Paroxysmal EEG Research Articles

Epilepsy and fragile X syndrome: A follow‐up study

This paper describes EEG and clinical findings resulting from a follow-up investigation in a group of 18 males with fragile X syndrome, in whom a characteristic paroxysmal EEG pattern was previously described. The following types of evolution were observed: (1) disappearance of the pattern (with a gradual lowering of the amplitude of spikes and in some cases with asynchrony between the two hemispheres); (2) disappearance of the quasi-rhythmic centrotemporal spikes and persistence of bisynchronous polyspike and wave complexes in the temporo-parieto-frontal regions; and (3) persistence of the previously observed pattern. These results confirm the already observed similarity between this condition and the benign childhood epilepsy with centrotemporal spikes, also from the maturational point of view; on the other hand, they also indicate some difference (i.e., mental retardation, slow background EEG activity, brain atrophy). Moreover, these findings are encouraging for the possible development of research in the field of molecular genetics in epilepsy, because they provide a precise site of investigation on the X chromosome.

Rapid diazepam introduction (venous or rectal) in childhood epilepsy: Taxonomic and therapeutic considerations

Rapid diazepam (DZP) introduction was investigated in 24 children with different types of cryptogenic or symptomatic generalized epilepsy and EEG epileptic "status" with EEG and pharmacologic monitoring. In 12 cases DZP was given intravenously and in another 12 by the rectal route. In general, intravenous administration proved more rapid and more effective as to high blood levels of DZP and the arrest of the paroxysmal activity. However, when the results were correlated to the different forms of paroxysmal EEG activity it was apparent that cases with a typical hypsarrhythmic EEG pattern under the age of 12 months and cases with unorganized paroxysmal activity over the age of 12 months are insensitive or only slightly sensitive to both intravenous and rectal introduction. A number of taxonomic and therapeutic considerations are presented.

Abnormal pulsatile secretion of luteinizing hormone in men with epilepsy

We compared the pulsatile secretion of luteinizing hormone (LH) between 13 men with clinically and electrographically documented temporal lobe seizures and 8 age-matched controls. Serum for LH measurement was drawn every 15 minutes during 8 hours of EEG telemetry in both groups. The 2 groups did not differ significantly in average mean baseline LH secretion, total LH secretion, or average pulse amplitude. The group with seizures, however, showed a significantly greater (p less than 0.05) variability of baseline LH secretion and pulse frequency. Among the men with unilateral paroxysmal EEG findings, pulse frequency was significantly greater (p = 0.05) with right epileptiform discharges or left slowing (6.4 +/- 0.4) than with left epileptiform discharges or right slowing (3.0 +/- 1.3). The relationship of pulse frequency to the nature and laterality of paroxysmal discharges makes it unlikely that endocrine abnormalities can be attributed to medication alone and strengthens the notion that temporal lobe epileptiform discharges may disrupt hypothalamic regulation of pituitary secretion.

The influence of vigilance states on paroxysmal EEG activities and clinical seizures in children

We studied the relationships between clinical variables and those related to the states of vigilance in 18 cases of benign partial epilepsy with centro-temporal spike-waves, 22 cases of definite symptomatic partial epilepsy, and 16 cases of undetermined partial epilepsy. The time of day during which the seizures appeared and the paroxysmal activity densities during non-REM and REM sleep are not distributed differently among the 3 electro-clinical types. However, the benign epilepsy with centro-temporal spikes group had more patients with sleep-sensitive paroxysmal activities. Patients who mainly had nocturnal seizures were found to have more frequent generalized seizures and a greater sleep-sensitive paroxysmal activity. Three cases demonstrated continuous spike-waves during sleep. The patients who had little or no paroxysmal activity during sleep were the youngest. This study illustrates that sleep-sensitive seizures and paroxysmal activities are not specific to benign childhood epilepsy with centro-temporal spikes, and that seizures and paroxysmal activities are two manifestations associated with epilepsy, affected in different ways by states of vigilance.

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.

Relationship between the distribution of paroxysmal EEG activity and sleep structure

Relationship between the distribution of paroxysmal EEG activity and sleep structure

Correlation of electroencephalogram, respiration and movement in the Rett syndrome

Day time video records of 14 girls with the Rett syndrome (RS) (6-17, mean 7 years) were analysed to correlate episodic abnormalities in respiration, movement and electroencephalograms (EEG). Records were compared with those of 12 healthy girls (6-18, median 14 years) who hyperventilated voluntarily. Three RS girls (6-7 years) had minimal respiratory dysrhythmia and showed no correlation between EEG respiration and movement. The other 11 RS girls (6-17 years) had severe awake respiratory dysrhythmia; 10 showing hyperventilation (with hypocapnia) which alternated with active expiratory apnoeic pauses and one with the latter only. All had periods of awake regular breathing with normal respiratory gases. In these girls EEG showed non-epileptic generalised slow activity some of which was paroxysmal. In the six youngest (6-10 years) of these 11 RS girls, non-epileptic paroxysms of EEG slow activity at 1 1/2-4 Hz occurred and were associated with periods of normal breathing and normal pCO2 levels whether girls were alert, drowsy or asleep, but were uncommon during episodes of hyperventilation (and hypocapnia). In four of these girls the EEG paroxysms occupied less than or equal to 1-3% of the time during periods of respiratory dysrhythmia (81 minutes) and 8-100% of the time during alert periods with normal breathing (29 minutes), p less than or equal to 0.001 for this difference. Short bursts of EEG slowing occasionally followed prolonged apnoeic pauses. In two cases brief partial complex seizures occurred. In five of these girls stereotypic movements exacerbated during episodes of respiratory dysrhythmia and reduced during normal breathing.(ABSTRACT TRUNCATED AT 250 WORDS)

Mechanisms of seizure suppression during rapid-eye-movement (REM) sleep in cats

REM sleep is the most antiepileptic state in the sleep-wake cycle for human generalized epilepsy, yet the neural mechanism is unknown. This study verified the antiepileptic properties of REM sleep in feline generalized epilepsy and also isolated the responsible factors. Conclusions are based on 20 cats evaluated for generalized EEG and motor seizure susceptibility before and after dissociation of specific REM sleep components. Bilateral electrolytic lesions of the medial-lateral pontine tegmentum created a syndrome of REM sleep without atonia. Systemic atropine created a syndrome of REM sleep without thalamocortical EEG desynchronization. Identical results were obtained in two seizure models, systemic penicillin epilepsy and electroconvulsive shock. (1) Normal REM sleep retarded the spread of EEG seizure discharges and had even more potent anticonvulsant effects. (2) Selective loss of ‘sleep paralysis’ (skeletal muscle atonia) during REM abolished REM sleep protection against myoclonus and convulsions without affecting generalized EEG paroxysms. (3) Conversely, selective loss of thalamocortical EEG desynchronization abolished REM sleep protection against generalized EEG seizures without affecting clinical motor accompaniment. These results suggest that the descending brainstem pathways which mediate lower motor neuron inhibition also protect against generalized motor seizures during REM sleep. Protection against spread of EEG paroxysms is governed by a separate mechanism, presumably the ascending brainstem pathways mediating intense thalamocortical EEG desynchronization during REM sleep.

Modulation of Generalized Spike‐and‐Wave Discharges During Sleep by Cyclic Alternating Pattern

Because arousal plays a critical role in activation of epileptic phenomena, we analyzed the behavior of interictal generalized spike-and-waves (S-W) during the two recently identified modalities of arousal control during NREM sleep: (a) the cyclic alternating pattern (CAP), expressed by successive biphasic (phase A and phase B) fluctuations of arousal; and (b) non-CAP (NCAP), characterized by prolonged stable periods of EEG and arousal level. Within the single NREM stages, phase A consists of clusters of phasic events associated with transient arousal activation, whereas phase B is represented by the periodic reappearance of the EEG background and reflects a rebound inhibitory condition. The polysomnograms of 10 subjects with a wide age range and affected by primary generalized epilepsy displayed significant differences (all at p less than 0.01) between the spike indexes (S-W/min) of CAP (2.9) and NCAP (1.3), of phase A (7.4) and phase B (0.3), and of NCAP and phase B. For distribution of S-W, a significant prevalence of EEG paroxysms was detected during CAP as compared with NCAP (68 vs. 32%, p less than 0.001), and 93% of all the interictal bursts that occurred in CAP occurred in phase A (p less than 0.001). Our data stress the arousal-dependent influence of CAP and NCAP on modulation of generalized epileptic mechanisms during sleep.

Landau-Kleffner Syndrome and Neurocysticercosis

A seven year old right-handed boy with a one year history of language disorder associated with clinical seizures and paroxysmal EEG is reported from the Division de Neurologia, Instituto Nacional de Neurologia Y Neurocirugia, Mexico, D.F.

Acquired Epileptic Aphasia (the Landau‐Kleffner Syndrome) Due to Neurocysticercosis

A healthy 7-year-old boy developed a language disorder associated with clinical seizures and a paroxysmal EEG. Computed tomography and magnetic resonance imaging revealed a small cysticercus deep in the left Sylvian fissure. We postulate a cause and effect relationship between the parasitic cyst and the clinical manifestations supported by the strategic location of the cyst and the critical age at which this lesion developed. This case provides evidence that the syndrome of acquired epileptic aphasia may be explained in terms of an unilateral structural brain lesion.

Adult Follow-Up of the Acquired Aphasia-Epilepsy Syndrome in Childhood. Report of 7 Cases*

The authors report at adult age 7 patients (6 men, one woman) with the syndrome of "acquired aphasia-epilepsy", 6 of which had been previously studied as children. The results of the language, neuropsychological and socio-educational evaluation detailed many years after the onset of the aphasia are the subject of this report. One man has recovered completely, one has a normal oral language but is severely dyslexic, one has recovered normal comprehension but has severe expressive language problems. Four have absent language comprehension and lack of expressive speech, and only one of them has learned and is using sign language with some efficiency. None has developed functional written language. Attempts to offer a substitutive language to children with prolonged inability to understand and use oral language appears important but is fraught with problems. Although there are no conclusive data about the role of the continuous paroxysmal EEG discharges and the effect of their suppression with drug treatment on the prognosis of the aphasia, the definite fluctuations of the aphasia in some cases, the isolated recent case reports of definitive improvement with drug treatment justify further trials in this potentially severe and chronic condition.

The effects of the everyday environment on epileptic activity in three mentally retarded individuals

Three mentally retarded epileptic subjects with frequent epileptiform EEG paroxysms were monitored with simultaneous radio-telemetered EEG and video recording while they were exposed to their everyday environmental conditions. These conditions included prompts and reinforcement for performing vocational training tasks, speech therapy, eating and drinking, and cues for resting, waiting, playing, excercising, and relaxing. Epileptiform EEG activity and the occurrence of clinical seizures varied as a function of the particular environmental conditions. Epileptiform EEG discharges were longer in duration, and clinical seizures were more frequent in all 3 subjects during conditions which produced inactive behavior than during conditions which produced active behavior. The modulation of epileptiform activity by everyday environmental conditions carries implications for (1) the optimum structuring of the environment for mentally retarded patients with frequent, subtle seizures, and (2) the analysis of the effects of epileptiform discharges on behavior.

Effect of gamma-vinyl GABA on interictal spikes and sharp waves in patients with intractable complex partial seizures.

The effect of gamma-vinyl GABA (GVG) on the interictal electroencephalogram (EEG) was studied in 13 patients with intractable complex partial seizures who participated in a single-blind, add-on, multicenter clinical trial of GVG. Precise operational definitions of epileptiform paroxysms were used to evaluate records before and after 3 months and 1 year of treatment with GVG. After 3 months of treatment, six patients exhibited reduction of both epileptiform paroxysms and seizure frequency, four had no change in seizure frequency nor in the EEG, and three had a reduction in seizure frequency but no concomitant reduction of epileptiform paroxysms in the EEG. Ten patients remained in the study after 1 year of treatment. In 4 patients both seizure frequency and EEG epileptiform paroxysms continued to decrease, in 1 patient both seizure frequency and number of EEG paroxysms increased, and in the remaining 3 there was no correlation between seizure frequency and EEG changes.

DIFFERENTIATION OF TYPICAL ABSENCE SEIZURES IN EPILEPTIC SYNDROMES

This is a comparative video-electroencephalographic (EEG) study of typical absence seizures in 4 epileptic syndromes. In 20 patients, 224 absences were recorded and analysed. Significant clinical and EEG differences were found in the seizure patterns of childhood absence epilepsy (CAE), juvenile absence epilepsy (JAE), juvenile myoclonic epilepsy with absences (JMEA) and myoclonic absence epilepsy (MAE). Clinically, CAE demonstrated more severe impairment of consciousness than JAE while, in JMEA, ictal manifestations were frequently mild and difficult to detect. In the latter, the adolescent patient usually continued his activity, was able to perform even mathematical calculations and often his speech was not disturbed. In children with JMEA, impairment of consciousness was more apparent and sometimes severe. Automatisms occurred in all 4 epileptic syndromes and were proportional to the severity of the demonstrated impairment of consciousness, being rare in JMEA but frequent in CAE and JAE. Expressive speech and overbreathing usually persisted for 1-2 s after the onset of the EEG ictal discharge in CAE. It was less disturbed in JAE where in some absence seizures, interrupted speech and overbreathing were restored during the ictus. A characteristic clinical manifestation of CAE was opening of the eyes in all absence seizures within 1.8 +/- 0.6 s (max. 2.5 s) from the onset of the EEG paroxysms. This early eye-opening behaviour was not observed in JMEA. In MAE, rhythmical myoclonic jerks at 3 Hz make the diagnosis unmistakable. Myoclonic jerks were extremely rare in the absences of JMEA, although all patients had independent myoclonic jerks on awakening. The ictal EEG discharge was longer in JAE (mean 16.3 +/- 7.1 s) than in CAE (12.4 +/- 2.1 s) or JMEA (6.6 +/- 4.2 s). The opening phase of the EEG paroxysms did not show significant differences in CAE, JAE and JMEA but significant changes were found in their initial and terminal ictal phases. In JMEA, the spike-multiple spike-slow wave complexes were not rhythmic and frequently demonstrated variable spike-slow wave relationships. Ictal discharge fragmentations and spike-wave discharges looking like compressed capital Ws were often seen and are characteristic of JMEA. seen and are characteristic of JMEA. Absence seizures demonstrated a more severe impairment of expressive rather than receptive speech, irrespective of differences between syndromes. Evoked as well as spontaneous automatisms occurred in the same patients.(ABSTRACT TRUNCATED AT 400 WORDS)

Anticonvulsant effects of localized chronic infusions of GABA in cortical and reticular structures of baboons

We studied the effects of chronic (7 day) infusions of GABA (100 and 20 μg/μl, 10 μl/h) applied in different cerebral structures of baboons made photosensitive by a subconvulsant dose of allylglycine. The GABA infusion has partial anticonvulsant effects when applied to the motor cortex, reticular magnocellular nucleus (RMC), or substantia nigra (SN), but when directed to the prefrontal cortex (area 8) it has no effect. These anticonvulsant effects of GABA infusion are more important when GABA is infused into the motor cortex, where paroxysmal discharges (PDs) originate, than when it is infused into the RMC. In contrast, the anticonvulsant effects on lightinduced generalized seizures are more pronounced when GABA is infused into the RMC than when it is infused into the motor cortex. GABA infusion into the SN has no effect on PDs and myoclonia and blocks seizures less effectively than the RMC infusion. These results are in accordance with the role of the motor cortex as a generator of PDs and of RMC in the generalization of seizures. Focal paroxysmal EEG and clinical activities, previously reported to appear at the end of the motor cortex GABA infusion, were not observed after RMC or SN infusions. However, behavioral hyperactivity occurring at the end of subcortical GABA infusions was observed. These behavioral signs could correspond to the clinical expression of a GABA withdrawal syndrome.

Acute effects of sodium valproate on epileptic photosensitivity in the lateral geniculate-kindled cat.

Epileptic photosensitivity was acquired as a result of kindling in the lateral geniculate body (GL), and a GL-kindled cat pretreated with DL-allylglycine was found to be a useful model of epilepsy for assessing the efficacy of anticonvulsant drugs. In the present study the acute anticonvulsant effects of sodium valproate (VPA) were examined in the GL-kindled cat under DL-allylglycine. An intravenous injection of VPA at 50 mg/kg induced a protective action against photically induced seizures and paroxysmal EEG activities. This protection persisted for up to 4 hours of the observation period and corresponded to plasma concentrations (61 to 123 micrograms/ml) similar to those considered therapeutic in humans. The present findings are consistent with those obtained in other animal models of photosensitive epilepsy, and lend experimental support to the idea that VPA possesses antiepileptic activity in human photosensitive epilepsy.

Effects of a behavioral intervention on epileptic seizure behavior and paroxysmal activity: a systematic replication of three cases of children with intractable epilepsy.

Three children with very frequent refractory epileptic seizures underwent a behavioral intervention consisting of symptom discrimination, countermeasures, contingent relaxation, and positive reinforcement for correct responses in a systematic replication series. The studies involved a 6-h nonintervention base rate, a 6-h treatment phase, and a 6-h nonintervention follow-up under laboratory conditions for each child. Neurophysiologic and behavioral measures of the effects of treatment were made using electroencephalogram (EEG)-video equipment. Effects of treatment were assessed by using a random sample of EEG-video sequences in base rate and follow-up. Results showed that no significant reduction of either seizure behavior or paroxysmal EEG activity was found subsequent to training in discrimination of early paroxysmal activity and/or sensations preceding seizures. Both seizure behavior and paroxysmal activity were significantly reduced in all three cases following intervention with an adapted countermeasure technique. No additional effects could be noted subsequent to the application of either contingent relaxation or positive reinforcement for correct responses. Paroxysmal EEG changes and seizure behavior were highly correlated. Reduction of the clinical manifestation or seizure response by behavioral manipulation was accompanied by a reduction of the total amount of paroxysmal activity as measured by the EEG.

Toxic ictal confusion

Nonconvulsive generalized status epilepticus is characterized by prominent paroxysmal EEG abnormalities and rarely occurs as an isolated confusional state in adult or elderly patients without an epileptic history. Ictal confusion occurring in 16 middle-aged nonepileptic patients and induced by drug withdrawal and toxic conditions is reported. The electroclinical features and pathophysiological considerations underlying this syndrome are discussed along with a review of the pertinent literature. Immediate relief by i.v. benzodiazepine is emphasized. It is argued that this type of confusion represents an ictal state occurring in a nonepileptic subject; this condition should be regarded as a separate epileptic entity based on a multifactorial etiology. It is also suggested that the syndrome be classified as a situation-related nonconvulsive generalized status epilepticus.

Progressive Supranuclear Palsy

Progressive supranuclear palsy (PSP) was first recognized as a distinct morbid entity by Richardson, Steele and Olszewski a quarter century ago. Subsequent experience has confirmed and extended their original observations. PSP has become familiar as a chronic progressive disorder with extrapyramidal rigidity, bradykinesia, gait impairment, bulbar palsy, dementia and a characteristic supranuclear ophthalmoplegia. It is an important cause of parkinsonism. Its etiology remains obscure. Familial concentrations have not been observed. Some cases exhibit no oculomotor dysfunction. Dementia is usually mild. Recent neuropsychological studies have defined features consistent with frontal lobe cortical dysfunction. Seizures and paroxysmal EEG activity may occur. CT and MRI scans show midbrain atrophy early and later atrophy of the pontine and midbrain tegmentum and the frontal and temporal lobes. PET scans have shown frontal hypometabolism and loss of striatal D-2 dopamine receptors. Postmortem studies have documented involvement of both dopaminergic and cholinergic systems. Treatment remains palliative and unsatisfactory.