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At least 19 recordsLinked to original sources
PubMed1992

[Magnetic stimulation motor evoked potential in multiple sclerosis. Comparison with visual evoked potentials, brain stem auditory evoked potentials and somatosensory evoked potentials].

This study consists of 45 patients with clinically definite MS, laboratory supported definite MS and clinically probable MS. We compared MEP results with other multimodal evoked potentials (VEP, BAEP and SEP). The abnormal rate of MEP was 87.6%, which was the highest. Abnormal MEP showed prolonged central motor conduction time (CMCT), consistent with pathological change of the demyelination. There was a evident correlation between the abnormal MEP and VEP, which is consistent with the most common MS (Devic Syndrome) in our country.

Adolescent↗
PubMed1980

The contralateral effects of large tumors on brain stem auditory evoked potentials.

Brain stem auditory evoked potential (BAEP) testing has been demonstrated to be a useful diagnostic tool in the presence of severe or complete sensorineural hearing loss. From a series of 38 patients with tumors in the vicinity of the VIIIth nerve, 13 patients with tumors larger than 2 cm had abnormal BAEP results contralateral to the involved side. The abnormalities observed on the noninvolved side included prolonged peak latencies, reduced amplitudes, poor wave shape and poor response stability. The significance of these findings is twofold: 1. Large tumors may disrupt BAEP test results on the side contralateral to the lesions, 2. Important information may be obtained on patients having complete sensorineural hearing loss on the involved side.

Adult↗
PubMed1982

Blink reflexes elicited by electrical, acoustic and visual stimuli. II. Their relation to visual-evoked potentials and auditory brain stem evoked potentials in the diagnosis of multiple sclerosis.

Blink reflexes, elicited by flashes of light, tone bursts and electrical stimuli, as well as checkerboard reversal visual-evoked potentials and brain stem auditory evoked potentials were investigated in 55 patients with different degrees of diagnostic probability of multiple sclerosis. It is demonstrated that electrically and acoustically elicited blink reflexes are simple but rather sensitive methods of indicating brain stem lesions. They should be used complementarily with brain stem auditory potentials. Flash-elicited blink reflexes, although sensitive, are thought to be of minor importance, since they give only restricted localizing information.

Acoustic Stimulation↗
PubMedDate not supplied

Monitoring therapeutic efficacy of decompressive craniotomy in space occupying cerebellar infarcts using brain-stem auditory evoked potentials.

Brain-stem auditory evoked potentials (BAEPs) have been used to gauge effects of brain-stem dysfunction in humans and animal models. The purpose of this study was to evaluate the usefulness of BAEP in monitoring patients undergoing decompressive surgery of the posterior fossa for space occupying cerebellar infarcts. We report on serial BAEP recordings in 11 comatose patients with space occupying cerebellar infarcts undergoing decompressive craniotomy. BAEP studies were performed within 12 h after admission, 24 h following surgery and prior to extubation. BAEP signals were analyzed using latency determination and cross-correlation. Following surgery, 9 patients regained consciousness; 2 patients persisted in a comatose state and died subsequently. BAEP interpeak latency (IPL) I-V assessed prior to surgery exceeded normal values in all patients in whom it could be reliably measured (N = 9). Following decompressive surgery BAEP wave I-V IPL normalized in 5 patients, but remained prolonged despite dramatic clinical improvement in 4 patients. We prospectively computed the coefficient of cross-correlation (MCC) of combined ipsilateral BAEP trials after right and left ear stimulation. In all patients increasing MCC was associated with clinical improvement. Unchanging or decreasing MCC indicated poor outcome. We conclude that serial BAEP studies are an appropriate perioperative monitoring modality in patients with space occupying cerebellar infarcts undergoing decompressive surgery of the posterior fossa. Our study suggests advantages of cross-correlation analysis as an objective signal processing strategy; relevant information can be extracted even if BAEP wave discrimination is impossible due to severe brain-stem dysfunction.

Acoustic Stimulation↗
PubMed1986

Correlation between a unilateral midbrain-pontine lesion and abnormalities of brain-stem auditory evoked potential.

Brain-stem auditory evoked potentials (BAEPs) were evaluated over a 39 day period in a patient with a unilateral pontine-midbrain lesion verified by CAT scan and at autopsy. Waves I, II and III were present on the side of lesion, whereas all 5 waves were present on the side opposite the lesion. The findings suggest that the BAEPs may be obtained with only an intact ipsilateral auditory pathway. Crossing fibers in the trapezoid body also appear to make contributions to the normal generation of wave V.

Adult↗
PubMed1982

Intraoperative monitoring of brain-stem auditory evoked potentials.

Brain-stem auditory evoked potentials (BAEP) were monitored during 545 neurosurgical operations in the cerebellopontine angle. The BAEP were irreversibly obliterated in five patients who required deliberate section of the auditory nerve. Technical difficulties interfered with monitoring in three cases, and three patients had deafness and absent BAEP preoperatively. Reversible alterations in BAEP were seen during 32 operations, with recovery after as long as 177 minutes of virtually complete obliteration. Changes in BAEP were associated with surgical retraction, operative manipulation, positioning of the head and neck for retromastoid craniectomy, and the combination of hypocarbia and moderate hypotension. In 19 cases, waveforms improved after specific interventions made by the surgeon or anesthesiologist because of deteriorating BAEP. In 13 other cases, BAEP recovered after maneuvers not specifically related to the electrophysiological monitoring, most often completion of operative manipulation. Whenever BAEP returned toward normal by the end of anesthesia, even after transient obliteration, hearing was preserved. Irreversible loss of BAEP occurred only when the auditory nerve was deliberately sacrificed. The authors conclude that monitoring of BAEP may help prevent injury to the auditory nerve and brain stem during operations in the cerebellopontine angle.

Adult↗
PubMedDate not supplied

Intra-ponto-mesencephalic recording of binaural interaction in human brain-stem auditory evoked potentials.

Brain-stem auditory evoked potentials (BAEPs) were recorded at intraparenchymatous sites along a ponto-mesencephalic stereotactic penetration path in a patient with the rare condition of a ponto-medullary lesion which required biopsy but did not grossly alter scalp BAEPs. Click stimuli were applied either monaurally (with contralateral masking noise against acoustic cross-talk; conditions 'R,' 'L') or binaurally (condition 'RL'). A binaural interaction trace ('BI') was derived by subtracting the sum of the monaural from the binaural responses: BI = (RL)-(R + L). Despite failure to obtain significant BI components above noise level for scalp BAEPs, at the lower pons clearly discernible, multiphasic BI activity could be recorded beginning at the peak latency of scalp wave III and extending over approximately the next 4 msec. Its amplitude rapidly fell off with distance toward more rostral, mesencephalic recording sites. In relation to this positive finding, the equivocality among some of the previous studies on the detection of BI components in human scalp BAEPs is tentatively rephrased in terms mainly of a low signal-to-noise ratio and of functional peculiarities introduced by the respective stimulation protocols.

Adult↗
PubMed1987

Comparison of cat and human brain-stem auditory evoked potentials.

Brain-stem auditory evoked potentials (BAEPs) elicited by clicks were recorded from both humans and cats. The responses of the two species were compared as functions of click level, click rate, ear stimulated, and electrode position. Since the BAEPs appear to have both high- and low-frequency components, the responses were filtered to analyze these components separately. The similarities and differences in the behavior of the peaks of the two species support the view that the first three (positive and negative) high-frequency peaks which are comparably numbered have similar generators, but the later comparably numbered peaks do not. The presence of binaural interaction beginning with P4 and PV suggests a correspondence between peaks P4 through P5 in cat with PV through PVI, respectively, in human. The similarity in behavior of these peaks also support this correspondence. Furthermore, when conduction times are estimated from interpeak latencies, this correspondence of peaks agrees more closely with the relative pathway lengths in the two species, than does the correspondence based on comparable numbering.

Adult↗
PubMed1983

Comparison of the latencies between bone and air conduction in the auditory brain stem evoked potential.

Brain stem auditory evoked potentials obtained by air and bone conduction were investigated in 22 subjects. The necessity for a carefully selected stimulus being presented to the headphone and the bone vibrator is discussed. Latency values of both responses are presented for wave V. Bone conduction showed latencies which were longer than those obtained by air conduction (about 0.9 msec). Possible mechanisms for this delay are discussed.

Audiometry↗
PubMed1983

Improved wave V resolution by dual-channel brain stem auditory evoked potential recording.

Brain stem auditory evoked potentials were recorded simultaneously from the vertex and ear contralateral to stimulation (Ac-Cz) and from the vertex and ear ipsilateral to stimulation (A1-Cz). There was clearer definition of wave V and less latency variability between trials in Ac-Cz channel recordings, resulting in enhanced wave form stability and greater reproducibility of wave I-V interpeak latencies. The clinical interpretation of dual-channel recordings is currently limited by the complexity of the auditory pathways, but the technique itself shows promise as a routine clinical procedure.

Adolescent↗
PubMed1992

Contralateral effects of cerebello-pontine angle exposure on human auditory brain-stem evoked potentials.

Auditory brain-stem evoked potentials (ABEPs) were recorded during surgical procedures which exposed the cerebello-pontine angle (CPA) in humans. Recordings made with the CPA contralateral to stimulus exposed were compared with those obtained with the skin sutured at the end of surgery. Single-channel as well as 3-channel Lissajous' trajectory (3-CLT) analyses were used to evaluate the effect of the surgical exposure on ABEP. The results suggest that exposure of the CPA contralateral to the stimulated ear did not affect dipole equivalent orientation nor magnitude, but did affect timing of the recorded activity being more pronounced for segments 'd'-'e' (corresponding to waves IV-V) than for 'a'-'b' (waves I-II). The results imply that the effects of disrupting the volume conductor may have been overwhelmed by other effects, such as local temperature changes. These changes, although not associated with clinical sequella, should be accounted for when analyzing subtle quantitative changes involving surgical exposures.

Acoustic Stimulation↗
PubMed2004

Effects of blood hyperviscosity on functional integrity in the brain stem: a brain stem evoked auditory potential study.

Clinical hemorheological and brain stem auditory evoked potential (BAEP) investigations were performed in patients with ischaemic brain stem stroke. Lesions were verified by MRI. 55 healthy persons with negative rheological and BAEP findings were used as controls (group A/1). 33 stroke patients with negative rheological parameters (group A/2) and 34 patients with hyperviscosity (group A/3) were also enrolled. In group A/3 bilateral pathological BAEP patterns were found, that could be explained by microcirculatory disturbances. 36 persons with verified blood hyperviscosity, but without neurological signs were also examined (group A/4). In this group, as in group A/3, either total lack of any waveforms, or a bilateral prolongation of wave III was observed. In 31 cases of group A/4, control BAEP was performed after effective haemodilution therapy, and 6-12 months later (group B/1). Here, normalization of rheological profile had a temporary beneficial effect on BAEP in 14 of 18 cases with former wave III prolongation, but had no effect on BAEP patterns in 13 cases, where lack of waves had been verified by the first investigation. These data suggest that hyperviscosity can result in subclinical pathological symmetric BAEP patterns, both in ischaemic stroke patients and in hyperviscosity patients without neurological symptoms.

Adult↗
PubMed1990

Alterations of brain stem auditory evoked potentials in hypothermia.

Brain stem auditory evoked potentials (BAEPs) were studied as a criterion for evaluating hypothermic effects on the brainstem in rats. Eleven adult male Long-Evans rats were cooled slowly from 37 degrees C to 25 degrees C by an ice pad. BAEPs were recorded at intervals of every 1 degree C of change, and both central and peripheral acoustic conductions were assessed. As the body temperature decreased, latencies significantly increased, with the most prominent effect at the higher brainstem level. Interpeak latencies were prolonged also, while the reverse occurred with warming. These data agree with previous studies in other animals and men. However, during analysis of the effects of hypothermia on the brain stem auditory pathway, it was shown that these hypothermic effects were equally distributed throughout the whole pathway in the present study, rather than being emphatic in the proximal portion only. Greater prolongation of latencies in the proximal portion was caused by a cumulative effect from the distal peaks. Recovery was attained completely after rewarming and subsequent survival. Under extreme hypothermia, BAEPs disappeared gradually with apnea and cardiac arrest; however, resuscitation and rewarming saved the rats. In addition to wishing to make conventional observations, the present study sought to recognize the section of the acoustic pathway most sensitive to hypothermic effects and interpret the outcome after hypothermia treatment.

Animals↗
PubMed1985

[Early brain stem auditory evoked potentials in brain death].

Brain-stem auditory evoked potentials (BAEPs) are realized after the first flat EEG in 50 patients. BAEPs were absent in 70% of the patients. In 22% of the patients, one- or two-sided peak I persists. In 8% the peaks I, II and IV exist after the first flat EEG. BAEP evolution with the course of time is realized. A complete disappearance is established after 24 h. The useful advantage of BAEPs in the early diagnosis of brain death is discussed.

Adolescent↗
PubMed1984

[Effect of sleep deprivation on visual evoked potentials and brain stem auditory evoked potentials in epileptics].

The article reports on the first study of the evoked activity of the brain in epileptic patients (n = 20) following sleep deprivation. An analysis of the data obtained has revealed a tendency to the shortening of the peak latent intervals of visual evoked potentials in the range of 100-200 mu sec and the V component and the interpeak interval III-V of evoked auditory trunk potentials in patients with temporal epilepsy. The phenomenon may indicate the elimination of stabilizing control involving the specific conductive pathways and, possibly, an accelerated conduction of a specific sensor signal.

Adolescent↗
PubMed1998

Brain-stem auditory evoked potential monitoring in experimental diffuse brain injury.

The time course of brain-stem auditory evoked potential (BAEP) changes was investigated using an impact-acceleration trauma model in 23 spontaneously breathing rats. Intracranial pressure (ICP), arterial blood pressure and respiratory rate were monitored. The experiments were terminated at four hours after trauma. No significant changes in intracranial pressure (ICP) occurred following the impact. After a short increase, blood pressure returned to baseline values within 5 min. Transient apnea was not followed by prolonged respiratory depression. Diffuse closed head injury (CHI) did not result in general, unidirectional changes of peak latencies or amplitudes of auditory evoked responses. Most BAEP changes developed slowly reaching a maximum at 1 to 4 hours after the injury. In the absence of ICP changes, this pattern reflects secondary ischemia in sensitive brain-stem areas rather than direct traumatic lesions or hypoxia due to respiratory depression.

Animals↗