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Biomedical subjects

C D Binnie

Publications and source records attributed to C D Binnie.

At least 109 records · Page 6Linked to original sources
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↗
PubMed1987

The influence of subclinical epileptiform EEG discharges on driving behaviour.

EEG and driving behaviour were monitored in 6 patients with subclinical focal and generalised epileptiform EEG discharges during 420 km of actual motorway driving in a suitably instrumented vehicle. Evidence of impaired driving performance during subclinical discharges was significant in 3 subjects (P less than 0.025 or less than 0.05) and was suggestive (P less than 0.1) in 1. The two patients with greatest impairment had active epilepsy, whereas the others had been seizure-free for upwards of 4 years. No other features appeared to be predictive of altered driving behaviour during discharges.

Adult↗
PubMed1987

Clinical and EEG prediction of seizure recurrence following antiepileptic drug withdrawal.

A prospective study is reported of antiepileptic drug withdrawal in 62 neurologically intact adult patients who had become seizure-free at least 3 years previously. No single clinical or laboratory finding was reliably predictive of outcome and in particular the presence of epileptiform EEG activity prior to AED withdrawal or appearance of such activity during withdrawal was not associated with relapse. A multivariate model was however developed which suggested that patients capable of remaining seizure-free without medication could be reliably identified at a much reduced cost of relapses in the remainder.

Adolescent↗
PubMed1987

Interactions of epileptiform EEG discharges and cognition.

Interactions of subclinical epileptiform EEG discharges and cognitive functioning were studied in 91 patients with epilepsy, under video monitoring, to exclude overt clinical ictal phenomena during the investigations. A short-term memory test was presented as an engaging television game, in two versions, using spatial, or verbal material. Transitory cognitive impairment (TCI) was demonstrated during EEG discharges, either generalised or focal, in half the patients. Right-sided discharges were associated with impairment of the spatial task and left-sided with errors on the verbal version. TCI was demonstrable only when the discharge occurred during presentation of the material to be recalled. Increasing task difficulty, up to the patients' limit of performance, was associated with increasing susceptibility to TCI. Sixteen patients showed a significant effect of task on discharge rate, but in some this increased during the stimulus and in others while responding. There are thus complex interactions of epileptiform EEG activity on cognitive function and vice versa.

Adolescent↗
PubMed1987

Seven day administration of lamotrigine in epilepsy: placebo-controlled add-on trial.

A double-blind placebo-controlled trial of 7 days administration of lamotrigine as add-on therapy was performed in 10 patients with frequent therapy-resistant, chiefly partial, seizures. Dosage was adjusted on the basis of estimated half-life. Six patients showed a 50% seizure reduction on lamotrigine and two an increase. Side effects (ataxia, dizziness and apathy) occurred in 3 patients, but only at blood levels above 3 micrograms/ml, and were rapidly relieved when the dose was reduced in two. EEG spike counts were significantly reduced on lamotrigine. There was no evidence of interactions with co-medication.

Adolescent↗
PubMed1987

Electroencephalographic findings in antiepileptic drug trials: a review and report of 6 studies.

A recent survey has shown that the EEG is of doubtful value as an outcome variable in clinical antiepileptic drug (AED) trials. Analysis of findings in 6 trials shows that in only two no consistent effect was seen; that in two power spectral analysis provided additional information to confirm changes in background activity; that in one a close relationship could be established between reduction in frequency of epileptiform discharges and administration of the trial drug (lamotrigine), and that in one, even though no correlation was apparent during use of the AED, there was an increase in frequency of both discharges and seizures on withdrawal (CGP 11952). In general the EEG would appear to be unsuitable as an outcome variable for assessing drug efficacy in AED trials. On the other hand it may give insight into the mode of drug action. Conceivably more efficient use could be made of the EEG if the methodology--including patient selection, consideration of circadian rhythms and of combination AED therapy, and standardized long-term recording--were to be improved and automation and quantification techniques used.

Adolescent↗
PubMed1987

Photosensitive patients: symptoms and signs during intermittent photic stimulation and their relation to seizures in daily life.

Thirty six patients were studied with a classical photoparoxysmal EEG response to intermittent photic stimulation (IPS). Clinical observations and complaints reported by patients during standardised IPS were recorded and compared with historical data. Twenty seven patients experienced impaired consciousness or showed motor phenomena such as involuntary opening of the eyes or jerking on one or both sides of the body. Twenty five patients had sensations such as pain in the eyes, jerking etc. There existed no relation between the duration of the evoked discharges (0.5-3 seconds) and observed signs or complaints. In 11 instances the clinical features found during IPS were not reported in a history taken from the patient and relatives.

Adolescent↗
PubMed1986

Photosensitivity as a model for acute antiepileptic drug studies.

A technique is described for assessing the efficacy and time course of effects of antiepileptic drugs, after a single acute dose, by means of their action on the human photo-convulsive response. The range of frequencies of intermittent photic stimulation to which the patient is sensitive (photosensitivity range) is determined in a standardized manner at hourly intervals over the course of a waking day. 82 controlled studies have established that, with the rare exceptions of patients showing a consistent circadian rhythm of photosensitivity, the photosensitivity range is stable over this time scale. A total of 72 studies have shown that representatives of all the major groups of established antiepileptic drugs, together with some experimental drugs, suppress photosensitivity following a single acute administration. By contrast barbiturates without antiepileptic action (methohexitone and quinalbarbitone) do not affect photosensitivity even in doses producing marked drowsiness. These findings suggest the technique to be a potentially useful tool for preliminary investigation of efficacy and duration of action of new potential antiepileptic drugs.

Adolescent↗
PubMed1986

Add-on therapy in epilepsy with calcium entry blockers.

In view of the known role of Ca2+ in the paroxysmal depolarization shifts of epileptic neurones, the possibility arises that certain Ca2+ entry blockers possess antiepileptic activity. The only drug of the class which readily passes the blood-brain barrier is flunarizine. This is effective in experimental models of epilepsy and produced significant seizure reduction in two therapeutic trials in therapy-resistant patients. It has few and mild side effects at therapeutic blood levels.

Adolescent↗