Brainstem Auditory Evoked Potentials Findings Research Articles

Subclinical neural hearing alterations in school children with type 1 diabetes mellitus

Background and objectivesEvidence has shown a cause-and-effect relationship between type 1 diabetes mellitus and auditory and cognitive dysfunctions. This study aimed to investigate the effect of type 1 diabetes mellitus (T1DM) on central auditory and cognitive functions in school-age children and adolescents. MethodsThe study sample consisted of 101 children and adolescents, 50 with T1DM, of both sexes, aged between 7 and 18 years. All participants were selected for a structured interview on hearing, behavioral, and cognitive health and assessment of brainstem auditory evoked potentials (BAEP) and event-related potentials (P300). ResultsSignificant differences were observed in memory (p=0.002) and attention (p=0.021) complaints between participants with and without T1DM. In the BAEP responses, there were differences between wave III latencies in the right (p=0.017) and left (p=0.019) ears and in wave V latencies in the left ear (p=0.001) between the evaluated groups. In addition, there was an association between BAEP findings and metabolic control in the T1DM group in the left ear in waves III (p=0.006) and V (p=0.005) and in the right ear in wave V (p=0.026). No differences were observed in the latencies of P300 between the evaluated groups. ConclusionThis study demonstrated the existence of a subclinical finding in the central auditory pathway, offering an increased risk for retrocollear alterations, which may be a consequence of poor metabolic control.

Subclinical neural hearing alterations in school children with type 1 diabetes mellitus

Background and objectivesEvidence has shown a cause-and-effect relationship between type 1 diabetes mellitus and auditory and cognitive dysfunctions. This study aimed to investigate the effect of type 1 diabetes mellitus (T1DM) on central auditory and cognitive functions in school-age children and adolescents. MethodsThe study sample consisted of 101 children and adolescents, 50 with T1DM, of both sexes, aged between 7 and 18 years. All participants were selected for a structured interview on hearing, behavioral, and cognitive health and assessment of brainstem auditory evoked potentials (BAEP) and event-related potentials (P300). ResultsSignificant differences were observed in memory (p=0.002) and attention (p=0.021) complaints between participants with and without T1DM. In the BAEP responses, there were differences between wave III latencies in the right (p=0.017) and left (p=0.019) ears and in wave V latencies in the left ear (p=0.001) between the evaluated groups. In addition, there was an association between BAEP findings and metabolic control in the T1DM group in the left ear in waves III (p=0.006) and V (p=0.005) and in the right ear in wave V (p=0.026). No differences were observed in the latencies of P300 between the evaluated groups. ConclusionThis study demonstrated the existence of a subclinical finding in the central auditory pathway, offering an increased risk for retrocollear alterations, which may be a consequence of poor metabolic control.

The Severity of Direct Antiglobulin Test Negative ABO Hemolytic Disease of Newborn: A Retrospective Analysis at a Tertiary Children’s Hospital

This study aimed to evaluate the severity of ABO hemolytic disease of newborn (ABO-HDN) with negative direct antiglobulin test (DAT), which was identified by elution test. We retrospectively reviewed the clinical records of all neonates admitted with the diagnosis of neonatal hyperbilirubinemia requiring phototherapy or exchange transfusion. Neonates were divided into four groups according to their immunohematology test results. Then their essential laboratory results, magnetic resonance image (MRI), brainstem auditory evoked potential (BAEP) findings, and rate of exchange transfusion were compared between different groups. We found that neonates in ABO-HDN with negative DAT group developed jaundice faster and anaemia more severely than those in the non-HDN group. Although they might get less severe anaemia than neonates in ABO-HDN with positive DAT group and the Rh-HDN group, neonates in ABO HDN with negative DAT group might develop jaundice as quickly as the latter two groups. As to MRI and BAEP findings, there were no significant differences among the four groups. The rate of exchange transfusion in ABO-HDN with negative DAT group was higher than that in the non-HDN group but lower than that in ABO-HDN with positive DAT group, though without statistical significance. It suggested that in the presence of clinical suspicion of ABO-HDN with negative DAT result, the elution test should be added to rule out or confirm the diagnosis to help prevent the morbidity from hyperbilirubinemia.

Risk Stratification for Immediate Postoperative Hearing Loss by Preoperative BAER (Brainstem Auditory Evoked Response) and Audiometry in NF2-Associated Vestibular Schwannomas.

Simple SummaryHearing preservation is one of the major goals in the surgical treatment of Neurofibromatosis Type 2 (NF2) associated vestibular schwannomas (VS) and hearing diagnostics are important monitoring parameters and intraoperative tools to pursue this goal. Our monocentric retrospective analysis aimed to predict postoperative hearing deterioration or loss based on preoperative audiometry and neurophysiological (brainstem auditory evoked potentials, BAEP) findings. In this respect and according to our data evaluation in 100 NF2-associated VS of 72 patients both parameters seem to be prognostic markers, particularly BAEP findings. Large discrepancies between both audiometry and BAEPs which were identified in twenty-one cases of our cohort appear to be at high risk of significant postoperative hearing worsening.Both brainstem auditory evoked potentials (BAEP) and audiometry play a crucial role in neuro-oncological treatment decisions in Neurofibromatosis Type 2 associated (NF2) vestibular schwannoma (VS) as hearing preservation is the major goal. In this study, we investigated the risk of immediate postoperative hearing deterioration (>15 dB and/or 15% loss in pure-tone average [PTA]/ speech discrimination score [SDS] in a cohort of 100 operated VS (ears) in 72 NF2 patients by retrospective analysis of pre- and postoperative hearing data (PTA, SDS, American Association of Otolaryngology–Head and Neck Surgery [AAO-HNS], and brainstem auditory evoked potential [BAEP] class) taking into account relevant influencing factors, particularly preoperative audiometry and BAEP status and the extent of resection. Immediately after surgery, the hearing was preserved in 73% of ears and approximately ~60% of ears kept their hearing classes. Preoperative BAEP (p = 0.015) and resection amount (p = 0.048) significantly influenced postoperative hearing outcome. The prediction model for postoperative hearing deterioration/loss between preoperative BAEP and AAO-HNS class showed increased risk by increasing BAEP class. Twenty-one tumors/ears were identified with large BAEP and AAO-HNS class discrepancies (≥2 points) and were associated with a high (48–100%) risk of deafness after surgery in ears with preoperative available hearing. Overall, the results were heterogeneous but the better both BAEP and audiometry class before surgery, the higher the chance of hearing maintenance afterwards. Large resection amounts (e.g., 100% risk in near-total resections) exhibit a significant (p < 0.05) higher risk compared to smaller amounts (e.g., 10/20% in laser-coagulated/partially resected tumors). Our results emphasized the indispensable role of both hearing monitoring in form of audiometry and neurophysiology (BAEP) in the pre-and perioperative monitoring of NF2-associated VS. Both BAEP and audiometry are good prognostic markers for the postoperative hearing outcome. The extent of resection should be strictly guided by and adjusted to the intraoperative neurophysiological monitoring.

Changes in Autonomic Nervous System in Patients with Multiple Sclerosis

AbstractBackground: Multiple sclerosis (MS) is one of the most disabling neurological disorders, in which autonomic impair-ment is not rare.Aim of Study: To assess the frequency of cardiovascular (CV) autonomic dysfunction in MS patients as well as to relate these autonomic abnormalities to the brainstem dys-functions in thoe patients evidenced by brainstem auditory evoked potential (BAEP) studies.Patients and Methods: We studied 20 patients with clin-ically definite relapsing remitting MS and 20 gender and age matched healthy control. The patients were evaluated clinically using expanded disability status scale (EDSS). Autonomic functions were evaluated with blood pressure response to both standing and static exercise (sympathetic), and 24-hour elec-trocardiographic (ECG) recording, time domain (parasympa-thetic). Brain stem auditory evoked potential was performed to all patients. Data were statistically analyzed using Epi-info software version 6.04.Results: The MS patients included 11 (55%) males and nine (45%) females with a mean age of 29.8-}8.4 years, whereas control group was composed of five (50%) males and five (50%) females with a mean age of 34.2±13.4 years. Regarding tests of CV autonomic functions, 13 (65%) patients had at least one abnormal test. The results showed statistically significant differences in all CV autonomic tests when com-paring MS patients to controls. We found significant correla-tions between autonomic tests with duration of the disease. Significant correlations were detected between autonomic tests and brainstem lesions. BAEP findings were indicative of brainstem affection and there was a significant correlation between autonomic tests and I-V inter peak latency.Conclusion: These results suggest that a significant number of patients with MS show evidence of CV autonomic dysfunc-tion, which is correlated with brainstem function.

Mobilization of the Anterior/Posterior Inferior Cerebellar Artery on the Cerebellar Surface in Microvascular Decompression Surgery for Hemifacial Spasm: Potential Effect on Hearing Preservation.

The infrafloccular approach in microvascular decompression (MVD) for hemifacial spasm (HFS) reduces the risk of postoperative hearing impairment. However, location of the anterior/posterior inferior cerebellar artery (AICA/PICA) on the cerebellar surface in the surgical route requires mobilization to maintain the approach direction for the protection of hearing function. To evaluate the effectiveness of mobilization of the AICA/PICA on the cerebellar surface in the surgical route. Retrospective review of 101 patients dividing their cases into 2 groups, the mobilized group and nonmobilized group. Surgical results, brainstem auditory evoked potentials (BAEPs), age, and duration of microsurgery were compared. In the mobilized group, whether the artery was responsible for the HFS or not, and whether the artery branched perforators to the cerebellar surface or choroid plexus or not, were analyzed. No permanent hearing impairment occurred in any patient. The AICA/PICA was mobilized in 26 patients. No significant difference was found in surgical results, BAEP findings, and duration of microsurgery between the 2 groups, but age was younger in the mobilized group (P<.01). The mobilized artery was responsible in 14 cases and branched perforators in 7 cases in the mobilized group. The perforators did not obstruct mobilization. Mobilization of the AICA/PICA from the cerebellar surface is a useful technique to maintain the infrafloccular approach in MVD for HFS. This technique reduces the risk of postoperative hearing impairment.

Prevalence and Parental Awareness of Hearing Loss in Children with Down Syndrome

Background:To establish the prevalence of hearing deficit in children with Down syndrome (DS) in Hong Kong as measured by brainstem auditory evoked potentials (BAEP). The secondary objective is to examine the agreement between BAEP and clinical questioning in detecting hearing deficit in DS.Methods:Consecutive DS patients attending the Down's Clinic in a regional pediatric referral center were recruited into this cross-sectional study. BAEP data performed within 12 months were retrieved. The care-taker was interviewed with a structured questionnaire to detect any symptom of hearing impairment. BAEP findings and clinical questionings were compared in an agreement analysis using quadratic weighted kappa statistics.Results:Fifty DS patients (35 male, 15 female, mean age 11.70 years ± 5.74 standard deviation) were recruited. Eighteen patients (36.0%) were identified having hearing deficit by BAEP. Among patients with hearing impairment, 13 patients (72.2%) had a conductive deficit, and most have mild to moderate hearing loss. Five patients (27.8%) had sensorineural deficit and most have moderate to severe degree. Eight (44.4%) had bilateral hearing deficit. Care-takers of 13 patients (26.0%) reported symptoms of hearing impairment, with 9 (69.2%) having mild symptoms, 3 (23.1%) had moderate symptoms and 1 (7.7%) had severe symptoms. The weighted kappa was 0.045 (95.0% confidence interval − 0.138–0.229), indicating very poor strength of agreement between BAEP and clinical questioning. For patients with conductive hearing impairment, only 1 patients (7.7%) recalled history of otitis media.Conclusions:The estimated point prevalence of hearing impairment in Chinese DS children in Hong Kong is 36%. Our finding of poor strength of agreement between objective testing and symptom questioning reflects significant underestimation of hearing impairment by history taking alone. In view of the high prevalence and low parental awareness, continuous surveillance of hearing is mandatory for DS patients throughout childhood and adolescence.

Microvascular decompression for hemifacial spasm: how can we protect auditory function?

Objective. The nerve function of the VIIIth nerve is at risk during microvascular decompression (MVD) for hemifacial spasm (HFS). Intraoperative monitoring of brainstem auditory evoked potentials (BAEPs) can be useful in decreasing the danger of hearing loss. This study assessed the intraoperative BAEP findings related to the surgical process to clarify the optimum maneuvers of MVD surgery to avoid hearing impairment. Methods. Hundred consecutive patients undergoing MVD for HFS with intraoperative BAEP monitoring were retrospectively reviewed. Patients were classified into four groups based on the greatest intraoperative latency prolongation and amplitude reduction of wave V of BAEP. Postoperative hearing function and surgical procedures including use of the brain retractor, preservation of arachnoid membrane along the VIIIth nerve, and duration of microscopic manipulation were analyzed in relation to the BAEP findings. Results. Three patients complained of hearing loss after the surgery, but two had complete recovery and only one suffered permanent moderate hearing impairment. Longer duration of microscopic manipulation and greater use of the brain retractor tended to have negative effects on the BAEP findings, whereas preservation of arachnoid membrane along the VIIIth nerve had a positive effect. Statistical analysis showed significant difference in preservation of arachnoid membrane along the VIIIth nerve in Groups 2 and 4 (p = 0.013). Conclusion. Stretching of the VIIIth nerve should be avoided to prevent postoperative hearing impairment. Adequate exposure of the lower cranial nerve roots and lateral medulla oblongata from the caudal side without using the brain retractor gives enough space for decompression with minimum stretching of the VIIIth nerve. Maximum preservation of the arachnoid membrane along the VIIIth nerve and shortening of the duration of microscopic manipulation may help in avoiding postoperative hearing impairment.

Brainstem auditory evoked potential findings in a French bulldog with bilaterally congenital sensorineural deafness

Abstract : A 3-month-old, intact male French bulldog was suspected of deafness. The dog was irresponsive toenvironmental noises generated out of sight, but normal responses were noted for visual stimuli. No abnormalitieswere observed on the neurological, otoscopic, radiographic, and blood examinations. To diagnose the apparent deafness,brainstem auditory evoked potential (BAEP) was recorded in the presented dog together with a normal dog. Whilethe BAEP from the control dog showed a normal wave consisting of 5 peaks, absence of all peaks was noted inthe suspected deaf dog. Therefore the dog was definitively diagnosed as bilaterally congenital sensorineural deafness.Keywords : brainstem auditory evoked potential, congenital sensorineural deafness, French bulldog In recent decades, the occurrence of congenital deafnesshas been increased in dogs relative to the increased aware-ness among breeders, owners and clinicians [13]. Generally,auditory function is necessary for avoiding traffic accidentand other danger incidence. Because deaf dogs are easily sur-prised and have an increased tendency to bite, they are hardlysuitable for use as working. Therefore the puppy with bilat-eral deafness needs to be trained by a responsible owner, butthis kind of training is difficult and unfamiliar. By these rea-sons, bilaterally deaf puppies are easily euthanized [7].If the proper diagnosis of hearing impairment could bedone in dogs, especially working breeds, it will decrease costand efforts for being needed in training. Bilateral deafnesscould be evaluated by monitoring behavioral responses forsound stimuli presented outside of the visual field or with theanimal blindfolded, taking care to avoid visual or vibratorycues [11]. However, behavioral testing is often unreliable andsubjective [1]. Therefore several objective methods, includ-ing electroaudiomerty-encephalographic, audiometry, respira-tory audiometry, tympanometry, auditory evoked responses,and acoustic reflexes, have been used for diagnosing audio-logical or otological disorders in veterinary medicine [10].Among those methods, the brainstem auditory evoked poten-tial (BAEP) has been proven to be the most objective andnon-invasive assessment of auditory function [14, 15]. There-fore the BAEP is frequently used as a screening test for deaf-ness. Previously congenital deafness had been recognized inFrench bulldog, but the BAEP finding has not been reportedin this breed [11, 13]. Therefore this report firstly describesthe clinical and diagnostic features of bilaterally congenitalsensorineural deafness (CSD) in a French bulldog using theBAEP.A 3-month-old, intact male French bulldog was presentedwith suspected deafness. This dog was the youngest onefrom 4 literamates, and the other 3 littermates had no hear-ing disabilities or other diseases. The owner had not observedany response of the dog for sound stimuli since 1 month agoadoption. There was no history of exposure to any causes ofdeafness; illness, head trauma or ototoxic drugs. Physicalexamination revealed mild erythema on the bilateral earpinna and epidermal collarettes on the abdomen. Its coatcolor was predominantly white and black, especially whiteareas presented on the ventral thorax, abdomen, feet, foreleg,and head. On behavior testing, the dog was irresponsive toenvironmental noises generated out of sight, but normalresponses were noted for visual stimuli. Any startle responseswere not elicited to sudden loud noises. Bilaterally, intacttympanic membranes and the grossly normal external earcanals were observed on the otoscopic examination. Thetympanic bulla was examined by radiography with differentviews of the open mouth dorsolateral, lateral-oblique, androstrocaudal projections. Those radiographic studies revealednormal bone density and no fluid density or diminution offoraminal detail within the tympanic bulla. In addition,

Fremkalt respons-undersøkelser i klinisk diagnostikk

Evoked potentials are used to detect conduction disturbances in the central nervous system. This paper provides an overview of the areas in which evoked potentials are used in clinical neurophysiological diagnostics, with the emphasis on coma and demyelinating disease. The article is based on a literature search in PubMed and the authors' long experience of neurological and neurophysiological diagnostics. Somatosensory evoked potential (SEP) can be a reliable predictor of failure to regain consciousness as early as 24 hours after anoxic coma has occurred. If coma is caused by a brain trauma, cerebrovascular episode or other neurological disease, information about which sensory brainstem pathways are damaged can be obtained from somatosensory evoked potentials and brainstem auditory evoked potentials (BAEP), which can also be useful for planning rehabilitation. Normal SEP and BAEP findings in cases of coma caused by trauma are associated with a favourable prognosis. Visually evoked potential (VEP) can often reveal signs of a history of optic neuritis. SEP and BAEP can also reveal subclinical lesions in the central nervous system and be a supplementary diagnostic test for multiple sclerosis. The clinical value of SEP and BAEP is high in coma cases. Evoked potentials are also important in intraoperative monitoring. The clinical value of VEP is high when a history of optic neuritis is a deciding factor for a multiple sclerosis diagnosis. Some selected patients who are being assessed for demyelinating disease will benefit from a full EP study.

Intraoperative Facial Electromyography and Brainstem Auditory Evoked Potential Findings in Microvascular Decompression for Hemifacial Spasm: Correlation with Postoperative Delayed Facial Palsy

Background: Delayed facial palsy (DFP) after microvascular decompression (MVD) in patients with hemifacial spasm (HFS) is not uncommon, but the cause remains unknown. Objectives: To assess whether intraoperative electromyography (EMG) and brainstem auditory evoked potential (BAEP) can predict DFP after MVD. Methods: Between September 2009 and February 2011 we examined 86 patients, 9 of whom (10.4%) developed DFP after MVD on the same side. All patients underwent MVD and were followed-up for a median period of 13 months (range 6–22). We retrospectively examined intraoperative facial EMG and BAEP findings using our MVD patients’ registry. We excluded secondary HFS and immediate postoperative facial palsy after MVD in this study. We assessed the prevalence and clinical characteristics of DFP and compared EMG and BAEP findings between DFP and non-DFP groups. Results: All patients recovered completely, with a mean time to recovery of 37.8 days (range 22–57). There were no significant differences between DFP and non-DFP patients in terms of the amplitude and latency of intraoperative EMG and BAEP. Conclusion: The usefulness of intraoperative facial EMG and BAEP is limited and cannot predict DFP after MVD for HFS. We speculate that DFP after MVD is not associated with permanent nerve damage according to the EMG findings.

聴性脳幹誘発電位による聴力推定で中耳炎と内耳炎が診断された咀噛筋萎縮を併発した犬の1例

Unilateral otitis media-interna was diagnosed in a dog (Welsh corgy, female, three-year-old) with severe atrophy of the masticatory muscles by computed tomography (CT) and brainstem auditory evoked potentials (BAEP) test. Because the dog did not have a history of otitis externa, difficulty in swallowing caused by atrophy of masticatory muscles had the potential to lead to otitis media-interna. Auditory activity was estimated using BAEP test. The threshold obtained by the stimulation of the affected ear was elevated 20 dB above that of the unaffected ear The neak latencies of each wave increased by stimulation of the affected ear in comparison to those of unaffected ear. Interpeak latencies (IPLs) between wave I and V and between wave I and III decreased with affected ear stimulation, but the M-VIPL showed the same value at 90dBHL stimulation. The slopes of the intensity-latency (I-L) curve of wave V with affected ear stimulation produced a larger value than those obtained from unaffected ear stimulation. Similar BAEP findings have been reported in a human patient with a cochlear hearing loss. Although vestibular signs such as head tilt or spontaneous nystagmus were not observed, not only conductive deafness but also sensorineural deafness with impairment of cochlear function could occur in this case.

Contribution of initial median-nerve somatosensory evoked potentials and brainstem auditory evoked potentials to prediction of clinical outcome in cerebrovascular critical care patients: a statistical evaluation.

In a prospective study of 200 patients with cerebrovascular disease (48 intracerebral hemorrhages, [ICH]; 64 subarachnoid hemorrhages, [SAH]; 48 supratentorial and 40 infratentorial ischemic strokes), we assessed the individual and combined prognostic value of median-nerve somatosensory evoked potentials (SEP) and brainstem auditory evoked potentials (BAEP) within 72 hours of admission. Clinical outcome was graded in three ranked categories according to a modified Glasgow Outcome Scale. Likewise, the initial SEP and BAEP findings were graded in a three-class score. In all groups, the SEP were significantly correlated with outcome (P < 0.01). Likewise, after partialling out the prognostic effect of SEP, the contingency between BAEP and outcome was statistically significant, except in ICH (P = 0.07). The contingencies of SEP and outcome in ICH and supratentorial infarcts were higher than the corresponding partial contingencies for BAEP, while the latter were higher in infratentorial infarction and SAH. Therefore, in all disease groups except for SAH, the multiple contingency coefficients ranging from 0.67 to 0.75 were statistically significant and greater than either simple or partial contingencies alone. The results of the two evoked potential modalities combined permit statistically significant superior prognostication in most cerebrovascular diseases when compared to those of either of the modalities alone.

The Usher syndrome type 2A: clinical findings in obligate carriers

Ten obligate carriers of Usher syndrome type 2A from 5 different families with 2 affected persons all underwent audiologic, vestibular and ophthalmologic examinations. They had a sensorineural hearing loss which was in excess of that expected for their age at all of the frequencies (0.25–8 kHz) tested, however, only a 10 dB (average) excess in hearing loss at 0.25–0.5 kHz proved to be significant. The speech discrimination scores obtained conformed with the hearing thresholds. Tympanometry, acoustic reflex and brain stem auditory-evoked potential findings were generally normal. Some vestibular abnormalities were found in a minority of the carrier sample, but not beyond the level of false positivity. Ophthalmologic findings were essentially normal, although in 5 carriers there was a subnormal electrooculography (EOG). These findings are not sufficient specific for carrier detection.

Abnormalities in auditory nerve potential in multiple sclerosis : A. Bogacz, D. Bogacz, O. Vincent. Montevideo, Uruguay

In 28 patients with vertebro-basilar or basilar artery thrombosis brain-stem auditory evoked potentials (BAEPs) and somatosensory evoked potentials (SEPs) have been recorded. Visual evoked potentials (VEPs) were recorded in 7 of these 28 patients. In 24 patients the diagnosis was angiographically proven and in 4 patients Doppler sonography and computerized tomography suggested this diagnosis. The BAEP and SEP findings were correlated to clinical and angiographical signs.BAEPs could be classified into 6 different patterns. In more than half of the patients different BAEP patterns from the two ears could be found. A pathological IV/V complex was most often found in comatose patients and in patients with a basilar artery occlusion distal to the anterior inferior cerebellar artery. Prolonged interpeak latency of I–III was mainly found in alert or drowsy patients with caudal occlusions. The frequent occurrence of a BAEP with only wave I preserved, or with no waves preserved, in patients with brain-stem functions suggests that BAEPs are not useful in the diagnosis of brain death when basilar artery thrombosis is suspected.SEPs were either absent bilaterally or else severely altered on one side in all comatose patients. In alert patients, including those with ‘locked-in’ syndrome, SEPs were never absent bilaterally. Increased N13–N20 interpeak latency was an uncommon finding in this series. There was no correlation between the SEP and the angiographically proven location of the occlusion. In the ‘locked-in’ syndrome both SEP and BAEP findings were non-uniform. Normal SEPs were sometimes found in combination with severely altered BAEPs, suggesting partial deafferentiation.Since basilar artery thrombosis is now a treatable condition, early diagnosis and documentation of functional deficits moves into a more important clinical area than heretofore.

Brain-stem auditory evoked potentials and blink reflex in friedreich's ataxia

The brain-stem involvement in Friedreich's ataxia (FA) was studied by using brain-stem auditory evoked potentials (BAEPs) and the blink reflex. Ten out of 18 patients had abnormal BAEPs, the main abnormality being complete absence of responses and disappearance of wave V. Combined degeneration of the peripheral and central acoustic pathways probably accounts for these findings. The blink reflex was abnormal in 50% of the cases. The outstanding abnormality was bilateral delay of late responses with normal early response, which could be correlated with the known pallor of the descending trigeminal tracts. In contrast with BAEP findings, blink reflex abnormalities did not correlate with either the age of patients or the severity and duration of the disease. These data suggest a difference in susceptibility to degeneration between the auditory system and neuronal system subserving the blink reflex. We conclude that systematic BAEP and blink reflex recording is useful in the electrophysiological evaluation of FA patients.

Auditory Evoked Potentials in Anxiety Disorder

The pathophysiology of anxiety has received much recent attention. EEG findings in anxiety are nonspecific, and some changes in psychophysiological measures have been reported. We recorded short-latency brainstem auditory evoked potentials (BAEPs) and long-latency auditory event-related potentials (AEPs) in 12 patients with generalized anxiety disorder. All 12 patients had BAEP latencies within clinical norms, but I-V interpeak latencies were significantly longer in patients with anxiety than controls. N1, N2, P2, and P3 AEP components were within normal limits; N1 and P2 were reduced in amplitude in anxiety patients, but differences from controls were not significant. The BAEP findings may suggest altered brain-stem function in anxiety, which has been implied by biochemical studies of anxiety and depression. AEP differences may be related to difficulties in concentration and attention direction reported by anxious patients.

Development of brainstem auditory evoked potentials in heterozygous and homozygous jaundiced Gunn rats

Bilirubin toxicity is a significant clinical problem causing neurologic and audiologic sequelae. To better understand the pathogenesis of bilirubin toxicity in the immature nervous system we studied the development of brainstem auditory evoked potentials (BAEPs) in jaundiced ( jj) Gunn rats and their non-jaundiced ( Jj) littermates. Littermate pairs of Jj and jj rats were studied serially from early infancy to adulthood. Replicated BAEPs to click stimuli at two different intensities (45 and 75 dB SPL) and rates (33 and 89/s) were obtained from animals anesthetized with ketamine and acepromazine and maintained at a constant rectal temperature. Jaundiced ( jj) rats had increased latencies of waves II and III and the I–II and I–III interwave intervals, and decreased amplitudes of waves II and III from 17 days of age through adulthood. For both groups, all latencies and interwave intervals decreased with age ( P < 0.0001 for each wave and interwave interval by repeated measures ANOVA), and the amplitude of II increased with age ( P < 0.0001). No group differences were found in wave I latency or amplitude, or in the latency change of waves I, II or III as a function of intensity (about 11 μs/dB at all ages), suggesting that peripheral auditory function is normal in jj rats. Finally, there were no different effects of stimulation rate on BAEP wave latencies between groups. The findings suggest dysfunction of the central (brainstem) auditory pathways at and rostral to the cochlear nuclei, and are consistent with studies showing destruction of the cochlear nuclei in this animal model and in humans with bilirubin toxicity. The central abnormalities previously found in adult, jaundiced rats are now demonstrated in animals as early as 17 days of age, when serum bilirubin concentration is maximum. The BAEP findings are similar to changes found in hyperbilirubinemic human neonates, and support the use of the Gunn rat animal model for the study of bilirubin encephalopathy.

Evoked potentials in basilar artery thrombosis: correlation with clinical and angiographic findings

In 28 patients with vertebro-basilar or basilar artery thrombosis brain-stem auditory evoked potentials (BAEPs) and somatosensory evoked potentials (SEPs) have been recorded. Visual evoked potentials (VEPs) were recorded in 7 of these 28 patients. In 24 patients the diagnosis was angiographically proven and in 4 patients Doppler sonography and computerized tomography suggested this diagnosis. The BAEP and SEP findings were correlated to clinical and angiographical signs. BAEPs could be classified into 6 different patterns. In more than half of the patients different BAEP patterns from the two ears could be found. A pathological IV/V complex was most often found in comatose patients and in patients with a basilar artery occlusion distal to the anterior inferior cerebellar artery. Prolonged interpeak latency of I–III was mainly found in alert or drowsy patients with caudal occlusions. The frequent occurrence of a BAEP with only wave I preserved, or with no waves preserved, in patients with brain-stem functions suggests that BAEPs are not useful in the diagnosis of brain death when basilar artery thrombosis is suspected. SEPs were either absent bilaterally or else severely altered on one side in all comatose patients. In alert patients, including those with ‘locked-in’ syndrome, SEPs were never absent bilaterally. Increased N13–N20 interpeak latency was an uncommon finding in this series. There was no correlation between the SEP and the angiographically proven location of the occlusion. In the ‘locked-in’ syndrome both SEP and BAEP findings were non-uniform. Normal SEPs were sometimes found in combination with severely altered BAEPs, suggesting partial deafferentiation. Since basilar artery thrombosis is now a treatable condition, early diagnosis and documentation of functional deficits moves into a more important clinical area than heretofore.

Electrocochleography and brain-stem potentials in Ramsay Hunt syndrome.

Audiometric investigations and electrophysiologic recordings of cochlear and brain-stem auditory evoked potentials (BAEPs) were performed in 13 patients to elucidate further the type of hearing disorders in Ramsay Hunt syndrome. Transtympanic electrocochleography showed no enhancement of summating potential and did not suggest secondary endolymphatic hydrops. The recording of BAEPs was clearly abnormal in several of the 13 patients. The striking feature of the abnormalities in these patients was the prolongation of the latencies of waves III and V with the preservation of wave I, which clearly suggests retrocochlear involvement. In all the patients tested, abnormalities of the BAEPs were present only on the affected side. It is possible, on the basis of BAEP findings, to suggest that in Ramsay Hunt syndrome both cochlear and retrocochlear involvement may occur.