Gerhard Bauer

Unified EEG terminology and criteria for nonconvulsive status epilepticus

The diagnosis of nonconvulsive status epilepticus (NCSE) relies largely on electroencephalography (EEG) findings. The lack of a unified EEG terminology, and of evidence‐based EEG criteria, leads to varying criteria for and ability to diagnose NCSE. We propose a unified terminology and classification system for NCSE, using, as a template, the Standardised Computer‐based Organised Reporting of EEG (SCORE). This approach integrates the terminology recently proposed for the rhythmic and periodic patterns in critically ill patients, the electroclinical classification of NCSE (type of NCSE) and the context for the pathologic conditions and age‐related epilepsy syndromes. We propose flexible EEG criteria that employ the SCORE system to assemble a database for determining evidence‐based EEG criteria for NCSE.

Nonconvulsive status epilepticus and coma.

Nonconvulsive status epilepticus (NCSE) in a comatose patient cannot be diagnosed without electroencephalography (EEG). In many advanced coma stages, the EEG exhibits continuous or periodic EEG abnormalities, but their causal role in coma remains unclear in many cases. To date there is no consensus on whether to treat NCSE in a comatose patient in order to improve the outcome or to retract from treatment, as these EEG patterns might reflect the end stages of a dying brain. On the basis of EEG, NCSE in comatose patients may be classified as generalized or lateralized. This review aims to summarize the ongoing debate of NCSE and coma and to critically reassess the available literature on coma with epileptiform EEG pattern and its prognostic and therapeutic implications. The authors suggest distinguishing NCSE proper and comatose NCSE, which includes coma with continuous lateralized discharges or generalized epileptiform discharges (coma‐LED, coma‐GED). Although NCSE proper is accompanied by clinical symptoms suggestive of status epilepticus and mild impairment of consciousness, such as in absence status or complex focal status epilepticus, coma‐LED and coma‐GED represent deep coma of various etiology without any clinical motor signs of status epilepticus but with characteristic epileptiform EEG pattern. Hence coma‐LED and coma‐GED can be diagnosed with EEG only. Subtle or stuporous status epilepticus and epilepsia partialis continua–like symptoms in severe acute central nervous system (CNS) disorders represent the borderland in this biologic continuum between NCSE proper and comatose NCSE (coma‐LED/GED). This pragmatic differentiation could act as a starting point to solve terminologic and factual confusion.

Video‐EEG monitoring: Safety and adverse events in 507 consecutive patients

Purpose:  Video–electroencephalography (EEG) monitoring plays a central role in the presurgical evaluation of medically refractory epilepsies and the diagnosis of nonepileptic attack disorders (NEADs). The aim of this study was to analyze safety and adverse events (AEs) during video‐EEG monitoring.

Outcome of adult patients with temporal lobe tumours and medically refractory focal epilepsy

SummaryBackground. Tumours are a well-recognized cause of medically intractable epilepsies. Tumours represent the primary pathology in 10%–30% of patients undergoing surgical treatment for chronic epilepsy. This study examines the surgical and epileptological outcome of adults with temporal lobe tumoural epilepsy treated within a comprehensive epilepsy surgery programme. Methods. Between 1999 and 2004, 99 consecutive patients have been operated for intractable temporal lobe epilepsy (TLE). Among these, 14 adult patients exhibited temporal lobe neoplasms associated with TLE. Every patient underwent a comprehensive presurgical evaluation including video-EEG monitoring, MRI, interictal PET scan, ictal SPECT and neuropsychological testing. Surgical strategies were determined in an interdisciplinary seizure conference and tailored to the findings of the presurgical evaluation. All patients were available for follow up at regular intervals after 3, 6, 12 months and yearly thereafter. Epileptological outcome was classified according to Engel [10] and the ILAE (International League Against Epilepsy)/systems [33]. Findings. The surgical procedures performed were temporal lobe resection in 3 patients, extended lesionectomy in 4 and extended lesionectomy with resection of the temporomesial structures in 7. One patient with an astrocytoma grade III underwent a second and third operation for recurrent disease. Histological results: Astrocytoma 5 patients, ganglioglioma/gangliocytoma 5, oligodendroglioma 2, ependymoma 1 and dysembryoplastic neuroepithelial tumour (DNET) 1. Postoperative follow-up was performed after 12–74 months (mean 31). The outcome according to the Engel classification indicated class IA in 9 patients, class IC in 3, and 1 each in classes IIIA and IVA. Epileptological outcome according to the ILAE classification indicated class 1 (12 patients) and class 4 (2 patients). Surgical mortality was zero and mild permanent neurological deficits due to surgery were seen in 2 patients. Postoperatively 3 patients showed a homonymous quadrantanopia. Conclusions. Patients with drug resistant epilepsy and temporal lobe tumours should undergo evaluation in dedicated epilepsy surgery programmes.

Interictal language functions in temporal lobe epilepsy.

Objective: To evaluate interictal language functions in patients with medically intractable left and right sided mesial temporal lobe epilepsy (TLE). Methods: Spontaneous speech, language comprehension, confrontation naming, repetition, reading, writing, and word fluency were examined in 12 patients with left sided TLE and 11 patients with right sided TLE. Results: Four patients out of 23 displayed language deficits in more than one language domain. Three further patients exhibited isolated language deficits. Linguistic deficits were observed in both left TLE and right TLE. In quantitative analyses left and right TLE only differed in spontaneous speech (p = 0.02); no difference was found in other language functions, laterality quotient of Wada test, or overall IQ. Qualitative error analysis of object naming, however, showed typical errors associated only with left TLE. Patients with linguistic deficits were older at testing compared to patients without linguistic deficits (p = 0.003), whereas other factors including side of TLE, handedness, educational level, age at epilepsy onset, and duration of epilepsy did not differ between groups. Conclusions: Possible explanations for these findings include neuronal cell loss and deafferentiation in cortical areas, and disruption of the basal temporal language area pathways. Our study suggests that some patients with chronic mesial TLE exhibit linguistic deficits when specifically tested, and underlines the need to routinely investigate linguistic functions in TLE.

Childhood febrile convulsions—which factors determine the subsequent epilepsy syndrome? A retrospective study

To analyze the spectrum of epilepsy syndromes which follow childhood febrile convulsions (FC) and to examine whether retrospective analysis of clinical features of the FC enables discrimination of patients who develop temporal lobe epilepsy (TLE) from those who develop generalized epilepsy (GE). One hundred and thirteen patients with epilepsy and antecedent FC were retrospectively analyzed. We inquired in detail about the clinical characteristics of FC (age, duration, number, focal symptoms) as well as family history, birth history, neurological status, and psychomotor development before onset of FC. Forty five (39.8%) patients had TLE, 41 (36.6%) GE, and 27 (23.9%) had extratemporal epilepsy (ETE). Patients with TLE had a significantly longer duration of FC (P< or =0.001), more often focal features (P< or =0.001), and febrile status epilepticus (P< or =0.001) than patients with GE. Age at FC, Number of FC, family history, birth history and neurological status at FC did not differ between groups. A stepwise discriminant model allowed correct assignment after cross validation in 84.2% to TLE and in 100% to GE. A broad spectrum of epilepsy syndromes follow FC. We found a strong association of prolonged and focal FC with later development of TLE. Short generalized FC were associated with GE.

Idiopathic generalized epilepsies with pure grand mal: clinical data and genetics

OBJECTIVE To analyze the clinical features and family history of patients with idiopathic generalized epilepsy (IGE), with pure grand mal (GM), divided into epilepsies with GM occurring exclusively on awakening (GMA) and random GM (RGM). METHODS We studied retrospectively 98 patients from a large epilepsy outpatient clinic. All patients had a full clinical examination and computed cerebral tomography scans (CCT) or magnetic resonance imaging (MRI) when feasible. We analyzed seizure type, seizure frequency, provocative factors, prognosis, electroencephalography (EEG) findings and family history. RESULTS Sixty-eight patients had GMA and 30 had RGM. The mean age at seizure onset was 16.6 years (+/-6.3 S.D., range: 5-41) and 16.7 years in those with RGM (+/-7.5 S.D., range: 4-42, NSD). Patients with GMA had a longer course of active epilepsy (median 8.5 years) compared to RGM (median 2 years). Seizure-provoking factors, especially sleep deprivation, were significantly (P=0.001) more common in patients with GMA (52/68, 77%) than in the group with RGM (13/30, 43%). Of all patients, 23% (23/98) reported first degree relatives with seizures or epilepsy. Pure GM was found in 41% (12/29) of affected first degree relatives, other idiopathic generalized epilepsy syndromes were less frequently observed (4/29, 14%). The concordance rate was high within the syndrome - none of the patients with RGM had an affected relative with GMA and vice versa only two of affected relatives of GMA patients had RGM. CONCLUSION GMA seems to be associated with a longer duration of active epilepsy, a higher relapse rate and a stronger tendency to be precipitated by seizure provoking factors. The different concordance rates between the syndromes suggest a genetically different background.

EEG patterns in hypoxic encephalopathies (post-cardiac arrest syndrome): fluctuations, transitions, and reactions.

Summary: In patients with coma resulting from hypoxic encephalopathy (e.g., after cardiac arrest), the EEG may reflect the severity of brain dysfunction, although the exact relationship among the EEG changes, the extent of neuronal damage, and consequent prognosis is still under study. Many prognostications are based on particular EEG patterns at a time point, such as burst suppression or generalized periodic discharges, but with sequential, repeated, or with prolonged or continuous EEG monitoring, it has become increasingly clear that more information might be gleaned from EEG pattern changes over time. Short-term fluctuations (as opposed to permanent transitions), or preserved reactions to exogenous stimuli, have to be differentiated. This review presents many of the typical postanoxic EEG patterns, along with their evolution over time. This preliminary report illustrates the temporal dynamic changes of EEG over time. It is hoped that it will act as a starting point for prospective and systematic investigation to test whether EEG evolution and transitions add diagnostic and prognostic value.

Hippocampal abnormalities in malformations of cortical development: MRI study.

Objectives: Hippocampal abnormalities may coexist with malformations of cortical development (MCD). This cross-sectional MRI study aimed at categorizing hippocampal abnormalities in a large group of MCD and comparing MCD patients with (group W) and without (group W/O) hippocampal abnormalities. Methods: Hippocampal anatomy, rotation, size, internal structure, and MRI signal alterations were assessed visually by 3 independent raters in patients with MCD and epilepsy. Four types of hippocampal abnormalities were examined in 220 patients (116 women, mean age 31 ± 16.6, range 2-76 years): partially infolded/hypoplastic hippocampus (HH), hippocampal sclerosis (HS), malrotated hippocampus (MH), and enlarged hippocampus (EH). The commonest MCD in the cohort were focal cortical dysplasia (27%), polymicrogyria (PMG) (21%), developmental tumors (15%), and periventricular nodular heterotopia (PNH) (14%). Results: Hippocampal abnormalities were seen in 69/220 (31%) patients: HH in 34/69 (49%); HS in 18/69 (26%); MH in 15/69 (22%); and EH in 2/69 (3%). PNH (21/30 [70%]) and PMG (22/47 [47%]) were most commonly associated with hippocampal abnormalities. Compared to the W/O group, patients in the W group had a higher rate of learning disability (W 41/69 [59%] vs W/O 56/151 [37%]; p = 0.003) and delayed developmental milestones (W 36/69 [52%] vs W/O 53/151 [35%]; p = 0.025); groups did not differ otherwise with regard to clinical presentation. HH was associated with symptomatic generalized epilepsies (11/34 [32%]) and high rate of learning disability (27/34 [79%]), neurologic deficits (25/34 [73%]), and delayed developmental milestones (23/34 [68%]). Conclusions: About a third of patients with malformations of cortical development had hippocampal abnormalities. Patients with hypoplastic hippocampus had the most severe clinical phenotype.

Computerized tremor analysis of valproate-induced tremor: a comparative study of controlled-release versus conventional valproate.

Summary:  Purpose: Valproate (VPA) induces postural tremor in 6–45% of patients. The characteristics of VPA‐induced tremor have not yet been quantitatively assessed, and it is not known whether tremor prevalence or severity is affected by VPA formulation (controlled‐release CR‐VPA vs. conventional VPA). The aim of this study was quantitatively to assess tremor in epilepsy patients receiving VPA and to compare the effects of two VPA formulations (CR‐VPA vs. VPA) on tremor severity.