Brainstem Auditory Evoked Response Abnormalities Research Articles

Evoked potential response in patients with idiopathic Parkinson’s disease and atypical parkinsonian syndromes: A comparative study

Patients with idiopathic Parkinson’s disease (IPD) and atypical parkinsonian syndromes (APSs) suffer from a range of disorders, especially in balance and locomotion, which necessitate visual, auditory, and somatosensory inputs. In this study, IPD patients, APS patients, and healthy controls (HCs) (n = 50 per group) underwent a series of assessments for visual evoked potentials (VEP), brainstem auditory evoked response (BAER), and short-latency somatosensory evoked potentials (SSEP). Results showed that VEP P100 latency was prolonged in multiple system atrophy-cerebellar type (MSA-C), multiple system atrophy-parkinsonian type (MSA-P), and corticobasal ganglionic degeneration (CBD) patients. The latency of peaks III and V was prolonged in IPD, MSA-C, dementia with Lewy bodies (DLB), and Parkinson’s disease dementia (PDD). BAER I-III and I-V interpeak latency were prolonged in IPD, DLB, and PDD, whereas BAER I-III, III-V, and I-V interpeak latencies were increased and the V/I amplitude ratio was decreased in MSA-C. The central sensory conduction time (N20-N13) was increased in MSA-P and MSA-C in SSEP. IPD patients had prolonged VEP P100 latency (P < 0.001), lower VEP N75-P100 amplitude (P < 0.001), prolonged BAER I, II, II, IV, V peak latencies (P < 0.001), I-III, I-V interpeak latencies (P < 0.001), lower BAER V/I amplitude ratio (P < 0.001), and prolonged SSEP N13, N20, central sensory conduction time (N20-N13) (P < 0.001) than HCs. IPD patients also had prolonged BAER I, II, II, IV, V peak latencies (P < 0.001), prolonged I-III, I-V interpeak latencies (P < 0.001), and shorter SSEP N13, N20, central sensory conduction time (N20-N13) (P < 0.001) than APS patients. Moreover, APS patients had prolonged VEP P100 and N145 latencies (P < 0.001) and decreased N75-N145 amplitude (P < 0.001) compared to HCs. APS patients also had prolonged BAER II, II, IV, V peak latencies (P < 0.001), prolonged I-III, III-V, I-V interpeak latencies (P < 0.001), decreased V/I amplitude ratio, and prolonged SSEP N13, N20, central sensory conduction time (N20-N13) (P < 0.001) than HCs. Postural instability and gait disorder (PIGD) IPD had significantly prolonged BAER III, V peak latencies (P < 0.05), and prolonged III-V interpeak latencies (P < 0.05) compared to tremor-dominant IPD. Overall, the IPD and APS patients had significant VEP, BAER, and SSEP abnormalities of demyelination and axonal variety in the visual, auditory, and somatosensory pathways. The changes were also correlated with the disease duration and severity. Although the diseases are predominantly motor disorders with significant non-motor components, these electrophysiological abnormalities might open a new avenue to assess the non-motor symptoms.

Targeted screening for hearing impairment in neonates: A prospective observational study

Background: The aim of this study is to estimate the incidence and determine the risk factors predictive of hearing impairment in newborn by targeted hearing screening. Methods: This was a prospective, observational study conducted over a period of 1 year. We screened high-risk neonates for hearing impairment admitted to the Neonatal Intensive Care Unit using evoked otoacoustic emissions (EOAEs) and brainstem auditory evoked response (BAER). Babies who tested refer on EOAE were subjected to BAER urgently. Babies having an abnormality on BAER where confirmed as hearing impaired for this study. Results: A total of 195 high-risk babies comprising males (95 = 48.7%) and females (100 = 51.3%) were screened. Fifteen neonates (7.69%) tested refer in the initial screening procedure, i.e., EOAE, who then underwent BAER and out of these 15 (7.69%) neonates, 12 (6.15%) had abnormal BAER, i.e., hearing impairment. The significant individual risk factors in neonates with hearing impairment were stigmata and/syndrome associated with hearing loss, craniofacial anomalies, and hyperbilirubinemia and Apgar score

P 38 Vestibular Schwannoma associated with hypertrophic neuropathy – An unusual manifestation of NF2 or not?

We report a case of generalized hypertrophic neuropathy, which was first noted with pressure palsy after surgery of a vestibular nerve schwannoma. A 46-year-old caucasian female presented with incomplete left radial nerve palsy and incomplete left ulnar nerve palsy with loss of muscle mass between the thumb and forefinger and additional slight hypaesthesia oft he fingertips dig. 1–2. Two weeks ago she underwent surgery for a left vestibular nerve schwannoma (see picture 1). One year before neurosurgery carpal tunnel syndrome was diagnosed bilaterally. In the first interview no family history of nerve diseases was reported. Neurography of median, ulnar, tibial and peroneal nerves showed very slow nerve conduction velocities (NCV) less than 30 m/s and diminished compound motor action potentials (CMAP) with prolonged duration. Electromyography showed no signs of acute denervation. High resolution nerve sonography (HRUS) showed markedly enlarged fascicles resulting in up to 6-fold nerve cross sectional areas (see picture 2, ulnar nerve oft he right upper arm) without vascularisation. This was present in all examined nerves in different expression. Family history was complemented by the patient: Her father suffered on a “disease of muscles” (has died at the age of 45 years) and her sister, too. No signs of neurofibromatosis (1 or 2) were reported. Genetic testing on mutations typically in neurofibromatosis 1 and 2 and schwannomatosis (“NF 3”) was negative. Because of demyelinating neuropathy (suspicious Charcot-Marie-Tooth disease) duplication of PMP22 gene was examined, but it was negative. At last heterozygous MPZ-Mutation was detected. This accounts for CMT1B neuropathy. The diagnosis of CMT1B is in accordance to the neurographic and sonographic findings of peripheral nerves. The focal enlargement of some fascicles is observed in schwannomas or neurofibromas, but usually they shows vascularisation, which was not present in this case. To date an association of CMT with vestibular schwannoma is not reported in the literature. Kwon et al. (2009) described a family with CMT1A caused by duplication of the PMP22 gene. Two family members had schwannomas of the spinal cord and median nerve. The authors argue that the co-occurrence of CMT1A and schwannomas in this family would be the result of independent events, but one could not completely ignore the possibility that the coincidence of two diseases might be due to a shared genetic background. Despite the missing association of CMT with vestibular schwannoma in the literature hearing loss seems not to be rare in CMT. Sanmaneechai et al. (2015) referred to patients with CMT disease caused by MPZ gene mutations. 21 of 103 patients had hearing loss, but tests like MRI or BAER (brainstem auditory evoked response) are not given in the paper. Grider et al. (2015) found in 25 CMT patients that BAER waveforms were robust even in the absence of acoustic reflexes, except for two patients with CMT1B who had abnormal BAER recordings that were not consistent with hearing thresholds. These observations supports for the neural nature of the hearing loss in CMT1B and should improve further investigations with MRI in those patients.

Brainstem Auditory Response Findings in Very Preterm Babies in the Intensive Care Unit

Background: There is a need to increase our understanding of whether there is compromised brainstem auditory function in very preterm babies in intensive care. Objectives: To evaluate brainstem auditory function in preterm babies born at 32 weeks of gestation or earlier in the intensive care unit to detect any abnormality and the prevalence of the abnormality. Methods: We analyzed the brainstem auditory evoked response (BAER) at term in 156 babies born at 32 weeks of gestation or earlier in an intensive care unit. The data were compared to those of normal term babies to detect any differences. Results: The threshold of BAER was elevated in babies born at 32 weeks of gestation or earlier. All BAER wave latencies were significantly increased. The I-V interpeak interval was also increased. The amplitudes of BAER components tended to be reduced. Twenty-five (16.0%) babies in the intensive care unit had a BAER threshold elevation (>20 dB normal hearing level), suggesting peripheral auditory dysfunction. Thirty-three (21.1%) had an increased I-V interval, and 3 (1.9%) had a decreased V/I amplitude ratio, suggesting central or brainstem auditory dysfunction. Some babies had more than one BAER abnormality. As a whole, 51 (32.7%) babies had BAER abnormalities. Conclusion: Very preterm babies in the intensive care unit are at a high risk for auditory dysfunction. At term, 1 in 3 of these babies has peripheral and/or central auditory dysfunction.

Screening for Hearing Impairment in High Risk Neonates: A Hospital Based Study.

Hearing loss very early in life can have multiple deleterious effects on the new born most commonly being related to attainment of speech and language. Also, it can affect social, emotional and academic achievement of the child.Early identification of hearing impairment has been shown to improve prognosis and hence screening programs have been widely and strongly advocated. To estimate the incidence of neonatal hearing loss in high risk neonates admitted in tertiary level teaching hospital and to determine the risk factors predictive of hearing impairment in them. It was a prospective study over a period of one year. We screened high risk neonates for hearing impairment admitted to NICU using Brain stem Auditory Evoked Response (BAER).The morphology of the response and wave and interwave latencies was examined in respect to age-appropriate forms. Follow up BAER after one month was performed in cases where initial BAER was abnormal. Babies who tested abnormal on the follow-up were referred for detailed audiology diagnostic work up. A total of 200 cases comprising 118 males (59%) and 82 females (41%) were enrolled. On initial BAER testing, 18 (15.25%) males and 14 (17%) female neonates had hearing loss. Whereas 7 males (70%) and 3 females (30%) had hearing loss out of the total 10 hearing loss cases in the Follow up-BAER testing. Two out of the 6 neonates with birth weight <1500g had hearing loss in the follow up of BAER testing. Use of ototoxic medications, hyperbilirubinemia requiring exchange transfusion, perinatal asphyxia and bacterial meningitis were the major risk factors occurring in 45%, 30% and 26% and 10%. Five neonates had unilateral hearing loss and the rest five (5%) had bilateral impairment.Meningitis was the significant independent clinical risk factors for predicting hearing impairment in high risk neonates.The risk of BAER increased cumulatively with BAER abnormality rate of 4.2%, 22.2% and 33.3% with one two and three risk factors respectively. The overall incidence of hearing loss in initial BERA testing was 16%, in males it was 15.25% in males and in 17% in females,only 62.5% of neonates had a persistent abnormal BAER, with male gender a significant risk factor for this. The incidence of hearing loss increased with number of risk factors. The study highlights that although universal hearing screening programs are warranted; most newborns with a detected hearing loss can be identified based on the risk factors. Thus, a targeted approach for hearing screening may be more feasible in resource limited settings.

Brainstem auditory evoked responses in foals: reference values, effect of age, rate of acoustic stimulation, and neurologic deficits.

BackgroundAge and rate of acoustic stimulation affect peak latencies in brainstem auditory evoked responses (BAER) in humans. Those effects are unknown in foals.Hypothesis/ObjectivesOur goals were to (1) establish reference values for BAER in foals by using 3 different stimulation protocols, (2) evaluate the effects of age and stimulation frequencies on BAER tracing in foals up to 6 months old, and (3) compare the data with BAER obtained from foals with central nervous system (CNS) disorders.AnimalsThirty‐nine neurologically normal foals and 16 foals with neurologic diseases.MethodsProspective observational clinical study. BAER recorded by using 3 protocols of stimulation (11.33 repetitions per second [Hz]/70 decibel normal hearing level [dBNHL]; 11.33 Hz/90 dBNHL; 90 Hz/70 dBNHL).ResultsNo effect of age was observed in normal foals (P > .005). No significant difference was observed for latencies and interpeak latencies (IPL) when comparing foals with neurologic diseases and normal foals (P > .05), but 78.6% of foals with neurologic diseases had an asymmetry in their tracing, reflecting a difference in conduction time between the left and right side of the brainstem. Increasing the stimulation rate did not improve detection of CNS disorders.Conclusions and Clinical ImportanceWe propose BAER reference values for foals up to 6 months of age by using 3 protocols. Most foals with neurologic deficits had abnormal BAER tracing.

Study of reversibility of auditory brainstem abnormalities in infants with high risk for hearing loss

ObjectivesThis study aimed at assessing the reversibility of Brainstem Auditory Evoked Response (BAER) abnormalities in neonates; with risk factors such as hyperbilirubinemia or hypoxia after therapy. MethodologyTwo groups A and B consisting of 10 neonates with hyperbilirubinemia (term and preterm) and 10 hypoxic neonates (term and preterm) respectively, had their BAER initially recorded at an age of less than 1month (as soon as they were discharged from the neonatal intensive care unit), and later at the age of 6months. Criteria for diagnosing infants with hyperbilirubinemia or hypoxia were a serum bilirubin of >20mg/dl and an Apgar score less than 6, respectively. A complete medical and family history was taken from the parents. Otoscopic examination, tympanometry, Transient evoked otoacoustic emissions (TEOAEs) were also done. ResultsAll neonates (100%) had initial BAER abnormalities; thus fulfilling our selection criteria. BAER after 6months showed significant improvements in both groups; 60% for group A and 55% for group B. ConclusionsSerial BAER is a useful, noninvasive tool to detect neurodevelopmental delay secondary to neonatal hyperbilirubinemia and hypoxia.

Brainstem auditory response findings in late preterm infants in neonatal intensive care unit

To examine brainstem auditory function at term in late preterm infants admitted to neonatal intensive care unit (NICU). Fifty-two preterm infants, born at 33-36 week gestation, were recruited in an NICU and were studied at term using brainstem auditory evoked response (BAER). Compared with normal term infants, BAER wave V latency in the NICU preterm infants was increased at 51 and 91/sec (p<0.05, 0.05). Intervals of III-V and I-V were increased at all 21, 51 and 91/sec clicks (p<0.05-0.01), which was more significant at higher than lower rates. Interval ratio of III-V/I-III was increased significantly at 51 and 91/sec (p<0.05 and 0.01). Wave I and III latencies and I-III interval did not differ significantly from normal controls at any click rates. All amplitudes of waves I, III and V amplitude tended to be reduced at higher rates, while wave I amplitude was reduced significantly at 91/sec clicks. There were BAER abnormalities in the NICU late preterm infants, suggesting compromised brainstem auditory function. Compared with a basically normal BAER in low-risk late preterm infants previously reported, the abnormalities suggest that perinatal problems or complications adversely affect the late preterm auditory brainstem.

Clinical correlates of abnormal brain-stem auditory evoked responses in multiple sclerosis.

Brain-stem auditory evoked responses (BAERs) were examined in 178 patients with multiple sclerosis (MS) and compared to the frequency of abnormalities in visually evoked responses (VERs) and in CSF electrophoresis. In clinically definite MS, BAERs were abnormal in 61% and a significant relationship was noted between disability due to MS and the frequency and severity of BAER abnormalities. In suspected MS, BAERs showed evidence of a second lesion in 14% whereas VERs indicated a second lesion in 24%. Abnormal BAERs in patients with suspected MS with brain-stem signs were significantly associated with the presence of truncal and limb ataxia. In progressive possible MS, abnormal BAERs were found in 49% but indicated a second lesion in 35% of patients and were significantly related to the duration of illness. In progressive possible MS, abnormal VERs but not abnormal BAERs, were significantly associated with the presence of CSF oligoclonal IgG banding. Normal BAERs in association with clinical brain-stem abnormalities were found in 24% of patients with clinically definite MS, 50% with suspected MS and 33% with progressive possible MS.

Brainstem Auditory‐Evoked Responses in Horses with Temporohyoid Osteoarthropathy

Facial and vestibulocochlear nerve dysfunction occurs commonly in horses with temporohyoid osteoarthropathy (THO); however, auditory dysfunction has not been thoroughly assessed. To determine if auditory abnormalities occur in horses with THO. Eleven diseased and 8 control horses. This is a prospective study in which brainstem auditory-evoked responses (BAER) were recorded in 11 horses diagnosed with THO through neurologic, endoscopic, radiographic, or computed tomographic examinations. BAER findings were compared with those recorded from 8 adult control horses. All horses with THO were found to have BAER abnormalities that included complete unilateral BAER loss (82%, n=9/11), partial unilateral BAER loss (18%, n=2/11) on the most affected side, and contralateral partial BAER loss (46%, n=5/11). Nine horses had bilateral THO based on diagnostic imaging findings; of these, 5 (56%) horses also had bilateral BAER abnormalities. The complete absence of BAER in affected horses was most consistent with peripheral sensorineural hearing loss. There was a significant association between complete BAER loss and neurologic and diagnostic abnormalities. Auditory abnormalities such as complete or partial BAER loss are common in horses with THO. The BAER test is an objective diagnostic tool that can aid along with other diagnostic modalities in the assessment, management, and follow-up of horses with THO. Furthermore, BAER studies may help to elucidate the pathophysiology of THO in horses.

Brainstem Auditory Outcomes and Correlation With Neurodevelopment After Perinatal Asphyxia

We used brainstem auditory-evoked responses and neurodevelopmental assessment to detect abnormalities and correlations between such responses and neurodevelopmental outcomes in 78 children (aged 4-12 years) who survived perinatal asphyxia. Twenty children had brainstem auditory-evoked response abnormalities, including increased threshold, reduced wave V amplitude, decreased V/I amplitude ratio, and prolonged I-V interval. Thirty-seven exhibited neurodevelopmental deficits, including cerebral palsy and developmental delay. The remaining 41 exhibited no deficits. Brainstem auditory-evoked response abnormalities were evident in 15 of 37 (40.5%) children with neurodevelopmental deficits, but in only 5 of 41 (12.2%) with no deficits, which differed significantly (chi(2) = 8.2, P < 0.05). The sensitivity, specificity, positive predictive value, and false-negative rate of brainstem auditory-evoked responses to reflect neurodevelopmental outcomes were 40.5%, 87.8%, 75.0%, and 59.5%, respectively. These findings suggest that in children who survive perinatal asphyxia, brainstem auditory impairment occurs more frequently in those with versus those without neurodevelopmental deficits. Brainstem auditory-evoked responses display a moderate correlation with clinically determined neurodevelopmental outcomes. Despite limitations, brainstem auditory-evoked response is valuable for assessing auditory and neurodevelopmental outcomes after perinatal asphyxia.

Auditory neural responses to click stimuli of different rates in the brainstem of very preterm babies at term.

Auditory neural responses to acoustic stimuli of different rates were studied by analyzing changes in brainstem auditory evoked responses (BAER) with increasing repetition rate of clicks, or rate-dependent changes, in 62 very preterm babies (gestation 24-32 wk). None had perinatal asphyxia or major complications at the time of testing (37-42 wk postconceptional age) to exclude their possible effects on the recorded BAER. As the rate of clicks was increased from 21/s to 51/s and 91/s, I-V interpeak interval in these babies increased similarly to that in normal term neonates. The rate-dependent change decreased significantly in I-III interval, but increased significantly in III-V intervals and III-V/I-III interval ratio (all p < 0.01). At all three rates of clicks, the I-V interval, the most commonly used BAER variable, tended to increase slightly but did not differ significantly from the term neonates. The I-III interval decreased significantly at higher click rates (ANOVA p < 0.05 at 51/s and < 0.001 at 91/s), whereas the III-V interval and III-V/I-III interval ratio increased significantly at all 21/s, 51/s, and particularly 91/s (p < 0.01-0.001). No abnormalities were found in wave V amplitude at any rates. These results suggest that very preterm babies have an advanced peripheral development of the brainstem auditory pathway but a retarded central development or central impairment. A nearly normal I-V interval does not exclude a possible abnormality in its subcomponents (I-III and III-V intervals). In babies who have a normal BAER at a conventionally used low rate of clicks, we cannot exclude an abnormal BAER at higher rates.

Evaluation of brainstem auditory evoked response audiometry findings in children with tuberculous meningitis at admission

Objective: To determine the characteristics of Brainstem auditory evoked response (BAER) findings in children with tuberculous meningitis (TBM) at admission. Methods: Twenty-seven children with highly probable TBM were admitted to the University Hospital. The control group was 23 healthy, age and sex matched subjects. Brainstem response audiometry recording was performed in all patients and controls. Ninety dB sound pressure level (SPL) was used for comparisons. The main BAER measurements analysed were the I–III, III–V, I–V interpeak intervals. In statistical analysis, t-test for independent groups were performed. At the same time, for interpeak intervals, values exceeding 2.5 standard deviations (S.D.) above the means of the normal controls were considered abnormal. To the result of BAER findings, HL was classified as mild (until 40 dBHL), severe (until 80 dBHL) and total HL (no hearing was detected). Results: The latencies of interpeak intervals (except III–V latency at 10 per s) have significantly prolonged in comparison with controls. Mild HL was detected in four ears. In eight ears, any wave form could not be obtained at 110 dBSPL. Abnormal BAER result was seen in 13 of 54 ears (24%) at the click of 10 per s and five ears (12%) at the click of 50 per s. Conclusion: Abnormal BAER result was seen in 24% of patients with TBM before treatment. Depending on these findings, it can be inferred that hearing impairments must be lower than those values which was detected by BAER during the acute phase of TBM, since the abnormal BAER may be reversible following the illness, returning to normal with recovery.

Developmental follow-up of breastfed term and near-term infants with marked hyperbilirubinemia.

In recent years, the increased prevalence of breastfeeding in conjunction with early discharge practices has increased the risk for marked hyperbilirubinemia in neonates. This has resulted in the potential for bilirubin brain injury in affected infants. The purpose of this study was to identify all infants >/=36 weeks' gestational age with bilirubin levels >25 mg/dL and evaluate them for early and late evidence of bilirubin brain injury. We reviewed the charts of all infants (from 1993-1996) >/=36 weeks' gestational age who were readmitted to the hospital during the first week of life with bilirubin levels >25 mg/dL. Readmission records were reviewed for early signs of bilirubin encephalopathy. Magnetic resonance imaging (MRIs) and Brainstem auditory-evoked responses (BAERs) were reviewed for evidence of bilirubin toxicity. At follow-up, study infants had a complete neurodevelopmental examination, repeat MRIs, and behavioral hearing evaluations. From 1993 to 1996, we identified 6 term and near-term infants readmitted to the hospital within the first week of life with peak bilirubin values ranging from 26.4 mg/dL (451 micromol/L) to 36.9 mg/dL (631 micromol/L). Five of 6 infants had bilirubin values >30 mg/dL (513 micromol/L). All were exclusively breastfed or fed a combination of breast and bottle feedings. Five of 6 infants presented with abnormal neurologic signs. Four infants had initial MRIs, 3 of whom had increased signal intensity in the basal ganglia consistent with kernicterus. Two infants had abnormal BAERs; both also had abnormal MRIs. Five of 6 infants received exchange transfusions and all were treated with phototherapy and intravenous fluids. Follow-up examinations between 3 months and 2 years showed resolution of clinical signs in all but 1 infant. Four infants had a subsequent normal MRI and 1 had residual hearing impairment. One infant demonstrated severely abnormal developmental evaluations, as well as both an abnormal initial MRI and BAERs. Follow-up MRI showed evidence of encephalomalacia with changes not characteristic of kernicterus. We observed transient neurologic abnormalities in 5 of 6 infants readmitted to the hospital during the first week of life with marked hyperbilirubinemia. The abnormalities resolved following aggressive management using hydration, phototherapy, and exchange transfusion and may not correlate with long-term prognosis. Less aggressive therapy may be associated with residual neurologic abnormalities. We speculate that inadequate establishment of breastfeeding coupled with early discharge practices may play a role in the development of marked hyperbilirubinemia in these infants.

Maximum length sequence brainstem auditory evoked responses in term neonates who have perinatal hypoxia-ischemia.

Maximum length sequence brainstem auditory evoked response (BAER) was studied within the first week after birth in 28 term neonates who had perinatal hypoxia-ischemia, or asphyxia. In the BAER recorded using conventional averaging techniques (click rate 21/s), the only abnormality was a slight increase in III-V interval, in addition to an increase in wave latencies when including those who had an elevated threshold (t test, all p<0.05). In the maximum length sequence BAER, however, both the III-V and I-V intervals in the asphyxiated infants were significantly increased at all the 91/s, 227/s, 455/s, and particularly 910/s click rates (p<0.05-0.001). The I-III interval was also increased significantly at 455/s and 910/s click rates (both p< 0.05). Wave V amplitude was significantly reduced at all the click rates used (ANOVA, p<0.05-0.001), particularly at 910/s, which sometimes was the only abnormality indicative of brain damage. Both the amplitude ratios V/I and V/III were significantly decreased at 455/s and 910/s click rates (p<0.01 or 0.001). A general trend was that BAER abnormalities after hypoxia-ischemia became more prominent as click rate was increased. Significant abnormalities occurred mainly at very high click rates (455/s and 910/s), which can be achieved using the maximum length sequence technique but not by using conventional averaging techniques. Thus, this technique, which can be used at the cribside, appears to be a better method for the early detection of brain damage after hypoxia-ischemia than using conventional averaging techniques, enhancing the diagnostic value of the BAER.

Visual and auditory evoked responses in acute severe hepatitis.

Evoked responses have not been studied in patients with acute severe hepatitis (ASH) with or without hepatic encephalopathy. This prospective study was undertaken to find out diagnostic as well as prognostic value of visual evoked responses (VER), and brain stem auditory evoked responses (BAER) in patients with ASH with or without encephalopathy. Visual evoked responses and BAER were studied in 20 patients (14 males and six females) with ASH. The patients were diagnosed as having severe hepatitis if acute hepatitis was associated with raised serum bilirubin and serum transaminases, and if they had a prothrombin time index of < 50%. After a detailed neuropsychiatric examination of each patient, the study sample was divided into two groups of 10 patients: ASH without encephalopathy (ASH-WOE), and ASH with encephalopathy (fulminant hepatic failure, FHF). The median P100 latencies of FHF patients were significantly increased compared with controls and patients in the ASH-WOE group. Abnormal P100 latencies, exceeding 95th percentile values of the controls, were present in one patient in the ASH-WOE group and six patients in the FHF group. The median interpeak latencies I-III, III-V and I-V were significantly prolonged in the FHF group. Interpeak latencies III-V were also increased significantly in patients in the ASH-WOE group. While abnormal BAER were seen frequently in both groups, VER abnormalities were largely confined to patients in the FHF group. In the FHF group, six out of 10 patients survived and exhibited clinical improvement in the status of hepatic encephalopathy. Evoked responses were repeated after 2-3 weeks of recovery in these patients and VER abnormalities showed a tendency to normalize, thereby suggesting a prognostic implication. The incidence of abnormal VER in hepatic encephalopathy complicating ASH far exceeded that of abnormal BAER. Markedly prolonged P100 latencies in FHF patients indicate poor prognosis.

Long-term effect of perinatal and postnatal asphyxia on developing human auditory brainstem responses: brainstem impairment

Long-term effect of perinatal and postnatal asphyxia on the developing auditory brainstem was investigated in children, particularly those who exhibited residual neurodevelopmental deficits, by analyzing the central components of brainstem auditory evoked responses (BAER). The major abnormalities in the BAER were a reduction of wave V amplitude, followed by a decrease in V I amplitude ratio, while abnormalities in interpeak intervals were relatively rare. These findings suggest that asphyxia could result in residual neural dysfunction of the brainstem but does not appear to exert any major long-term effect on neuronal transmission. BAER abnormalities occurred more frequently in the children with residual neurodevelopmental deficits than those without these deficits after perinatal asphyxia. The occurrence of BAER abnormalities was related to the duration as well as the degree of asphyxia. No significant difference was found in the abnormalities of the central BAER components between the children after perinatal asphyxia and those after postnatal asphyxia, suggesting that perinatal and postnatal asphyxia exerts a similar long-term effect on the developing central nervous system.

Vibroacoustic Stimulation and Auditory Acuity in Preterm Infants

Vibroacoustic stimulation (VAS) is widely accepted as a simple and inexpensive adjunctive antenatal test for fetal well-being. However, possible adverse effects of VAS on auditory acuity are not completely known and are of concern, especially for infants delivered prematurely. The purpose of our study was to evaluate neonatal hearing with the brain stem auditory evoked response (BAER) in 33 preterm neonates exposed to acoustic stimulation in utero and to compare the results with those of 33 preterm neonates who were not exposed to acoustic stimulation. Of the 33 exposed neonates, four had abnormal BAER results, indicating an apparent hearing loss. In three of four cases, an infectious etiology was found, suggesting a lack of association between antenatal VAS and hearing loss. By comparison, of the 33 preterm infants not exposed to VAS antenatally (control group), one infant had an abnormal BAER result and was subsequently diagnosed to have suffered a congenital hearing loss.Thus, the risk of acoustic trau...

Neurological manifestations of hypothyroidism: a retrospective study of 29 dogs.

Neuromuscular signs in association with hypothyroidism are described in 29 dogs. Eleven dogs had lower motor neuron signs, 9 had peripheral vestibular deficits, 4 had megaesophagus, and 5 had laryngeal paralysis. Primarily older (mean = 9.5 years), large-breed dogs were affected, and there was no sex or breed predisposition. Duration of clinical signs before presentation ranged from 2 to 8 weeks (mean = 5 weeks). The diagnosis was based on (1) results of neurological examination (29 dogs); (2) electromyographic abnormalities (18 dogs), including fibrillation potentials (n = 18), positive sharp waves (n = 15), and complex repetitive discharges (n = 4); (3) high serum cholesterol concentration (10 dogs; mean = 335 mg/dL); (4) low response to thyroid-stimulating hormone (29 dogs; mean T4 prestimulation concentration = 0.8 micrograms/dL; mean T4 poststimulation = 1.2 microgram/dL); and (5) good response to thyroxine supplementation (26 dogs). Dogs with vestibular deficits had abnormal brainstem auditory-evoked responses (BAER), including increased latencies of P1-P6 and decreased amplitude of P4,5-N5. Seven other dogs had similar BAER abnormalities without manifesting clinical signs of vestibular involvement. Three dogs with vestibular signs had fibrillation potentials and positive sharp waves without exhibiting lower motor neuron signs. All dogs were supplemented with levothyroxine (0.02 mg/kg PO bid). The follow-up period ranged between 6 and 30 months (mean, 14 months). Serum T4 concentrations were measured at least 3 times for each dog every 2 months (mean T4 concentration = 2.6 micrograms/dL). All but 1 dog with lower motor neuron signs and 1 dog with vestibular signs recovered after 2 months (mean, 57 days).(ABSTRACT TRUNCATED AT 250 WORDS)

Brain stem auditory-evoked response abnormalities in 14 dogs with confirmed central nervous system lesions.

Abnormal brain stem auditory-evoked responses (BAER) were recorded on 14 dogs with brain lesions confirmed by necropsy (n = 13) or magnetic resonance imaging and surgical biopsy (n = 1). Lesions included brain stem or cerebellar tumors (6 dogs), brain stem trauma (1 dog), forebrain tumors (3 dogs), hydrocephalus (2 dogs), granulomatous meningoencephalitis (1 dog), and meningoencephalitis (1 dog). Five affected dogs were comatose at the time of recording. BAER abnormalities could be classified as (1) absence of some or all of waves I to V, (2) increased latencies, with wave V being most frequently affected, or (3) a reduction in the amplitude ratio of waves V/I.