Serial EEG Recordings Research Articles

THE EFFECT OF SEVERE HYPOGLYCAEMIA AND DIABETES ON THE EEG IN DIABETIC CHILDREN

Insulin hypoglycaemia(H)is the commonest form of H in childhood and severe and recurrent H can cause brain damage. Serial EEG recordings were made in 70 diabetic children(DC)(age 11,2±0, 5 yr, duration of diabetes (DD) 5,1±0, 4 yr, mean±SE)and EEG findings were related to age (at EEG and at diagnosis), DD, daily insulin dose, long-term metabolic control assessed by HbAI and severe H episodes. EEG abnormalities(EEG-A) were found in 26 p.d. of DC. There was no relationship between EEG-A and DD, daily insulin dose or HbA1. DC with EEG-A were younger(9,6±0,7 vs. 12,8±0,7 yr, p 0, 01), had an earlier onset of diabetes(4,8±0,6 vs. 7,6±0,6 yr) and 78 p.c. of them had severe antecedent H, whereas EEG-A were found in only 22 p.c. of DC with no H(p<0,001). All DC with H and convulsions had permanent EEG-A. The degree of metabolic control has no effect on the EEG during the early years of D, but severe antecedent H, young age and early onset are important risk factors.

Etude chez l'homme, par tomographie a emission de positons, du metabolisme et du debit sanguin cerebral dans les epilepsies partielles complexes et dans differents etats de mal

Positron Emission Tomography (PET) with the oxygen-15 steady state inhalation technique was used to provide quantitative values of regional cerebral blood flow (CBF), oxygen consumption (CMRO2) and oxygen extraction ratio (OER) in 25 patients with partial complex seizures during the interictal state, in 1 patient with recurrent temporal seizures and in 3 patients whose EEGs were characterized by periodic lateralized epileptiform discharges (PLEDs). Interictal scans showed temporal zone(s) of hypoperfusion and hypometabolism in 80% of patients with normal X-ray CT Scan. In all cases, ictal scans revealed a focal or multifocal increase in CBF and CMRO2. The localization of the most affected regions correlated well with the spatial distribution of the EEG abnormalities. Comparison of the different values of CBF, CMRO2 and OER showed that the increase in perfusion always exceeded that of oxygen consumption and hence was accompanied by a significant decrease in OER, the latter was always the most prominent in the region of the focus determined by serial EEG recordings. The observed imbalance between blood flow and oxidative glucose metabolism could suggest an impairment of O2 utilization by the mitochondria in the epilepticus focus during seizures or status epilepticus.

The acquisition of a kindled response in developing rats using 24-h intertrial intervals

The purpose of this study was to evaluate a methodology which would permit serial EEG recordings and daily amygdaloid kindling stimulations in young rats (16–26 days old). The preparation was sufficient to maintain the developing rats for 26 consecutive days of stimulation and recording and to permit the acquisition of kindled seizures. Developing rats required a slightly greater number of trials to acquire the kindled response than did adult rats in previous studies using a 24-h intertrial interval.

Neuromonitoring.

Neuromonitoring--the continuous or intermittent observation of nervous system functions--has become a field of interdisciplinary interest. Basically there are two major applications of neuromonitoring: in the operating theatre and the neurological or neurosurgical intensive care unit. Evoked potential recording, intracranial pressure measurement, serial EEG recording, cerebral blood flow measurement and ultrasound techniques have all been used as monitoring methods. The application of these techniques for operations, intensive care and the evaluation of brain death will be described.

Effect of Magnesium Sulfate On Electroencephalographic Findings in Preeclampsia-Eclampsia

Electroencephalograms (EEGs) were recorded in 36 eclamptic, 14 preeclamptic, and 13 normotensive control patients. In the eclamptic group, EEGs were recorded while patients were receiving intravenous magnesium sulfate (MgSO4) with serum magnesium (Mg) levels of 4.5 to 11 mg/dL, and recorded again after MgSO4 was discontinued (serum Mg levels 1.8 to 2.5 mg/dL). In preeclamptic patients, EEGs were recorded before starting MgSO4, during administration of the loading dose (serum Mg levels 6 to 10 mg/dL), and eight hours through the maintenance dose (serum Mg levels 3.6 to 6.2 mg/dL). Twenty-seven (75%) eclamptic patients had abnormal EEGs, four patients showed paroxysmal spike activity, and the others showed focal or diffuse slowing (delta waves). Seven (50%) preeclamptic women had abnormal EEGs (all had generalized slowing). In preeclamptic-eclamptic patients who had serial EEG recordings, the gross EEG findings obtained during MgSO4 infusion and in the absence of MgSO4 were similar. In addition, the abnormal EEG findings were frequent despite the serum Mg levels considered therapeutic in the clinical management of these patients. Two eclamptic patients had seizure activity at serum Mg levels of 9.6 and 11 mg/dL. These findings suggested that abnormal EEGs are frequent in preeclamptic-eclamptic patients. Abnormal EEG findings in such patients are not altered by serum Mg levels achieved in the clinical management of these patients.

The EEG in progressive dialysis encephalopathy. The EEG and clinical indices of PDE in cases treated with desferrioxamine. (Part. II).

Two patients with progressive dialysis encephalopathy (PDE) were subjected to serial EEG recording and neuropsychological tests in order to assess the value of the investigations as indices of the course of PDE during desferrioxamine treatment. EEG proved unreliable for this purpose.

Periodic lateralized discharges in Creutzfeldt-Jakob disease: Serial electroencephalographic studies

Serial EEG recordings in 12 cases of Creutzfeldt-Jakob disease were analyzed. Focal abnormalities, consisting of unspecific slowing of the rhythm or periodic lateralized discharges (PLD), were observed in 50% of cases in the prodromal stage. As the disease progressed, conversion of unspecific focal alterations into PLD and of these into generalized periodic patterns was seen. This evolution and the correlation between PLD and focal epileptic phenomena suggest that the discharges are cortical in nature.

Prevention of iron-induced epileptiform discharges in rats by treatment with antiperoxidants

Head trauma and hemorrhagic cortical infarction in humans are associated with the development of late epilepsy. Hemosiderin deposition within brain is a frequent histopathologic accompaniment of chronic seizures induced by trauma. In this study an aqueous solution of iron salts, the principal metallic ion found in whole blood, was injected subpially into rat isocortex. Ninety-four percent of untreated animals developed epileptiform discharges on serial EEG recording. Pretreatment of rats with the antioxidant α-tocopherol, and with selenium, prevented the development of iron-induced epileptiform activity in 72% of the animals. Iron is known to cause formation of superoxide radicals with resulting peroxidation of membranous components of tissue. The use of antioxidants in preventing the development of iron-induced epileptiform discharges suggests that peroxidative injury may be an important mechanism in the development of experimental post-traumatic epilepsy as induced by isocortical injection of ferrous chloride.

Sodium valproate

The clinical and electroencephalographic (EEG) effects of sodium valproate were studied in four patients by means of serial 24-hour EEG recordings and simultaneous hourly determinations of serum drug concentrations. The patients all had frequent clinical seizures and generalized spike-wave discharges. Valproate appeared to reduce diurnal paroxysmal discharges (PD) and clinical seizures, but the effect on nocturnal PD was less marked. The extent and duration of the depression of PD and seizures varied. Altering the distribution of the total daily dose may change the pattern of clinical seizures and PD. Valproate concentrations fluctuated widely over 24 hours, and the significance of single estimations often cited in the literature appears dubious. Peak serum concentrations above 100 micrograms per milliliter may be necessary in some patients to achieve clinical and EEG improvement.

Heart rate variability during sleep and wakefulness in low-birthweight infants.

The effects of various stages of sleep and wakefulness on heart rate were studied, with R-R interval histograms computed by a ATAC computer, in serial polygraphic EEG recordings made on 22 low-birthweight infants. The heart rate depended on postnatal age rather than on conceptional age, decreasing progressively after birth to each a minimum at various days between 7 and 30 days old, followed by a gradual increase. The heart rate was higher during stage 3 than during stage REM. The heart rate variability was greatest during stage REM and stage 1; it was smallest during stage 3. During crying and bottle feeding, the variability was as small as during stage 3. The variability during wakefulness was larger than during stage 3, but far smaller than during stage REM. The heart rate was very regular, and without the changes associated with sleep stages in infants of 25 to 30 weeks’ conceptional age.

The effect of high doses of 5-hydroxytryptophan on a patient with trisomy 21 Clinical, chemical and EEG correlations

A patient with trisomy 21, who had been started on 5-hydroxytryptophan administration at 3 days of age, received a very high dose of up to 97.8 mg/kg for a 7-week period beginning when the patient was 4 months of age. Total 5-hydroxyindoles in whole blood rose to 1750 μg/ml with 1100 μg/ml of serotonin as the major component. During the high dosage, the patient's muscular tone became mildly hypertonic, the bucco-lingual dyskinesia became more marked and the baby was obtunded. In follow-up studies, the child showed marked psychomotor retardation. Serial EEG recordings during sleep showed no gross abnormality in the proportions of REM and spindling sleep. Click and flash evoked EEG potentials remained abnormally high in amplitude in all recordings made during the 1st year of the patient's life but response latency showed a decrease with age. Much remains to be learned about the mechanisms by which 5-HTP affects the function of the central nervous system in patients with trisomy 21.

The electroencephalogram in three cases of periodic psychosis

Three patients suffering from periodic psychosis have been intensively studied in a Metabolic Unit. All show alternating phases of mood, and correlated biochemical changes. Serial EEG recordings were made under controlled and uncontrolled dietary conditions. The primary traces were assessed visually. The EEGs were all analysed by a low frequency wave analyser which had been modified to provide a digital output of abundance. This output was automatically punched and encoded and the results fed to a computer for statistical analysis of harmonic mean, mean abundance and variability of alpha rhythm. Although all three patients showed cyclical mood changes, and each showed biochemical and EEG changes according to the mood, there was no pattern common to all three. Case 1 and Case 3 gave very similar EEG and biochemical results and it is possible that the minor differences between these two were attributable to diet. Case 2, on the other hand, gave almost entirely opposite results to Cases 1 and 3. It is therefore clear that although there are changes in the EEG which are related to the phase of the individual cycle, there is no clear generalized relationship between the EEG, the mood and the biochemistry.