Focal Spikes Research Articles

Generalized Cortical Electrodecremental Event

Patients with seizures accompanied by generalized cortical electrodecremental event (CEE) have clusters of clinical spells with tonic, dystonic, or atonic components and involvement of autonomic functions. When electroencephalographically detectable foci are present, they behave in a peculiar way; throughout the entire cluster of seizures focal spiking is reduced in the short interictal periods as well as during each individual seizure with CEE, at which time it is suppressed. Focal firing reappears reinforced at the end of each spell and also at the end of the cluster. These facts suggest that the foci responsible for CEE are deeply located. A complex excitatory-inhibitory feedback probably exists between cortical and subcortical foci. These seizures should be differentiated from similar attacks of nonepileptic or epileptic nature. A correct diagnosis is essential given the different therapeutic implications.

M.Pneumoniae感染症に続発したと思われる中枢神経合併症の3例

CNS complications of M. pneumoniae infections are not widely known yet. The relation between M. pneumoniae and CNS disease has been based mainly on clinical observations and serological data from serial serum samples. Isolations of this organism from CSF, blood and throat culture have been tried, but direct evidences of an etiologic relationship have been very few.In this paper, we reported three patients complicated with meningitis (case 2) and meningoencephalitis (case 1 & 3) who had respiratory tract infections diagnosed on the basis of clinical symptomes and serological findings of M. pneumoniae infection.Although nourologic symptomes have been improved, in two cases with meningoencephalitis, abnormal findings of EEG were respectively noticed about one and three months after onset. In one case (case 1), focal spike and wave were recognized in the left temporal area with a natural sleep activated EEG. In another case (case 3), 3-4c/s atypical spike and wave complex were recognized dominantly over the left hemisphere with a natural sleep activated EEG. These abnormal EEG findings have persisted for months or longer period. Accordingly, a long term follow-up by EEG should be required for these cases. R. J. Lerer stated that 21% of CNS complications of M. pneumoniae infections had no antecedent respiratory symptomes.This suggests that culture of M. pneumoniae and the serological tests for those cases of aseptic meningitis and meningoencephalitis, the etiology of which is unknown, should be carried out.

The evolution of electroencephalographic features in lissencephaly syndrome

The electroencephalographic features and their evolutional changes with age were described in three cases of lissencephaly syndrome diagnosed by CT scan. The case with more severe lissencephaly displayed very similar EEG findings. In early or middle infancy when infantile spasms began, EEG showed very high amplitude (more than 400 microV) slow waves mixed with sharp theta-waves. In their clinical course, they showed extreme spindles and in late infancy, the EEG revealed a tendency towards bilaterally synchronous discharges of high amplitude sharp and slow waves. On the other hand, milder forms of lissencephaly showed hypsarrhythmia in early infancy. In the late infancy the EEG showed bisynchronous sharp and slow waves of more than 200 microV. The anomaly ranging from agyria to pachygyria seems to be closely associated with varying EEG abnormalities from extremely high voltage hypsarrhythmia to focal spikes. The very high voltage of hypsarrhythmic patterns and the very low frequency of sharp wave discharges seem to be typical in the most severe lissencephaly or agyria

Childhood epilepsy uncontrolled by phenytoin: Clinical and electroencephalographic study

Nine cases of childhood epilepsy manifesting motor convulsions uncontrolled despite high levels of phenytoin (PHT) were studied clinically and electroencephalographically. These cases consisted of five cases of partial seizures without impairment of consciousness, two cases of partial seizures (occasionally generalized seizures beginning locally), one case of predominantly unilateral seizures, and one case of generalized tonic-clonic seizures. the onset of seizures was at a rather early age, between 3 months and 9 years, and under 3 years of age in eight cases. All cases had single or multiple, cortical epileptic foci in EEG. The projection of spikes was localized to a rather limited area. Seizures of these patients were frequent. All cases, except one, did not respond to other medication. Convulsive seizures with cortical focal spike foci in EEG uncontrolled despite high levels of PHT were thought to have poor responsiveness to not only PHT itself, but also to other anticonvulsants.

Clinical and electroencephalographic correlates of the multiple independent spike foci pattern in children.

The multiple independent spike foci (MISF) pattern on electroencephalograms occurred in 4.2% of 1,500 recordings obtained from patients between the ages of 6 months and 15 years. Among the 63 patients with MISF, 53 (84%) had a seizure disorder and 48 (76%) had generalized motor seizures. Half the study group had daily seizures and half had more than one type of attack. Sixty-eight percent of MISF patients were intellectually subnormal. The intellectual status varied according to age at seizure onset, findings on clinical neurological examination, incidence of spikes in the recording, number of spike foci, and presence of excessive delta activity.

Ontogenetic development of acetylcholine and atropine epileptogenic cortical foci in rats

In acute experiments on male albino rats aged from 9 days to adulthood, cortical epileptogenic foci were elicited by the local application of acetylcholine and/or atropine. Focal spike discharges after the administration of acetylcholine were registered for the first time in 12-day old rats; during the third week of life, groups of spikes and ictal activity appeared, so that 20-day-old rats did not differ qualitatively from adult animals. Subsequent application of atropine blocked the actions of acetylcholine in all age groups. The isolated local application of atropine provoked focal discharges already in 9-day-old rats and the shape of the discharges did not change during the whole course of development. The transmission of discharges of acetylcholine- as well as atropine-foci to the other cortical areas was slight in all age groups. The results indicate that different mechanisms are involved in the epileptogenic actions of the two drugs.

Acute Prolonged Confusion in Later Life as an Ictal State

Six patients ranging in age from 42 to 69 with no prior history of seizure disorder presented an acute prolonged or intermittent confusional state, with or without psychotic symptoms, as an ictal manifestation. The EEGs demonstrated protracted generalized spike and wave discharges, but full diagnostic evaluation disclosed no evident cause for the seizures. All promptly responded to small amounts of intravenous diazepam and subsequent oral phenytoin and phenobarbital. Three of the six patients had focal spike or sharp wave discharges on EEGs recorded subsequently, suggesting that the episodes may reflect secondary generalized seizures in some cases. These cases do not fit in the classic category of petit mal status and appear to be a distinct entity.

Fluorometric Monitoring of NADH Levels in Cerebral Cortex

In 14 patients operated upon for focal cerebral seizures under local anesthesia, cortical electrical activity was compared with the levels of nicotinamide adenine dinucleotide (NADH) observed fluorometrically. NADH levels fell 3 to 15% in response to 5-second intervals of cortical stimulation in 42 of 70 observations. Although a rough correlation was seen between the quantity of current delivered (milliamperes X seconds) and the NADH decrease, this varied from case to case. The presence of cortical afterdischarge often, but not invariably, corresponded to a greater percentage of change in the NADH levels. Averaging the NADH response to sporadic interictal epileptiform discharges failed to demonstrate concomitant NADH reductions. A similar lack of change was seen in four patients in whom low frequency spike foci were induced by topically applied penicillin in cortex destined for excision. Preliminary studies of the topography of spread of NADH change after cortical stimulation indicate that this is usually asymmetrical in human epileptogenic cortex. Under experimental conditions in cats, it seemed possible to differentiate primary from projected epileptiform activity, in that the projected activity had little or no concomitant fall in the NADH level after the electrographic spike. Pathological examination of the excised sites of NADH recording showed, with one exception, fibrous astrocytic transformation of the central cortex layers.

THE ACTIONS OF DIAZEPAM AND PHENYTOIN ON A LOW DOSE PENICILLIN EPILEPTIFORM FOCUS IN THE ANAESTHETISED RAT

1 A technique is described for the induction of an acute short-lived epileptiform focus by the local injection of benzyl penicillin 25 units into the cerebral cortex of rats anaesthetized with urethane. The effects of anticonvulsants on this microfocus have been studied. 2 Phenytoin 20 mg/kg and diazepam 1 mg/kg intravenously significantly reduced the frequency of the normally occurring surface positive electrocorticogram (ECoG) plateaux and caused a greater decrease in the frequency of the epileptiform spikes normally associated with these plateaux. 3 A novel effect was seen in that both anticonvulsant drugs significantly reduced the amplitude of the epileptiform spike within the focus, as well as causing an even larger decrease in the amplitude of the propagated spike. The contribution of the anticonvulsant drug effect on the focal spike to its effect on propagated activity is discussed.

The influence of natural sleep on focal spiking in experimental temporal lobe epilepsy in the monkey

In 12 rhesus monkeys, made epileptic by injection of alumina cream into the temporal lobe structures, the changes of spike frequency were studied in wakefulness and natural sleep on 78 occasions. Five monkeys had a focus in the lateral surface of the temporal lobe and seven had a focus in the mediotemporal structures. Basic cortical and subcortical EEG patterns, recorded through chronic indwelling electrodes, showed fairly consistent changes in the course of natural sleep, allowing a classification of the sleep into stages. During slow wave sleep, the focal spikes increased in all 12 cases. The increase was more prominent during the light stage of slow wave sleep in the neocortical foci and during REM sleep, the mediotemporal foci showed a marked decrease of spiking, whereas changes in the neocortical foci were inconsistent.

"Spike focus" during the evolution of febrile convulsion: an electrophysiological and clinical study of 35 patients (author's transl)

Out of 500 patients with febrile convulsions, 41 were found to have a spike focus on E.E.G., 35 of these were then followed up. The clinical features of the seizure in these 35 children did not differ from the group in general. The initial focus was practically always unilateral, except for one case with an asynchronous bioccipital focus. The most frequent site was occipital (43 p. 100). Migration of the focus was relatively rare. In 35 patients the focus disappeared, in 45 p. 100 within a year and in 88 p. 100 within 3 years. Following the disappearance of the focus, generalised sharp wave activity was seen in 30 p. 100 cases, all 35 children being under treatment. All the seizures with the exception of two children who have become epileptic were benign rendering long term anticonvulsant therapy unnecessary.

Parietal focal spikes evoked by tactile somatotopic stimulation

Tactile stimulation of the foot evoked contralateral parietal spikes in the EEG of young, non-epileptic, subjects. After this initial finding, the authors systemically tested about 8000 patients, aged from 2 months to 15 years. The phenomenon was evoked in 80 cases, of which 60 had never presented epileptic seizures. Slow sleep markedly facilitated this phenomenon; on the contrary paradoxical sleep reduced it. In 20 of the 60 nonepiletic subjects a spontaneous focus of spikes appeared after a variable delay; in some of these cases tonic-clonic seizures developped in the following years.

Polygraphic Study on the Clinical Seizures Induced During Nocturnal Sleep

The subjects of this study consisted of 17 epileptic patients with clinical seizures during all-night sleep recording (the seizure group) and another 17 epileptic patients without clinical seizures (the control group). The results obtained were as follows: 1) The 50-90% out of total clinical seizures were induced in non-REM sleep, while a few clinical seizures were induced in REM sleep. The number of clinical seizures in sleep stage of higher activity level increased as the incidence of clinical seizure during all-night grew. 2) In the seizure group REM sleep could not be detectable during all-night in five cases out of 17 cases, while we could not find cases lacking REM sleep in the control group. This difference between two subject groups was statistically significant (P less than 0.025). 3) As to focal spike group, the spike discharge incidence of total sleeping time and of each sleep stage was higher respectively in the seizure group than that in the control group, and particularly in St.1, St.2 and REM sleep the figure of the discharge incidence was found significantly higher in the seizure group than that in the control group (P less than 0.05). We discussed on above-mentioned results, and we emphasized particularly that REM-sleep suppresses clinical seizures, although non-REM sleep induces clinical seizures.

Periodic EEG Patterns Observed in Two Cases With Partial Seizures

Two cases with partial seizure and periodic EEG pattern were reported. Case 1. A 74-year-old woman reveal typical periodic lateralized epileptiform discharges (PLED's) on the right hemisphere. The patient was semicomatous with mild jaundice and epilepsia partialis continua in the left lower limb. Postmortem examination revealed a main metastatic carcinoma of pancreas head origin in the right parietooccipital region. In the right hemisphere, the cortical structures were relatively preserved, but the white matter including the frontal lobe was swollen and its demyelinating changes were observed diffusely. The PLED's might result from an anatomical or functional severance of the cerebral cortex from normal connections with deeper structures. Case 2. A 61-year-old woman, with idiopathic hypoparathyroidism showed partial complex seizure. The EEG revealed an anterior temporal spike focus and slowing in the right hemisphere, corresponding with repetitive seizures of about one minute duration and with several minutes interval. An interictal periodic EEG pattern appeared in the right anterior and mid-temporal region. No cerebral abnormalities were found with other neurological examinations including brain scanning, carotisangiogram, and echoencephalogram. The periodic pattern was assumed as subclinical focal seizure discharges from the right anterior temporal deep structures.

Inhibition of brain stem neuronal activity by electrochemical stimulation of the dorsal hippocampus in the freely moving proestrous rat

The involvement of the hippocampus with gonadotropin release and ovulation was studied in unanesthetized, freely moving rats. Monopolar stainless-steel or platinum electrodes were implanted bilaterally in the dorsal hippocampus; electrodes for recording multiunit activity were placed in the preoptic area and the mesencephalic reticular formation. After recovery from surgery and the completion of two or more consecutive 4-day estrous cycles, the animals were subjected to electrochemical stimulation of the dorsal hippocampus at 1200 h on the day of vaginal proestrus. Stimulation consisted of the passage of 50 μA anodal direct current through stainless-steel electrodes. Continuous multiunit recordings were obtained both before and as much as 5 or more hours after stimulation. Next day the uterine tubes were examined for ova as evidence of ovulation. Electrochemical stimulation of the dorsal hippocampus led to a decline in the activities of both the preoptic area and the mesencephalic reticular formation. Episodic focal spiking activity was observed in these animals, with a latency of 60 to 80 min after stimulation. Control rats, “stimulated” through platinum electrodes, did not show any consistent changes in their hypothalamic or midbrain electrical activity, nor did they reveal any sign of focal spiking activity. Hippocampal stimulation through stainless-steel electrodes led to the inhibition of spontaneous ovulation in 44% of the rats, whereas all animals bearing platinum electrodes ovulated in spite of the direct current. It is clear that the hippocampus is capable of influencing both neuronal and endocrine events, and our results suggest that the decrease in multiunit activity of the preoptic area and the mesencephalic reticular formation may be related to inhibition of the ovulatory surge of pituitary gonadotropins.

Focal positive spikes in electroencephalography

Focal positive spikes and sharp waves in clinical EEG are uncommon (about 1.3 per 1,000 EEGs in this series) and encountered chiefly in early life. All of our seven patients suffered from a convulsive disorder. These discharges must be differentiated from 14 and 6 c/sec positive bursts. Artifactual electrical transients with apparent focal positivity must always be ruled out. Whenever focal positive spikes and sharp waves are identified, it is advisable to search for simultaneous focal negative discharges. The literature indicates that focal positive spikes and sharp waves could be classified according to the presumed pathophysiological mechanisms and illustrative patients were described.

Focal reflex epilepsy with myoclonus; electrophysiological investigation and therapeutic implications

A middle-aged man suffering from myoclonic jerks of the right arm and leg and occasional grand mal seizures was investigated electrophysiologically. The EEG showed a left central spike focus which could be activated by any stimulus which distorted the biceps, triceps or brachioradialis muscles but skin stimulation was ineffective. Electrical nerve stimulation subthreshold to the alpha motoneurone fibres evoked cortical spikes and myoclonic jerks. The evidence supports the hypothesis that the myoclonus was triggered by muscle spindle afferent fibres (Ia) which projected to an epileptogenic focus in the sensori-motor area. A marked improvement of symptoms was achieved by a combination of baclophen and dipropylacetate.

Computerized Axial Tomography in Chronic Seizure Disorders of Childhood

Ninety-eight children with chronic seizure disorders were studied by computerized axial tomography (CAT). Structural abnormalities were identified in 30% of these children. The greatest incidence of abnormalities was in children with focal motor seizures (43%) and in those whose EEG demonstrated focal slowing together with focal spikes (38%). The most common abnormality was either focal or generalized atrophy (13%). Only about 2% of the abnormalities discovered by CAT were potentially of therapeutic significance. However, the demonstration of a static process, or the finding of a normal CAT, may be quite helpful to the family and physician in certain children with chronic seizure disorders.

Lennox-Gastaut's Syndrome—Prognosis of the Secondary Generalized Epilepsies

On 62 cases with Lennox-Gastaut's syndrome aged four to 31, the clinical-electroencephalographic findings were summarized as follows; (1) Age of onset was over 10 years in 10 cases (16.1%). (2) Mental deficiencies were more severe in those with onset earlier than age three. (3) Behavioral problems were observed in 34 cases (54.8%); 21 with hyperactive and 13 with hypoactive ones -- 18 hyperactive cases (85.7%) with the onset taking place before age six, and 12 hypoactive cases (92.3%), all whose age is now over 10. (4) The number of clinical seizures showed a tendency in which monoictal manifestation decreased from 25 to three whereas polyictal one increased from 13 to 59 cases during the course of a decade. (5) Interictal EEG findings were pseudorhythm of slow spike-wave with or without focal spikes, and so-called runs of rapid spikes during sleep recording. Focal spikes were observed in 25 cases (40.3%); mainly in the frontal area among those under 10 years old, and in the anterior temporal area among those over 20. The rapid spikes were demonstrated in 19 cases (30.6%) in the over-15 age group and appeared to be correlated with epileptic drop seizures and atypical complex absences.

Forebrain influences on an amygdaloid acute focus in the cat

Amygdaloid activity was recorded in immobilized, artificially ventilated cats, after induction of an acute epileptogenic focus in the nucleus basalis amygdalae followed by electrical stimulation of the head of the caudate nucleus of the medial septal nuclei and of the nucleus accumbens. Septal stimulation at low frequency induced a driving in the amygdaloid spiking, but at high frequency it invariably evoked a seizure. Low frequency caudate stimulation had no detectable effect on amygdala activity even when, by increasing stimulation voltage to 25 V, cortical caudate spindles were elicited. With high-frequency sets (> 30 Hz, > 1.5 V) the caudate exerted a prolonged inhibitory influence on interictal epileptiform activity of the homolateral amygdala. Contrary to the initial effect, a delayed effect was often observed after both septal and caudate stimulation. Accumbens stimulation at low frequency occasionally induced a driving in the focal spiking, but at high frequency had no detectable effect. It is postulated that septal stimulation results in acetylcholine release in the amygdala, and that the different effects of caudate stimulation at various frequencies probably indicate frequency-related preferential activation or inhibition of individual neuronal systems within the caudate nucleus.