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Biomedical subjects

B E Swartz

Publications and source records attributed to B E Swartz.

At least 19 recordsLinked to original sources
PubMed2003

Body part asymmetry in partial seizure.

Clinically differentiating between localisation related and generalised epilepsy is important because it carries significant implications for planning diagnostic management strategy. Asymmetry of body parts such as toes, popliteal crease levels, thumbs, cubital crease levels, and forehead and facial structures, are common in patients with localisation related epilepsy syndromes. We retrospectively studied 337 patients with seizure disorders. Body part asymmetry was routinely documented. Fifty-six were excluded because of non-epileptic seizures, pure psychiatric disorders, non-epileptic neurological disorders, brain tumours and strokes. The relationship between clinically detectable body asymmetry (BA) and the electro-anatomic characteristics of their epilepsy was explored. Body asymmetry was found in 88 out of 282 cases, in which 64 (73.5%) suffered from localisation related epilepsy. Among localisation related epilepsy, BA were found in 41.5% (n=64/154) of patients. In contrast, only 18.75% (n=24/128) of patients with generalised seizure disorders showed similar findings (P<0.0001). Among patients with partial onset seizures, lateralisation of BA was concordant with their seizure origin in 75.9% (n=41/54) and discordant in 24.1% (n=13/54). Investigation results of 10 partial epilepsy cases were non-lateralising at the time of study. Peak age of onset of concordant case was 0-5 years old while discordant group was 6-15 years old. We conclude that BA in patients with seizure disorder is a useful clue to diagnosis of localisation related seizure and may provide clues for lateralising seizure origin in partial onset seizures.

Adolescent↗
PubMed2000

The effects of an alpha-2 adrenergic agonist, guanfacine, on rCBF in human cortex in normal controls and subjects with focal epilepsy.

Alpha-2 noradrenergic agonists may have wide applicability in the treatment of pre-frontal cortex deficits in primates and behavioral dysfunction in man. We have undertaken this study to determine the effect of an alpha-2 agonist, guanfacine, on regional cerebral blood flow (rCBF) in humans. Three subject groups were evaluated: normal controls, subjects with frontal lobe epilepsy (FLE), and subjects with temporal lobe epilepsy (TLE). All underwent a number of PET scans using 15O-water, with half before and half after a single dose of guanfacine. A wide area of increased rCBF was seen in the frontal lobe, maximal at the central region, following guanfacine in controls and subjects with TLE. Smaller areas of decrease in rCBF were seen in the posterior temporal-occipital cortex. In the FLE group a decrease in rCBF was seen in the dorsal prefrontal cortex on the epileptogenic side with only small increases seen in the mid- to anterior temporal perisylvian areas. The ability of alpha-2 agonists to enhance performance of tasks reliant on prefrontal cortex, without improving tasks believed to rely on intact temporal-hippocampal function, may be explained by these results. Epileptogenic zones appear to create both direct and indirect changes in patterns of drug response. Further studies on the cognitive properties of these agents in humans should be encouraged.

Adrenergic alpha-2 Receptor Agonists↗
PubMed1999

Positron emission tomography: the contribution of cognitive activation paradigms to the understanding of the epilepsies.

Cognitive activation paradigms coupled with positron emission tomographic techniques may aid in the identification of functional and epileptogenic zones for presurgical evaluation. More work is needed to determine the most clinically efficacious paradigms for different seizure types. The real strength of activation positron emission tomography lies in the ability to study shifts in cognitive circuitry that accompany a fixed neuropathologic entity for both groups of similar subjects and individuals. These techniques are enhancing our understanding of the fundamentals of brain plasticity and may be used in the future to predict precise surgical risks.

Brain↗
PubMed1998

Dynamic [18F]fluorodeoxyglucose positron emission tomography and hypometabolic zones in seizures: reduced capillary influx.

We performed dynamic [18F]fluorodeoxyglucose ([18F]FDG) positron emission tomographic (PET) analyses in 8 patients. Rate constants of influx (K1*), efflux (k2*), phosphorylation (k3*), and dephosphorylation (k4*) were derived for the regions of interest (ROIs), which included (1) the hypometabolic epileptogenic regions and (2) the homologous regions in the contralateral hemispheres. In addition, the four constants were determined from at least one clearly defined (control) ROI from the same plane and its homologous contralateral ROI. Influx (K1*) in the epileptogenic region was reduced in comparison with the contralateral ROI. Reductions in influx (K1*), which averaged 18 +/- 13% (mean +/- SD), [18F]FDG phosphorylation (k3*) (25 +/- 20%), and brain glucose utilization rates (26 +/- 10%) were observed in the epileptogenic region. Reductions in efflux were not statistically significant (k2* = 13 +/- 28%) but were comparable in magnitude to the average reduction in K1*. No ipsilateral versus contralateral differences were seen for any rate constants measured outside the epileptogenic region. Influx correlated highly with phosphorylation in the epileptogenic region. Our data suggest that the hypometabolic epileptogenic focus seen in [18F]FDG-PET studies is also a region of reduced blood-brain barrier glucose transporter activity and that reductions in phosphorylation are proportional to reductions in [18]FDG influx.

Adult↗
PubMed1998

Surgical outcomes in pure frontal lobe epilepsy and foci that mimic them.

In this study we examined 37 subjects with a diagnosis of intractable frontal lobe epilepsy (FLE) based on non-invasive pre-surgical evaluation. Twenty-six underwent chronic intracranial ictal recordings (CIR) with video monitoring; 20 of these went on to surgical resection. Eleven underwent surgery without CIR. Retrospectively, we determined that 19 had pure FLE, 12 had frontal plus extrafrontal epileptogenic zones, and six others did not have FLE. We analysed the whole group and individual categories to evaluate the determinants of surgical outcome. Sixty percent of the pure frontal group is seizure free with all having > or = 75% reduction. The frontal-plus group had only 10% seizure free with 70% having > or = 75% reduction. Being in the pure frontal group was associated with better outcomes than the 'frontal-plus' group (P < 0.05; chi-square). Subjects with FSIQ > or = 85, focal pathologies and 18FDG-PET scans which were normal or had focal abnormalities (P < or = 0.05, all, chi-square) were more likely to have excellent outcomes. MRI abnormalities, surface EEG, and location and size of resection were not predictive of surgical outcomes. Rasmussen's encephalitis, incomplete surgical strategies and bilateral foci were apparent in those with poor outcomes, and surgical size predicted post-operative deficits (chi-square; P < 0.001). We conclude that careful, hypothesis-driven implants and operating procedures can result in good surgical outcomes for frontal lobe epilepsy subjects even when lesions are not apparent on routine neuroimaging.

Adolescent↗
PubMed1998

The advantages of digital over analog recording techniques.

In the past few years digital technology has brought EEG and evoked potentials into emergency rooms, intensive care units and operating rooms with a variety of automatic data trending. Networking of these systems makes access to clinical neurophysiologists nearly immediate. Digital EEG has made montage reformatting and quantitation of parameters readily available. Increased spatial and temporal resolution is available with routine EEG, and combined topographic and frequency mapping of a given potential, spike or seizure focus is possible. In the future, these and other features such as dipole mapping and cognitive EP analysis will be available on a routine basis.

Animals↗
PubMed1997

Presence of herpes simplex DNA in surgical tissue from human epileptic seizure foci detected by polymerase chain reaction: preliminary study.

OBJECTIVES: To determine whether herpes simplex virus causes monofocal epilepsy and to assess the presence of herpes simplex virus 1 (HSV-1) and HSV-2 in surgical specimens from patients with epilepsy by using polymerase chain reaction and Southern blot analysis. BACKGROUND: Herpes simplex virus is a common neurotropic virus capable of latency within the central nervous system; it has a predilection for the temporal lobe. Central nervous system infection with HSV has been associated with seizure activity. DESIGN AND METHODS: Surgical specimens were removed from 50 patients as part of a treatment protocol for monofocal epilepsy. Neuropathological classification was done, and adjacent sections were screened for HSV by using polymerase chain reaction. Tissues obtained post mortem from the temporal lobe cortex of persons with Alzheimer disease (n=17), Parkinson disease (n=14), or nonneurological disease (n=17) served as controls. RESULTS: Twenty (40%) of the 50 epilepsy cases and 2 (4%) of the 48 control cases had at least one sample that tested positive for HSV (P<.001). Sixty-seven percent (8/12) of the epilepsy cases with heterotopia were positive for HSV. CONCLUSIONS: There was a statistically significant difference in the frequency of HSV-positive surgical specimens from monofocal seizure epicenters compared with nonepilepsy control specimens. These data suggest an association of the virus with seizure activity. All specimens positive for HSV (surgical specimens and control specimens) should be examined to determine the activity or latency state of the virus and cellular localization.

Adolescent↗
PubMed1996

Studies of working memory using 18FDG-positron emission tomography in normal controls and subjects with epilepsy.

We have studied three groups of subjects with a working memory paradigm, using 18FDG-PET. Controls show the greatest increase on uptake in dorsolateral prefrontal cortex, basal forebrain and angular gyrus. A group of subjects with focal frontal epilepsy did not show increases compared to a control task of attention. Primary generalized epilepsy subjects show the greatest changes in angular gyrus, dorsal temporal, medial frontal and parietal regions. Factor and regression analyses extend these observations and show reliance of both patient groups on the medial and inferior temporal lobe. We propose that the normal network of working memory is disrupted by these two forms of epilepsy and different networks are accessed. Declarative memory may be used as a compensatory system, which results in decreased performance.

Adult↗
PubMed1996

The safety and efficacy of chronically implanted subdural electrodes: a prospective study.

BACKGROUND: The popularity of subdural electrodes for the presurgical evaluation of patients with intractable seizures is increasing. However, few reports have prospectively dealt with their efficacy and safety. METHODS: We conducted a 5-year prospective study of patients evaluated by the California Comprehensive Epilepsy Program, who subsequently underwent subdural electrode implantation at one of two institutions. Efficacy was examined by ultimate outcome with regards to postsurgery resection seizure frequency. Fifty-five patients underwent 58 implant procedures and postresection outcomes were available in 47 patients. Safety was defined by the incidence of expected and unexpected complications, and neuropathologic examination of tissue specimens. RESULTS: The most common expected adverse effects during implant were fever < or = 102 degrees (41%), cerebrospinal fluid leakage (19%), headache (15%), and nausea (4%). There were no infections. Unexpected adverse events included fever > 102 degrees F (5%), migraine (5%), iatrogenic electrode dysfunction (5%), and temporalis muscle fibrosis (5%). The incidence of pathologic findings suggestive of foreign body reaction was 10%. There were no permanent sequelae. Surgical outcomes were excellent in all (> or = 75% seizure reduction) with 50% seizure free regardless of the focus. CONCLUSIONS: Subdural electrodes are a safe, easy, and efficacious tool for evaluating seizure foci prior to resective surgery. They should no longer be considered investigational devices.

Anticonvulsants↗
PubMed1996

Primary or working memory in frontal lobe epilepsy: An 18FDG-PET study of dysfunctional zones.

INTRODUCTION: We previously demonstrated that patients with frontal lobe epilepsy show deficits on a visual working memory paradigm and that this paradigm produces increased 18FDG uptake in the dorsolateral prefrontal cortex (DPFC), premotor cortex, angular and supramarginal gyri, basal forebrain, and ventral frontal poles of normal subjects when compared with a control task. We hypothesized that subjects with frontal lobe epilepsy would have impaired frontal activation during this task. METHODS: One resting and two activated images were obtained with 18FDG-PET in 15 subjects and 14 controls. One was a delayed (DMS) and one an immediate (IMS) match to sample paradigm. Discriminant and factor analyses were used to analyze the data, supplemented by selected t tests. RESULTS: No differences in glucose uptake were found between the DMS and IMS in the epilepsy subjects, in distinct contrast to controls. A comparison between controls and epilepsy subjects showed differences both ipsilateral and contralateral to the epileptic focus in the frontal regions involved in the task, with small changes in nonfrontal, task-related regions as well. The task itself brought out or highly exaggerated differences seen at rest. There was weak evidence that other frontal and temporal regions were attempting to compensate for the DPFC deficit. CONCLUSION: A unilateral epileptic focus is capable of suppressing function along a large task-related circuit ipsilateral and contralateral to the focus. Peripheral cortical regions compensate poorly for the area of dysfunction.

Adult↗
PubMed1996

Visual working memory in primary generalized epilepsy: an 18FDG-PET study.

It is generally believed that patients with primary generalized epilepsy have normal cognition and neuroimaging studies. We have previously shown that patients with juvenile myoclonic epilepsy (JME) have impaired visual working memory. In this study we examined relative regional changes in 18FDG uptake during a visual working memory paradigm in patients with JME. At rest, there were regional decreases in relative glucose uptake compared to controls. Unlike control subjects, increased activity in the dorsolateral prefrontal cortex was not found during the working memory task. Other regions with increased uptake in controls, such as premotor cortex and basal frontal cortex, also showed no increases, whereas medical temporal structures appeared to play a role in JME but not in control subjects' task performance. The data suggest that JME, a type of primary generalized epilepsy, may suffer from cortical disorganization that affects both the epileptogenic potential and frontal lobe cognitive functioning.

Adult↗
PubMed1995

Unusual seizure types.

There is no consensus as to what constitutes a diagnostic complex partial seizure type for any given focus. Nevertheless, some forms are seen infrequently, such as in the patient just described who had parietal seizures, whereas others, such as the bland onset followed by oral-alimentary automatisms of temporal lobe epilepsy, are more common. It helps to be aware of the possible origins of these unusual forms when differentiating electrical seizures from pseudoseizures, planning for use of specific pharmacologic treatments, or planning a surgical resection. Although one cannot recommend a surgical resection based on semiology alone, one can place intracranial electrodes more strategically when the hypothesis regarding the seizure focus includes the clinical characteristics of the patient's seizures.

Epilepsy, Frontal Lobe↗
PubMed1994

An 18FDG-PET study of cortical activation during a short-term visual memory task in humans.

Studies of subhuman primates and man have shown that the prefrontal cortex is important for spatial working memory. We have used 18fluorodeoxyglucose positron emission tomography (18FDG-PET) to study a non-spatial, abstract visual memory task of in man. Using a regions-of-interest approach with discriminant analysis of the relative regional cerebral metabolic rate of glucose consumption (rCMRGlc), we found that changes in dorsal prefrontal, premotor/motor frontal and posterior cingulate areas differentiated the primary memory task from the control task. Less robust increases in glucose uptake were observed in lateral parietal cortex, while some subcortical and limbic regions showed decreases. This is the first activation study with a non-spatial, visual task. These results complement previous studies in that they substantiate the role of the prefrontal cortex in the mediation of cross-temporal contingencies of behavior, and point to a role of the premotor region in this mediation as well.

Adult↗
PubMed1994

The human brain GLUT1 glucose transporter: ultrastructural localization to the blood-brain barrier endothelia.

Immunogold electron microscopy was used to examine human brain resections to localize the GLUT1 glucose transporter. The tissue examined was obtained from a patient undergoing surgery for treatment of seizures, and the capillary profiles examined had characteristics identical to those described previously for active, epileptogenic sites (confirmed by EEG analyses). A rabbit polyclonal antiserum to the full-length human erythrocyte glucose transporter (GLUT1) was labeled with 10-nm gold particle-secondary antibody conjugates and localized immunoreactive GLUT1 molecules in human brain capillary endothelia, with < 0.25% of the particles beyond the capillary profile. Erythrocyte membranes were also highly immunoreactive, whereas macrophage membranes were GLUT1-negative. The number of immunoreactive sites per capillary profile was observed to be 10-fold greater in humans than in previous studies of rat and rabbit brain capillaries. In addition, half of the total number of immunoreactive gold particles were localized to the luminal capillary membrane. We suggest that the blood-brain barrier GLUT1 glucose transporter is up-regulated in seizures, and this elevated transporter activity is characterized by increased GLUT1 transporters, particularly on the luminal capillary membranes. In addition, acute modulation of glucose transporter activity is presumed to involve translocation of GLUT1 from cytoplasmic to luminal membrane sites, demonstrable with quantitative immunogold electron microscopy.

Blood-Brain Barrier↗
PubMed1994

Subdural recording and electrical stimulation for cortical mapping and induction of usual seizures.

Chronic subdural strip electrodes were used for recording of seizure origin, cortical mapping and confirmation of seizure foci by electrical stimulation. Seventeen patients were comprehensively evaluated for epilepsy surgery. All patients had failed medical treatment. Intracranial recording was necessary in 12 patients. Speech area was determined in 50% of the patients stimulated. Seizure origin was confirmed by stimulation-induced usual seizures or aura in 75% of the patients stimulated. Intracranial chronic recordings were safe and added important prognostic information, as well as helped decide the extent of resection.

Adult↗