Biomedical subjects

Christoph Baumgartner

Publications and source records attributed to Christoph Baumgartner.

32 records · Page 2Linked to original sources

PubMed2003

Electrocardiographic changes at the onset of epileptic seizures.

PURPOSE: We studied heart-rate (HR) changes at the transition from the preictal to the ictal state in patients with focal epilepsies to gain some insight into the mechanisms involved in the neuronal regulation of cardiovascular function. METHODS: We assessed ECG changes during 145 seizures recorded with scalp EEG in 58 patients who underwent video-EEG monitoring. Consecutive RR intervals were analyzed with a newly developed mathematical method for a total of 90 s. RESULTS: Ictal-onset tachycardia occurred in 86.9% of all seizures, whereas bradycardia was documented only in 1.4%. The incidence as well as the amount of ictal HR increase was significantly more pronounced in patients with mesial temporal lobe epilepsy (TLE) as compared with those with non-lesional TLE or extratemporal epilepsy. Moreover, right hemispheric seizures were associated with ictal-onset tachycardia. On average, ictal HR increase preceded EEG seizure onset by 13.7 s in TLE patients and 8.2 s in patients with extratemporal epilepsy. This difference was significant. Ictal HR changes could be classified according to their temporal evolution into two different patterns. These two patterns differed significantly between the temporal lobe and the extratemporal epilepsy patient group. CONCLUSIONS: Epileptic discharges directly influence areas of the central autonomic network, thus regulating HR and rhythm. Such changes occur before ictal discharges appear on surface electrodes. Our newly developed method may be of potential use for clinical applications such as automatic seizure-detection systems. Moreover, our method might help to clarify further the basic mechanisms of interactions between heart and brain.

Autonomic Nervous System↗

PubMed2003

Increased expression of GABA(A) receptor beta-subunits in the hippocampus of patients with temporal lobe epilepsy.

It has been postulated that dysfunction of the GABA-ergic transmission is causatively related to the development of epilepsy. Animal models of temporal lobe epilepsy (TLE) revealed considerable changes in the expression of GABA(A) receptor subunits in the hippocampus. Using immunocytochemistry, we investigated the expression of GABA(A) receptor subunits alpha1, alpha3, beta1-3, and gamma2 in hippocampal specimens obtained at surgery from TLE patients with and without hippocampal sclerosis and in autopsy controls. Consistent with the severe neurodegeneration in the CA1 sector, significant decreases in alpha1-, alpha3-, beta3-, and gamma2-subunit immunoreactivity (IR) were detected in sclerotic but not in nonsclerosic specimens. In contrast, pronounced increases in IR of all 3 beta-subunits were observed in most sectors of the hippocampal formation both in sclerotic and nonsclerotic specimens, being especially pronounced in the dentate molecular layer and in the subiculum where subunit alpha3- and gamma2-IR were also elevated. Using in situ hybridization for subunits beta2 and beta3, increased expression of the respective mRNAs was detected in dentate granule cells of patients with and without hippocampal sclerosis. Beta-subunits are important constituents of the GABA(A) receptor and contribute to the binding site of GABA. Our data indicate pronounced adaptive changes in the expression of these GABA(A) receptor subunits related to seizure activity and indicate altered assembly of GABA(A) receptors in TLE.

Adolescent↗

PubMed2002

[Frontal lobe epilepsy--clinical seizure seminology].

The aim of this study was an analysis of the localizing and lateralizing value of clinical symptoms in frontal lobe epilepsy. Nineteen patients with medically refractory seizures originating from the frontal lobe were examined retrospectively, seven of these patients underwent subsequent neurosurgical removal of the epileptogenic zone. The predominant clinical symptoms were clonic (53%) and tonic motor phenomena (89%). Dystonic posturing (32%) and postictal paresis (37%) occurred frequently, indicating a seizure onset in the contralateral hemisphere. Head version contralateral to the seizure onset zone, as demonstrated in 53% of the patients, was a reliable lateralizing sign, whereas early head and eye turning (11%) had no lateralizing significance. 37% of the patients showed ictal vocalisation, another 37% presented with automatisms--so called hypermotor seizures should be considered as a special subtype. An aura was present in 26% of the patients--in most cases as a somatosensory manifestation or a feeling of dizziness, especially with seizures originating from the supplementary motor area (SMA) or the precentral area. Secondary generalization and seizure series occurred frequently. Unilateral automatisms, head version, tonic phenomena, dystonic posturing, unilateral grimacing, postictal paresis and unilateral clonic movements could be identified as reliable lateralizing signs. We conclude that the analysis of clinical symptoms plays an important role in presurgical epilepsy diagnosis.

Adult↗

PubMed2002

A functional polymorphism in the prodynorphin gene promotor is associated with temporal lobe epilepsy.

The prodynorphin gene (PDYN) encoding the anticonvulsant peptide dynorphin is a strong candidate for a seizure suppressor gene and thus a possible modulator of susceptibility to temporal lobe epilepsy. We performed a case control association study in 155 patients with nonlesional temporal lobe epilepsy and 202 controls and found that PDYN promotor low-expression L-alleles confer an increased risk for temporal lobe epilepsy in patients with a family history for seizures. Irrespective of the familial background, L-homozygotes display a higher risk for secondarily generalized seizures and status epilepticus.

Enkephalins↗

PubMed2002

Magnetoencephalography in presurgical epilepsy evaluation.

The introduction of whole-head magnetoencephalography (MEG) systems facilitating simultaneous recording from the entire brain surface has led to a major breakthrough of MEG in presurgical epilepsy evaluation. Localizations of the interictal spike zone with MEG showed excellent agreement with invasive electrical recordings, were useful to clarify the spatial relationship of the irritative spike zone to structural lesions, and could attribute epileptic activity to lobar subcompartments both in temporal lobe and extratemporal epilepsy. MEG was especially useful for the study of patients with non-lesional neocortical epilepsy and of patients with large lesions, where it provided unique information on the epileptogenic zone. It could reliably localize sensorimotor cortex prior to surgical procedures adjacent to central fissure. MEG language mapping yielded concordant results with the Wada test and cortical stimulation studies. MEG localizations of epileptic activity and essential brain regions were successfully integrated into frameless stereotaxy systems providing accurate functional information intraoperatively. Because MEG and EEG yield both complementary and confirmatory information, combined MEG-EEG recordings in conjunction with advanced source modeling techniques will further improve the noninvasive evaluation of epilepsy patients and constantly reduce the need for invasive procedures.

Brain↗

PubMed2002

Semiology of temporal lobe epilepsy in children and adolescents. Value in lateralizing the seizure onset zone [corrected].

PURPOSE: To determine the frequency and lateralizing value of clinical seizure symptoms in children and adolescents with drug-resistant temporal lobe epilepsy (TLE). METHODS: Patients enrolled had to be <18 years of age and seizure free at follow-up for at least 12 months after epilepsy surgery. Patients were assigned to two age groups, children (age<12 years) and adolescents (age>12 and <18 years). Video-tapes were reviewed blinded to patients' demographic data and results of additional investigations by two independent raters. Clinical signs of known lateralizing significance in adults and additional clinical signs without lateralizing value were assessed. RESULTS: 14 patients (eight boys; 2-18 years) fulfilled the inclusion criteria. Inter-observer agreement was excellent (kappa coefficient: 0.82). Compared with adult series, no differences were found concerning overall occurrence of lateralizing signs and lateralizing accuracy. There were age-related differences, however, concerning the occurrence of individual signs: secondary generalization, complex automatisms and version were less frequent in children than in adolescents. CONCLUSIONS: Clinical signs of lateralizing value can also be found in children and adolescents, provided that the evaluation protocols used consider developmental aspects.

Adolescent↗

PubMed2002

Focal features in patients with idiopathic generalized epilepsy.

PURPOSE: The stringent dichotomy between focal and generalized epilepsies has become a contentious issue, since neuropathological studies as well as structural and functional imaging data hypothesized the existence of focal brain abnormalities in patients with well-documented idiopathic generalized epilepsy. The aim of our study was to investigate whether clinical and EEG features generally considered typical for a focal seizure disorder also occur in patients with generalized epilepsies to further support the hypothesis of a more continuous transition between focal and generalized epilepsies in contrast to the present concept of a stringent pathophysiologic dichotomy. METHODS: We retrospectively studied 20 consecutive patients with idiopathic generalized epilepsy who underwent video EEG monitoring either because of uncertainty of their epilepsy syndrome or because of a difficult to treat epilepsy. We determined the incidence of (a) focal interictal epileptiform discharges (IEDs), (b) intermittent temporal slow waves, and (c) clinical signs that are widely accepted as typical for a focal seizure onset, i.e. version, tonic/dystonic unilateral posturing, postictal hemiparesis, postictal nose wiping and figure of 4. RESULTS: Focal IEDs occurred in seven patients (35.0%), intermittent temporal slow waves in six (30%), and clinical signs pointing towards a focal seizure onset were found in seven patients (35%). CONCLUSION: Our study of EEG and clinical data supports the more sophisticated previous investigations in which structural and functional imaging as well as histopathological data suggested the presence of focal brain abnormalities in patients with 'generalized' epilepsies. Furthermore we emphasize the cautious use of isolated focal EEG abnormalities and certain clinical signs to prevent a premature diagnosis of focal epilepsy in patients who may indeed suffer from a generalized seizure disorder.

Age of Onset↗

PubMed2002

Is refractory epilepsy preventable?

About a third of the patients diagnosed with epilepsy will not be fully controlled with antiepileptic drugs (AEDs), and many of them will have frequent and disabling seizures. These patients will undergo multiple drug trials, most often without complete seizure remission. Moreover, refractory epilepsy is associated with increased morbidity (from seizures and medications), social isolation, unemployment, and overall reduced quality of life. There is evidence that refractory epilepsy can be a progressive disorder, which, if controlled early, might never develop into a full syndrome with all of its associated sequelae. The difficulty lies in identifying at an early stage patients who are likely to progress to intractability. No currently known markers enable clinicians to make this identification with confidence. Advances in pharmacogenomics and our understanding of pharmacologic responsiveness in epilepsy may change this situation. Even now, we are able to identify many patients with a poor prognosis earlier than before, particularly in the pediatric population, in which syndromic classification may provide an approach to predict intractability. The early initiation of aggressive therapy may improve outcome and overall quality of life.

Disease Progression↗

PubMed2002

Serum s-100 protein is not a suitable seizure marker in temporal lobe epilepsy.

PURPOSE: S-100 protein is a sensitive marker of various brain diseases; however, its role in epilepsy is controversially discussed in the literature. We therefore studied the temporal profile of serial concentrations of S-100 protein in serum after secondarily generalized tonic-clonic seizures during video-EEG monitoring. METHODS: Ten patients with mesial temporal lobe epilepsy were prospectively studied. Serum S-100 protein was measured after a seizure-free period of > or =24 h (baseline) and 30 min, 3, 6, 12, and 24 h after a secondarily generalized tonic-clonic seizure of temporal lobe origin in nine and a convulsive status epilepticus in one patient. RESULTS: All S-100 levels were within the normal range, except for those of one patient at baseline. Mean values were 0.045 microg/L (range, 0.003-0.13 microg/L) at baseline, 0.038 microg/L (range, 0.003-0.09 microg/L) at 30 min, 0.036 microg/L (range, 0.003-0.08 microg/L) at 3 h, 0.034 microg/L (range, 0.003-0.07 microg/L) at 6 h, 0.034 microg/L (range, 0.003-0.08 microg/L) at 12 h, and 0.035 microg/L (range, 0.003-0.09 microg/L) at 24 h after seizure offset. There were no significant differences between mean concentrations at any interval postictally. CONCLUSIONS: We could not detect any significant alterations in serum S-100 protein concentration either after a single secondarily generalized tonic-clonic seizure or after convulsive status epilepticus in patients with temporal lobe epilepsy. Our data do not confirm previous work, which suggested serum S-100 protein to be a suitable marker for epileptic seizures.

Biomarkers↗

PubMed2002

Individual variations in the sulcal anatomy of the basal temporal lobe and its relevance for epilepsy surgery: an anatomical study performed using magnetic resonance imaging.

OBJECT: The concept of selective amygdalohippocampectomy is based on pathophysiological insights into the epileptogenicity of the hippocampal region and the definition of the clinical syndrome of mesial temporal lobe epilepsy (TLE). High-resolution magnetic resonance (MR) imaging allows correlation of the site of histologically conspicuous tissue with anatomical structure. The highly variable sulcal pattern of the basal temporal lobe, however, definitely complicates the morphometric analysis of histomorphologically defined subdivisions of the hippocampal region. The goal of this study was to define individual variations in the sulcal anatomy on the basis of preoperative MR images obtained in patients suffering from TLE. METHODS: The authors analyzed coronal MR images obtained in 50 patients for the presence of and intrinsic relationships among the rhinal, collateral, and occipitotemporal sulci. The surface relief of consecutive sections of 100 temporal lobes was graphically outlined and the resulting maps were used for visual analysis. The sulci were characterized by measurement of their depth, distance to the temporal horn, and laterality. The anatomical measurements and frequencies of sulcal patterns were assessed for statistical correlation with patients' histories and the lateralization of the seizure focus. CONCLUSIONS: Statistical assessment shows that patient sex is a significant factor in sulcal patterns. Anatomical measurements are significantly decreased on the side of the seizure origin, which relates to loss of white matter, a known morphological abnormality associated with TLE. Magnetic resonance imaging allows for accurate preoperative knowledge of individual sulcal patterns and facilitates intraoperative orientation to anatomical landmarks.

Adolescent↗

PubMed2002

Postictal signs of lateralizing and localizing significance.

Epileptic seizures are followed by dynamic alterations in neurological function in the postictal period. Although the first observation of such phenomena dates back to Bravais who described postictal hemiparesis in 1827, this critical period of time after seizure offset has received little attention in the literature. In this article, we report some of the most important postictal signs, such as postictal hemiparesis, postictal nose wiping, postictal language dysfunction, postictal headache and postictal cognitive impairment. Summarizing our own experience of the postictal state in more than 160 patients with focal epilepsy, we conclude that postictal signs can provide reliable information for the localization of the seizure onset zone in patients with focal epilepsy. Since the lateralization and localization of the seizure onset zone has become a major issue for the presurgical evaluation of those patients, we argue that more attention should be paid to the postictal state during video EEG monitoring. Moreover, in an ambulatory setting, the postictal period and its related signs is usually the only part of an epileptic seizure that is accessible to the physician's examination and might therefore add some information to the differential diagnosis of paroxysmal events, such as epileptic or psychogenic seizures [published with videosequences].

Brain↗

PubMedDate not supplied

The chance of cure following surgery for drug-resistant temporal lobe epilepsy. What do we know and do we need to revise our expectations?

Although surgery is often seen as a curative treatment for patients with drug-resistant temporal lobe epilepsy, little information is available how many cases can be considered cured after surgery, i.e. are seizure-free for several years without taking antiepileptic drugs (AEDs). In our review, 13 retrospective and five prospective clinical observations published since 1980 provided data on long-term seizure control off AEDs in a total of 1658 patients. No randomized studies were found. Following temporal lobe surgery, approximately one in four adult patients and approximately one in three children or adolescents can currently shown to be seizure-free for 5 years without AEDs (25%, mean of eight studies in adults, 95% CI: 21-30%, and 31%, mean of three studies in children, 95% CI: 20-41%). The rate of seizure control off AEDs seemed to be stable after 2 years of follow-up. However, as 55% of patients free of disabling seizures preferred not to discontinue their medication completely as late as 5 years after surgery, it is impossible to know if they are cured or not. No features predictive of surgical cure were detected except for better cure outcome in children versus adults with hippocampal sclerosis and in patients with typical versus atypical Ammonshorn's sclerosis or tumor in one small study each. In conclusion, the available evidence on seizure outcome off AEDs after temporal lobe surgery is based on non-randomized studies and, in part, data were collected retrospectively. A randomized controlled trial is needed to determine if, in fact only one in three to four patients with temporal lobe epilepsy undergoing surgery can be considered cured.

Adolescent↗

PubMedDate not supplied

MEG and EEG in epilepsy.

Both EEG and magnetoencephalogram (MEG), with a time resolution of 1 ms or less, provide unique neurophysiologic data not obtainable by other neuroimaging techniques. MEG has now emerged as a mature clinical technology. While both EEG and MEG can be performed with more than 100 channels, MEG recordings with 100 to 300 channels are more easily done because of the time needed to apply a large number of EEG electrodes. EEG has the advantage of the long-term video EEG recordings, which facilitates extensive temporal sampling across all periods of the sleep/wake cycle. MEG and EEG seem to complement each other for the detection of interictal epileptiform discharges, because some spikes can be recorded only on MEG but not on EEG and vice versa. Most studies indicate that MEG seems to be more sensitive for neocortical spike sources. Both EEG and MEG source localizations show excellent agreement with invasive electrical recordings, clarify the spatial relationship between the irritative zone and structural lesions, and finally, attribute epileptic activity to lobar subcompartments in temporal lobe and to a lesser extent in extratemporal epilepsies. In temporal lobe epilepsy, EEG and MEG can differentiate between patients with mesial, lateral, and diffuse seizure onsets. MEG selectively detects tangential sources. EEG measures both radial and tangential activity, although the radial components dominate the EEG signals at the scalp. Thus, while EEG provides more comprehensive information, it is more complicated to model due to considerable influences of the shape and conductivity of the volume conductor. Dipole localization techniques favor MEG due to the higher accuracy of MEG source localization compared to EEG when using the standard spherical head shape model. However, if special care is taken to address the above issues and enhance the EEG, the localization accuracy of EEG and MEG actually are comparable, although these surface EEG analytic techniques are not typically approved for clinical use in the United States. MEG dipole analysis is approved for clinical use and thus gives information that otherwise usually requires invasive intracranial EEG monitoring. There are only a few dozen whole head MEG units in operation in the world. While EEG is available in every hospital, specialized EEG laboratories capable of source localization techniques are nearly as scarce as MEG facilities. The combined use of whole-head MEG systems and multichannel EEG in conjunction with advanced source modeling techniques is an area of active development and will allow a better noninvasive characterization of the irritative zone in presurgical epilepsy evaluation. Finally, additional information on epilepsy may be gathered by either MEG or EEG analysis of data beyond the usual bandwidths used in clinical practice, namely by analysis of activity at high frequencies and near-DC activity.

Brain↗

PubMedDate not supplied

Temporal evolution and prognostic significance of postoperative spikes after selective amygdala-hippocampectomy.

The purpose of this study was to quantify the temporal evolution and to determine the prognostic significance of spikes on serial postoperative EEGs after selective amygdala-hippocampectomy. The authors performed postoperative EEGs 4 months, 1 year, and 2 years after surgery in 31 patients with unilateral mesial temporal lobe epilepsy. Spike frequency was determined ipsilateral to the resection (group I, no spikes; group II, 1 to 10 spikes; group III, 11 to 20 spikes; group IV, more than 21 spikes during the 30-minute recording). The temporal evolution of postoperative spike frequency was assessed, and these parameters were correlated with surgical outcome. Twenty-two patients showed spikes on postoperative EEG. Spike frequency decreased over time in 14 patients, while no changes or minimal changes occurred in seven patients, and spike frequency increased in one patient. Nine patients had no spikes. There was no correlation between occurrence, frequency, and temporal evolution of spikes with postoperative seizure control. The authors' results demonstrate a progressive decrease of spike frequency during the postoperative period after selective amygdala-hippocampectomy, although occurrence, frequency, and temporal evolution of postoperative spikes had no implications on surgical outcome.

Adult↗