Prolonged brainstem transmission time in autism

The Effect of Artery Ligation and Asphyxia on Auditory Evoked Brain Stem Response

The critical warning sign of real-time brainstem auditory evoked potentials during microvascular decompression for hemifacial spasm

A case of multiple sclerosis with acute deafness and dizziness as initial symptoms was reported. The pure-tone audiometry showed a high-frequency sensorineural hearing loss; in the auditory evoked brain stem response (ABR), the left side had a normal peak I with an absence of subsequent peaks. In the equilibrium test, Bruns' nystagmus was present, and the caloric test demonstrated CP on the left side. MRI disclosed a high-intensity lesion in the cerebellar peduncle (T2-weighted image). With steroid therapy, the deafness and dizziness improved within 10 days, although, after 20 days, the findings of the ABR and caloric test remained unchanged.

Purpose The brainstem dysfunction in multiple sclerosis (MS) often causes significant functional impairment leading to disability. This study aims to explore modified brainstem auditory evoked potential (BAEP) scores based on the pattern of BAEP abnormalities and relate with brainstem symptoms, brainstem functional system scores (BFSS), brainstem lesions, and disability. Method Forty-five participants with relapsing-remitting MS and 45 age- and gender-matched healthy controls underwent case history assessment, otoscopic examination, pure-tone audiometry, and BAEP testing. Also, neurological examination (Expanded Disability Status Scale, FSS scales) and magnetic resonance imaging were carried out on MS participants. Patterns of BAEP abnormalities were categorized and converted to BAEP scores. Results Out of 45 participants' brainstem symptoms, BFSS > 1, brainstem lesions (magnetic resonance imaging), and BAEP abnormalities were observed in 75.6%, 42.2%, 62.2%, and 55.56% of participants, respectively. Waves V and III abnormalities were more common among MS participants and showed a significant difference from the control group in the Mann-Whitney U test. Chi-square test did not show a significant association of BAEP abnormalities with brainstem symptoms and lesions but showed significant association with BFSS. The mean and standard deviation of BAEP scores in MS participants were 1.73 + 2.37. All healthy controls showed BAEP scores of 0. BAEP scores in MS participants showed significant correlation with BFSS scores and predict Expanded Disability Status Scale scores. Conclusion BAEP scores based on the pattern of BAEP abnormality can be a valid and useful measure in evaluating brainstem functions and predicting disability in MS.

BackgroundThe purpose of this study was to compare the effectiveness of methods for screening for retrocochlear pathologies based on auditory evoked brainstem responses (ABRs). The study compared the sensitivity, specificity, and effectiveness of these 3 techniques.Material/MethodsThe methods were: (i) standard ABR utilizing click-evoked responses, (ii) stacked ABR based on derived-band responses, and (iii) ABRs evoked by tone-pips (ABR TP). The methods were tested on patients with retrocochlear pathologies confirmed by MRI-Gd, normal-hearing subjects, and patients with cochlear hearing loss. The system and software used in the tests was NavPro AEP v.6.2.0 (BioLogic – Natus). Prior to testing, all subjects were given comprehensive audiologic and otologic examinations, including MR imaging. Sensitivity and specificity functions and predictive values of methods were determined.ResultsThe stacked ABR method as realized in the NavPro system exhibited high sensitivity but specificity was very low, due to the high variability of stacked ABR amplitudes. The standard ABR method had good specificity, but low sensitivity in cases of small tumors (below 1 cm in diameter). Best sensitivity and specificity was obtained with the ABR TP method.ConclusionsThe stacked ABR method allows small acoustic tumors to be detected, but produces high percentage of false positive results. The ABR TP method offers good sensitivity and specificity, and relatively high predictive value. The best option would be to use a two-stage screening, consisting of a standard ABR in the first stage and an ABR TP test in the second.

Brainstem auditory evoked potentials (BAEPs) are a sensitive indicator of bilirubin neurotoxicity. Somatosensory evoked potentials (SEPs) have been proposed as another measure of toxicity, though the lemniscal pathways that generate the SEP are not involved in kernicterus. In 16 to 17-d-old jaundiced (jj) Gunn rats, serial BAEPs and SEPs were obtained up to 8 h after acute bilirubin toxicity. jjs were injected with 150 mg/kg sulfadimethoxine to displace bilirubin into brain tissue (n = 8); littermate controls were jjs given saline (n = 4) and nonjaundiced given sulfadimethoxine or saline (n = 7). After anesthesia, BAEP and SEP recordings were obtained at baseline and serially after injection. SEPs to median nerve stimulation were recorded from surface electrodes over the brachial plexus (Erb's) and contralateral parietal cortex, and subtracted to obtain central conduction time (CCT). There were no statistically significant different baseline values between groups. Baseline BAEP I, I-II, and I-III were 1.22 ± 0.13, 1.11 ± 0.12, and 2.10 ± 0.15 ms, and SEP Erb's and CCT were 1.48 ± 0.20 and 5.59 ± 0.50 ms, respectively (n = 19). At 6.8 ± 1.5 h after injection BAEP I, I-II, and I-III increased 0.10 ± 0.08, 0.18 ± 0.17, and 0.56 ± 0.33 ms over baseline, respectively (p = 0.005, 0.01, and 0.001, respectively, paired, 1-tailed t-tests), in experimental but not control groups. SEP Erb's decreased slightly, −0.06 ± 0.04 ms in experimental and −0.08 ± 0.08 ms in control groups, while CCT did not change significantly. BAEPs were completely abolished in two jjs with no SEP changes. When injection of sulfonamide induced significant peripheral and central BAEP abnormalities in jaundiced rats, no SEP abnormalities occurred. SEPs assess proprioception but not other somatosensory function or sensory integration. The results demonstrate the selectivity of acute bilirubin toxicity for the auditory nervous system.

Objective To study the pathogenesis and surgical treatment of atypical hemifacial spasm.Methods The clinical data of 36 patients who underwent microvascular decompressions (MVD) for atypical hemifacial spasm(HFS)from July 2005 to July 2010 were retrospectively analyzed.Results The HFS disappeared immediately after MVD in 32 patients.The postoperative spasm was weaker in 4 patients and the residual spasm was disappeared within 5 months.There was no reoccurrence of spasm during follow -up period.The postoperative complications included:transient moderate facial paralysis accompanied with hearing dysfunction in 3 cases,and transient hearing dysfunction accompanied with tinnitus in 3.Conclusions Atypical hemifacial spasm is caused by vessels on the posterior rostral side of facial nerve.The effectiveness could be predicted after MVD.But the rates of facial paralysis and/or hearing loss are relatively higher.The rates of complications could be reduced significantly by correct identification of offending vessels,fewer disturbance to cranial nerves,avoiding the injury to the penetrating vessels,and intraoperative brain stem auditory evoked potential monitoring during. Key words: Microsurgical decompression; Atypical hemifacial spasm; Facial nerve ; Brain stem auditory evoked potential

AimsAssessing neurological outcome after cardiac arrest (CA) remains challenging. We aim to evaluate the prognostic value of brainstem auditory evoked potentials (BAEPs) and middle latency auditory evoked potentials (MLAEP) in patients with disorders of consciousness (DoC) after CA and indeterminate outcome according to current recommendations (i.e., no highly malignant EEG and bilateral absence of N20).MethodsA retrospective analysis was conducted using data collected prospectively from two intensive care units. The prognostic value of the absence of wave V, an abnormal conduction latency between waves III and V, an abnormal I/V amplitude ratio on BAEPs, and the absence of Na and Pa responses on MLAEPs was assessed. The primary outcome was the best Glasgow Outcome Scale-Extended (GOS-E) level within 3 months. A GOS-E level ≤ 2 (death or vegetative state) was defined as a poor outcome.Results93 patients were included, 74.2% of whom were men, with a mean age of 58 years IQR [47–67]. Of these, 67/93 (72%) had a poor outcome. Unilateral absence of wave V on BAEPs was highly specific for poor outcome (Sp 96.1%), despite low sensitivity (Se 10.4%). A unilateral I/V amplitude ratio > 1 had a specificity of 87.5%, but a low sensitivity of 11.5%. Prolonged brainstem conduction time (III-V latency > 2 ms) was poorly specific for a poor outcome (Sp 70.8%). Conversely, the absence of Na and Pa on MLAEP had 100% specificity for poor outcome, with a sensitivity of 31.8%.ConclusionIn unconscious patients after CA with an indeterminate outcome based on neurophysiological criteria, the absence of wave V on BAEPs and the absence of Na/Pa on MLAEPs were highly specific for poor outcome, despite a low sensitivity. These results suggest that AEPs may serve as a second prognostic marker to fulfill the two-criterion requirement of the ERC/ESICM recommendations.

A developing method for testing auditory function and detecting neurological disorders is the brain stem auditory evoked response (BAER) to sound stimuli. Elicitation of the BAER is noninvasive and produces an objective measurement of a subject's auditory function. Basic principles of this technique and normative data are presented in this paper. It was found that the BAER can detect asymptomatic high-frequency hearing losses. The sensitivity of this technique makes it an ideal method for evaluating functional hearing losses. Two illustrations of functional hearing losses are presented. Wave V's threshold, latency and amplitude, along with comparisons between the auditory (subjective) and BAER threshold, are useful parameters when testing for nonorganic hearing disorders. However, this sensitivity to minor hearing losses makes it imperative that all control subjects be established as normal by an audiogram. A mere negative history for hearing disorders is felt by the authors to be an inadequate screening of control subjects.

With the requirement of universal newborn hearing screening from the year 2010, throughout the Brazilian territory, more children are undergoing audiologic diagnosis in their first months. The Brainstem Auditory Evoked Potential and the Steady State Evoked Potential are widely used for closing the audiologic diagnosis at this age, since they assist in the characterization of hearing loss as to the degree, type and configuration. The stimuli used in these procedures pose limitations inherent to the acoustic characteristics of each subject and should be taken into account by the professional analyzing the results. Therefore, this study aimed to compare the applicability of the Narrow Band CE-Chirp stimulus to predict the psychoacoustic thresholds in severe and profound sensorineural hearing loss. This was a cross-sectional prospective study in which 28 children, being 15 females and 13 males, aged 6 to 37 months, presented with sensorineural hearing loss and with thresholds above 61 dBNA, were assessed. The used procedures were Brainstem Auditory Evoked Potential with tone burst stimuli and Narrow Band CE-Chirp, Steady-state auditory evoked potential and audiometry with visual reinforcement or conditioned ludic audiometry. The results showed that the electrophysiological thresholds in the Brainstem Auditory Evoked Potential were closer to the psychoacoustic thresholds obtained in the visually reinforced audiometry or conditioned ludic audiometry when using the Narrow Band CE-Chirp stimulus in lieu of the tone burst. In the absence of response in the Brainstem Auditory Evoked Potential with both stimuli, it was observed that the Steady State Auditory Evoked Potential performed at high intensities presented good correlation with the psychoacoustic thresholds, nevertheless, high intensity should be used with caution in the frequencies 2000 and 4000 Hz, for unreal electrophysiological thresholds not to be obtained. It was concluded that, clinically, the use of Brainstem Auditory Evoked Potential with the Narrow Band CE-Chirp stimulus showed electrophysiological thresholds closer to psychoacoustic ones of the audiometry with visual reinforcement/conditioned ludic audiometry than when using the tone burst. Nevertheless, further studies should be performed to verify the benefits of this stimulus in children and with some hearing impairment. For using stimuli in higher intensities, the Steady-state auditory evoked potential characterized the residual hearing, accurately, at frequencies of 500 and 1000 Hz.

This retrospective study evaluated the length of cerebellar retraction and the changes of intraoperative brainstem auditory evoked potential (BAEP) during microvascular decompression (MVD), and assessed the predictive value of the hearing loss as a prognostic indicator for the treatment outcome of hemifacial spasm (HFS). This series included 1,518 consecutive patients affected with HFS who underwent MVD, during which BAEP was monitored. Patients were divided into two groups based on whether hearing loss occurred following decompression or not. Each patient underwent a similar procedure performed by one neurosurgeon. The two patients groups were matched with regard to sex, age, and degree of spasm. Among the 1,518 patients, 106 (6.98 %) displayed functional hearing changes. Hearing loss was permanent in 12 patients (0.79 %). Of the 1,412 patients with stationary hearing compared with preoperative audiometry, 96 patients were selected who were individually matched with respect to sex, age, and degree of spasm. BAEP changed immediately after cerebellar retraction in 7 of 12 hearing-loss patients, suggesting the importance of retraction on hearing outcomes. The distance from the cerebellar surface of the petrous temporal bone to the neurovascular compression point was measured. The median distance of cerebellar retraction in the hearing-loss group was 13.77 mm, which was longer than the median distance in the control group. Preoperative measurement of the cerebellar retraction distance can be a valuable clue to predict and prevent postoperative hearing loss in MVD for HFS.

Objective: To investigate the possible risk factors that may lead to hearing loss in newborns who failed the hearing screening tests. Material and Methods: In this retrospective study, 546 newborns who failed the evoked otoacoustic emission (TEOAE) test or who underwent screening auditory evoked brainstem response (ABR) due to detected risk factors were included between 2010 and 2018. The risk factors of 78 patients who failed the screening ABR test were documented. A total of 468 newborns who passed ABR screening test were evaluated as control group. The data were compared statistically. Results: In the comparison of groups who failed and passed the ABR screening test, the mean birth time was found to be significantly earlier (38.1±2.6 and 39.25±1.4 weeks, respectively) (p=0.049), and the mean birth weight was found to be significantly lower (3001 ±628.2 and 3334.82 ±418 g, respectively) (p=0.032) in the failed group. The incidence of neonatal jaundice and jaundice requiring phototherapy was higher in patients who failed the screening ABR test, and this difference was statistically significant (p=0.043 and p=0.028, respectively). The newborns receiving intensive care treatment were also found to be statistically higher (p=0.028). Conclusion: The highest risk group for sensorineural hearing loss in newborns may be considered as the ones with low birth weight, early birth time and receiving intensive care treatment.

Brainstem auditory-evoked potentials (BAEPs) were recorded from 26 dogs with intracranial neoplasia. The tumors were grouped according to their neuroanatomic location. Normal BAEPs were recorded from 12 dogs with cerebral (6/7), diencephalic (4/4), cerebellar (1/1), and multifocal tumors (1/5). Abnormal BAEPs were recorded from 14 dogs were cerebral (1/7), cerebellar/brainstem (4/4), brainstem (5/5), and multifocal tumors (4/5). Analysis of the multifocal neoplasms showed that alterations of BAEPs correlated with the degree of brainstem involvement. Overall, 13 of the 14 dogs with abnormal BAEPs had tumors involving the brainstem. The changes of the BAEP correlated with the extrinsic or intrinsic location of the tumor relative to the brainstem. The BAEP reflected the right, left, or median location of the tumor in 7 of the 14 abnormal recordings. In 1 dog, the BAEP was abnormal contralateral to the tumor side. A peripheral hearing disorder was excluded in most dogs based on the presence of peak I.

OBJECTIVE In this study, the authors describe the brainstem auditory evoked potential (BAEP) and somatosensory evoked potential (SSEP) alterations found in a large cohort of patients with Chiari malformation Type 1 (CM-1), the relationship between the BAEPs/SSEPs and the clinical findings, the abnormalities in patients with associated syringomyelia, and the clinical and neuroradiological risk factors that are associated with abnormal evoked potentials (EPs). METHODS A prospectively collected database containing 545 patients with CM-1 was queried to search for patients satisfying the following criteria: 1) an age of at least 14 years, 2) neuroradiological criteria of CM-1, 3) no prior Chiari-related surgeries, and 4) preoperative EP studies conducted at the authors' institution. The 200 patients included in this cohort were classified into CM-0, CM-1, and CM-1.5 subtypes. Linear, planimetric, and angular measurements of the posterior fossa were conducted, as well as syringomyelia measurements. Two separate multiple logistic regression models were used, one to predict the covariates associated with abnormal BAEPs, and a second model to explore the variables associated with an abnormal SSEP. In these models, the BAEPs and SSEPs were dichotomized as being normal or abnormal. RESULTS Headaches were the main symptom in 70.5% of the patients, and Valsalva-induced headaches were most frequent in patients with CM-1 and CM-1.5 compared with patients with CM-0 (p = 0.031). BAEPs were abnormal in 38.5% of patients, and abnormal SSEPs were found in 43.5% of the entire cohort. Syringomyelia was most frequent in patients with CM-0 (64.3%) and CM-1 (51.1%) compared with those with CM-1.5 (34.7%; p = 0.03). Age (OR 1.03, 95% CI 1.00-1.06), the degree of tonsillar herniation (OR 1.08, 95% CI 1.01-1.16), and lower cranial nerve dysfunction (OR 3.99, 95% CI 1.29-14.01) had a statistically significant correlation with abnormal BAEPs. Only age (OR 1.07, 95% CI 1.04-1.10) and the degree of tonsillar herniation (OR 1.11, 95% CI 1.04-1.19) had a statistically significant correlation with abnormal SSEPs. CONCLUSIONS A high percentage of patients with CM-1 exhibited EP alterations regardless of their clinical or radiological findings. These findings suggest that EPs do not add any clinically relevant information nor are they helpful in establishing which symptomatic patients with CM should undergo surgical treatment. However, BAEP and SSEP studies clearly play an important role in incidentally detected patients with CM and may help to establish objective evidence of subclinical dysfunctions. In addition, neurophysiological studies may help to define subgroups of patients who require further testing and follow-up to personalize strategies for the management of incidental and oligosymptomatic patients.

Objective To compare the effect of repeated transcranial magnetic stimulation (rTMS) at different frequencies acting on left dorsolateral prefrontal cortex (LPFC) on arousal for coma patients after brain stem injury. Methods Ninety-nine patients with coma resulted from brain stem injury, admitted to our hospital from February 1, 2015 to April 10, 2018, were chosen in our study. Among them, 30 patients weren't treated with rTMS (control group), 33 patients were treated with 10 Hz rTMS (10 Hz rTMS treatment group), and 36 patients were treated with 20 Hz rTMS (20 Hz rTMS treatment group); treatments lasted for 20 d. All patients received routine coma arousal treatment. Glasgow coma scale (GCS) scores, electroencephalogram (EEG) grading, brainstem auditory evoked potential (BAEP) grading and incidence of adverse reactions were compared among the three groups before and after treatment. Results Before treatment, there were no significant differences in GCS total scores, language response scores, motor response scores, eye opening reaction scores, EEG grading and BAEP grading among the three groups (P>0.05). The total GCS scores, and scores of language response, motor response and open eye response of patients in the 20 Hz rTMS treatment group and 10 Hz rTMS treatment group after treatment were significantly higher than those in the control group (P<0.05); the total GCS scores and motor response scores of patients in the 20 Hz rTMS treatment group were significantly higher than those in 10 Hz rTMS treatment group after treatment (P<0.05). After treatment, patients in the control group, 10 Hz rTMS treatment group, and 20 Hz rTMS treatment group showed statistically significant differences in EEG grading and BAEP grading (P<0.05). The incidence of adverse reactions in the 20 Hz rTMS group (19.4%) was statistically higher than that in the 10 Hz rTMS group (3.0%, P<0.05). Conclusion High-frequency rTMS has an awakening effect on patients with coma resulted from brain stem injury, and the coma awakening effect of 20 Hz rTMS is partially better than that of 10 Hz rTMS, but it has the risk of increasing side effects such as epilepsy and scalp burn. Key words: Repetitive transcranial magnetic stimulation; Coma arousal; Brain stem injury