Biomedical subjects

B B Gallagher

Publications and source records attributed to B B Gallagher.

At least 37 records · Page 2Linked to original sources

PubMed1990

Cerebral language lateralization: evidence from intracarotid amobarbital testing.

Cerebral language lateralization was investigated in 103 patients undergoing intracarotid amobarbital testing as part of their diagnostic work-up for epilepsy surgery. Inclusion criteria included adequate bilateral intracarotid amobarbital studies and no radiologic lesion in areas other than the temporal lobe. Language was evaluated with respect to strict presence or absence of language representation, in which a patient was considered to have bilateral language despite potentially having asymmetric language representation, and with respect to forced relative hemispheric dominance, in which a single side could be considered dominant despite bilateral language representation. Seventy-nine patients displayed exclusive left hemisphere language representation, two patients showed exclusive right hemisphere language representation, and 22 patients had language represented in each hemisphere. In the 22 patients with bilateral language, an asymmetry was present in 17 cases (13 L greater than R, 4 R greater than L). These data indicate that language restricted only to the right hemisphere is rare, and that in the absence of purely left hemisphere language, most patients exhibit bilateral representation. Previously reported incidence of exclusive right hemisphere language may be an artifact of dichotomizing a continuous variable.

Amobarbital↗

PubMed1990

An 8-year experience with depth electrodes in the evaluation of ablative seizure surgery candidates.

Stereotactically implanted depth electrodes are one means of localization of seizure foci. Unilateral seizure focus localization was obtained in 72.7% mesial temporal (MT) implants and 50% of focus/extramesial temporal (MT-XMT) implants. Recent increase in localization to over 80% in MT implants was possible because a larger percentage of patients had MT-XMT implants. Increased localization to 60% in MT-XMT implants was related to using more XMT electrodes per patient and to orienting electrodes to monitor larger limbic XMT and neocortical areas. Since MT foci were localized in 25% of MT-XMT cases, MT electrodes should be included with all MT-XMT implants. Depth electrography can also be used to rule out certain patients as surgical candidates. Therefore, a surgical decision can be reached in a very high percentage of patients undergoing depth implantation. Surgical results are comparable to those in our overall series.

Brain Mapping↗

PubMed1990

Comparative cognitive effects of anticonvulsants.

We investigated the neuropsychological effects of carbamazepine, phenobarbital, and phenytoin in 15 partial complex epilepsy patients treated with each drug for 3 months, using a randomized double-blind, triple crossover design. Neuropsychological evaluation at the end of each treatment period included Digit Span, Selective Reminding Test, Digit Symbol, Finger Tapping, Grooved Pegboard, Choice Reaction Time, P3 evoked potential, and Profile of Mood States. Employing anticonvulsant blood levels and seizure frequencies as covariates, the only significant difference was for Digit Symbol. Performance with phenobarbital was significantly worse than with the other 2 anticonvulsants despite phenobarbital's having had the lowest overall blood levels. Our data show that patients receiving carbamazepine, phenobarbital, and phenytoin have comparable neuropsychological performance on most measures. The results suggest that the differential cognitive effects of anticonvulsants may be subtle.

Adult↗

PubMed1990

Human hippocampal EEG: effects of behavioral activation.

We studied spectral components of human hippocampal EEG in relation to behavioral status in 19 patients with intractable complex partial seizures who had depth electrodes implanted into the anterior hippocampi as a part of their preoperative evaluations. Behavioral conditions included: eyes closed resting, eyes open resting, eyes open with a verbal task, and eyes open with a visuospatial task. Hippocampal EEG spectral power uniformly decreased during behavioral activation. EEG activation was quantitatively different among the 3 activated conditions, with the most prominent change occurring during the visuospatial task. The degree of EEG activation corresponded inversely with the site of epileptic focus during the verbal task. The results demonstrate the response of human hippocampal EEG to behavioral activation. The magnitude of EEG change may reflect the degree of functional activation of the given hippocampus.

Adult↗

PubMed1990

Long-latency evoked potentials during aura of temporal lobe origin.

Long-latency evoked potentials recorded from scalp or scalp/sphenoidal electrodes have been shown to have diminished amplitude and power during interictal recordings on the side ipsilateral to an unilateral mesial temporal lobe (MTL) focus. We now report recordings of long-latency evoked potentials both during a prolonged aura and also on two seizure-free days. P3 amplitude and sphenoidal evoked potential (SpEP) spectral power in the scalp/sphenoidal channels were less, ipsilateral to the MTL focus. During the aura, the SpEPs had reduced power and reduced amplitude. However, the amplitude of the N2 component for the target averages in the CZ-A1A2 channel was markedly enhanced during the aura.

Adolescent↗

PubMed1989

Effect of kainate-induced seizures on tissue trace element concentrations in the rat.

It has been shown that epileptics have lower mean blood concentration of manganese than do controls but the cause of this abnormality has not been determined. In order to investigate the effects of seizures on manganese distribution in the body, rats were treated with kainic acid to produce spontaneous seizures which were quantitated for number and severity. Manganese, zinc, copper and iron concentrations were determined in blood, brain, liver, heart and kidney. Kainate-treated animals ate more food but gained less weight than controls. Liver and kidney manganese concentrations were significantly higher in kainate-treated animals than in controls. Blood manganese concentration showed a significant negative correlation with seizure index while heart manganese concentration showed a significant positive correlation with seizure index. None of the other trace elements showed a significant correlation between trace element concentration and seizure index in any of the tissues, although iron concentration was lower in brain and copper concentration was lower in kidney of kainate-treated animals than in their appropriate controls. These data show that manganese concentrations are generally elevated in tissues of kainate-treated animals. This increased manganese concentration may be related to the increased energy demand of these animals.

Animals↗

PubMed1989

Surgical management of epilepsy.

About 300,000 people in the United States suffer from medically uncontrolled focal epilepsy. It is estimated that about 40,000 of these patients are candidates for surgery. Underuse of surgical treatment of epilepsy is reflected by the fact that only about 1% of these candidates are operated on. Candidates for ablative surgery (ie, removal of seizure focus) must have a focus demonstrated by either extracranial or intracranial electrode recordings. Nearly half of the patients who have ablative surgery become seizure-free, and nearly two thirds have no seizures or only rare ones. Candidates for corpus callosotomy are those patients with multiple seizure types and nonfocal EEG abnormalities. Almost half of these patients have at least a 50% reduction in seizure frequency. Patients with infantile hemiplegia and seizures may have marked improvement in seizure control after physiologic hemispherectomy.

Corpus Callosum↗

PubMed1989

Adult-onset chorea and dementia with propionic acidemia.

Propionic acidemia usually presents in the newborn period with severe metabolic acidosis and lethargy. A 31-year-old man with adult onset chorea and dementia had propionic acidemia due to propionyl CoA carboxylase deficiency. Metabolic investigations may prove useful in patients with movement disorder of unknown etiology.

Adult↗

PubMed1988

Spectral power of human limbic evoked potentials: relationship to seizure onset.

Limbic evoked potentials were recorded from intracerebral electrodes bilaterally implanted in the hippocampi of 16 epileptic patients undergoing evaluation for surgical resection of a seizure focus. Spectral analysis of the limbic evoked potentials revealed consistently lower spectral power of both low-band (1-12.6 Hz) and high-band (13-20 Hz) components recorded form the hippocampus that was associated with the electrographically confirmed seizure focus as compared to the contralateral side. Limbic evoked potential recordings appear to be useful in the determination of a focal functional deficit and thus in identifying the site of epileptogenic pathology. Further, the results support the hypothesis of a local generator for limbic evoked potentials and demonstrate that limbic evoked potentials in humans include not only low-frequency, high-amplitude electric field changes, but also a high-frequency component.

Adolescent↗

PubMed1988

Relationship of limbic evoked potentials to recent memory performance.

The relationship between limbic evoked potentials (LEPs) and memory performance was investigated in eight patients with intractable epilepsy who were candidates for temporal lobectomy. No relationship between the presence or absence of unilateral LEP and memory deficits was present. However, in both patients with bilaterally poorly developed hippocampal LEPs, verbal and visual-spatial memory tasks were impaired. In one patient with well developed LEPs bilaterally, memory function was normal. These data suggest that LEPs may assist in the evaluation of memory function during the preoperative work-up for temporal lobectomy.

Epilepsy↗

PubMed1988

Cholinergic modulation of human limbic evoked potentials.

Limbic evoked potentials (LEPs) were recorded from the hippocampi of three epilepsy surgery patients with unilateral medial temporal lobe seizure onset. In each patient, stable large amplitude LEPs which displayed polarity inversion across successive levels of hippocampus were present unilaterally, but were absent or rudimentary in the hippocampus corresponding to the electrographically proven seizure onset. After administration of scopolamine, LEPs in the "normal" hippocampi were markedly altered with slowing of the individual components and increased trial to trial variability. In addition, two patients developed reliable, high amplitude, polarity inverting LEPs on the side of seizure onset which had either absent or rudimentary LEPs in the baseline state. The results suggest that LEPs are under cholinergic modulation.

Acetylcholine↗

PubMed1987

Analysis of a four-year experience with depth electrodes and a two-year experience with subdural electrodes in the evaluation of ablative seizure surgery candidates.

Chronically implanted depth and subdural electrodes have both been shown to be satisfactory means of localizing epileptogenic foci. Utilizing bilateral mesial temporal depth electrodes, we have localized mesial temporal foci in a large percentage of patients. Depth electrode investigation of a more limited number of patients with suspected extramesial temporal foci has not been as reliable in giving localizing information. We have more recently used subdural electrodes to investigate this latter category of patients, and preliminary findings suggest that this technique may be of localizing value in several subcategories.

Electrodes, Implanted↗

PubMed1987

The effect of electrical stimulation of medial temporal lobe structures in epileptic patients upon ACTH, prolactin, and growth hormone.

We measured ACTH, cortisol, prolactin, and growth hormone concentrations in patients with temporal lobe epilepsy who were having depth electrode studies. During the collection period, electrical stimuli were applied to amygdala and hippocampus to establish after-discharge thresholds. After-discharges that lasted at least 10 seconds or seizures caused secretion of ACTH and prolactin but not growth hormone. Stimuli that did not produce after-discharges of this duration inhibited ACTH secretion, but had no effect on prolactin or growth hormone secretion.

Adrenocorticotropic Hormone↗

PubMed1987

Limbic evoked potentials predict site of epileptic focus.

Limbic evoked potentials (LEPs) were recorded from intracerebral electrodes in the hippocampi of seven preoperative epilepsy surgery patients. LEPs were evaluated using amplitude, form, and asymmetry by raters blinded as to the side of electrographically proven seizure onset. Raters correctly predicted the side of focus in all four patients with proven unilateral temporal lobe seizure onset. Further, LEP amplitudes in two patients with bilateral independent temporal lobe seizure onset were markedly diminished compared with one patient with a nontemporal lobe seizure onset. LEP recordings may assist in determination of the site of epileptogenic pathology.

Epilepsies, Partial↗

PubMed1986

Techniques and applications of sphenoidal recording.

Sphenoidal electrodes were introduced in the late 1940s and early 1950s to record EEG activity from the inferior mesial temporal region. They are inserted percutaneously beneath the zygomatic arch to rest in the vicinity of the foramen ovale. They are safe, easy to insert, and well tolerated for up to 3 weeks. Artifacts are less prominent than with other types of basal electrodes. Complications are rare. Sphenoidal electrodes are superior to scalp electrodes in detecting interictal epileptiform discharges and ictal EEG patterns from the inferior mesial temporal lobe. Clinical indications include: documentation of epileptiform activity in patients with partial complex seizures in whom scalp recording has been inconclusive; diagnosis of episodes of uncertain mechanism; and localization of an epileptogenic focus in patients being evaluated for temporal lobectomy.

Barbiturates↗

PubMed1986

Association of low blood manganese concentrations with epilepsy.

A comparison of hospitalized epileptic patients with matched normals showed that the mean whole blood manganese (Mn) concentration of the epileptic population was significantly lower than the mean of the normal population. The whole blood Mn concentration in the epileptics did not correlate either with seizure frequency or with anticonvulsant therapy. It was observed, however, that patients whose epilepsy was a result of trauma had significantly higher blood Mn concentrations than patients whose history was negative for trauma.

Adolescent↗

PubMed1986

Temporal lobectomy for partial complex seizures: evaluation, results, and 1-year follow-up.

Twenty-six patients were evaluated for temporal lobectomy. Fourteen underwent initial monitoring with electrodes in the amygdala and hippocampus bilaterally. Twelve had initial monitoring with scalp and sphenoidal electrodes. Four had conclusive localization without depth electrodes. Twenty-three patients underwent lobectomy. At 1-year minimum follow-up, 15 were seizure free. Five had greater than 90% reduction in seizure frequency. Complications of depth electrodes were one hemorrhage and one abscess. One patient developed impaired memory following surgery. Temporal lobectomy is effective in well-selected patients. Depth electrodes localize seizure onset from mesial temporal structures. Scalp and sphenoidal recording may be sufficient in some cases.

Adolescent↗

PubMed1984

Pituitary and adrenal function in epileptic patients.

ACTH and cortisol were measured simultaneously in plasma samples obtained every 5 min from subjects at two different diurnal times. In the first study adrenocorticotropic hormone (ACTH) mean concentration and secretory rate were elevated in anticonvulsant drug-treated temporal lobe epileptic patients in comparison to anticonvulsant drug-treated patients with pseudoseizures. Cortisol mean concentrations and secretory rate were similar in these groups of subjects. In the second study, mean ACTH concentration and secretory rate were higher in temporal lobe epileptic patients than in normal controls. Both measures of ACTH secretion were similar in post-temporal lobectomy patients and normal controls. Mean cortisol concentration and secretory rates were highest in the temporal lobe epileptic patients, lowest in normal controls, and intermediate in post-temporal lobectomy patients. We conclude that ACTH and cortisol secretion is abnormal in temporal lobe epileptic patients. Temporal lobectomy restores abnormal ACTH secretion to normal whether or not seizures are controlled. The absence of ACTH changes in the pseudoseizure patients suggests that these changes are not drug induced. Cortisol secretion is similar in temporal lobe epileptic patients and pseudoseizure patients, suggesting a direct effect of the drugs upon the adrenal cortex.

Adolescent↗