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Biomedical subjects

C D Binnie

Publications and source records attributed to C D Binnie.

At least 19 recordsLinked to original sources
PubMed1992

Cognitive correlates of interictal discharges.

Interictal discharges can occur silently without apparent simultaneous clinical manifestations. Nevertheless, formal testing during electroencephalographic (EEG) recording may demonstrate transitory cognitive impairment (TCI). The probability of demonstrating TCI is related to the nature of the test employed and the type of epileptiform discharge. Difficult tasks are more useful to detect TCI, and working memory and language tests may be particularly sensitive. Generalized 3-Hz spike-wave bursts lasting at least 3 s are most likely to produce demonstrable TCI, but they can also be found during briefer and even focal discharges. The latter exhibit some specificity: left-sided focal spiking more frequently produces errors in verbal tasks, whereas right-sided discharges are more often accompanied by impairment in handling nonverbal material. TCI may adversely affect the patient's psychosocial functioning in daily life, as has been shown by some studies pointing out an impairment of educational skill in epileptic children and of driving performance in motorists. Our study on benign childhood epilepsy with Rolandic spikes also detected TCI in the majority of the patients. Nevertheless, it is not possible to claim that everyone with subclinical EEG discharges has TCI that adversely affects their psychosocial functioning. It may be possible to treat TCI by antiepileptic drugs.

Anticonvulsants↗
PubMed1991

Predictive value of intraoperative electrocorticograms in resective epilepsy surgery.

The preresection and postresection intraoperative electrocorticograms of 76 consecutive patients undergoing resective surgery for intractable epilepsy were analyzed to see if location, configuration, and discharge rate of epileptiform activity correlated with type and location of pathology of the resected specimens and outcome in regard to seizure control. The location of the predominant spike focus did not correlate with either type of location of pathology or with seizure outcome from temporal lobe surgery (n = 58). The presence of spontaneous or activated spikes outside the resected area did not correlate with outcome from any surgery type. Positive spikes recorded from the amygdala and anterior hippocampus (n = 37) were not associated with type or location of pathology, but bursts of fast repetitive spikes on these needle recordings tended to associate with mesiotemporal pathology (p = less than 0.02) and with mesial temporal sclerosis (p = less than 0.04). A preresection spike discharge rate of 1 per 4 minutes or less was associated with a poor outcome in 5 of 6 patients (p = 0.03), whereas a rate of 18 or more per minute was associated with a good outcome in 15 of 18 patients (p less than 0.06). Persistence of 50% or more of the preresection epileptiform activity in the postresection electrocorticogram after temporal lobectomy correlated with poor outcome in 80% (p = less than 0.03), although the absolute amount of epileptiform activity remaining in the postresection electrocorticogram did not correlate with outcome. Further studies are needed to define the role of intraoperative electrocorticograms in resective epilepsy surgery.

Action Potentials↗
PubMed1991

Outcome following resective surgery for temporal lobe epilepsy: a prospective follow up study of 102 consecutive cases.

The long term outcome has been assessed in a consecutive series of 102 cases undergoing resective temporal lobe surgery because of medically intractable epilepsy. Patients were followed prospectively for a median of 61 months. Actuarial statistics were used to measure the temporal patterns of remission and stability of outcome over prolonged periods of observation. The probability of achieving one year remission was 57% by one year, 70% by two years, and 77% by seven years. Once a patient was in one year remission the probability of remaining seizure free was 90%. This rose to 94% after two consecutive years of being seizure free. The majority of patients who remit following surgery have done so by two years of follow up. Outcome at the end of the second post operative year is a good predictor of long term prognosis.

Adolescent↗
PubMed1990

Combined use of subdural and intracerebral electrodes in preoperative evaluation of epilepsy.

For intracranial recording of partial seizures considered to originate from one of the temporal or frontal lobes, the team in the Utrecht Academic Hospital has used subdural, multicontact, flexible electrodes since 1972. These are introduced through bilateral, frontocentral trephine holes and are manipulated under fluoroscopy to cover most of the cerebral convexity. It became evident that in many patients, additional placements to record from intracerebral structures were indispensable. Therefore, using the same trephine holes, an additional 2 to 4 depth electrodes were stereotactically implanted in the mesial temporal and/or frontal structures, as appropriate. An extensive intra- and extracerebral spatial representation of the epileptogenic zone was thus obtained. We report here the methods for manufacturing and applying these electrodes and our clinical experience with 28 patients. The results obtained so far stress the value of combining subdural and depth electroencephalographic monitoring in the presurgical selection of patients suffering from medically refractory complex partial seizures. By miniaturizing the electrodes, extensive areas of the brain can be investigated without craniotomy or multiple burr holes.

Adult↗
PubMed1990

Learning disabilities in epilepsy: neurophysiological aspects.

Subclinical generalized spike-wave discharges are often accompanied by transitory cognitive impairment, demonstrable by psychological testing during EEG recording. Transitory cognitive impairment is demonstrated most readily by difficult tasks and during generalized regular spike-wave bursts lasting for more than 3 s, but can also be found during briefer and even focal discharges. That this is not simply a consequence of global inattention is shown by the fact that focal discharges exhibit some specificity: left-sided focal spiking is more likely to produce errors on verbal tasks, for instance, whereas right-sided discharges are more often accompanied by impairment in handling nonverbal material. Both learning difficulties in general and specific abnormal patterns of cognitive functioning are well documented in children with epilepsy and are most pronounced in those with frequent interictal discharges. However, there is now evidence that intermittent cognitive impairment due to the discharges themselves contributes significantly to such neurophysiological abnormalities. The significance of transitory cognitive impairment accompanying subclinical EEG discharges for everyday functioning is uncertain, but there is experimental evidence that subclinical discharges may be accompanied by disruption of educational skills in children or by impairment of driving performance in motorists. In some individuals, suppression of discharges by antiepileptic drugs has demonstrably improved psychological function, but further work is required to determine the indications for such treatment.

Animals↗
PubMed1989

Treatment of narcolepsy with L-tyrosine: double-blind placebo-controlled trial.

A randomised, double-blind, placebo-controlled study of L-tyrosine was done in ten subjects with narcolepsy and cataplexy. Of twenty-eight visual analogue scales rating mood and arousal, the subjects' ratings in the tyrosine treatment (9 g daily) and placebo periods differed significantly for only three (less tired, less drowsy, more alert). Ratings of daytime drowsiness, cataplexy, sleep paralysis, night-time sleep, overall clinical response, and measurements of multiple sleep latency and tests of speed and attention did not differ significantly between tyrosine and placebo periods. Dietary supplementation with tyrosine 9 g daily for 4 weeks seems to have a mild stimulant action on the central nervous system but this effect is not clinically significant in the treatment of the narcoleptic syndrome.

Adult↗
PubMed1989

Distribution of temporal spikes in relation to the sphenoidal electrode.

Sphenoidal EEG recordings were performed in 111 patients with epilepsy, who showed antero-mesial temporal epileptiform discharges. In 6, a multipolar sphenoidal electrode showed a shallow potential gradient between the standard sphenoidal site and the surface. In 17 patients a superficial electrode at the site of entry of the sphenoidal wire recorded all discharges seen at the sphenoidal. Out of 165 foci, in only 2 instances were less than 90% of sphenoidal discharges recognisable on the surface. In 39 patients who underwent surgery, lesions confined to mesial temporal structures were found to be associated with inter-ictal discharges maximal at the sphenoidal electrode. A mid-temporal maximum was always associated with diffuse non-specific, or lateral temporal pathology. It is concluded that sphenoidal recording offers no advantage over suitably placed scalp contacts for detecting inter-ictal epileptiform discharges. It may be of some value for differentiating between mesial and lateral temporal foci.

Electrodes↗
PubMed1989

Acute hippocampal recording and pathology at temporal lobe resection and amygdalo-hippocampectomy for epilepsy.

An electrocorticographic (ECoG) study is reported of patients undergoing surgery for epilepsy of temporal lobe origin. During 22 en bloc resections and six out of a total of 18 amygdalo-hippocampectomies, the activity of the hippocampus was also recorded by a multipolar strip electrode placed along its axis on the ventricular surface. Patients with mesial temporal pathology, chiefly mesial temporal sclerosis, made up the majority of those selected for amygdalo-hippocampectomy. They showed a characteristic ECoG pattern, with spikes localised to the mid part of the second and third convolutions and inferior aspect of the temporal lobe. Typically, this was associated with hippocampal discharges showing an anterior maximum. Pathology involving lateral temporal neocortex and non-specific findings were associated with more widespread temporal spikes and a maximum discharge amplitude over the mid and posterior parts of the hippocampus. It is suggested that intraoperative recording of the ECoG and hippocampal activity may provide a guide to the choice between en bloc resection and amygdalo-hippocampectomy.

Action Potentials↗
PubMed1989

Comparison of the effects of lamotrigine and phenytoin on the EEG power spectrum and cortical and brainstem-evoked responses of normal human volunteers.

Phenytoin and lamotrigine (a new antiepileptic drug with an animal experimental profile resembling phenytoin) have closely similar effects on the quantitative pharmaco-electroencephalogram. These characteristics do not provide a basis for the functional classification of antiepileptic drugs nor for prediction of clinical efficacy, but they do give some insight into the probable secondary psychotropic effects which may arise with use of these drugs. Central conduction in cortical (visual) and brainstem (auditory) event-related potentials are not influenced by either drug, but peripheral nerve conduction is delayed with the use of phenytoin as reflected in increased latency wave I in the brainstem auditory-evoked response. The evidence suggests that in equivalent therapeutic dosage, lamotrigine may be less neurotoxic than phenytoin.

Adult↗
PubMed1988

Preliminary evaluation of potential anti-epileptic drugs by single dose electrophysiological and pharmacological studies in patients.

In phase 1 evaluation of potential anti-epileptic drugs (AEDs), insufficient attention has perhaps been directed to the transition from single, and multi-dose studies in normal volunteers to clinical trials of some weeks duration in patients. Acute single dose studies in epileptic patients already receiving AEDs may reduce avoidable errors in early controlled trials. Acute single dose studies provide the opportunity of obtaining some preliminary evidence of efficacy by observing the effects of the drug on quantified epileptiform EEG discharges, both those occurring spontaneously in long term telemetric recordings and those elicited by standardised photic stimulation in susceptible subjects. The pharmacokinetics of the new drug may be profoundly influenced by the comedication (as illustrated by lamotrigine, the half life of which varies by a factor of 10 depending on comedication). Conversely, the new drug may so influence metabolism of the comedication that the results of add-on trials may be virtually uninterpretable, unless steps are taken to maintain blood levels of the other AEDs. A method of addressing this problem is illustrated in the case of an imidazole, R57720. Adverse experiences may also occur more readily when a new drug is added to comedication than when it is given to normal volunteers and these problems in chronic trials can be anticipated from acute studies.

Anticonvulsants↗
PubMed1988

Self-induction of seizures: the ultimate non-compliance.

The most extreme form of non-cooperation in the treatment of epilepsy is seen in those patients who deliberately induce their own seizures. The overwhelming majority of these patients are photosensitive and make use of visual stimuli to induce either overt seizures or 'sub-clinical' epileptiform EEG discharges. Best documented is the use of flicker produced by waving one hand in front of the eyes, but much more frequent, if less easily recognised, is the use of a manoeuvre involving slow closure and forced upward deviation of the eyes. This is exhibited by a quarter of patients with photosensitive epilepsy, many of whom report that the manoeuvre gives a pleasant sensation or relieves feelings of stress. Other forms of reflex epilepsy are used less often for self-induction and for a variety of motives. Often there is clear social advantage such as avoidance of school or gaining attention. Some patients find that the risk of a spontaneous attack is lessened following a self-induced seizure and can therefore contrive their fits to occur only in situations which are safe and convenient. Self-induced seizures are notoriously resistant to antiepileptic therapy even if the patient is compliant. Preliminary trials suggest, however, that in some patients dopamine antagonists may reduce this behaviour, apparently by making self-induced discharges or seizures non-rewarding.

Adolescent↗