors, laboratory setup etc. Hence it is concluded that each laboratory should have its own normative data which can be used as a baseline data for screening of patients with hearing loss.

Brainstem Auditory Evoked Potential in Type 2 Diabetes Mellitus

Background and objectives: There are many studies showing involvement of the peripheral and autonomic nervous system in type 2 diabetes, but very few evidences are present in the literature for central diabetic neuropathy. Therefore, we aimed to evaluate whether the brainstem auditory evoked potential (BAEP) study can be used to detect subclinical central diabetic neuropathy at an early stage of the disease. Materials and methods: The BAEPs were studied in 30 patients of type 2 diabetes mellitus, aged 46–75 years, and compared with the control group. Statistical analysis was performed by using t-test and Pearson's correlation. Results: There was significant increase in right ear absolute peak latencies of waves I-V and latencies of waves I, II, V and IPL (inter-peak latency) III–V of left ear in diabetic patients. There were no significant correlations between the duration of diabetes, glycaemic levels of patients and the latencies of wave V of both ears. Interpretation: Diabetics had significantly prolonged BAEP latencies, which were neither correlated with plasma glucose levels nor with duration of the disease when compared with age- and sex-matched controls. Conclusions: Diabetes affects the central nervous system and that can be detected easily by the BAEPs at an early stage of the disease.

Brainstem auditory evoked potential abnormalities in type 2 diabetes mellitus

Background:Diabetes mellitus represents a syndrome complex in which multiple organ systems, including the central nervous system, are affected.Aim:The study was conducted to determine the changes in the brainstem auditory evoked potentials in type 2 diabetes mellitus.Materials and Methods:A cross sectional study was conducted on 126 diabetic males, aged 35-50 years, and 106 age-matched, healthy male volunteers. Brainstem auditory evoked potentials were recorded and the results were analyzed statistically using student's unpaired t-test. The data consisted of wave latencies I, II, III, IV, V and interpeak latencies I-III, III-V and I-V, separately for both ears.Results:The latency of wave IV was significantly delayed only in the right ear, while the latency of waves III, V and interpeak latencies III-V, I-V showed a significant delay bilaterally in diabetic males. However, no significant difference was found between diabetic and control subjects as regards to the latency of wave IV unilaterally in the left ear and the latencies of waves I, II and interpeak latency I-III bilaterally.Conclusion:Diabetes patients have an early involvement of central auditory pathway, which can be detected with fair accuracy with auditory evoked potential studies.

MATURATION OF BRAINSTEM AUDITORY EVOKED POTENTIAL FROM FULL TERM INFANTS &amp; CHILDREN TO YOUNG ADULT

Age is one of the important factors in the clinical interpretation of Brainstem auditory evoked potential waveform components and it can change the value of peak latencies and interpeak latencies among different age groups. Initial auditory responses in neonates appear in the 26th and 27th weeks of pregnancy. Progressively over time, these follow a

Effect of female sex hormones on central auditory conductivity in young rural females in Bathinda district of Punjab.

Background: The auditory, olfactory and taste thresholds get modified by changes in gonadal function. Auditory brainstem responses vary with age and sex of the individual. Auditory acquity also varies with the phase of menstrual cycle. Aims & Objective: To study the effects of cyclical changes of endogenous sex hormones in different phases of menstrual cycle on Brainstem Auditory Evoked Responses. Materials and Methods: The brainstem auditory conduction (BAEPs) recording was done in normal 40 healthy regular menstruating females in age group 19-23 years during three phases of same menstrual cycle. Phase 1:1-3 days with lowest level of oestrogen and progesterone, Phase 2:11-14 days with peak level of β-oestradiol and Phase 3:17-23 days with peak level of progesterone. Absolute latencies of I, III & V waves and interpeak latencies (IPL) of waves I-III, I-V and III-V were recorded in three phases of menstrual cycle and compared statistically. Results: The comparison showed a statistically significant increase in absolute latencies of I, III & V waves in phase 2 compared to phase 1 and a statistical significant decrease in their values in Phase 3 compared to Phase 2. However, the variation in interpeak latencies I-III, I-V and III-V showed insignificant variation. Conclusion: The study showed that variation of hormones during menstrual cycle affect the central auditory conductivity in young rural females.

Auditory and Neurological Correlation in Auditory and Peripheral Neuropathy in Type II Diabetes Mellitus

Background: Diabetes mellitus is metabolic disorder of multiple etiologies characterized by chronic hyperglycemia with disturbances of carbohydrate, fat and protein metabolism resulting from defects of insulin secretion, insulin action or both. The study was conducted with an aim to evaluate the effect of type II Diabetes mellitus on auditory brainstem response and conduction velocity of median nerve(motor component) and sural nerve (sensory component) and to correlate between auditory neuropathy and peripheral neuropathy due to type II Diabetes mellitus. The present study was undertaken in the Neurophysiology Laboratory, Department of Physiology, Jawaharlal Nehru Medical College Sawangi(Meghe) Wardha. It was a cross sectional case control study and a total of 100 subjects were studied out of which 50 were diabetics and 50 were age and sex matched controls. Effective nerve stimulation was obtained by the stimulus duration of 50μs to 1000μs and 0-100mA. Supramaximal stimulation (10-30% more than the current)was given. Electrode impedence was kept below 5k. BAEPs were recorded with the help of a computerized evoked potential recording system by monoaural stimulation and all the parameters have been compared at 70dBnHL stimulus intensityThe duration of diabetes in the study group with mean+S.D. is 6.92+2.08 years. There was no statistical significant difference in mean age and gender between the control group andstudygroup We founded increase in latency of waveV and interpeak latency III-V. There was decreased conduction velocity in median nerve and sural nerve of upper limb and lower limbfor motor nerve and sensory nerve respectively

Pattern of BAER abnormalities in neonatal hyperbilirubinemia

Article history: This study was done to determine the various abnormalities of Brain Auditory Evoked Response (BAER) in neonates with hyperbilirubinemia and to correlate the specific BAER abnormality with a particular range of bilirubin levels. Prospective study was done in 100 cases in a tertiary care hospital over a period from 2007-2008. All cases with hyperbilirubinemia were subjected to BAER test. Fifty five percent (n=44) out of 80 cases showed abnormal BAER test and 24 of them showed bilaterally in babies having peak serum bilirubin levels of more than 20mg/dL. Seventy five percent (n=33) showed prolong interpeak latency in wave III-V indicating that the conduction from superior olivary complex (wave III) to inferior collicullus (wave V) were more commonly affected with peak levels of bilirubin when compared to control which were found to be statistically significant (p<0.05). BAER is a simple and effective tool for determining the auditory functions in neonates with hyperbilirubinemia and could predict the impending encephalopathy or to identify subtle findings that could be reversed.

Brainstem auditory evoked potentials and middle latency auditory evoked potentials in young children

Measurements of brainstem auditory evoked potentials (BAEP) and middle latency auditory evoked potentials (MLAEP) are readily available neurophysiologic assessments. The generators for BAEP are believed to involve the structures of cochlear nerve, cochlear nucleus, superior olive complex, dorsal and rostral pons, and lateral lemniscus. The generators for MLAEP are assumed to be located in the subcortical area and auditory cortex. BAEP are commonly used in evaluating children with autistic and hearing disorders. However, measurement of MLAEP is rarely performed in young children. To explore the feasibility of this procedure in young children, we retrospectively reviewed our neurophysiology databank and charts for a 3-year period to identify subjects who had both BAEP and MLAEP performed. Subjects with known or identifiable central nervous system abnormalities from the history, neurologic examination and neuroimaging studies were excluded. This cohort of 93 children up to 3years of age was divided into 10 groups based on the age at testing (upper limits of: 1week; 1, 2, 4, 6, 8, 10 and 12months; 2years; and 3years of age). Evolution of peak latency, interpeak latency and amplitude of waveforms in BAEP and MLAEP were demonstrated. We concluded that measurement of BAEP and MLAEP is feasible in children, as early as the first few months of life. The combination of both MLAEP and BAEP may increase the diagnostic sensitivity of neurophysiologic assessment of the integrity or functional status of both the peripheral (acoustic nerve) and the central (brainstem, subcortical and cortical) auditory conduction systems in young children with developmental speech and language disorders.

Canine brainstem auditory evoked responses are not clinically impacted by head size or breed

Accurate assessment of canine hearing is essential to decrease the incidence of hereditary deafness in predisposed breeds and to substantiate hearing acuity. The Brainstem Auditory Evoked Response (BAER) is a widely accepted, objective test used in humans and animals for estimation of hearing thresholds and deafness diagnosis. In contrast to humans, testing and recording parameters for determination of normal values for canine hearing are not available. Conflicting information concerning breed and head size effects on canine BAER tests are major contributors preventing this normalization.The present study utilized standard head measurement techniques coupled with BAER testing and recording parameters modeled from humans to examine the effect canine head size and breed have on BAER results. Forty-three adult dogs from fourteen different breeds had head size measurements and BAER tests performed. The mean latencies compared by breed for waves I, II, III, IV, and V were as follows: 1.46±0.49ms, 2.52±0.54ms, 3.45±0.41ms, 4.53±0.83ms and 5.53±0.43ms, respectively. The mean wave I–V latency interval for all breeds was 3.69ms. All dogs showed similar waveform morphology, structures, including the presence of five waves occurring within 11ms after stimulus presentation and a significant trough occurring after Wave V. All of the waveform morphology for our subjects occurred with consistent interpeak latencies as shown by statistical testing. All animals had diagnostic results within the expected ranges for each wave latency and interwave interval allowing diagnostic evaluation.Our results establish that neither differences in head size nor breed impact determination of canine BAER waveform morphology, latency, or hearing sensitivity for diagnostic purposes. The differences in canine head size do not have a relevant impact on canine BAERs and are not clinically pertinent to management or diagnostic decisions.

The Influence of Aging on Auditory Evoked Potential in Advanced Age Group

Each sensory system has its own time of maturation. The individuation of the exact period of life when brain aging starts is difficult to define. Normally, the amplitude of evoked potentials decreases, and their latency increases from adult to elder life. The absolute latencies of Waves I, III, and V are 0.1 to 0.2 ms longer for subjects aged 50 years and older than for those aged 2030 years. The influence of age on interwave latency is inconclusive but also suggests that there may be an age-related prolongation of 0.1 to 0.2 ms for the IV interpeak interval. Age related changes may be confounded by the presence of sensory hearing loss. Since age effects on central conduction time in the acoustic pathway are still debated, the present study was conducted to assess the effects of aging on central conduction time & compared with the young adult. Auditory evoked potential were studied in twenty five normoacoustic elderly subjects & results were compared with twenty five age and sex matched controls (young adults between 18-25 years age group). The older adults had prolonged wave III & wave V latencies. The interpeak latency I-III and I-V are also prolonged which suggest that aging process is central phenomenon.

Auditory brainstem response in gas station attendants

Ototoxicity of organic solvents can affect the hearing system up to the cochlea level and the central structures of hearing. ObjectiveTo evaluate the neurophysiological integrity of the hearing system in subjects exposed to fuels using ABR. MethodProspective study. We evaluated attendants from three gas stations in Santa Maria/RS. The sample had 21 subjects, who were evaluated by auditory brainstem response. ResultsWe found an alteration in the absolute latencies of Waves I and III and in all the interpeak latencies, in the right ear. In the left ear there was a change in the absolute latencies of all Waves, and in all the interpeak intervals. A change in the interaural difference of Wave V was found in 19% of the individuals. In the group exposed for more than five years, there were subjects with a statistically significant changes: in the I-V interpeak of the right ear; in the absolute latency of Wave I and in the III-V interpeak of the left year. ConclusionExposure to fuels can cause alterations in the central hearing system.

Audiologic features of mitochondrial DNA A3243G mutation and its correlation with mutation rate

To summarize the clinical audiologic features of patients with mitochondrial DNA (mtDNA) A3243G mutation and explore the lesion location of hearing loss so as to examine its correlation with the related syndrome. A total of 44 patients with mtDNA A3243G mutation from 2009-2011 were studied. Audiological evaluations consisted of measurements of pure-tone and speech audiometry, tympanometry, distortion-product otoacoustic emissions and auditory brainstem response. We investigated a possible correlation between the degree of hearing loss and gender, age and mutation rate. (1) Pure tone test was performed in 41 patients and showed normal hearing or symmetrical sensorineural hearing loss. Pure tone audiogram (PTA) showed high-frequency loss and descending curve in a majority of patients. There were 75 ears with hearing loss in 82 ears (91.46%), 22 ears with abnormal speech audiometry in 26 ears, 77 ears with abnormal distortion product otoacoustic emissions (DPOAE)testing in 86 ears, including 5 ears with normal PTA, 31 ears with abnormal electrocochleography in 75 ears, 25 ears with abnormal auditory brainstem response (ABR) in 82 ears. The abnormal ABR showed elevated threshold in 10 ears, delayed interpeak latencies of wave I-V in 2 ears and disappearance of wave V before wave I in 1 ear. In addition, there were 2 ears with speech audiometry abnormal but with normal ABR. (2) The correlation between the severity of hearing and gender did not reach statistical significance, nor the severity of hearing and mutation ratio. Age could influence the hearing of A3243G-induced MELAS. The predominant lesions of mtDNA A3243G is at cochlea and retrocochlear sites. Significant variations in clinical manifestation of hearing are the prominent features in patient with A3243G mutation. There was no correlation between the degree of hearing loss and mutation load. However, hearing impairment is the most common symptom of A3243G mutation.

Brain-stem auditory evoked responses in COPD patients

BackgroundCOPD is a multi-system disorder. It appears to be associated with the presence of systemic inflammatory markers as C reactive protein. Aim of the workThe present study aimed to evaluate the brain-stem auditory evoked potentials (BAEP) abnormalities in stable COPD patient and its correlation with high sensitivity C reactive protein (hs-CRP) as a part of multi-system disorder. Subjects and methodsThis case control study was carried out at Mansoura University Hospital Egypt from October 2009 to February 2010. The study comprised 40 stable COPD patients and 15 healthy controls with no risk that may lead to neuropathy. All the patients and controls were subjected to the following: I-Thorough history taking and clinical examination. II-Pulmonary function tests including: 1-Spirometry 2-Body plethsymography 3-Arterial blood gases analysis. III- Record of brain-stem auditory evoked potentials (BAEP) including: latencies of waves I, II, III, IV and V together with interpeak latencies (IPLs) of I–III, I–V and III–V and amplitudes of waves I–Ia and V–Va. IV–Measurement of serum high sensitivity C reactive protein (hs-CRP) by ELISA technique. V–Statistical analysis. ResultsThe level of hs-CRP reactive protein in COPD was significantly elevated and correlated with spirometric, blood gases parameters and GOLD stage. The BAEP latencies of waves I, II, III, IV and V, together with interpeak latencies and amplitudes of waves I–Ia and V–Va measured on both ears were significantly different in COPD patients than controls. The prevalence of brain-stem auditory evoked potentials abnormalities was higher among very severe group of COPD. Most of BAEP wave latencies together with interpeak latencies and wave amplitudes on both ears were significantly correlated with the spirometric and blood gases parameters. The level of hs-CRP was correlated significantly with abnormalities of BAEP variables. ConclusionThis study showed significant subclinical BAEP abnormalities in studied stable COPD male patients. This indicates conductive defect of auditory nerve, cochlea and even hearing pathway in the brain as a part of systemic inflammation.Theses BAEP abnormalities were significantly correlated with GOLD classification, hs-CRP and PaO2.

BRAINSTEM AUDITORY EVOKED POTENTIAL IN DIFFERENT AGE GROUPS

Brainstem auditory evoked potential is a physiological technique for evaluation of auditory pathway. A number of electrical potentials can be recorded from the human scalp following acoustic stimulation. The potentials which occur within 10 msec of the stimulus onset termed the brain stem auditory evoked potentials (BAEPs). Latency appears to be the most stable measure and in consequence knowledge of the exact limits of normal latency of each wave is important. Since age effects on central conduction time in the acoustic pathway are still debated, the following study was conducted to investigate possible age differences in BAEP component latencies in different age groups. BAEP were elicited from seventy five normoacoustic male subjects aged from 11-60 years. The recorded results are grouped according to patients age ranges of 11-20 (15), 21-30 (15), 31-40 (15), 41-50 (15) and 51-60 (15) years. The absolute peak latency of waves I, III & V and interpeak latency of wave’s I-III, III-V & I-V in various age groups are analyzed. The data collected from both ears showed that increase in age will cause an increase in peak latency and interpeak latency values of all waves. Significant changes in the BAEPs in our study support the possible role of age as contributory factors for normal variations.