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Biomedical subjects

C D Binnie

Publications and source records attributed to C D Binnie.

At least 73 records · Page 4Linked to original sources
PubMed1998

Predictive value of interictal epileptiform discharges during non-REM sleep on scalp EEG recordings for the lateralization of epileptogenesis.

PURPOSE: EEG recording during sleep is widely used in the assessment of epilepsy, particularly in candidates for surgery, yet the diagnostic value of this procedure is not well established. We evaluated the predictive reliability of interictal epileptiform discharges (IEDs) for localization in presurgical patients with temporal lobe epilepsy (TLE) during non-REM sleep. METHODS: Preoperative scalp EEG recordings with waking and sleep states were assessed in 83 patients with TLE in whom localization of the epileptogenic zone was subsequently confirmed by successful surgical treatment (patient seizure-free >1 year). RESULTS: The accuracy of EEG recordings for prediction of lateralization significantly changed from 51.8% during waking to 78.3% during sleep. After exclusion of patients who showed no discharges, the predictive value changed from 74.1 to 86.7%. However, in patients in whom the waking scalp EEG lateralized incorrectly, no improvement in reliability was achieved by sleep recording. CONCLUSIONS: Our results suggest that IEDs occurring in non-REM sleep provide more accurate information for lateralization of epileptogenesis than do those occurring during waking. This gain of diagnostic information was obtained in patients who showed either bilateral or no discharges in waking records, because unilateral discharges arising de novo in sleep were always correctly lateralizing. On the other hand, in patients who showed unilateral discharges in the awake state, whether ipsilateral or contralateral to the epileptogenic zone, the findings were generally unchanged during sleep.

Adult↗
PubMed1998

Interictal regional slow activity in temporal lobe epilepsy correlates with lateral temporal hypometabolism as imaged with 18FDG PET: neurophysiological and metabolic implications.

OBJECTIVES: The phenomenon of interictal regional slow activity (IRSA) in temporal lobe epilepsy and its relation with cerebral glucose metabolism, clinical data, MRI, and histopathological findings was studied. METHODS: Interictal 18F-fluorodeoxyglucose positron emission tomography (FDG PET) was performed under continuous scalp EEG monitoring in 28 patients with temporal lobe epilepsy not associated with intracranial foreign tissue lesions, all of whom subsequently underwent resective surgery. Regions of interest (ROIs) were drawn according to a standard template. IRSA was considered lateralised when showing a 4:1 or greater ratio of predominance on one side. RESULTS: Sixteen patients (57%) had lateralised IRSA which was always ipsilateral to the resection and of maximal amplitude over the temporal areas. Its presence was significantly related to the presence of hypometabolism in the lateral temporal neocortex (p=0.0009). Logistic regression of the asymmetry indices for all measured cerebral regions confirmed a strong association between IRSA and decreased metabolism of the posterior lateral temporal neocortex only (p=0.009). No significant relation could be shown between slow activity and age at onset, duration of the epilepsy, seizure frequency, and MRI evidence for hippocampal atrophy. Furthermore, IRSA was not specifically related to mesial temporal sclerosis or any other pathology. CONCLUSIONS: Interictal regional slowing in patients with temporal lobe epilepsy not associated with a mass lesion is topographically related to the epileptogenic area and therefore has a reliable lateralising, and possibly localising, value. Its presence is irrelevant to the severity or chronicity of the epilepsy as well as to lateral deactivation secondary to neuronal loss in the mesial temporal structures. Although slow EEG activity is generally considered as a non-specific sign of functional disturbance, interictal regional slowing in temporal lobe epilepsy should be conceptualised as a distinct electrographic phenomenon which is directly related to the epileptogenic abnormality. The strong correlation between interictal regional slowing and lateral temporal hypometabolism suggests in turn that the second may delineate a field of reduced neuronal inhibition which can receive interictal and ictal propagation.

Adolescent↗
PubMed1998

Epilepsy--a guide to medical treatment. 1: Antiepileptic drugs.

The epilepsies are the commonest of serious disorders of brain function. Medical, psychological, social and financial implications can adversely affect quality of life in both patient and family. Accurate categorization of seizure type and epilepsy syndrome, with appropriate choice of drug and other management, can minimize the burden of a seizure disorder.

Adult↗
PubMed1998

Epilepsy--a guide to medical treatment. 2: Non-drug aspects.

Approximately 30-40% of people with epilepsy continue to have seizures despite drug treatment. Factors related to cognitive abilities, physical handicap, psychiatric illness and social circumstances are of great importance in the overall management.

Adolescent↗
PubMed1997

Origin and propagation of interictal discharges in the acute electrocorticogram. Implications for pathophysiology and surgical treatment of temporal lobe epilepsy.

Although acute electrocorticography (ECoG) is routinely performed during epilepsy surgery there is little evidence that the extent of the discharging regions is a useful guide to tailoring the resection or that the findings are predictive of outcome or pathology. Patterns of discharge propagation have, however, rarely been considered in assessing the ECoG. We hypothesize that regions where discharges show earliest peaks ('leading regions') are located in the epileptogenic zone, whereas sites in which late, secondary, propagated activity occurs have less epileptogenic potential and do not need to be excised. To allow intraoperative topographic ECoG analysis, a computer program has been developed to identify leading regions and the sites showing greatest rates or amplitudes of spikes. Their topography has been compared retrospectively with pathology and seizure control in 42 consecutive patients following temporal lobe surgery. Leading regions were most often found in the hippocampus, the subtemporal cortex and the superior temporal gyrus. The most common propagation patterns were from hippocampus to subtemporal cortex and vice versa. There was no association between seizure outcome and the location of regions with greatest incidence or amplitude of spikes or location of leading regions. There was, however, a strong and significant association between poor outcome and non-removal of leading regions other than those in the posterior subtemporal cortex. All leading regions (other than posterior subtemporal) were resected in 27 patients of whom 25 had a favourable outcome. Leading regions (other than posterior subtemporal) remained in 14 patients of whom only four had a good outcome. One patient had no epileptiform activity in the ECoG and good outcome. Persistent posterior subtemporal leading regions remained in nine subjects; all had favourable outcome (Grades I or II) but only three were seizure free. These results suggest that: (i) interictal epileptiform discharges may originate from a complex interaction between separate regions, resulting in propagation and recruitment of neuronal activity along specific neural pathways; (ii) removal of all discharging areas appears unnecessary to achieve seizure control provided that leading regions (other than posterior subtemporal) are removed; and (iii) identification of such leading regions could be used to tailor resections in order to improve seizure control and reduce neurological, neuropsychological and psychiatric post-surgical morbidity.

Adolescent↗
PubMed1996

[Cognitive effects of subclinical EEG discharges].

Many patients with epilepsy display cognitive deficits and consequent psychosocial dysfunction. Of the various biological factors contributing to these problems, the most distinctive is the momentary disruption of psychological function by subclinical EEG discharges. This is demonstrable in 50% of subjects with subclinical epileptiform activity performing a suitable task under EEG control. Transitory cognitive impairment (TCI) can often be detected during even brief focal discharges, including single spikes. The effects are material specific: right-sided discharges are more likely to affect verbal functions, whereas the left-sided produce more deficits demonstrable by non-verbal tasks. Monitoring of children during neuropsychological or educational testing shows that subclinical discharges can selectively impair performance of specific subtests, giving abnormal test profiles, and lead to errors in reading. The impact of such transitory cognitive impairment on psychosocial function in daily life is uncertain. If TCI produced significant disability, anti-epileptic drugs could improve cognition by suppressing EEG discharges, provided that any benefits were not outweighed by sedation. The author has reported a randomised, double-blind, controlled trial which showed significant improvement on the Conner's rating scales when sodium valproate was added to the drug regimen. Further studies are required to determine the role of TCI in the psychosocial dysfunction in epilepsy and the indications for pharmacological treatment.

Cognition Disorders↗
PubMed1996

Clinical pharmacokinetics of newer antiepileptic drugs. Lamotrigine, vigabatrin, gabapentin and oxcarbazepine.

The clinical pharmacokinetics of the 4 antiepileptic drugs lamotrigine, vigabatrin, gabapentin and oxcarbazepine have been reviewed in this paper. All the drugs have linear kinetics and reliable absorption, although the saturation of transport across the gut may occur at high doses with gabapentin. All the drugs can be conveniently given as a twice daily dosage apart from gabapentin, which has a short half-life and a midday dose is needed. Unlike many of the older drugs, lamotrigine, vigabatrin and gabapentin have a predominantly renal excretion and are not metabolised through the cytochrome P450 system. They do not induce their own metabolism or that of other commonly used anticonvulsants. Similarly, clinically important interactions with other major classes of drugs metabolised this way, such as anticoagulants or steroid hormones, do not occur. Oxcarbazepine, however, can cause oral contraceptive pill failure. Oxcarbazepine is immediately metabolised to a hydroxy metabolite and could be considered a prodrug. It appears to have fewer pharmacokinetic interactions than carbamazepine. Valproic acid (sodium valproate) inhibits the glucuronidation of lamotrigine and increases its half-life; when used together, dosage modification of lamotrigine is needed to avoid toxicity.

Acetates↗
PubMed1995

Power spectrum and intracranial EEG patterns at seizure onset in partial epilepsy.

Intracranial electroencephalographic patterns of seizure onset during preoperative assessment with intracerebral and subdural electrodes have been correlated with surgical outcome in 15 patients with partial epilepsy assessed for surgery. The presence and topography of electrodecremental events, high frequency activity, irregular sharp waves intermixed with slow activity, spike-wave activity and rhythmic ictal transformation at seizure onset were studied in a total of 78 complex partial seizures. Raw traces from intracerebral and subdural recordings were assessed visually in conjunction with changes in the following spectral variables (calculated for consecutive 1.28 sec epochs): amplitude (sum of amplitude of all components within a frequency band), activity, mobility, and complexity. The time course of these variables during preictal and ictal periods was displayed and assessed. This technique proved effective for detecting low-amplitude high-frequency activity and subtle electrodecremental events. It was concluded that: (a) most patients (12/15) showed early electrodecremental events, generalised or local, mainly involving frequencies below 40 Hz; (b) generalised electrodecremental events at onset did not imply poor outcome; (c) localised high-frequency activity, between 20 and 80 Hz, was associated with a good outcome.

Adolescent↗
PubMed1995

Design of clinical antiepileptic drug trials.

It may fairly be claimed that up to the last decade no antiepileptic drug (AED) had undergone rigorous testing. The development programmes of the new AEDs registered in recent years have necessarily been innovative, and methods of AED testing are still undergoing rapid evolutionary change. Clinical evaluation of AEDs is both difficult and complex, due mainly to two factors: (1) intermittence of clinical events, which means that dosing for periods of several weeks is generally necessary, leading to problems of poor compliance and inaccurate reporting of events by carers and patients; and (2) therapeutic necessity, which means that it is, in general, unacceptable to withhold effective treatment from a person with epilepsy. Consequently monotherapy, either with a trial drug or with placebo, can rarely be justified. In consequence most phase II trials use add-on therapy which in turn causes various problems. Conventional phase II AED trials are usually placebo-controlled add-on studies employing either a parallel or crossover design. The latter is subject to a number of practical and theoretical objections, notably on grounds of carry-over and order effects. Increasing attention has recently been directed to ethically acceptable monotherapy designs. One approach first exploited in the development of felbamate is the performance of monotherapy trials in patients whose AEDs have been withdrawn as part of a preoperative assessment protocol. Other possibilities for achieving monotherapy are also discussed.

Anticonvulsants↗
PubMed1995

Multiple subpial transection: a review of 21 cases.

Multiple subpial transection (MST) is a novel technique in surgery for epilepsy, employed in patients where some or all of the epileptogenic zone cannot be resected because it lies in a vital cortical area. Twenty one patients subjected to MST were reviewed. Eighteen patients had medically intractable epilepsy and three patients had Landau-Kleffner syndrome. Their ages ranged from 6 to 47 (mean 15-9) and duration of epilepsy ranged from 0.33 to 42 (mean 8.6) years. Preoperative MRI showed focal abnormalities in eight cases. Detailed electrophysiological examination was carried out on all patients. Brain resection was performed in addition to MST in 12 patients. A further six patients underwent brain biopsy. Three patients with Landau-Kleffner syndrome were subjected neither to resection nor to biopsy. Histopathological examination showed Rasmussen's syndrome in six patients, cortical dysplasia in six, cerebral tumour in one, and non-specific changes in five. Multiple subpial transection was carried out mainly in precentral and postcentral regions. Eighteen patients have been followed up for one to five years, and three for 10 months. The three patients with Landau-Kleffner syndrome were mute before operation and have shown substantial recovery of speech. Of the other 18, 11 showed a worthwhile decrease in seizure frequency. None of the patients developed chronic neurological deficits attributable to MST. It is concluded that MST leads to worthwhile seizure control without major neurological deficit in patients who would otherwise be inoperable.

Adolescent↗
PubMed1994

Fractal analysis of electroencephalographic signals intracerebrally recorded during 35 epileptic seizures: evaluation of a new method for synoptic visualisation of ictal events.

Traditional electroencephalography (EEG) produces a large volume display of brain electrical activity, which creates problems particularly in assessment of long periods of intracranial, stereoelectroencephalographic (SEEG) recording. A method for fractal analysis that describes 100 SEEG data points in terms of a single estimate of fractal dimension (1 < FD < 2) is reported; the central processing unit time costs amount to approximately 2 min/Mbyte of input signal (using a Sun SPARCstation LX). The diagnostic sensitivity of this method, applied to quantification and synoptic visualisation of SEEG signals recorded during 35 epileptic seizures in 7 patients, is evaluated. It is found that the method consistently defines ictal onset in terms of rapid relative increase in FD across several channels. Clinically severe seizures are characterised by more intense and generalised ictal changes in FD than clinically less severe events. For all 7 patients, and for 75% of individual seizures, "fractal diagnoses" of anatomically defined ictal onset zone coincided closely with ictal onset zone independently determined by inspection of traditional EEG displays of the same data. We conclude that the method is a computationally feasible way to achieve substantial reduction in the volume of SEEG data without undue loss of diagnostically important information in the primary signal.

Brain↗
PubMed1994

Electrocorticography and stimulation.

Although acute electrocorticography (ECoG) is routinely used during epilepsy surgery there is little agreement as to its value nor criteria for its interpretation. Specific issues are reviewed on the basis of the literature and personal studies: does failure to resect the entire irritative zone prejudice seizure control, and are residual discharges predictive of failure; does activation of the ECoG by intravenous barbiturates provide information of clinical value; does intraoperative electrical stimulation help to improve localisation or avoid postoperative deficits; is the ECoG of value for monitoring functional procedures; can the value of ECoG be increased by new interpretive approaches? It is suggested that resection of the entire area of interictal discharge is not essential for satisfactory surgical outcome, but a distinction may need to be made between those discharging regions that function as pacemakers and those in which ECoG spikes appear secondarily. There is also evidence that, apart from any consideration of determining the area resected, the topography of epileptiform discharge may be predictive of pathology and surgical outcome. It is concluded that more detailed topographic and quantitative analysis of the ECoG is required before its value in planning surgery can be determined or objective interpretive criteria established.

Cerebral Cortex↗
PubMed1994

Utility of stereoelectroencephalography in preoperative assessment of temporal lobe epilepsy.

Of 269 consecutive patients entered into a preoperative assessment programme for possible surgical treatment of epilepsy, 33 had intracranial recording (SEEG) with combined subdural and depth electrodes for the purpose of localising a suspected temporal site of seizure onset. The findings in these patients are analysed with particular reference to: 1) the criteria of selection for SEEG and their validity; 2) information on SEEG compared with that obtained by less invasive means, including foramen ovale telemetry; 3) information on the use of intracerebral electrodes compared with subdural placements; 4) possible predictors of failure of localisation by SEEG and of surgical outcome. It was concluded that SEEG had usefully contributed to the management of 69% of the patients in whom it was used, establishing a previously unidentified site of seizure onset in 33%, correcting an erroneous localisation in 15%, and establishing inoperability in 21% of patients. No predictors of failure of SEEG or of surgery emerged; thus there was no evidence of unnecessary use of this procedure. Five patients were found with incorrect lateralisation of seizure onset on foramen ovale recording (of a total of 192 foramen ovale telemetries). Localisation of the ictal onset zone either by the distribution of inter-ictal discharges or by the initial ictal changes at subdural electrodes was unreliable, confirming the need for ictal, depth recordings.

Adult↗