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Biomedical subjects

E P Vining

Publications and source records attributed to E P Vining.

At least 19 recordsLinked to original sources
PubMed1992

Motor and sensory cortex in humans: topography studied with chronic subdural stimulation.

Classic neurosurgical teaching holds that once the Rolandic fissure (Rf) has been located, there are distinct differentiated primary motor and sensory functional units confined within a narrow cortical strip: Brodmann's Areas 4 and 6 for primary motor units in front of the Rf and 3, 1, and 2 for sensory units behind the Rf. To test this assumption, we examined in detail the records of cortical mapping done by electrical stimulation of the cerebral cortex via implanted subdural electrode grids in 35 patients with seizure disorders. Of 1381 stimulations of the electrode sites, 346 (25.1%) produced primary motor or motor-arrest and sensory responses in contralateral body parts: 56.8% were primary motor responses; 16.2% were motor-arrest; 22.5% were sensory; and the remaining 4.5% were mixed motor and sensory responses. Two-thirds (65.9%) of the primary motor responses were located within 10 mm of the Rf, and the remaining one-third (34.1%) were more than 10 mm anterior to the Rf or were posterior to the Rf. Furthermore, in the patient group with brain lesions, fewer than one-third (28.1%) of the responses were within the 10-mm narrow anterior strip. Our study reconfirmed that a significant number--at least one-third--of motor responses are distributed outside the classic narrow cortical strip. In patients with brain lesions, the motor representation is further displaced outside the narrow strip. This finding indicates that primary motor cortex may extend beyond the gyrus immediately anterior to the Rf.

Adolescent↗
PubMed1991

Multifocal independent epileptiform discharges in children: ictal correlates and surgical therapy.

We obtained continuous EEG/video recordings on four children who had the interictal EEG pattern of multifocal independent epileptiform discharges (MIED). The prominent feature of their evaluation was the evidence that their clinical seizures appeared to be of focal origin; 42/44 seizures were manifested by "fencing postures." Three patients subsequently underwent epilepsy surgery: one focal resection of superior frontal-parietal cortex and two hemidecorticectomies. Seizure control improved in all three patients, and one patient is now seizure-free. Our patients differ from those previously reported in that they had a predominance of tonic seizures and had no history of infantile spasms or Lennox-Gastaut syndrome. Some patients, such as ours, with MIED may have clinical seizures of more focal origin than might be expected from their interictal EEG and, therefore, may benefit from resective epilepsy surgery.

Adolescent↗
PubMed1990

Chaos, balance, and development: thoughts on selected childhood epilepsy syndromes.

Age-specific epilepsy syndromes raise important questions about developmental susceptibility to seizures and epileptogenesis and about the effect of seizures on function. The diagnosis and treatment of these syndromes has been enhanced by the use of modern science and technology. Epidemiologic studies have changed our approach to febrile convulsions. This developmental seizure disorder is benign and self-limited. We have been forced to think carefully about threshold, therapy, and whether other seizures in childhood may be equally benign. This framework of developmental specificity can also be applied to West syndrome, especially with respect to neurophysiology, neurochemistry, neuroimaging, and epidemiology--the types of seizures, clustering, variations associated with sleep, PET scans, and therapy. Rasmussen's syndrome and other unilateral developmental epilepsies are progressive but remain confined to a single hemisphere. However, they usually are devastating to global neurologic function. They are models for examining the impact of epilepsy in one pathologic hemisphere on the function of the entire brain. Current therapy for this condition is hemispherectomy. Recovery of function after this major surgery is striking and provides clues to brain organization. The analysis of these three syndromes provides windows on the dynamic, changing central nervous system of the child and may lead to better understanding and therapy for other seizure disorders.

Brain↗
PubMed1990

Central nervous system vasculitis after chickenpox--cause or coincidence?

A 7.5 year old boy, known to have a seizure disorder, presented with an infarct in the left middle cerebral artery territory, 10 weeks after severe chickenpox. Immunofluorescent antibody titre to the varicella zoster virus in the cerebrospinal fluid was 1:32. Cerebral angiography showed evidence of focal vasculitis. He presented again seven months later with an acute exacerbation of seizures. Magnetic resonance imaging of the brain showed an old posterior extension of the infarct, but a repeated angiography demonstrated an improvement in the vasculitic process. Cerebrospinal fluid antibody titre was again 1:32. Although this may have been an unfortunate coincidence, a possible association between chickenpox and vasculitis, similar to that reported with herpes zoster, and with potentially significant clinical implications, should be considered. As a definite proof can be obtained only by a brain biopsy, however, which is generally not indicated in such cases, only additional clinical reports can lead to delineation of this association as a definite entity.

Brain Diseases↗
PubMed1990

Resection of the epileptogenic area in critical cortex with the aid of a subdural electrode grid.

Electrode grids were implanted subdurally in 28 patients with epilepsy. In 16 of the 28 patients, an epileptogenic area was located in the speech-dominant left temporal lobe. Recordings made with the grid revealed that the epileptogenic areas in the patients varied widely in extent: the area was confined within the first 10 mm of the temporal lobe in some patients or it was scattered throughout the entire anterior to posterior 80-mm extend in others. Resection of the epileptogenic area was adjusted accordingly in each case. In 6 of 16 patients who were left-hemisphere-dominant for language, up to 55-80 mm from the tip of the temporal lobe was removed, a measure that exceeds the conventional limit of 50 mm from the tip of the dominant hemisphere. In the remaining 12 of the 28 patients, epileptogenic areas were located in a combination of several lobes. In 7 of these 12 patients, the epileptogenic area encompassed the rolandic area; it was removed without deficit in 4 patients and with expected deficit in 3. Of the latter 3 patients, 1 patient underwent hemispherectomy, and a large portion of the epileptogenic rolandic cortex in the frontal and parietal lobes was removed from the other 2. There were 2 cases of grid-related infection, which cleared with antibiotic treatment; there were no lasting complications of grid implantation in any patient. There was no mortality. Electroencephalographic recording and functional mapping using subdural electrode grids allow a tailored, maximal resection of epileptogenic tissue with minimal injury to critical cortex.

Brain Diseases↗
PubMed1990

Characterization of the basal temporal language area in patients with left temporal lobe epilepsy.

We evaluated 5 consecutive patients with subdural grid electrodes (including placement over the left basal temporal region) for focal resections for control of intractable epilepsy. All 5 had language dysfunction when we performed cortical stimulation over the basal temporal region (the inferior temporal gyrus, the parahippocampal gyrus) using a systematic battery of language tests. The area in which language interference could be produced began from at least 11 to 35 mm posterior to the temporal tip and ended at least 39 to 74 mm posterior to the temporal tip. The most consistently impaired language tasks were spontaneous speech and passage reading, but there was impairment of all language functions tested in some patients. Language deficits after dominant temporal lobectomy may result from resection of this area.

Adult↗
PubMed1987

Cognitive dysfunction associated with antiepileptic drug therapy.

Epilepsy is frequently associated with cognitive dysfunction. However, the reasons for this correlation are unclear. Possible influential factors include patient age; duration, frequency, etiology, and type of seizures; hereditary factors; psychosocial issues; and antiepileptic drug (AED) therapy. Whereas many of these factors are beyond the physician's control, AED therapy is one element that can be addressed in treatment decisions by recognizing the potential cognitive effects of particular AEDs. For example, phenobarbital impairs memory and concentration; phenytoin affects attention, problem solving ability, and performance of visuomotor tasks. In contrast, carbamazepine may affect concentration, while valproate would appear to have minimal effects on cognition. Moreover, cognitive effects of AEDs are amplified with coadministration of multiple anticonvulsants (polytherapy). A review of studies on the cognitive effects of monotherapy with AEDs, as opposed to those of polytherapy, provides evidence that drug-related cognitive dysfunction can be reversed if patients are switched to a simpler therapeutic regimen. Future research should be directed toward developing reliable measures for assessing and monitoring cognition, and understanding the particular cognitive side effects of each AED. Physicians also need to revise their opinions about which side effects are "tolerable" for epileptic patients.

Anticonvulsants↗
PubMed1987

Psychologic and behavioral effects of antiepileptic drugs in children: a double-blind comparison between phenobarbital and valproic acid.

Traditional clinical monitoring of children with epilepsy does not appear to be sufficiently sensitive to cognitive functioning and behavioral problems. Although subtle, these changes may alter a child's ability to perform well in school and in society. Physicians must prevent seizures without producing intolerable side effects, and ways of more appropriately assessing these side effects must be developed. In this double-blind, counter-balanced, crossover study of 21 children, the effects of phenobarbital and valproic acid on cognitive functioning and behavior were measured. There was no difference in seizure control between the drugs, and each medication was maintained in the therapeutic range for 6 months (mean phenobarbital level, 21.2 micrograms/mL; mean valproic acid level, 94.1 micrograms/mL). Children were treated with each drug for 6 months. Differences between the drugs were seen on measurements of cognitive function and behavior. On four tests of neuropsychologic function, children performed significantly less well while receiving phenobarbital (P less than .01). There was no evidence that the patients were sedated or less able to perform continuous performance tasks while receiving phenobarbital. Parental assessment of behavior indicated significantly worse behavior with the phenobarbital regimen for three items (P less than .01) and children were measurably more "hyperactive" (P less than .05). Routine clinical assessment of the patients did not reveal differences between the drugs with respect to routine laboratory measurements or side effects as assessed by history or physical examination. Although children may appear to tolerate a medication without clinically apparent problems, subtle but significant changes in intellectual function and behavior may be occurring. Additional, more sensitive, methods of monitoring patients while receiving these drugs is necessary.

Adolescent↗
PubMed1986

Use of barbiturates and benzodiazepines in treatment of epilepsy.

Barbiturates and benzodiazepines may be very effective in controlling seizures, especially status epilepticus. However, their chronic use may be associated with serious sedative-hypnotic effects that interfere with cognitive function and behavior. When utilized, patients must be carefully monitored to be certain that these side effects are not occurring.

Adult↗
PubMed1985

Discontinuing antiepileptic medication in children with epilepsy after two years without seizures. A prospective study.

Antiepileptic medications were discontinued in 88 children with epilepsy of various causes who had been free of seizures for two to four years. The subjects were then followed for six months to five years (mean, 22 months). Sixty-six (75 per cent) remained free of seizures. Electroencephalographic characteristics, type of seizure, and age at onset were important in predicting outcome. Specific electroencephalographic features (such as the presence or absence of slowing or spikes) were more predictive than simple classification of an electroencephalogram as normal or abnormal. A history of complex partial seizures that had been controlled for two years carried a relatively favorable prognosis (P less than 0.05), whereas a history of atypical febrile seizures carried a poor prognosis (P less than 0.05). The variable of a younger age at onset was also associated with a better outcome (P less than 0.05), but only if accompanied by electroencephalographic slowing. Altogether, six variables (the interaction of age at onset with electroencephalographic slowing, electroencephalographic spikes, atypical febrile seizures, complex partial seizures, electroencephalographic slowing, and electroencephalographic change) were statistically significant (P less than 0.05) in predicting outcome. We conclude that in most children with epilepsy who have been free of seizures for two or more years, antiepileptic medications can safely be discontinued, and that it is possible to predict reasonably well which children will remain free of seizures.

Adolescent↗
PubMed1985

Donor-recipient interconnections between giant nerve fibers in transplanted ventral nerve cords of earthworms.

Twelve segments of ventral nerve cord (VNC) from donor earthworms, Eisenia foetida, were transplanted into recipient worms from which a comparable length of VNC had been removed. Within the first few days after transplantation, bud-like formations, containing outgrowths of the giant nerve fibers, were evident at the ends of transplanted and recipient VNC. Morphological and electrophysiological evidence indicated that by 4-10 days after transplantation, medial (MGF) and lateral (LGF) giant fibers within the transplanted VNC formed cell-specific connections with their counterparts in the recipient VNC. Although the diameters of the giant fiber connections in the transplant-recipient junctions were often larger than normal, spike conduction across the junction was initially slow (approximately 1.0 m/s) but gradually increased over the next 2-3 weeks. Within the transplant, giant fibers were initially normal in appearance, but spike conduction was slow (1-2 m/s). During the next few weeks velocities increased by as much as fourfold and then stabilized for the next several months. However, by 4-5 weeks after transplantation, giant fiber morphology within the transplant was altered significantly, as indicated by the formation of numerous branch-like extensions along the length of each giant fiber. By 9-10 months there were further morphological changes in the transplant, as indicated by decreased branching of the giant fibers and altered neuropile. Despite these morphological changes, through-conduction of giant fiber spikes remained reliable.

Animals↗
PubMed1985

Restoration of sensory and motor function in earthworm escape reflex pathways following ventral nerve cord transplantation.

Twelve segments of earthworm ventral nerve cord (VNC) were excised from either segments 10-22 (i.e., within the MGF sensory field) or segments 75-87 (i.e., within the LGF sensory field) in donor worms and heterotopically, or homotopically, transplanted into recipient animals. Morphological evidence indicated that by four days after transplantation, peripheral connections were formed between the transplanted VNC and the body wall of the recipient, many of these connections involving novel pathways projecting ventrally from the transplant. Restoration of giant fiber touch sensitivity in the transplant occurred from 4-14 days after transplantation. Regardless of the site of transplantation, the restored sensitivity (i.e., MGF versus LGF sensory field) always reflected the origin of the donor VNC. Restoration of MGF-mediated motor activity in the transplant occurred approximately 17-22 days after transplantation. In the case of heterotopic transplants (i.e., anterior VNC into posterior segments), the restored MGF-mediated muscle potentials were facilitating, indicating at least some tendency for persistence of this feature after transplantation. Behavioral observations suggested that reconnections involving other reflex pathways (e.g., those controlling setal movements and peristaltic locomotion) were made within the transplant region and that properties of the restored reflexes reflected those of the donor VNC. The rapid restoration of sensory and motor connections, despite heterotopic placement, indicates a significant capacity for peripheral regeneration by the transplanted VNC. On the other hand, the maintenance of various properties of reflex function, despite heterotopic transplantation, suggests a limited capacity for rearrangement of established central connections in the transplanted VNC.

Afferent Pathways↗