Measurement Of Brainstem Auditory Evoked Potentials Research Articles

A Pilot Study for Gender Variation and Correlation of Anthropometric Parameters on the Variables of Brainstem Auditory Evoked Potentials in Audiometrically Normal Young Adults

Head size gender and BMI have found to have correlation with Brainstem Auditory Evoked Potentials (BAEPs) in some studies but other have expressed doubts. There is no common consensus. To add to the complexity, the range of normative values also vary. The present pilot study was done aiming to study effect of gender and anthropometric parameters on the variables of BAEPs in audiometrically normal young adults and collect normative values for further studies. This was an observational prospective, cross sectional, pilot study conducted among 100 medical students with 50 males and 50 females. The selected students fulfilled the inclusion and exclusion criteria and had given informed consent for the study. In the study RMS EMG EP MARK II machine was used to measure and record the absolute, interpeak and wave amplitudes. The data was collected and statistically analysed. The BAEP measurements from the subjects were compared with gender and anthropometric measurements. The age of students enrolled in subject ranged from 18–21 years. The difference between Left and Right ears Wave I, III and V, besides I-Ia and V-Va difference was found to be significant; while differences between male and female peak latencies of Wave III (left and right) and V (left and right) and Wave IV right ear, I-V IPL and V-Va of Right ear were found to be statistically significant. BMI did not show any statistically significant correlation with BAEPs. AEP results were definitely individual effected by gender, with latency duration more among males than females in most BAERs but were significant in few. The head circumference of a person appears to affect the BAER. BMI in the study was not significant with BAER variables.

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

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

Apparent Diffusion Coefficient on Magnetic Resonance Imaging in Pons and in Corona Radiata and Relation with the Neurophysiologic Measurement and the Outcome in Very Preterm Infants

Background: New imaging techniques allow a detailed visualization of the brain and the findings possibly correlate with neurophysiologic measurements and neurosensory and motor outcomes. Postnatal clinical factors known to associate with neurologic disabilities may contribute to brain abnormalities not visible to the naked eye. Objectives: We evaluated whether quantitative measurement of organized water diffusion on MR imaging, apparent diffusion coefficient (ADC), relates to neurophysiologic function and to clinical risk factors and motor outcome in preterm infants. Methods: Diffusion-weighted imaging was successfully performed at term age on 30 infants born <32 weeks of gestation, birth weight <1,000 g. Infants with major destructive brain lesions were excluded from the final analysis (n = 2). ADC was calculated within regions of interest placed in pons and in white matter regions known to contain motor fibers. Brain stem auditory evoked potentials (BAEP) were registered at term age. Gross motor outcome was assessed using Griffiths Scales at 2 years of corrected age. Results: A positive correlation was found between ADC in the pons and the latency of wave III in BAEP (r = 0.619, p = 0.024). Need for inotrope support during the postnatal period and bronchopulmonary dysplasia associated with high ADC values in the pons and in the corona radiata. Infants with poor gross motor outcome had higher ADC in the corona radiata than infants with better outcome (mean = 1.343 vs. 1.197, p = 0.004). Conclusions: This is the first study to report a relationship between ADC and BAEP measurements in the pons. The study may add to the current knowledge about the relation between postnatal clinical factors and diffusion-weighted imaging when evaluating the high-risk infants.

Diffusion tensor imaging of the inferior colliculus and brainstem auditory-evoked potentials in preterm infants

Preterm and low-birth-weight infants have an increased risk of sensorineural hearing loss. Brainstem auditory-evoked potentials (BAEP) are an effective method to detect subtle deficits in impulse conduction in the auditory pathway. Abnormalities on diffusion tensor imaging (DTI) have been shown to be associated with perinatal white-matter injury and reduced fractional anisotropy (FA) has been reported in patients with sensorineural hearing loss. To evaluate the possibility of a correlation between BAEP and DTI of the inferior colliculus in preterm infants. DTI at term age and BAEP measurements were performed on all very-low-birth-weight or very preterm study infants (n=56). FA and apparent diffusion coefficient (ADC) of the inferior colliculus were measured from the DTI. Shorter BAEP wave I, III, and V latencies and I-III and I-V intervals and higher wave V amplitude correlated with higher FA of the inferior colliculus. The association between the DTI findings of the inferior colliculus and BAEP responses suggests that DTI can be used to assess the integrity of the auditory pathway in preterm infants.

Nutritional effects on auditory brainstem maturation in healthy term infants

<b>Objective:</b> To assess the effects of dietary long chain polyunsaturated fatty acid (LCPUFA) supplementation on auditory brainstem maturation of healthy term newborns during the first 16 weeks of life by measuring brainstem auditory evoked potentials (BAEPs). <b>Design:</b> Throughout the 16 week study period, infants in the formula A group (n = 28) were assigned to be fed exclusively with the same formula supplemented with DHA, and infants in the formula B group (n = 26) were assigned to receive only a DHA unsupplemented but otherwise similar formula. During the study period, the first 26 consecutive infants to be fed exclusively on their mother’s milk for at least the first 16 weeks of life were chosen as the control group. BAEP measurements were performed twice: at the first and 16th week of age. <b>Results:</b> There were no significant differences among the study and control groups in the BAEP measurements performed at the study entry. At 16 weeks of age, all absolute wave and interpeak latencies in the study and control groups had significantly decreased. The decreases were significantly greater in the formula A and control groups than in the formula B group. <b>Conclusions:</b> Infants fed on human milk or a formula supplemented with LCPUFAs during the first 16 weeks of life show more rapid BAEP maturation than infants fed on a standard formula. Although the clinical importance and long term effects of these findings remain to be determined, routine supplementation of formulas with LCPUFAs should be considered.

Amikacin alters auditory brainstem conduction time in newborns.

The purpose of this paper was to describe whether there are some relationships between amikacin serum levels and central conduction time in brainstem auditory evoked potentials (BAEP) within therapeutic range levels in newborns as index of drug toxicity in brainstem auditory centers in neonatally exposed infants. We performed a cross-sectional study to compare BAEP from 35 infants under amikacin administration and 24 control infants; both examinations were blinded to investigators. Bivariate and partial correlations were calculated between amikacin and BAEP measurements in treated infants. Amikacin determinations were within therapeutic levels. No clinical alterations in BAEP were found and no differences between amikacin-treated and control infants were found. Significant positive Pearson correlation between latency of I-III interwaves interval and amikacin Cmin serum levels was found and was present when calculations were controlled by partial correlations for gestational age at birth and Apgar score at 5 min. The findings suggest that increased amikacin levels in newborns are related to increased latencies in I-III interwave interval in infants, which may be an early index of brainstem effects of subclinical neurotoxicity of amikacin.

The brainstem auditory evoked potential abnormalities in severe chronic obstructive pulmonary disease.

The aim of the study was to investigate the abnormalities of brainstem auditory evoked potentials (BAEP) in patients with severe chronic obstructive pulmonary disease (COPD). Twenty-one patients with severe COPD (16 men, five women; mean age: 64 +/- 6.5 years), in whom other causes of BAEP abnormalities had been excluded, were studied. Age-matched, non-smoking, healthy subjects acted as a control group. We performed pulmonary function tests, arterial blood gas analysis and bilateral BAEP measurements in COPD patients and control groups. Brainstem auditory evoked potentials were abnormal in 16 (76.1%) of the 21 COPD patients. Most prominent BAEP abnormalities were prolonged wave I peak latencies (42.8%), V wave peak latencies (38.1%), and III-V interpeak latencies (IPL) (38.1%). In five patients, a prolonged central transmission time (I-V IPL) was observed. No significant correlation was evident between the BAEP parameters and pH, PaO2, PaCO2, FEV1%, FEV1/FVC, haematocrit, duration of disease or cigarette consumption. The functions of the eighth cranial nerve and brainstem were highly impaired in severe COPD. These pathological BAEP alterations in severe COPD might be due to the chronic hypoxic-hypercapnic status occurring in the brainstem.

Wound healing and brain stem auditory evoked potentials after experimental total ear canal ablation with lateral tympanic bulla osteotomy in dogs.

Experimental total ear canal ablation with lateral tympanic bulla osteotomy (TECA-LBO) was performed in 13 normal dogs to evaluate healing and retention of brain stem auditory evoked potentials (BSAEP) after surgery. Healing was evaluated by gross and microscopic examination of the surgery sites after 1 (n = 2), 4 (n = 8), 5 (n = 1), and 6 (n = 1) weeks. One dog was eliminated from the study. Brain stem auditory evoked potentials were measured using an air-conducted sound stimulus before and after surgery and before killing. Two dogs had nearly complete obliteration of the tympanic cavity by immature fibrous connective tissue. Eight dogs responded to surgery by either complete or partial re-formation of the tympanic cavity. Retention of the tympanic membrane in three dogs promoted re-formation of the tympanic cavity and blind epithelialized pockets in the surgery site with accumulation of keratinized debris. Granulation tissue formation and extensive proliferation of new bone on the internal surface of the tympanic bulla was seen in 10 dogs. Proliferative bone completely obliterated the tympanic cavity in two of these dogs. Eleven of 13 dogs had no detectable air-conducted BSAEP after surgery. There was no change in BSAEP measurements before killing compared with postoperative measurements in any dog. Two dogs with retained tympanic membranes had measurable BSAEP after surgery. This study shows that healing after TECA-LBO may be highly variable. Retention of the tympanic membrane and small osteotomies appeared to promote reformation of tympanic cavities and prevent ingrowth of granulation tissue.(ABSTRACT TRUNCATED AT 250 WORDS)

Brainstem auditory evoked potentials in patients with multi-infarct dementia and dementia of the Alzheimer type.

Brainstem auditory evoked potentials (BAEPs) were recorded in 25 patients with multi-infarct dementia (MID) (mean age 71.2 years), 16 patients with dementia of the Alzheimer type (DAT) (mean age 70.6 years), and 34 normal subjects (mean age 69.1 years). Both MID and DAT patients showed significant prolonged interpeak latencies between waves I and V (I-V IPLs) compared to normal subjects (p less than .001 and p less than .01, respectively). In patients with MID, both I-III IPLs and III-V IPLs were significantly longer than those of normal subjects (p less than .01 and p less than .01 respectively). On the other hand, only III-V IPLs were significantly prolonged in patients with DAT (p less than .01). There were no significant differences between MID and DAT with regard to any of the IPLs. Present results suggest that the brainstem lesions are located in the auditory pathways in patients with MID and DAT. However, with BAEP measurements, we were not able to discriminate between patients with MID and DAT.

BAEP abnormalities in tardive dyskinesia.

To evaluate brainstem dysfunction, brainstem auditory-evoked potentials (BAEPs) were recorded in 13 patients with tardive dyskinesia. Only patients under 60 years of age were included because of the spontaneous dyskinetic syndromes that frequently occur in elderly persons. Clinical assessment was performed with the Abnormal Involuntary Movement Scale (AIMS). BAEP measurements were taken in order to detect lesions in the brainstem. In 14 of 26 pathways (13 patients), abnormalities in the BAEPs were found which corresponded well to lesions found in former neuropathological reports of patients with tardive dyskinesia. The functional disturbance causing abnormal BAEPs may be an expression of structural brain changes in tardive dyskinesia patients.

Brain stem auditory evoked potentials in posterior circulation surgery.

The objectives of this study were to evaluate the use of brain stem auditory evoked potentials (BAEPs) in 10 adult patients with vascular disorders of the posterior circulation that were treated surgically and to compare the BAEPs with the neurological findings. The vascular lesions included basilar artery stenosis in 3 patients, vertebral artery stenosis in 1 patient, brain stem/cerebellar arteriovenous malformation in 2 patients, and basilar artery aneurysm in 4 patients. Measurement of BAEPs were carried out during operation in all cases. Eight patients had BAEPs measured before operation, and 9 patients had BAEPs measured after operation. Repeat postoperative studies were performed in patients with changes in neurological status. In general, BAEP abnormalities correlated with the neurological findings before and after operation. Six patients had normal intraoperative studies. None of them had clinical findings of pontomesencephalic dysfunction after operation. Three patients with significant BAEP abnormalities during operation had neurological findings of pontomedullary ischemia after operation. Transient BAEP changes in 1 patient were thought to be the result of brain stem retraction. The BAEPs were lost in 3 patients who died. The use of BAEP measurement did not lengthen the operative procedures. However, the technique used in this study required 4 to 8 minutes for the accumulation and interpretation of each average, thereby delaying feedback to the surgeon. The results of this study suggest a potential role for BAEP monitoring in identifying brain stem injury during posterior circulation surgery.