PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Brain Stem”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 recordsLinked to original sources
PubMed1978

Afferents to brain stem nuclei (brain stem raphe, nucleus reticularis pontis caudalis and nucleus gigantocellularis) in the rat as demonstrated by microiontophoretically applied horseradish peroxidase.

Using a retrograde tracer technique with microiontophoretically applied horseradish peroxidase (HRP), afferent projections to the brain stem raphe nuclei (BR, raphe magnus, pallidus and obscurus) and to two adjacent reticular nuclei, nucleus reticularis pontis caudalis (nRPC) and nucleus gigantocellularis (nGC) were identified. The most striking difference between the afferent projections to the BR and the adjacent nuclei as determined by this method is that afferents to the BR originate primarily from structures rostral to the pons, especially the mesencephalic central gray and the dorsal and ventral tegmentum. In contrast, the two reticular nuclei studied (nGC and nRPC) received afferent projections within or caudal to the pons-medulla. For example, the nGC receives prominent afferent projections from the gray matter of the spinal cord. In addition, evidence for interconnections between all of the adjacent nuclei (BR, nGC and nRPC) was found. Such afferent projections are compatible with the notion that the brain stem raphe nuclei may serve as connections within the brain stem for a descending system, while the nGC may be a relay in a feedback loop between the spinal cord and the reticular formation.

Animals↗
PubMed1979

Acute intracranial hypertension and auditory brain-stem responses. Part 2: The effects of brain-stem movement on the auditory brain-stem responses due to transtentorial herniation.

Movement of the upper brain stem (inferior colliculus) was correlated with the alterations in the amplitude of wave V of the auditory brain-stem responses (BER's) during supratentorial brain compression in cats. In vivo observation of the brain stem and postmortem inspection show that suppression of the amplitude of BER wave V reflects the extent of caudal displacement of the inferior colliculus. Marked suppression of the amplitude of BER wave V (approximately 30% of control) correlates with the beginning of transtentorial herniation, and complete suppression of the wave V indicates complete transtentorial herniation of the brain-stem and supratentorial structures. The BER wave V is thought to be a sensitive index of caudal movement of the upper brain stem due to transtentorial herniation.

Animals↗
PubMed1978

Compound impulse response for the brain stem derived through combinations of cochlear and brain stem recordings.

To overcome some of the problems involved in the application of brain stem evoked responses (BSER) in otoneurological diagnosis an approach is developed which combines cochlear and brain stem recordings. The activity of the cochlea and brain stem generators, as seen from the far-field recording electrode, is considered to be the output from a single system. The impulse response of this system can be derived through deconvolution of the brain stem evoked responses, BSER, with the compound action potential, AP, followed by appropriate filtering. This method is used on the recordings from 15 subjects with various degrees of cochlear hearing loss. The results show that the compound impulse response, CIR, for the brain stem consists of five recognizable peaks. From the individual subjects this response pattern is largely independent of intensity. By plotting the amplitude and latency of the individual peaks for all 15 subjects a set of normative data is retrieved. The variation in the data is small, probably because interfeerence from the periphery is eliminated and the separation of activity from the different brain stem generators is improved.

Audiometry↗
PubMed1978

Auditory brain-stem responses in comatose patients: relationship with brain-stem reflexes and levels of coma.

Auditory brain-stem responses (BSR) were recorded in 20 comatose patients in whom the level of brain-stem dysfunction was defined by clinical assessment of brain-stem reflexes and posture. No BSR abnormalities were found in the 10 cases with cortico-subcortical or diencephalic levels. The other 10 patients showed a clear relationship between alteration of the different components of the BSR and the clinical levels of brain-stem dysfunction caused by the rostro-caudal evolution. Alteration of wave P5 seems related to a midbrain dysfunction, of P3 to a pontine dysfunction and of P1 or P2 to a lower brain-stem dysfunction.

Brain Stem↗
PubMed1979

Acute intracranial hypertension and auditory brain-stem responses. Part 1: Changes in the aduitory brain-stem and somatosensory evoked responses in intracranial hypertension in cats.

Changes in auditory brain-stem responses (BER's) and somatosensory evoked responses (SER's) were investigated to correlate mass volume, intracranial pressure, and neurological dysfunction in mass-induced intracranial hypertension in cats. As the intracranial pressure was raised by expansion of a supratentorial balloon, the late components of the SER's were suppressed first, followed by the early components of the SER's, then Wave V and Wave IV of the BER's, in that order. This suggests that the nonspecific reticular projections are most vulnerable to compression ischemia, and the specific somatosensory pathways are the next most vulnerable. Neural activity of the auditory pathways in the upper brain stem was also gradually suppressed, but less so than that of the somatosensory pathways. After complete transtentorial herniation, in spite of immediate mass evacuation, the function of the somatosensory pathways was greatly impaired, often irreversibly. The neural activity of the auditory pathways in the upper brain stem revealed progressive recovery during a 3-hour period. The measurements of BER Wave V is thought to be useful in predicting transtentorial herniation.

Animals↗
PubMed1979

Brain stem audiometry: status and clinical applications of click evoked brain stem responses.

Over the past 10 years, numerous reports on click evoked brain stem responses have appeared in both the general otolaryngologic and the audiologic literature. Equipment is now commercially available, is relatively simple to operate, and permits the routine recording of these potentials. The technique is especially useful in the objective establishment of hearing thresholds in the newborn and in adult subjects and appears to be more reliable than the cortical evoked response (AEP). Other uses and applications of the technique, as in the detection of brain stem lesions and acoustic tumors, in coma and brain death, are discussed.

Adult↗
PubMed1979

Bilaterally recorded brain stem auditory evoked responses. Their asymmetric abnormalities and lesions of the brain stem.

Simultaneous bilateral recordings (C3 to A1 and C4 to A2) of brain stem auditory evoked responses have been studied in 67 supratentorial lesions, nine midbrain lesions, 21 intrinsic pontine lesions, and 23 extrinsic compressions of the pons. The responses in supratentorial lesions showed completely normal records. In midbrain lesions, wave V was specifically altered. As wave 1 has been shown to be a far-field seventh nerve potential, and wave V the midbrain potential, waves II to IV can be inferred to originate in the central auditory pathway between the seventh nerve and the midbrain. Alterations of waves II to IV correlated well with localization of pontine lesions, and asymmetric alterations of the bilaterally recorded responses were associated with unilateral lesions of the brain stem auditory pathway and/or lesions of the crossed auditory projections.

Acoustic Stimulation↗
PubMedDate not supplied

[Evoked brain stem potentials in cases of traumatic coma of: value in determining the degree of brain stem dysfunction (author's transl)].

Auditory brainstem potentials were recorded in 22 comatose patients in whom the level of brainstem dysfunction was defined by the clinical assessment of brainstem reflexes and posture. The patients with cortico-subcortical or diencephalic levels showed normal brainstem potentials. The other patients showed a relationship between the abnormalities of the different components of the brainstem potentials and the clinical levels of brainstem dysfunction caused by the rostro-caudal evolution. Alteration of wave V seemed to be related to a midbrain dysfunction, alteration of wave III to a pontine dysfunction and alteration of waves I and II to a lower brainstem dysfunction.

Brain Injuries↗
PubMed1978

Acoustic neuroma: results of brain stem evoked response audiometry.

Brain stem evoked response (BER) audiometry presents abnormal findings in patients with acoustic neuromas. The test involves averaging of recordings at the vertex as sound-triggered nerve impulses travel from the cochlea to the brain stem. From the time the sound stimulus arrives at the cochlea until it reaches the first major brain stem synapse (within 10 milliseconds), five major waves have been identified as typical of normal averaged responses. Abnormality in the cochlea or eighth nerve causes specific changes in pattern, primarily in wave latency. These latency shifts can be used to predict the site of the lesion. In evaluating 17 lesions of the cerebellopontine angle, BER audiometry was accurate in the diagnosis of all of the tumors. This diagnostic tool should play a prominent role when acoustic tumor is suspected.

Adolescent↗
PubMed1978

[Electric response audiometry (brain stem potentials and late potential N1) in patients with acoustic neurinoma or space-occupying lesion in the region of the brain stem].

In patients with acoustic neuronoma or space-occupying lesion in the region of the brainstem we recorded preoperatively the brainstem potentials as well as the late potential N1. With one exception all patients investigated showed changes in the brainstem potential pattern. When stimulating monaurally there exists a clear side difference, that means the changes in the potential pattern are more distinct on the side of the tumour than on the opposite side and then only if an obstructive hydrocephalus exists. Moreover we could demonstrate in patients with tumours in the region of the brainstem that the brainstem potential IV is no longer suitable for measuring the hearing threshold. On the other hand in these patients an exact determination of the hearing threshold is possible with the late potential N1. Altogether the findings show, that the recording of the brainstem potentials when stimulating monaurally is an important additional diagnostic tool to recognize impairment of the acoustic pathways within the brainstem and probably affords the possibility of perceiving pathological pressure within the brain.

Adult↗
PubMed1977

Anoxic-ischemic encephalopathy in the human neonatal period. The significance of brain stem involvement.

Although the human brain stem is considered relatively invulnerable to ischemic anoxia, evaluation of 16 cases of a single acute asphyxial episode either at or following birth indicates that such involvement is a frequent and characteristic aspect of anoxic encephalopathy in the infant. Ischemic cell change, neuronal loss, and nuclear or reticular formation gliosis were present in the brain stem of all but one infant. At least two topographic patterns of anoxic encephalopathy exist: (1) a rostrocaudal pattern of decreasing vulnerability, with the cerebral cortex being most sensitive and the brain stem least sensitive, and (2) a pattern of brain stem and thalamic damage. Of the two, the latter pattern appears to follow most acute asphyxial episodes in the human neonate and infant.

Adolescent↗
PubMed1978

Clinical applications of the auditory brain stem response.

The auditory brain stem response is a powerful new tool for the detection and quantification of hearing impairment, especially in the pediatric population. It gives exact information about the functional status of the cochlea and brain stem pathways. The technique distinguishes recruiting from nonrecruiting losses, predominantly high frequency from flat losses, and retrocochlear from peripheral disorders. The recent introduction of bone conducted stimuli should soon permit the unambiguous separation of conductive and sensorineural losses.

Adult↗
PubMed1975

Comparison of behaviors elicited by electrical brain stimulation in dorsal brain stem and hypothalamus of rats.

Four brain-stimulation phenomena elicited from both dorsal brain stem and hypothalamic sites were investigated with the following results: (a) intracranial self-stimulation rate-intensity functions for dorsal brain stem and hypothalamic sites yielded very high (over 1,000 responses/15 min.) to moderate (201-500 responses/15 min.) response rates; (b) d-amphetamine produced higher response rates than either l-amphetamine or saline at both dorsal brain stem and hypothalamic sites, indicating that noradrenergic dorsal brain stem fibers (or cell bodies) support intracranial self-stimulation; (c) dorsal brain stem and hypothalamic self-stimulation sites reliably produced escape behavior; (d) simultaneous stimulation of dorsal brain stem and hypothalamic sites at subthreshold intensities interacted to produce suprathreshold response rates.

Adrenergic alpha-Agonists↗