Biomedical subjects

D R Fish

Publications and source records attributed to D R Fish.

At least 109 records · Page 6Linked to original sources

PubMed1993

Hippocampal sclerosis in epilepsy and childhood febrile seizures.

The connection between hippocampal sclerosis and childhood febrile seizures (CFS) is a contentious issue in the study of epilepsy. We investigated 107 patients with drug-resistant epilepsy by high-resolution volumetric magnetic resonance imaging (MRI). 20 had a history of CFS, 45 had focal (26) or diffuse (19) hippocampal volume loss (HVL). The frequency of CFS was significantly (p < 0.001) higher in the patients with HVL, especially of the diffuse pattern, compared to other epileptic patients without HVL and to the general population. Furthermore, the severity of HVL was greatest in those with a history of CFS. No other clinical or demographic features were associated with either a history of CFS or HVL. The frequency of CFS in patients with other structural congenital causes of epilepsy did not differ from that in a general population. Although these findings show that hippocampal sclerosis is strongly associated with a history of CFS, they do not indicate whether this is a causal relationship. If CFS do cause some cases of hippocampal sclerosis, this can not be the only mechanism, as 64% of those with HVL gave no history of CFS. As diffuse HVL is more strongly associated with a history of CFS than focal HVL, it is also possible that CFS convert pre-existing congenital focal abnormalities into diffuse hippocampal sclerosis. Given the possibility that CFS may cause hippocampal damage and epilepsy, they require urgent medical intervention.

Adolescent↗

PubMed1993

Open stereotactic amygdalohippocampectomy--clinical, psychometric, and MRI follow-up.

The clinical results of six cases of open stereotactic amygdalohippocampectomy for medically intractable epilepsy are presented. Outcome in terms of seizure control (highly satisfactory in five patients) and neuropsychological sequelae (all cases had poor functioning of the contralateral temporal lobe pre-operatively) are detailed. In addition the use of post-operative Magnetic Resonance Imaging (MRI) is demonstrated and shown to be a valuable tool in providing the crucially accurate baseline that is required for more meaningful follow-up outcome studies.

Adult↗

PubMed1993

A specialised computer-based monitoring system for intraoperative electrocorticography.

We have developed a computer-based intraoperative ECoG monitoring system which offers the flexibility of digital recording and allows detailed review of recorded events without interrupting monitoring. In addition, a diagram showing the electrode positions on the brain can be generated on computer screen and subsequently displayed during monitoring--this allows automatic indication of the electrode positions corresponding to specific ECoG channels and can provide the surgeon with a clear visual impression of the area of spiking.

Cerebral Cortex↗

PubMed1993

Clinical responses to electrical brain stimulation of the temporal and frontal lobes in patients with epilepsy. Pathophysiological implications.

The clinical responses elicited by electrical stimulation of discrete cerebral structures in the temporal and frontal lobes were studied in 75 patients undergoing pre-surgical evaluation using chronic intracerebral electroencephalographic recordings. Responses without after-discharge spreading beyond the site of stimulation included somatosensory, autonomic, thermoregulatory and viscerosensory phenomena, simple motor responses, some simple automatisms, changes in facial expression or voice tone, vocalizations, conscious confusion and experiential phenomena. Except for oro-alimentary automatisms, these responses were similar to the initial responses elicited by stimulations followed by a spreading after-discharge. Responses were most often obtained from limbic structures, sometimes from the temporal isocortex, and rarely from frontal sites (except for simple motor activity and some simple automatisms). Specific clinical responses could often be elicited from more than one site (74 out of 147), frequently even from non-contiguous areas in the same or both hemispheres. This suggests that the neuronal substrates responsible for the production of some of these phenomena are widespread neuronal matrices linked through connections which have become strengthened through repeated use as hypothesized by one of us [Gloor (1990), Brain, 113, 1673-1694]. Such a hypothesis could also account for the individually idiosyncratic nature of many of these responses.

Amygdala↗

PubMed1993

Investigation of the opioid system in absence seizures with positron emission tomography.

The neuroanatomical and pathophysiological basis of primary generalised absences is uncertain. Administration of endogenous opioids has been shown to result in absence-like seizures in animal models. Positron emission tomography scans were performed in eight patients with primary generalised epilepsy and eight control subjects. Regional cerebral blood flow was measured interictally with C15O2, after which a 90 minute dynamic study with the opioid-receptor ligand 11C-diprenorphine was performed. Serial absences were precipitated by hyperventilation for 10 minutes, starting 30-40 minutes after injection of diprenorphine. Absences, with generalised spike-wave discharges on the EEG, occurred for between 10% and 51% of the provocation period. No individual (normal or patient) had any interictal focal abnormalities of cerebral blood flow. After provocation of serial absence seizures, there was increased diprenorphine elimination from the association cortex, but not from the thalamus, basal ganglia, or cerebellum, compared with control subjects and patients scanned without provocation of absences. It was possible to simulate the observed increased diprenorphine elimination following seizures in cerebral cortex using a two tissue compartment model, with an estimated 15-41% decrease in the specific tracer uptake rate constant (k3). These results suggest that endogenous opioids are released in the association cortex at the time of serial absences, lead to increased receptor occupancy, and may have an important role in the pathophysiology of generalised absences.

Adult↗

PubMed1993

Stereotactic insertion of intracerebral electrodes in the investigation of epilepsy.

Intracerebral electroencephalography is sometimes necessary in the pre-surgical evaluation of patients with drug-resistant epilepsy, in order to define the site(s) of seizure onset. Accurate depth electrode insertion would ideally require multimodal image integration, repetitive and non-invasive localization, assessment of positional accuracy and freedom in target and entry point selection. A method for the acquisition of the multimodal image stereotactic information, necessary for the precise targeting of the mesial temporal structures, and the operative technique used for the accurate placement of the intracerebral electrodes is described. The use of the Gill-Thomas (G-T) stereotactic repeat localizer offers the degree of temporal freedom during the data acquisition period of the electrode implantation procedure which leads to the advantage of an unhurried multi-image integration and targeting in any individual case combined with less discomfort for the patient. The integration of the G-T repeat localizing system with the existing components of the Cosman-Roberts-Wells (CRW-3) stereotactic system offers additional advantages. The target-centered arc-radius design allows complete freedom in the selection of the entry point, offers the possibility of multiple trajectories through the same entry point and permits a choice of either oblique or orthogonal lateral approaches, that are particularly useful for the electroencephalographic sampling of the posterior mesial temporal structures. The satisfactory localizing value of the technique and the additional advantage of easy confirmation of the positional accuracy of the electrodes during the postoperative period, using standard radiographic and magnetic resonance imaging studies, increases the potential of the technique for precise placement of depth electrodes during the pre-surgical evaluation of patients with epilepsy.

Amygdala↗

PubMed1993

Volumetric analysis of epilepsy surgery resections using high resolution magnetic imaging: technical report.

A method is described for accurately measuring the volume and site of epilepsy surgery resections utilizing magnetic resonance imaging. Accuracy has been assessed using post-mortem studies, and both the intra- and interobserver variability is consistently less than 5%. The technique has so far been applied to 25 patients following a variety of operations for medically intractable epilepsy. It provides the crucially accurate baseline required for meaningful follow-up outcome studies of epilepsy surgery. Consequently, it should allow the development of more precise prognostic indices for such operations.

Brain↗

PubMed1993

New Perspectives in Edema Control via Electrical Stimulation.

Clinicians commonly use electrical stimulation (ES) to control acute edema. But, except for anecdotal reports, there is little evidence to support that practice. We recently conducted a series of controlled, blinded studies on several nonhuman animal models to determine the efficacy of several forms of ES, but high-voltage pulsed current (HVPC) in particular, in controlling acute posttraumatic edema. We observed that acute posttraumatic edema is curbed by HVPC when certain protocols are used. Results of these studies suggest to us that wave form, polarity, treatment schedule, intensity and frequency of pulses all influence ES, and that clinical protocols need revision.

Journal Article↗

PubMed1992

Is nocturnal paroxysmal dystonia a form of frontal lobe epilepsy?

The sex ratio, age at onset, and ictal features of nine patients with nocturnal paroxysmal dystonia were compared with those of eight patients with daytime frontal lobe seizures and eight patients with nocturnal motor attacks of known epileptic origin. All patients underwent video electroencephalography telemetry. There were no clinical features that would allow distinction between the groups and no single phenomenon was uniquely seen in nocturnal paroxysmal dystonia. This study provides no evidence that nocturnal paroxysmal dystonia is a separate diagnostic entity.

Adolescent↗

PubMed1992

Open stereotactic selective amygdalo-hippocampectomy for drug resistant epilepsy.

Selective removal of the medio-basal temporal structures has been introduced as an alternative to standard temporal lobectomy in the treatment of intractable temporal lobe epilepsy not related to gross structural lesions. Various approaches have been described for the surgical excision of the amygdalo-hippocampal complex, each of them presenting advantages and limitations. The recently introduced computer-assisted technique of volumetric stereotactic excision of deep-seated intracerebral lesions combines precision of targeting with elimination of unnecessary cortical trauma and may potentially provide an alternative method in the treatment of temporal lobe epilepsy. We present our experience of stereotactic volumetric selective amygdalo-hippocampectomy in six patients with medically intractable temporal lobe epilepsy. The criteria for selection, the pre-operative evaluation and the operative technique are discussed. All patients had a cessation or considerable reduction in seizure frequency while the morbidity was minimal.

Adolescent↗

PubMed1992

Very high-frequency rhythmic activity during SEEG suppression in frontal lobe epilepsy.

Intracerebral EEG (SEEG) recordings showing the development of fast rhythmic activity at seizure onset provide important evidence for the localisation of an epileptic focus. However, very high-frequency activity (greater than 50 Hz) of low amplitude relative to the background may not be apparent on the paper record due to the limited bandwidth and dynamic range of conventional SEEG recording and display methods. The use of a digital telemetry system with a fast sampling rate (400 Hz) and a wide dynamic range (1 microV resolution, 4 mV range) has allowed us to utilize expanded time scale SEEG plots and autoregressive spectral estimation to identify this activity in chronic SEEG studies. This may be particularly useful in frontal lobe epilepsy, where rapid propagation often prevents adequate localization using conventional methods of analysis.

Adult↗

PubMed1992

Hippocampal volumetric and morphometric studies in frontal and temporal lobe epilepsy.

The most common temporal lobe pathology is Ammons Horn sclerosis (AHS), and several different imaging techniques have been utilized to detect this with varying success. We describe the clinical application of magnetic resonance imaging (MRI) using a three-dimensional volume technique which allows total hippocampal volume to be measured and symmetry evaluated. Hippocampal surface area was calculated in sequential 1.5 mm thick contiguous images, using a GE IC workstation. Total volumes and surface areas were calculated. The cross-sectional surface area at 1.5 mm intervals was displayed graphically, permitting morphometric analysis of the hippocampus throughout its length. Focal atrophy within any part of the hippocampal formation (HF) and its extent could thus be assessed. Patients with well-lateralized temporal lobe epilepsy (TLE) (n = 20) and well-defined frontal lobe epilepsy (FLE) (n = 20) were studied, and volumes compared with normal values derived from 10 neurologically normal controls. Asymmetric hippocampal volume loss was demonstrated in all 20 patients with clinically typed TLE, but not in normal controls or patients with FLE. Volume loss distribution was anterior in 12 patients, posterior in one patient and widespread in seven patients. Secondarily generalized seizures were strongly associated with widespread loss. This method of surface area and volumetric analysis of the hippocampus in TLE can demonstrate asymmetry and focal involvement, and help distinguish between hippocampal and frontal pathologies.

Adult↗

PubMed1992

Effect of a single 30-minute treatment of high voltage pulsed current on edema formation in frog hind limbs.

The purpose of this study was to investigate the effect of a single treatment of high voltage pulsed current (HVPC) on edema formation. Twenty-four frogs were anesthetized, and both hind limbs of each frog were traumatized by impact. Limb volumes were measured by water displacement immediately before and after trauma and at predetermined intervals for 24.0 hours posttrauma. One limb of each frog was randomly selected to receive 30 minutes of continuous, 120-pulse per second, cathodal HVPC at voltages 10% less than motor threshold levels. Data were analyzed by an analysis of variance for repeated measures. Sources of significant differences were determined by paired t tests (probability values determined by Bonferroni adjustment). A single 30-minute application of HVPC significantly curbed edema formation for between 4.0 and 7.5 hours following treatment (ie, volumes of treated limbs were significantly less than those of untreated limbs). These results suggest that regimens currently applied to humans (ie, one treatment per day or three times per week) may be insufficiently aggressive to provide sustained treatment effects.

Animals↗

PubMed1992

Effect of electrically induced muscle contractions on posttraumatic edema formation in frog hind limbs.

We tested the hypothesis that repeated muscle contractions induced by high voltage pulsed current (HVPC) would limit volume increases in traumatized frog hind limbs. Twelve frogs were anesthetized, and both hind limbs of each frog were traumatized by impact. Limb volumes were measured via water displacement over a 24-hour period. Four 30-minute treatments of continuous 1-pulse per second HVPC were applied to one limb selected randomly. Stimulation produced muscle contractions that resulted in minimal joint movements. Volume changes from pretrauma limb volumes (in milliliters per kilogram) were analyzed by an analysis of variance for repeated measures. Our hypothesis was rejected (ie, repeated muscle contractions, as induced in this study, did not limit posttraumatic edema formation in frogs). Further investigation of the relative influences of limb position and varying pulse rates, pulse durations, and intensities of HVPC on edema formation may provide valuable insights on effective treatment of edema in humans.

Animals↗

PubMed1992

Effects of low voltage pulsed current on edema formation in frog hind limbs following impact injury.

The purpose of this study was to test the effect of low voltage pulsed current (LVPC) on posttraumatic edema formation in frog hind limbs. Feet of 26 anesthetized bullfrogs were systematically injured by weight drop. One hind limb of each animal was randomly selected to receive continuous 100-pps LVPC at 90% of motor threshold; the opposite hind limb served as a control. A series of four 30-minute treatments (interrupted by 30-minute rests) was begun minutes after injury. Changes from pretrauma limb volumes were determined before and after each treatment and at 8, 17, 20, and 24 hours posttrauma. Analysis of variance revealed no significant treatment effect. Similar studies utilizing high voltage pulsed current (HVPC) at 90% of motor threshold revealed significant curbing of edema formation in frogs. Waveform (LVPC versus HVPC) seems to influence the efficacy of electrotherapy for edema control.

Analysis of Variance↗

PubMed1992

Influence of high voltage pulsed current on edema formation following impact injury in rats.

High voltage pulsed current (HVPC) has been shown to be effective in curbing posttraumatic edema formation in frogs. The purpose of this study was to establish the utility of HVPC in controlling edema formation in a mammalian model. Both feet of 20 anesthetized rats were traumatized following initial determination of hind-limb volumes. Four 30-minute cathodal HVPC treatments at 120 pulses per second and 90% of visible motor threshold interspersed with 30-minute rest periods were applied to one randomly selected hind limb of each rat via the immersion technique. The other hind limb served as a control. Limb volumes were measured after each treatment and rest period. All data were expressed as changes from pretrauma limb volumes in milliliters per kilogram of body weight; these data were analyzed by repeated-measures analyses of variance and post hoc paired t tests. Volumes of untreated limbs were significantly greater than volumes of treated limbs after the second treatment. Evidence of significant treatment effects in frogs, and now rats, provides a compelling rationale for initiating trials of efficacy of cathodal HVPC in inhibiting acute edema formation in humans.

Animals↗

PubMed1991

The effect of sleep on the dyskinetic movements of Parkinson's disease, Gilles de la Tourette syndrome, Huntington's disease, and torsion dystonia.

The effect of sleep on the involuntary movements or dyskinesias in Parkinson's disease, Huntington's disease, primary and secondary torsion dystonia, and Gilles de la Tourette syndrome was studied in a total of 52 patients and 10 normal subjects using video electroencephalographic telemetry. Movements typical of the wake pattern were seen occasionally during unequivocal sleep in all but two completed studies, and in each condition reappeared under similar circumstances. The movements were most likely to occur after awakenings or lightenings of sleep, or in stage one sleep. The movements were very rare during the deeper phases of sleep. Those movements that occurred during sleep without awakenings were usually preceded by arousal phenomena and, rarely, by sleep spindles or slow waves. The control group showed normal "semipurposeful" movements under the same conditions during sleep. The rare appearance of the different dyskinesias and normal movements under similar circumstances during sleep could be a result of common effects on the generator systems or changes in the excitability of the final common motor pathway.

Brain↗

PubMed1991

Effect of anodal high voltage pulsed current on edema formation in frog hind limbs.

We have recently demonstrated that some forms of cathodal high voltage pulsed current (HVPC) curb posttraumatic edema formation in frog hind limbs. The purpose of this study was to determine, by assessing the capacity of anodal HVPC to curb posttraumatic edema formation, whether polarity is an important variable. Fourteen anesthetized bullfrogs were placed on large dispersive electrodes lining body slings that maintained the frogs' limbs in a dependent position throughout data collection. The frogs' feet were traumatized by impact following initial measurement of limb volumes. At the commencement of each of four 30-minute treatments, hind limbs were immersed in separate beakers and briefly stimulated until motor threshold was determined. One limb, randomly selected, received anodal HVPC at 90% of motor threshold and 120 pulses per second; the other limb served as a control. Treatments were followed by 30-minute rests. Limb volumes were measured by water displacement immediately after trauma and following each treatment and rest period. Data were expressed as changes from pretrauma volumes in milliliters per kilogram of body weight. A repeated-measures analysis of variance was used to test for treatment effect. Despite an aggressive series of treatments, virtually symmetrical bilateral edema occurred; therefore, no treatment effect was evident. This result contrasts with treatment effects previously reported for cathodal HVPC.

Analysis of Variance↗