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At least 487 records · Page 27Linked to original sources
PubMed1994

[Probable Bickerstaff's brainstem encephalitis associated with anti-GQ1b antibody].

We presented a case of probable Bickerstaff's brainstem encephalitis. A 39-year-old woman developed easy falling, progressive consciousness disturbance, total ophthalmoplegia, and bilateral pyramida tract sign. In serum anti-ganglioside antibody assay using enzyme-linked immunosorbent assay, high anti-GQ1b antibody was found. Electroencephalography was dominated by alpha activity, superimposed with occasional theta wave bursts. Brain MRI showed abnormal signal hyperintensities in the tegmentum of the midbrain to the upper pons on T2 weighted images and swelling of the midbrain and pons on T1 weighted images. Five days after the onset of the disease, she had respiratory arrest, which necessitated artificial ventilation for a few days. Then, she began to recover. However, she gained only partial recovery, leaving upward gaze palsy, right abducens nerve palsy, pseudbulbar palsy and quadriplegia.

Adult↗
PubMed1999

Time course of frontal somatosensory evoked potentials. Relation to L-dopa plasma levels and motor performance in PD.

OBJECTIVE: To verify whether the change in L-dopa plasma levels after a single dose of carbidopa/L-dopa 50/200 (controlled-release) transiently modifies frontal components of somatosensory evoked potentials (SEPs) in patients with PD in parallel with improvement of motor performance. BACKGROUND: Apomorphine, a potent dopamine-agonist drug, transiently increases frontal SEP components, which may be depressed in PD; however, relationships between clinical status, frontal SEPs, and therapy are still unclear. METHODS: Nineteen PD patients (mean age 65.9 years, range 52 to 77, responders to L-dopa therapy, were studied in the same day at times T0 (baseline predose level), T1 (presumed L-dopa peak time), and T2 (end of dose-induced motor response). The following were monitored: L-dopa plasma concentration, tapping test, reaction times, peak latency (with central conduction times), and amplitude of cervical, subcortical, as well as cortical parietal and frontal SEP components elicited by median nerve stimulation of the more clinically affected arm. RESULTS: The average amplitude of frontal components of PD patients was significantly reduced at T0 with respect to control subjects. A significant and transient amplitude increase of frontal SEPs was found at T1, in parallel with the L-dopa peak concentration and improvement in motor performance (tapping and reaction times), without significant changes in amplitude of parietal SEP waves. No latency shifts were observed in brain and spinal waves. CONCLUSIONS: L-Dopa may influence the responsiveness of the parkinsonian brain as assessed by frontal somatosensory evoked potentials. The time course of these modifications coincides with that of the clinical response in the motor performance.

Aged↗
PubMed2004

Zeta waves, an unusual EEG finding in structural brain lesions: report of two patients.

We report two patients with acute cerebral conditions and zeta waves on their EEGs. The first patient, a 48-year-old lady, had acute disseminated encephalomyelitis (ADEM)following afebrile illness. Neurological examination showed expressive dysphasia and a mild right hemiparesis. The magnetic resonance imaging (MRI) scan of the brain showed multiple, bilateral, subcortical white matter hyperintensities, predominantly in the centrum semiovale region of the left hemisphere, and also in the corpus callosum. An EEG done 21 days after the onset of the neurological deficit showed intermittent, sharply contoured, predominantly biphasic delta waves (zeta waves) over the left frontotemporal region. The second patient was a 2-year-old child, who had a head-injury resulting in bilateral, frontoparietal fractures of the skull; acute epidural hematoma on the left frontoparietal region; and a cerebral contusion on the right frontotemporal region. An EEG done one day after the evacuation of the hematoma showed zeta waves over the right frontal region. To the best of our knowledge, the association of zeta waves and ADEM has not been previously reported. The EEG findings in our patients again supports the hypothesis that these waves are seen predominantly in patients with structural brain lesions. Other conditions causing zeta waves in the EEG are briefly reviewed.

Brain↗
PubMed1989

[Monitoring of intracranial pressure in patients with brain tumors. Clinical study of the A wave mechanism].

Intracranial pressure (ICP) was continuously monitored in 70 patients with brain tumors. Simultaneous recording of respiration and systemic blood pressure was carried out in 20 and 13 cases, respectively. In 13 of the former 20 cases, blood gases were analyzed during typical A waves (Lundberg's A wave). In addition, in four cases cerebral blood flow (CBF) was measured during typical A waves. The A wave appeared when the baseline ICP exceeded 20 mmHg, and the higher the baseline pressure was, the more frequently the A wave was recorded. Three respiratory patterns occurred during typical A waves: hyperventilation, hypoventilation, and normal respiration. However, these respiratory patterns were not always clear-cut, and the three often were mixed. Systemic blood pressure during the typical A wave phase was either elevated (Cushing's response) or normal. All patients who showed Cushing's response had high baseline ICP and, with the frequently appearance of the A wave, had such symptoms of increased ICP as headache, nausea, and disturbance of consciousness. In all four cases studied, CBF decreased during typical A waves. These results, indicate that the A wave is associated with elevation of ICP and intracranial tightness. A particular region in the brainstem reportedly participates in the generation of the A wave. However, the mechanism of its development appears complex and involves such secondary factors as respiration and systemic blood pressure.

Adolescent↗
PubMed2004

Positive temporal sharp waves in preterm infants with and without brain ultrasound lesions.

OBJECTIVE: Clinical significance of neonatal positive temporal sharp waves (PTS) is controversial. The aim of this work is to study (1) PTS incidence in preterm infants with or without major ultrasound lesion (MUL) per gestational age (GA), and (2) the relationship between PTS in both sleep states and other electroencephalographic (EEG) findings with poor prognoses. METHODS: 97 preterm infants of <27-36 weeks GA, and 12 full-term healthy infants were presented. Prospective study included (1) neurodevelopmental assessment at 40-42 weeks conceptional age (CA), (2) serial neurosonography, and (3) EEG recording at postnatal week 1, 2, 4 and at 40-42 weeks CA. RESULTS: In 50 neonates without MUL, peak PTS was at 31-32 weeks GA. In 47 neonates with MUL, PTS increased significantly from week 2 after birth, descending at the 4th. Neonates of <33 weeks GA with MUL showed significantly increased PTS at term. A significant relationship was found between PTS and other EEG abnormalities with poor neurologic prognoses. PTS incidence varied with sleep states, being predominant in indeterminate sleep in neonates with MUL. CONCLUSIONS: PTS increased significantly in infants with MUL, mainly at week 2 of postnatal life, persisting high until term CA, and correlated with other abnormal EEG findings. SIGNIFICANCE: PTS are highly sensitive to MUL.

Brain↗
PubMed1979

Cochlear processes affecting wave V latency of the auditory evoked brain stem response. A study of patients with sensory hearing loss.

The effects of inner ear pathologies on wave V latency of the auditory evoked brain stem response (BSR) were studied in 12 selected patients with flat, low-frequency, severe high-frequency, and gradual high-frequency sensory hearing loss. In patients with flat and low-frequency sensory hearing loss (Meniere's disease), the latencies of wave V at intensities 4--10 dB greater than their response thresholds were roughly the same as those in normal-hearing subjects. In patients with severe high-frequency sensory hearing loss (sharp cut-off at about 2 or 3 kHz), the latencies of wave V were always delayed, compared with those in normal-hearing subjects. In patients with gradual high-frequency sensory hearing loss, the latency of wave V was delayed according to the degree of hearing loss (as determined by pure tone audiometry) above 2 kHz. The data are interpreted as showing that the wave V latency is sensitive to a kind of recruiting phenomenon in the transduction process as well as being an index of the pressure wave travel time to the cochlear portion responsible for the elicitation of the BSR.

Adult↗
PubMed2005

Modulation of intercellular calcium signaling by melatonin in avian and mammalian astrocytes is brain region-specific.

Calcium waves among glial cells impact many central nervous system functions, including neural integration and brain metabolism. Here, we characterized the modulatory effects of melatonin, a pineal neurohormone that mediates circadian and seasonal processes, on glial calcium waves derived from different brain regions and species. Diencephalic and telencephalic astrocytes, from both chick and mouse brains, expressed melatonin receptor proteins. Further, using the calcium-sensitive dye Fluo-4, we conducted real-time imaging analyses of calcium waves propagated among mammalian and avian astrocytes. Mouse diencephalic astrocytic calcium waves spread to an area 2-5-fold larger than waves among avian astrocytes and application of 10 nM melatonin caused a 32% increase in the spread of these mammalian calcium waves, similar to the 23% increase observed in chick diencephalic astrocytes. In contrast, melatonin had no effect on calcium waves in either avian or mammalian telencephalic astrocytes. Mouse telencephalic calcium waves radially spread from their initiation site among untreated astrocytes. However, waves meandered among mouse diencephalic astrocytes, taking heterogeneous paths at variable rates of propagation. Brain regional differences in wave propagation were abolished by melatonin, as diencephalic astrocytes acquired more telencephalon-like wave characteristics. Astrocytes cultured from different brain regions, therefore, possess fundamentally disparate mechanisms of calcium wave propagation and responses to melatonin. These results suggest multiple roles for melatonin receptors in the regulation of astroglial function, impacting specific brain regions differentially.

Analysis of Variance↗
PubMed2002

Biomechanical changes in the head associated with penetrating injuries of the maxilla and mandible: an experimental investigation.

PURPOSE: In this experiment, we studied the craniocerebral injury that occurs due to the transmission of forces when maxillofacial gunshot wounds are sustained by the facial bones and cranium. MATERIALS AND METHODS: Forty fresh pigs' heads were wounded by one of the following methods: steel spheres weighing 1.03 g at an impact velocity of 1,400 m/s, steel spheres weighing 1.03 g at an impact velocity of 800 m/s, M193 military bullets, or M56 military bullets. Pressure waves in the brain, acceleration of the head, and stress changes in the facial bones and cranium at the moment of the impact were recorded by pressure and acceleration transducers and strain gauges and were statistically compared. RESULTS: Some obvious differences between the mechanical values obtained from high-and low-velocity missile wounds were found. A negative relationship between the peak value of the pressure wave in the brain and the distance from the point of impact to the transducer was obtained. The acceleration of the head in the direction of the ballistic path was the strongest in absolute value. There were differences in the stress values between the mandible and the temporal bone. CONCLUSIONS: Acceleration of the head, pressure wave changes in the brain, and injury from bony stress conduction all play important roles in associated craniocerebral damage after maxillofacial firearm wounds.

Acceleration↗
PubMed1988

[Experimental study of single and combined coaxial exposure by high-peaked pulse wave CO2 and Nd:YAG laser on the brain: effect on the brain microvasculature in the subacute stage].

The effect of single or combined coaxial exposure by Nd: YAG and CO2 (pulse wave) laser on the brain at the subacute stage was examined in experimental animals. Soft X-ray microangiography and histological examination of the brain were performed 48 hours after laser exposure. The lasers in this study were pulse wave form CO2 of 2, 4 and 8 watts and YAG lasers of 10, 20 and 40 watts, employed separately or simultaneously using 130 YZ of Nihon Infrared Industries Company. Japanese white rabbits were anesthetized with pentobarbital. Bilateral fronto-parietal craniectomy were made, and the dura was removed. After intravenous injection of Evans blue, the lasers were employed to the cerebral cortex using a micromanipulator attached to the operation microscope. The spot size was 0.7 mm in diameter for CO2 laser and 1.2 mm for Nd: YAG laser. Forty-eight hours after exposure, microangiography was performed and brains were prepared for the histological examination. Histological examination and microangiogram of the brain after CO2 laser exposure revealed semilunar avascular area in the edematous layer surrounded with dilated vessels. Histological examination and microangiogram of the brain after Nd: YAG laser exposure revealed broad avascular or oligovascular zones in the surrounding edematous tissue, in which the surviving vessels were narrowed. Edematous zones were also shown in the subcortical portion. The histological examination and microangiogram after combined coaxial exposure of CO2 and Nd: YAG lasers revealed triangular avascular or oligovascular zones in the edematous tissue, in which the surviving vessels were narrowed.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed2000

Maturation of the auditory system in clinically normal puppies as reflected by the brain stem auditory-evoked potential wave V latency-intensity curve and rarefaction-condensation differential potentials.

OBJECTIVE: To evaluate auditory maturation in puppies. ANIMALS: Ten clinically normal Beagle puppies. PROCEDURE: Puppies were examined repeatedly from days 11 to 36 after birth (8 measurements). Click-evoked brain stem auditory-evoked potentials (BAEP) were obtained in response to rarefaction and condensation click stimuli from 90 dB normal hearing level to wave V threshold, using steps of 10 dB. Responses were added, providing an equivalent to alternate polarity clicks, and subtracted, providing the rarefaction-condensation differential potential (RCDP). Steps of 5 dB were used to determine thresholds of RCDP and wave V. Slope of the low-intensity segment of the wave V latency-intensity curve was calculated. The intensity range at which RCDP could not be recorded (ie, pre-RCDP range) was calculated by subtracting the threshold of wave V from threshold of RCDP RESULTS: Slope of the wave V latency-intensity curve low-intensity segment evolved with age, changing from (mean +/- SD) -90.8 +/- 41.6 to -27.8 +/- 4.1 micros/dB. Similar results were obtained from days 23 through 36. The pre-RCDP range diminished as puppies became older, decreasing from 40.0 +/- 7.5 to 20.5 +/- 6.4 dB. CONCLUSION AND CLINICAL RELEVANCE: Changes in slope of the latency-intensity curve with age suggest enlargement of the audible range of frequencies toward high frequencies up to the third week after birth. Decrease in the pre-RCDP range may indicate an increase of the audible range of frequencies toward low frequencies. Age-related reference values will assist clinicians in detecting hearing loss in puppies.

Animals↗
PubMed1988

[Evoked potentials and the prediction of the efficacy of psychopharmaceutical agents].

The authors have studied early brain stem auditory evoked potentials (EPs) registered after a single intramuscular administration of 2.5 mg of haloperidol in 32 healthy volunteers and 14 schizophrenic patients. Haloperidol led to a significant decrease in the latency of wave V of brain stem auditory EPs in patients with schizophrenia and to its increase in normal subjects. A diminution in wave V of brain stem auditory EPs directly correlated with a reduction of psychopathology expressed in points of the Overall-Gorham scale (BPRS) and observed after one-month haloperidol treatment. The authors discuss the possibility of using changes in brain stem auditory EPs after a single administration of various psychotropics to select an optimal drug for a given patient and also as a possible supplementary diagnostic criterion.

Adolescent↗
PubMed1999

Brain histamine levels and neocortical slow-wave activity in rats with portacaval anastomosis.

To determine whether the increased histamine levels in the brain of rats with portacaval anastomosis (PCA) are associated with the development of sleep disturbances during the light phase, the neocortical slow-wave activity of PCA-operated rats was examined with electroencephalography (EEG) 1 month and 6 months after the surgery. The tissue levels of histamine, tele-methylhistamine, 5-hydroxytryptamine (5-HT) (serotonin), and 5-hydroxyindole-3-acetic acid (5-HIAA) in frontal cortex were assayed by high-performance liquid chromatography 6 months after the surgery. PCA surgery led to changes in the synchronized, low-frequency, high-amplitude frontal cortex EEG activity recorded during the light phase. Delta-wave amplitude but not delta time was significantly decreased, whereas both spindle amplitude and spindling time were significantly decreased. There were also significant age-related changes, presented as increases in the duration of spindles and the amplitude of both delta waves and spindles. PCA-operated rats showed a change in the pattern of EEG activity with increasing age similar to sham-operated rats. This suggests that once established, the resetting of the systems regulating the sleep-waking behavior is being maintained with time. The tissue levels of both histamine and metabolite in the frontal cortex were increased, whereas the serotonin system showed only an increase in the level of the metabolite. There was a significant negative correlation between the spindling time and the tissue histamine levels. We suggest that histamine, which participates in the control of vigilance, sleep, and wakefulness, as well as in the modulation of circadian rhythmicity, may play a role in the development of sleep disturbances in rats with PCA.

Animals↗
PubMedDate not supplied

Slow wave field potentials in the rat brain during the estrous cycle.

Twenty-one rats were implanted with chronic electrodes in the amygdala, preoptic area, and arcuate nucleus-median eminence region in an effort to learn more about electrical activity in the limbic system and the relationship to the estrous cycle. Slow wave field potentials from these three areas were recorded for ten minutes of each half-hour between 10:00 a.m. and 3:30 p.m. each day of the four-day estrous cycle. These recordings were analyzed for amount of correlation and direction of conduction between pairs of electrodes and for conduction times between pairs of sites. Slow wave field potential conduction from the amygdala to the preoptic area during the "critical period" on the day of proestrus lasts longer and takes longer en route than at other times of the cycle. This is statistically significant at p < 0.002 and implies a change in the conducting pathway during this time.

Action Potentials↗