Initial EEG Research Articles

EEG changes and seizure exacerbation in young children treated with carbamazepine.

Carbamazepine (CBZ) has been reported to exacerbate some seizure types in children. We studied the correlation between CBZ-associated EEG changes and seizure exacerbation in 59 children aged < 6 years treated with CBZ. All patients had EEGs before and after initiation of treatment; initial EEGs were not significantly different among the patients. In 33 children (56%), the subsequent EEGs were either unchanged or improved or demonstrated minor changes (Group I), and excellent to complete seizure control was achieved in 67% of patients. In 26 children (44%), the EEG became significantly more abnormal and was characterized predominantly by new appearance of generalized spike/polyspike-and-wave discharges (group II). The majority of these patients (65%) experienced seizure exacerbation (p < 0.001). For group I, symptomatic partial epilepsy, idiopathic focal epilepsy, and complex febrile seizures were significantly more common; in group II, cryptogenic seizure disorders were more common (p < 0.005). Children in group I were more likely to remain on CBZ or to be weaned from medication after successful treatment, whereas children in group II required additional medication(s) or complete discontinuation of CBZ. Our results suggest that new appearance of generalized paroxysmal discharges after treatment is highly correlated with seizure exacerbation or suboptimal control as well as with adverse outcome. Conversely, absence of significant EEG deterioration on CBZ is usually associated with good seizure control.

Glutamatergic antagonism: effects on lidocaine-induced seizures in the rat.

We tested the hypothesis that glutamate receptor antagonists increase the dose of lidocaine required to induce seizure activity. Sprague-Dawley rats were anesthetized with halothane in 40% O2/balance N2 and mechanically ventilated. After surgical preparation, halothane was discontinued. Normocapnia, normoxia, and normothermia were maintained. The electroencephalogram (EEG) and arterial blood pressure were monitored continuously. Rats were then randomized to one of six groups (control, one of three intravenous [i.v.] bolus doses of the competitive glutamate N-methyl-D-aspartate [NMDA] receptor antagonist CGS 19755, or one of two i.v. bolus and continuous infusion regimens of the competitive glutamate alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid [AMPA] receptor antagonist 2,3-dihydroxy-6-nitro-7-sulfamoyl-benzo-(F)quinoxalline [NBQX]). Thirty minutes after onset of CGS 19755 or NBQX administration (end-tidal halothane < 0.2%), rats received a continuous i.v. infusion of 1.5% lidocaine until EEG seizures occurred. The duration of the infusion (min) and total lidocaine dose (mg/kg) administered were recorded. CGS 19755 increased the lidocaine seizure threshold in a log-linear dose-dependent fashion (P < 10(-6)). The largest dose of CGS 19755 (112.5 mg/kg) increased the time to initial EEG seizure activity more than twofold (e.g., control = 12.6 +/- 2.6 min; CGS 19755 = 28.6 +/- 6.9 min). The effect of AMPA receptor antagonism was less obvious because treatment resulted in an EEG morphology dissimilar to that observed in the CGS 19755 or control groups. Our findings indicate that competitive NMDA receptor antagonists (e.g., CGS 19755) increase the dose of lidocaine required for seizures.(ABSTRACT TRUNCATED AT 250 WORDS)

Risk of seizure recurrence after early withdrawal of antiepileptic treatment in the neonatal period

Recent data indicate that a majority of neonatal seizures arc subclinical and therefore only possible to diagnose with EEG or continuous EEG-monitoring. We estimated the risk of seizure recurrence after neonatal seizures diagnosed with a combination of clinical signs, EEG and continuous amplitude-integrated EEG-monitoring (Cerebral Function Monitoring, CFM). Patients and Methods: During a two-year period (1990-1991) 1283 patients were treated in our NICU. Among these infants 58 (4%) had a seizure diagnose. Antiepileptic treatment (AET) aimed to be as short as possible. Follow-up was made in surviving infants at an age of 12-24 months. Results: Thirtyone of the infants with seizures were full-term babies and 26 preterm (GA 26-36 w). The initial moratlity was 38% (21/58), 54% in the preterm infants vs 19% in the fullterm babies. Among the 36 surviving infants available for follow-up AET was discontinued in 34. Two infants with abundants seizures in combination with multifocal epileptiform activity on the initial EEG's continued AET, one had recurrence of seizures. In 3 fullterm infants with <10 seizures no AEt was given, none of these infants had later recurrence of seizures. Twentynine infants were treated for 1-65 days (median 4.5 days). Three infants (9%) had recurrence of seizures at 6-22 months of age, all had > 10 neonatal seizures. The presence of structural changes in the brain (diagnosed with CT, MRT or US) did not increase the risk of seizure recurrence in the full-term infants (10%) recurrence vs 15% in infants with no changes). Among the preterm infants most of the babies with structural chages died of IVII. We conclude that the risk of seizure recurrence within the first year of life after neonatal seizures is low. With close clinical and EEG follow up most AET can be discontinued when the baby is still in the NICU.

Ｔｒａｕｍａｔｉｃ ａｓｐｈｙｘｉａによる心停止後に一過性の脳幹障害を伴ったα昏睡の１例

We describe a patient with brainstem dysfunction who developed alpha coma after cardiac arrest due to traumatic asphyxia. A 22-year-old man was brought to our hospital in deep coma after being resuscitated. Neurological examination revealed no brainstem reflexes except breathing. The results of a CT scan of the brain were unremarkable. The initial EEG was flat, but BAEPs showed no abnormal findings. On hospital day 3 the patient was still comatose with tetraplegia and bilateral facial palsy, but the brainstem reflexes had returned. An EEG showed a 12Hz alpha rhythm of about 50μV with preponderance over the anterior regions. SEPs showed prolonged latency upon stimulation of left median nerve and left posterior tibial nerve. The blink reflexes showed a normal R1 latency, but a prolonged R2 latency, directly and indirectly. MRI of the brain showed no abnormal findings. Two weeks later, the patient assumed a decorticate posture. Serial CTs showed moderate cerebral atrophy, and serial EEGs showed that low-amplitude delta activity had supervened. One year later, the patient was able to wink and swallow, but still suffered tetraplegia. Residual SEP abnormalities had improved, however, the prolonged R2 latency remained unchanged. Serial neurological and electrophysiological findings suggested that alpha coma occurs not as a result of damage to the brainstem, but of extensive damage to the cerebrum.

Comparison of EEG derived from sphenoidal, infrazygomatic, anterior temporal, and midtemporal electrodes during complex partial seizures

A prospective study was performed to determine whether complex partial seizures are better, or differently, recorded by sphenoidal (SP) or infrazygomatic (IZ) electrodes. Two seizures in each of 20 patients were recorded from radiographically documented SP and IZ, as well as anterior temporal (AT) and mid-temporal (MT) electrodes. Initial ictal bipolar EEG changes appeared at means of 0.57 s (SP) and 0.16 s (IZ) before, and 0.06 s (AT) and 2.36 s (MT) after, the onset of clinical signs. Mean first lateralized ictal bipolar EEG discharges appeared 0.11 s (SP), 0.88 s (IZ), 2.98 s (AT), and 3.94 s (MT) after behavioral seizure onsets. These changes occurred earlier (statistically significant) at SP than at other electrodes. Referentially, mean first ictal EEG changes occurred 0.28 s (SP) before to 0.20 s (MT) after, and ictal lateralization appeared 0.68 s (IZ) to 1.19 s (MT) after, the appearance of clinical seizure onsets. Ictal EEG amplitudes were largest (statistically significant) at SP and progressively smaller at IZ, AT, and MT electrodes. Overall, however, SP electrodes closer to the foramen ovale did not consistently reveal earlier ictal features or higher EEG amplitudes than SP electrodes farther from this landmark. For clinical purposes, SP and IZ electrodes were virtually equivalent.

Seizures as the presenting symptom of brain tumors in children.

Epileptic seizures caused by tumors in children have been regarded as uncommon. We have studied 99 consecutive cases of brain tumors during the period 1980-1987. In 20 cases the tumor was localized to one of the hemipheres and 10 of the cases had seizures, in 9 as the only initial symptom. Details of the clinical picture and the course are presented. Delay from initial symptoms to correct diagnosis was considerable in 4 cases--more than six years. The factors mainly responsible for this delay were: initial EEG normal or soon normalized, misinterpretation of computerized tomography and seizure freedom with or without antiepileptic drug treatment. We conclude that regional slowing in the EEG is a common, although not obligatory, finding. Computerized tomography should be performed in all children with newly presented epilepsy of partial type, except for those with benign partial epilepsy with centro-temporal spikes.

Burst-suppression patterns in status epilepticus. The burst-suppression duration ratio: A marker of the end of clinical status epilepticus

The clinical and EEG response to treatment of five patients with status epilepticus whose initial EEG pattern was burst suppression is reported. Control of clinical seizure activity best correlated with a significant decline in a new index, the burst-suppression duration ratio. The data suggest that the burst-suppression duration ratio may be useful in helping to determine the end point in treatment of refractory status epilepticus.

Morphological patterns of seizures recorded intracranially.

We analyzed the frequency and morphological characteristics of the initial EEG manifestations of spontaneous seizures recorded from depth and subdural electrodes in 26 patients for whom pathological analysis of the area of seizure onset was available after resective surgery. Pathological features considered to be positive findings included well-defined structural lesions (hamartoma, neoplasm) or strictly defined mesial temporal sclerosis. Seizure onset was characterized by the frequency of the rhythmic discharge greater than 2 Hz in the first second and by the presence or absence of periodic low-frequency spikes (less than 2 Hz) preceding this stable change in background frequency. These features were correlated with the presence or absence of pathologic abnormalities in temporal and extratemporal locations. Although all patterns and frequencies of seizure onset were recorded in both medial temporal and extratemporal locations, medial temporal seizure onset was significantly more likely to have high frequency (greater than 13 Hz, p less than 0.00001) and tended to show periodic spikes prior to the seizure when it was associated with medial temporal sclerosis compared to when it was not. Extratemporal seizure onset associated with abnormal pathological substrate was significantly more likely to have a lower frequency (less than 13 Hz, p less than 0.05) and no periodic spikes before seizure onset (p less than 0.00001) than extratemporal seizure onset recorded from areas without pathological findings. Variability of seizure onset frequency was a characteristic of temporal, but not extratemporal, seizures (p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Febrile Seizures: Clinical Characteristics and Initial EEG

We examined the relationship between clinical characteristics and EEG classification in all children with febrile seizures examined at the University Pediatric Clinic, Skopje, Yugoslavia between 1982 and 1984. This is the only facility in Macedonia providing EEG or neurologic consultation for children. EEGs were classified as paroxysmally abnormal if they contained spikes, sharp waves, or spike-wave complexes considered abnormal for age. In all, 22% of the 676 children had an abnormal initial EEG. The most common basis for classification as abnormal was spike-wave complexes greater than 3 Hz; the next most common basis was the presence of spikes. Birth weight, gender, accompanying illness, and family history of seizures, and whether the index seizure was single or multiple were not associated with differences in rate of abnormal EEG. Clinically focal index seizures and longer duration were associated with EEG abnormality. Number of previous febrile seizures was associated with an increasing rate of EEG abnormality, from 18% in children with no previous seizures to 63% in those with four or more previous seizures. Age at EEG was linearly related to likelihood of paroxysmal EEG abnormality, both for the total cohort and for the 376 children with no previous seizures. In the total cohort, logistic regression identified leading predictors of abnormal initial EEG to be older age, number of previous febrile seizures, preexisting motor abnormality, and focal seizures. For children with a first febrile seizure, leading predictors were focal seizure, older age, and preexisting motor abnormality.

EEG Features and Their Evolution in the Acute Phase of Haemorrhagic Shock and Encephalopathy Syndrome

Serial EEGs have been carried out during the acute phase of haemorrhagic shock and encephalopathy syndrome (HS&E) in 22 infants and children aged 3 months to 14 years. Most patients presented with fits and coma and all had shock with bleeding and disseminated intravascular coagulation (DIC). The initial EEG showed prolonged runs of often rhythmic discharges which fluctuated in amount and amplitude with varying distribution and morphology ("electrical storms"). Over a period of days the "electrical storms" gradually decreased leaving only low amplitude EEG activities or evolving to electrocerebral silence (7 cases). Fifteen patients died and all five children with multifocal "electrical storms" who survived showed gross neurological handicap. The rather distinctive EEG pattern is unusual in the context of an acute encephalopathy outside the neonatal period although similar "electrical storms" may be seen in a less extreme form in infants and children with other conditions associated with DIC. This EEG pattern presumably reflects changes in the cerebral microcirculation which in HS&E are usually relentlessly progressive and associated with devastating cortical damage.

EEG and pathologic findings in patients undergoing brain biopsy for suspected encephalitis

Previous studies have suggested that EEG may be helpful in the diagnosis of herpes encephalitis (HE). To further define the value of EEG in an acutely ill, febrile, encephalopathic patient suspected as having encephalitis, we reviewed initial preoperative EEGs with the results of cerebral biopsies in 24 consecutive patients suspected of having encephalitis. Statistical analysis demonstrated that EEG patterns have only limited association with biopsy results. Since diseases which mimic encephalitis may also generate identical EEG changes, this is not an unexpected finding. EEG is useful in the evaluation and management of patients with encephalitis. However, the absence of specific wave forms or focal EEG abnormalities in the proper clinical setting should not deter consideration of HE or delay treatment.

RISK OF RECURRENCE AFTER A SINGLE, UNPROVOKED, GENERALIZED TONO‐ CLONIC SEIZURE

A cohort of 119 two- to 16-year-old patients was followed to assess the risk of recurrence after a single, unprovoked, generalized tonic-clonic seizure. Only children with a normal neurological examination and intellectual development, and an EEG showing no focal abnormality, were studied. The risk of recurrence at six months was 22 per cent, at one year 28.5 per cent, at three years 32.6 per cent and at eight years 37.7 per cent. 58 per cent of recurrences occurred within the first six months and 87 per cent within the first two years. Initial EEGs showing generalized, unprovoked spikes and waves, generalized paroxysmal discharges precipitated by intermittent photic stimulation, or isolated slowing, were associated with risks of recurrence at two years of 40, 50 and 26 per cent, respectively. These results do not differ significantly from those obtained when the initial EEG was normal (29 per cent). Age, seizure duration and history of epilepsy in the family were not associated with a significantly higher risk of recurrence. The risk of recurrence was similar for treated and untreated patients.

EEG monitoring of prolonged thiopentone administration for intractable seizures and status epilepticus in infants and young children.

Thiopentone anaesthesia was used in the treatment of seizures in 19 infants and young children. Nine had a pre-existing seizure disorder without acute cerebral injury and 10 had status epilepticus secondary to an acute cerebral illness. Clinical details, drug levels and findings from serial multichannel electroencephalograms (EEG) and continuous 1 to 2 channel signal processed EEGs using a Cerebral Function Analysing Monitor (CFAM) were reviewed to evaluate the contribution of these techniques to clinical management. Initial EEGs showed discharges that were not generalised in 16/19 patients. This necessitated the use of 7 different montages for continuous monitoring. Three different CFAM patterns representing particular EEG paroxysmal findings were seen. Acute seizure control was achieved in all 19 patients. All patients with a pre-existing seizure disorder survived, although 4/10 with an acute cerebral illness died. During treatment, patterns of burst-suppression to electrocerebral silence (ECS) were eventually seen in 16/19 patients and repeat EEGs demonstrated concordant multi-channel findings in 8/8. Although increasing thiopentone levels (13 patients) correlated with deeper suppression of cortical electrical activity, there was marked inter-patient variability. Inotropic support was not required during the period of treatment even when ECS was induced. In young children a combination of multi-channel EEG and continuous 1 to 2 channel monitoring has advantages over either method used alone. In individual patients on-line monitoring can be easily incorporated in a protocol of controlled cortical suppression and drug titration for seizure control.

Haloperldol pretreatment unmasks the [formula omitted] opioid effects of U-50, 488H on cortical EES and EEG power spectra in rats

Adult female Sprague-Dawley rats were implanted with chronic cortical EEG electrodes and Intravenous cannulae. U-50,488H injection (5.0 mg/kg) produced Initial EEG desynchrony and EEG spectral power that was mainly distributed over the zero to 10 Hz range, including a relatively small spectral peak in the 4–6 Hz band. In contrast, following haioperidol pretreatment (0.1 mg/kg), U-50,488H injection produced high-voltage EEG bursts and a predominant EEG spectral peak in the 4–6 Ha band. These effects of U-50,488H after haloperidol pretreatment were identical to those previously demonstrated with the benzomorphan kappa agonist ethylketocyclazoclne. Thus, haloperidol.pretreatment unmasked the kappa opiold effects of U-50, 488H.

MR-Tomographie nach Schädel-Hirn-Trauma: Vergleich mit Computertomographie, Elektroenzephalographie und neurologischem Status

56 patients with head and brain trauma and in coma were studied prospectively by means of MRT, CT, EEG and neurological examination. All patients had initial CT and EEG admission. MRT showed that in our patients morphological return to normal was the exception. Patients with head and brain injuries should be examined by MRT during the course of their illness. The use of special sequences, such as gradient-echo sequences for the diagnosis of haemorrhagic contusions, is indicated. CT should be retained for evaluating bone injury and cerebral damage during the acute stage.

Seizure prognosis for partial epilepsies in India

The long-term prognosis and factors associated with good and poor prognosis were studied in 95 patients with partial seizures. Thirty-nine per cent of the patients became seizure free. Significant prognostic factors were: male sex, most attacks while awake, attacks precipitated by a hot-water bath, presence of autonomie phenomena and complex symptoms, chronicity and severity of the illness, and seizure activity and the presence of symmetric synchronous EEG foci in the initial EEG records. Regularity of medication, duration of illness and autonomie phenomena were 3 predictive factors for long-term prognosis.

Recovery from cerebral ischaemia. EEG, cerebral blood flow and clinical symptomatology in the first three years after a stroke

In 43 patients suffering from unilateral supratentorial ischaemia the changes over an interval of 3 years in clinical score, quantified EEG (using the neurometric method) and CBF (Xenon inhalation method) were studied. The patients were examined 3 times: shortly after the onset of ischaemia and respectively 3 and 36 months after this first measurement. Three patients died from causes not related to cerebral ischaemia. In the surviving patients the EEG and clinical score improved, often dramatically; the CBF values did not change significantly. Most of the changes occurred in the first 3 months after the stroke. For the evaluation of the prognostic value of the various parameters, 2 sub-groups of patients with different outcome but comparable initial clinical scores were studied. A persistent neurological deficit was predicted by a low CBF at the first measurement. The neurometric parameters obtained from the initial EEG had no value in this respect.

Abces cerebraux neo-nataux (27 cas): Etude electroclinique initiale, evolution

The authors studied 27 brain abscesses in neonates. The neonates were divided in two groups: neonates with seizures and neonates without seizures. The authors tested the diagnostic and predictive value of the initial EEG aspect. They noted the absence of correlation between EEG focal abnormalities and localizations shown by the CT scan. They observed a severe electroclinical evolution in more than fifty percent of the cases presented.

Continuous 4-channel EEG monitoring: a guide to interpretation, with normal values, in preterm infants.

A system is described for the rapid analysis of the extensive EEG data produced by continuous 4-channel monitoring. Using this system, the initial EEGs of 44 low-risk preterm infants between 26 and 37 weeks gestation have been analysed and quantified in order to establish standard values. This provides a basis for assessment of the acute EEG as an index of cerebral function in high-risk or abnormal preterm infants.

Neurophysiological and neuroradiological features preceding infantile spasms

Neonatal EEG, cerebral evoked potentials, CT scan findings and their evolution were investigated in 42 neonates who eventually developed the West syndrome. In infants with perinatal hypoxia, the EEG displayed most often marked or maximal depression in the first week of life. The highly abnormal initial EEG improved progressively with time. The most frequent findings in early infancy was discontinuous tracing and persistent alternating tracing at 1-2 months, and absent sigma rhythms at 3-4 months. The VEP, AEP and CT scan also showed findings suggesting severe degree of brain damage. In infants with meningitis, the initial EEG was less depressed but the EEG abnormality persisted or worsened. In infants with prenatal causes the neonatal EEG was variable, ranging from a normal background EEG to specific abnormalities. The evolution of paroxysmal abnormalities was similar in all groups. There were no epileptiform discharges in early months. The appearance of hypsarrhythmia was preceded by focal and then multifocal spike or sharp wave discharges.