Can epileptologists without access to intracranial EEG use reliably the International League Against Epilepsy classification of the localization-related epileptic syndromes? A stereo-electroencephalographic study.

The goal of the present study was to investigate the reliability of clinical and electroencephalographic (EEG) criteria for the classification of localization-related epileptic syndromes as listed in the Proposals of Revised Classification of Epilepsies and Epileptic Syndromes 1989 (ICE). ICE distinguishes between multiple syndromes within epilepsies of a given lobe. Intracranial recordings were the main element in the development of the revised ICE. Considering that most epilepsy centers have no access to such invasive techniques for precise anatomic localization, it was of interest to assess how accurately the seizure origin could be determined from the scalp EEG and clinical data as reported in ICE. In this retrospective study, we compared the accuracy of the topographic diagnosis made by two groups of physicians evaluating the same patients-one group with and the other without access to results of stereo-EEG (SEEG). Medical files of 87 patients with intractable localization-related epilepsy were analyzed: 38 with frontal, 37 with temporal, 10 with parietal, and 2 with occipital lobe epilepsy were included in the study. All patients underwent previous SEEG and successful cortectomy. Minimum follow-up was 5 years. In most cases, noninvasive techniques and criteria suggested by ICE allowed topographic diagnosis of focal epilepsies according to brain lobe involvement. More detailed diagnosis, localizing the origin of critical activity within a lobe, was often unreliable. Further data are required for a definition of the epileptogenic zone. A spatiotemporal evaluation of critical events, including the intracranial EEG recording, remains the best method for topographic diagnosis of localization-related epilepsy.

Spatiotemporal analysis of interictal epileptic spikes. A stereoelectroencephalographic study.

Interictal epileptic spikes (IES) were recorded and averaged in 4-15 channels, in seven adult epileptics with intracerebral electrodes. IES relations were revealed by comparing the onset of the averaged IES in each channel, with one being used alternatively as the triggering channel. The records were analysed and sorted by comparing the morphology of individual IES and the final average morphology. There was a dominant group of IES on each recording site channel representing about 65-80% and decidedly influencing the average morphology of all IES. The major limitation of IES averaging is the loss of information due to the IES relative heterogeneity. Nevertheless, it reveals the main basic relationships in the large numbers of IES. On the other hand, IES averaging helps to minimize fortuitous spatiotemporal relations between recording sites. The relationship between IES in two channels was considered as significant only when these channels were observed both before and after the mutual switching of the role of triggered and triggering channel. The relations were then considered significant in only about 18% of all possible relations.

The cholinergic system-dependent myoclonus of the baboon Papio papio is a reticular reflex myoclonus.

Neurophysiological studies were performed on four Papio papio baboons presenting with nonepileptic myoclonus (a startle response resembling stimulus-sensitive jerk). Investigations of the EEG, back-averaged EEG, and somatosensory evoked potentials revealed the absence of cortical correlates preceding the jerks, and exclusion of cerebral cortex involvement. No long-latency reflexes could be recorded in these animals. The jerks were symmetric when evoked by unilateral stimulation in normal baboons as well as in a split-brain animal. Polymyographic records showed that the first muscle involved during the jerk was the trapezius; other muscles were involved with latencies increasing in both cranial and caudal directions. From these data, nonepileptic myoclonus of baboons can be classified as a reticular reflex myoclonus. The involvement of cranial nerves did not follow the layout of the nuclei in the brainstem, indicating that the jerk is most likely generated as a complete movement. The generating structure is probably under cholinergic control. Finally, the Papio papio baboon, which was already known as a model for cortical myoclonus elicited by intermittent photic stimulation in predisposed animals, can also be considered a model for the study of the reticular reflex myoclonus.

Inhibition of the startle reaction by physostigmine in patients with early brain damage.

The influence of physostigmine and atropine on the startle reaction and EEG epileptic paroxysmal activity was examined in 24 severely impaired children with early brain damage. The startle motor reaction could be regularly evoked by tapping on the sternum in 12 of the patients. Physostigmine inhibited this reaction significantly, while atropine was without effect. In 12 patients without a previous startle reaction, atropine had a possible activating effect, however, the result was not significant. Physostigmine had no effect. The EEG paroxysmal activity was inhibited by physostigmine and activated by atropine in both groups of patients. A cholinergic system disturbance was suggested in the pathophysiology of the paroxysmal activity. The disturbance which is probably present in early brain damage, is presumed to be also involved in the genesis of the startle reaction.

Influence of cholinergic system on myoclonus in myoclonic epilepsies.

The effect of two drugs upon multifocal myoclonic jerks was evaluated. The drugs influence the central cholinergic system in opposite ways. Eight patients with progressive and nonprogressive myoclonic epilepsy were tested. The single blind test was used. The number of myoclonic jerks after intravenous physostigmine (mean dose 0.02 mg/kg) and that after atropine (0.04 mg/kg) was compared to number of myoclonic jerks in the drug-free periods and with placebo. Placebo was without an effect. Physostigmine slightly increased the number of jerks. Atropine decreased the number significantly. In most patients the results were not striking. It is suggested that the cholinergic system may participate in the physiopathology of the studied myoclonus in a rather indirect, perhaps modulating way.

Cholinergic system disturbance in the West syndrome.

The effects of drug on the cholinergic system (atropine and physostigmine) were evaluated in acute tests in 12 infant patients with the West syndrome (WS) and in 12 older ones who had suffered from WS at typical ages, displaying various types of epileptic symptoms. In both groups paroxysmal EEG activity was inhibited by physostigmine and enhanced by atropine. In two infants who had frequent clinical seizures, the seizures were temporarily blocked by physostigmine. These effects in WS are different from those reported in some other experimental and clinical epilepsies, where physostigmine has a proepileptic and atropine often an antiepileptic effect, thus indicating that a cholinergic system disturbance may occur in patients with WS.

Unexpected potentializing effect of a tacrine derivative (9-amino-7-methoxy-1,2,3,4 tetrahydroacridine) upon the non-epileptic myoclonus in baboons Papio papio.

1. The influence of 7-methoxytacrine (7-MEOTA) on the non epileptic myoclonus of the Papio papio baboon was studied in 5 animals. 2. This type of myoclonus is thought to depend on a cholinergic system dysfunction since it can be induced by atropine and blocked by physostigmine. 3. 7-MEOTA, a tacrine derivative, is believed to display a conspicuous anticholinesterase activity but, surprisingly, it here potentiated the non epileptic myoclonus occuring either spontaneously or induced by atropine. 4. In baboons not spontaneously presenting the non epileptic myoclonus, 7-MEOTA induced the myoclonus in a fashion similar to atropine; such a myoclonus was blocked by physostigmine. 5. These data indicate a possible antagonist action of tacrine on the muscarinic acetylcholine receptor. From these data, it is suggested that caution is necessary when introducing a tacrine derivative in clinical practice.

[Neurogenic muscular lesion presenting a picture of "central core disease"]. / Neurogenni svalová léze s obrazem "central core disease".

A neurogenic lesion has been described in mother and son. In the son there was a prevalence of denervation changes whereas reinervation ones prevailed in the mother. In both, "central cores" were present in aggregations of type-1 fibres. In the authors' opinion the findings represent a neurogenic lesion (also verified clinically and electromyographically), less advanced in the son and more advanced in the mother, ultimately stabilizing to yield a pattern resembling that of the "central core disease".