Transient global amnesia as an epileptic manifestation

Summary The case of an 11-year-old girl with typical attacks of transient global amnesia is presented. The attacks occurred repeatedly and the EEG showed spike discharges in the right anterior temporal region. The disorder is assumed to be epileptic. Attacks and spike discharges disappeared immediately after beginning anticonvulsive therapy. Disorder of limbic structures that normally counteract the decay of stored information in memory units is discussed.

---

Zusammenfassung Ein Fall eines elfjährigen Mädchens mit wiederholten Attacken einer transienten globalen Amnesie wird dargestellt. Im EEG fand sich ein rechts temporal vorn gelegener Spitzenherd. Eine Epilepsie wird angenommen. Nach der antikonvulsiven Therapie sistierten die Anfälle und der Spitzenherd wird unterdrückt. Die Funktionsstörung eines aktivierenden Systems innerhalb limbischer Strukturen, das normalerweise den Zerfall neu gespeicherter Informationen in den Zellen entgegenwirkt, wird diskutiert.

     

Anesthetic-dependent excitability changes in the hypothalamic ventromedial nucleus of the rat

In acute experiments in rats anesthetized with urethane, the field potentials, population spike, and unit activity evoked in the hypothalamic ventromedial nucleus (HVM) by amygdaloid stimulation are significantly increased with respect to control when preceded by a conditioning volley at 20- to 100-ms intervals. Under pentobarbital anesthesia, in contrast, the evoked responses were inhibited by the conditioning stimulus for similar interstimulus intervals. In unanesthetized animals chronically implanted with stimulating and recording electrodes, a facilitation of responses by a conditioning stimulus was observed when they were awake or anesthetized with urethane. When the same animals were anesthetized with pentobarbital the HVM evoked response was inhibited by a conditioning pulse. Frequency facilitation and post-tetanic potentiation of HVM responses were markedly enhanced under urethane, whereas in pentobarbital-anesthetized animals inhibition predominated. Picrotoxin reversed the inhibition under pentobarbital to facilitation. These results suggest that the HVM neuron population is under both excitatory and inhibitory influences from the amygdala, the former being predominant in awake and urethane-anesthetized animals and the latter being expressed under pentobarbital anesthesia and is probably mediated by γ-aminobutyric acid.     

Longitudinal study of epileptiform EEG patterns in normal children

EEG were recorded in 3,726 children, from 6 to 13 years of age who were neurologically normal and had no history of epileptic seizures. The records were taken during wakefulness, at rest, and during hyperventilation. In 131 cases (3.54%) epileptiform patterns were found. They consisted of 3 count/sec spike and slow waves discharges (4 cases), multiple spike and slow wave complexes (37 cases), midtemporal spikes (50 cases), rolandic or parietal spikes (27 cases), occipital spikes (2 cases), and multifocal spikes (11 cases). Half of the subjects with EEG abnormalities had behavior problems and/or slight psychomotor ability disturbances. Follow-up studies over an 8 to 9 year period were performed. These demonstrated the spontaneous disappearance of the EEG abnormalities, usually within school age or, at the latest, during adolesence. Only seven individuals developed epileptic seizures of the primary generalized type which responded well to anticonvulsant drug treatment. From this study we can deduce that the epileptiform EEG patterns that often are found in children during school age have no clinical relationship to epilepsy in the great majority of cases. The relationship with epilepsy exists probably on a genetic level for the generalized discharges. The spike foci are non-epileptic in nature in all probability, especially if they emerge from a fairly normal background activity and their duration is very similar to that of the constituents of the background activity, as found in the majority of these subjects. On the contrary, it is probable that these alterations express difficulties in affective or motor adaptation during childhood.     

Hemispheric imbalances in schizophrenia

Evidence is presented of two syndromes in schizophrenia distinguished by opposite asymmetries in hemispheric activation. A florid syndrome is coincidental with left hemisphere overactivation and a non-florid syndrome with right hemispheric overactivation. In each case underactivation characterizes the opposite hemisphere. While this was first revealed by electrodermal lateral asymmetries, a review of the literature provides support from other measures of dynamic process asymmetries such as arousal and attention, and includes electrocortical activity in the form of EEG activity and evoked potentials (EP), the Hoffman reflex, lateral eye movements, auditory thresholds, dichotic listening, somatosensory extinction and handedness. A preliminary empirical test of the model involving a spectral analysis of EPs recorded from occipital and temporal placements was also confirmatory. While hemispheric imbalance may result from asymmetries in fixed structural processes the imbalance itself determines the form the psychosis follows which, due to the dynamic nature of the neuropsychological process, is presumably modifiable.     

Effect of piracetam on EEG spectra of boys with learning disorders

Piracetam was compared with placebo in a double-blind cross-over study of 30 learning-disabled boys. Power spectral analyses revealed that piracetam caused a decrease in the amount of delta activity and an increase in the average EEG frequency. This result is in agreement with those obtained by other workers in adult patients. Some clinical effects of piracetam may be mediated by increased alertness and/or decreased fatigue.Presented in part at the International Symposium on Nootropic Drugs in Rio de Janeiro, October 1979     

Effects of scopolamine upon hippocampal electrical activity associated with running and swimming in rats

In freely moving rats with implanted hippocampal electrodes, the influence of scopolamine HBr (5–10 mg/kg IP) on hippocampal rhythmic slow activity (RSA) was studied quantitatively during running for water reward and swimming. Scopolamine treatment caused a significant upward frequency shift of RSA during these behaviors. Thus, in contrast to previous reports it is concluded that anticholinergics do not leave movement associated RSA unaffected.     

The effectiveness of O2 administration for transient ischemic attacks in moyamoya disease in children

Moyamoya disease is a cerebrovascular obstructive disease of unknown etiology. The rebuild-up phenomenon, slowing of waves on electroencephalogram (EEG) seen after cessation of hyperventilation (HV), is one of the characteristic phenomena of the disease and is though to be related to a development of its symptoms. Therefore, we investigated the mechanism involved in the rebuild-up phenomenon to clarify the mechanism of development of transient ischemic attack (TIA) in moyamoya disease. Ten patients with moyamoya disease were studied; they ranged in age from 7 to 17 years. The power spectra of the EEGs in the occipital region were obtained with a Berg Fourier EEG analyzer for quantitative analysis. Arterial blood gas change (pH,PaO₂,PaCO₂), respiratory pattern (abdominal and nasal), tidal volume and respiratory rate were analyzed simultaneously every 30 s-1 min before, during, and after HV. The slow wave power spectrum (rebuild-up) increased and symptoms of TIA developed as a result of the sharp decrease inPaO₂ (PaO₂ 60.5±15.4 mmHg) after cessation of HV. Based on the fact that hypoxemia was playing a main role, 100% oxygen was administered at a rate of 0.5 l/min in 4 cases where the rebuild-up phenomenon was clear. The EEG power spectra and arterial blood gas were analyzed during rebuild-up with and without O₂ administration. The effectiveness of O₂ administration at the beginning of rebuild-up as measure to prevent the symptoms was checked by a recovery rate of slow wave power percentage, a recovery time of slow wave power percent and by clinical observation. The recovery rates were 11.8±4.2% min and 5.5±4.0% min with and without O₂ inhalation, respectively (P< 0.001). Recovery times of slow wave power percentage were 4.3±1.8 min and 8.1±1.2 min with and without O₂ inhalation, respectively (P< 0.01). Thus, oxygen administration soon after the cessation of HV was shown to be effective in eliminating the rebuild-up phenomenon and hence in abolishing its symptoms.     

Comparative pharmacodynamic studies with the novel serotonin uptake-enhancing tianeptine and — inhibiting fluvoxamine utilizing EEG mapping and psychometry

Summary In a double-blind, placebo-controlled study, the encephalotropic and psychotropic effects of tianeptine (TIA) — a new tricyclic antidepressant, enhancing serotonin reuptake — were investigated as compared with the serotonin reuptake inhibiting antidepressant, fluvoxamine (FLU), utilizing EEG mapping, psychometric and psychophysiological measures. 16 healthy volunteers (8 males, 8 females) aged 21–35 (man 27) years received randomized and at weekly intervals single oral doses of placebo, 12.5 and 25 mg TIA and 50mg FLU. EEG recordings, psychometric and psychophysiological tests and evaluation of pulse, blood pressure and side effects were carried out at 0,2,4,6 and 8 hours; blood sampling, in addition, at hour 1.TIA plasma levels rose fast to peaks at 1–2 hours and declined rapidly as well, while the MC₅ metabolite peaked in the 4th hour and declined more slowly. EEG mapping demonstrated that both TIA and FLU induced significant changes in brain function between the 1st and 8th hour, which, however, differed in their time course. 12.5 mg TIA exhibited, as compared with placebo, slight activating properties in the EEG (decrease of delta and theta, increase of alpha and beta, acceleration of the centroid), parallelled by thymopsychic improvement (mood elevation). 25 mg TIA showed EEG activation up to the 4th hour, later EEG sedation, accompanied by an initial thymopsychic improvement and differential changes thereafter (improved mood, decreased vigility), with the noopsyche improving at all times (attention, Pauli test). 50mg FLU induced initially sedation and thereafter activation, accompanied by thymopsychic deterioration and subsequent improvement, the latter also being observed in the noopsyche (attention, memory). In pupillary and skin conductance measures, generally a slight activation occurred after placebo, which was attenuated by 25 mg TIA. Correlation maps between plasma levels and EEG changes demonstrated: the higher the TIA plasma levels, the more absolute and relative beta power, the less alpha power and the faster the centroid of the total power spectrum, reflecting CNS-activation. Topographically, the correlations were mostly seen over both fronto-temporal regions. In the latter, dominant frequency signalled desactivation in the right and activation in the left hemiphere after both antidepressants, which thereby induced changes in brain function opposite to those observed in depression. Both drugs were well tolerated.     

Stability of EEG Laterality Effects

Task related interhemispheric asymmetries of ongoing EEG activity (alpha band) were tested for stability across three separate occasions. Seven cognitive tasks, presumed to differentially engage either the left or right cerebral hemisphere, were presented to 6 subjects. Involvement with the tasks was determined by evaluation of performance and with a subjective report on degree of involvement. Bilateral EEG was recorded over the parietal areas referenced to an ipsilateral ear, vertex and a central placement, on separate channels. Spectral intensity estimates of 8–13 Hz activity were used to form left/right ratios for determination of asymmetry. Intra-subject stability of alpha band activity was found to improve with the establishment of task validity and to be related to the electrode placement used.     

Spike EEG Abnormalities in Patients without Epileptic Seizures: A Clinical and Long-Term Follow-Up Study

Abstract: A study was conducted on a total of 850 patients who had not previously manifested any epileptic seizures but exhibited at least one spike EEG abnormality. They accounted for 7.2% of the total number of patients without epileptic seizures (850/11,773). Among the 850 patients, 564 were followed up for 1–24 years. Nine boys and one girl, 1.e. 1.8% of the 564 patients, had manifested epileptic seizures during the observation period. They expressed the following six characteristics: males, first EEG examination at 0–4 years of age, onset of initial chief complaints at 04 yeurs of age, mental retardation, spike and wave EEG abnormalities and past history of perinatal birth injuries. These factors are considered to be efficient in detecting patients liable to manifest epileptic seizures later.