Biomedical subjects

H Stefan

Publications and source records attributed to H Stefan.

At least 37 records · Page 2Linked to original sources

PubMed2004

Epilepsy surgery, resection volume and MSI localization in lesional frontal lobe epilepsy.

To verify whether interictal noninvasive information detected by magnetoencephalography (MEG) recordings can contribute to localize focal epileptic activity relevant for seizure generation in lesional frontal lobe epilepsy, magnetic source imaging (MSI) localizations of epileptic discharges were compared to the extent of neurosurgical resection and postoperative outcome. Preoperative MEG spike localizations were displayed in postoperative magnetic resonance imaging (MRI) scans to check whether dipole sites were located within the resection cavity. Moreover, MEG localizations were compared with results of prolonged video-EEG monitoring and, in three cases, with invasive EEG recordings. Our results in five cases with lesional frontal lobe epilepsy showed that good surgical outcome could be achieved in those patients where the majority of MEG spike localizations were located within the resected brain volume.

Adult↗

PubMed2004

A new approach in anti-epileptic drug evaluation.

Presurgical trials with video-electroencephalogram (EEG) monitoring for a couple of days provide the possibility to objectively and quantitatively analyze seizure activity during different drug treatments. Patients are provided with the optimal medical care and safety precautions when hospitalized. Hereby a method used in the antiepileptic drug (AED) trials called therapeutic intensive seizure analysis (TISA) has been recently introduced, by which AED efficacy on seizure activity can be objectively quantified by using continuous video-EEG monitoring. This could be used not only as a supplement to the traditional evaluation of AEDs' efficacy by treatment failure designs in large groups, but also can provide early individual information on the changes of seizure activity of each patient during the therapy. Data from TISA studies suggest that secondarily generalized tonic-clonic seizures (SGTCs) mostly occur in patients with a SGTC history after withdrawal of AED. The first 3 days of titration of a newly introduced AED was important for efficacy assessment; with a low risk of SGTCs. By using the TISA method an early recognition of first effects of a new AED on seizure activity and neuropsychological changes is possible, which can be correlated to serum concentration levels in a small sample size. The essentials of the proposed modification to the conventional presurgical trial are: (1) a complete withdrawal of AEDs should be avoided, if possible and (2) a titration phase limited to 3 days is suggested, using a condensed evaluation setting including the TISA method, serum concentration and neuropsychological monitoring. In addition long-term effects can be evaluated by repeated video-EEG monitoring.

Anticonvulsants↗

PubMed2004

Cavernous haemangiomas, epilepsy and treatment strategies.

BACKGROUND: Cavernous haemangiomas (cavernomas) are benign vascular malformations which can be found at any region within the central nervous system. Epilepsy is the most frequent manifestation of this malformation. Magnetic resonance imaging (MRI) used for the diagnostic evaluation of symptomatic seizures is a sensitive and specific method for the detection of cavernomas. Due to an increased application of MR imaging in the diagnostic evaluation of symptomatic seizures cavernomas have been found with increasing frequency over the past years. To achieve optimal treatment of patients with cavernous haemangiomas and epilepsy both medical and surgical treatment have to be considered. OBJECTIVE: This paper reviews published studies and presents our own results concerning current treatment schedules of epileptogenic cavernomas. RESULTS: In patients with intractable epilpesies surgical treatment of cavernomas seems to be the most successful antiepileptic therapy. Whether microsurgical lesionectomy, including the removal of only the cavernoma, or a more extensive resection is needed to achieve this aim are discussed. CONCLUSION: New data acquired with high-resolution imaging (MRI, PET) and electrophysiology indicate that magnetencephalography (MEG) may contribute to the delineation of epileptogenic tissue bordering the lesion, thus permitting appropriate inclusion of this specific area within the resection, instead of performing a simple lesionectomy.

Epilepsy↗

PubMed2004

Magnetoencephalography (MEG) predicts focal epileptogenicity in cavernomas.

OBJECTIVE: The aim of this study was to identify the irritative epileptic zone in patients with cavernomas by means of magnetoencephalography (MEG). METHOD: Among 82 patients operated for epilepsy, whose presurgical evaluation had included MEG, histological assessment of the tissue removed had confirmed cavernomas in eight. These eight patients had epilepsy since 18.6 (SD 12.7) years on average. The monitoring lasted about 2.1 (SD 1.3) hours and a median 20.9 (SD 14.3) spikes per hour were recorded. Spontaneous brain activity was recorded by means of a 74 channel dual unit MEG system (Magnes II, 4-D Neuroimaging) with simultaneous EEG recording (31 scalp electrodes). Spike analysis was performed using different source (moving dipole, current density reconstruction) and head models (spherical shells, BEM). Co-registration of neurophysiological and imaging data (MRI) was based upon anatomical landmarks. RESULTS: In 6/8 patients co-localisation from the cavernoma and epileptic zone was found. In two patients the focus was localised in the parieto-occipital lobe, in three patients in the frontal lobe and in three patients in the temporal lobe. In one case of temporal and one case of frontal lobe focus localisation there was no spatial relationship to the cavernoma. CONCLUSION: In cases of focal seizures due to a single cavernoma, MEG may precisely delineate the epileptogenic tissue bordering the lesion. In patients with multiple cavernomas or dual pathology, MSI may reveal the complexity of the case, and contribute to the decision about further invasive diagnostics and more sophisticated therapeutic measures. MEG is a promising method for prediction of the epileptic zone in cavernoma related epilepsies, and thus it can contribute to decision making about and planning of epilepsy surgery.

Adolescent↗

PubMed2003

1H-MR spectroscopy: a promising method in distinguishing subgroups in temporal lobe epilepsy?

Proton MR spectroscopy offers an additional noninvasive method of supporting focus lateralization in patients with intractable temporal lobe epilepsy. In this study involving 57 patients, the ability of multivoxel 1H-MRS to differentiate between mesial and lateral TLE was investigated in addition to its ability to lateralize the epileptogenic focus. Temporal lobe epilepsy (TLE) was classified into mesiobasal or lateral temporal lobe epilepsy according to the results of preoperative diagnostics including neurological and neuropsychological examinations, video-EEG monitoring and high resolution MRI. 1H-MR-spectroscopy (1H-MRS) showed that pathological changes in the mesial temporal lobes indicate a predominance in different parts of the ipsilateral temporal lobe (hippocampal and parahippocampal areas) correlating to the clinically defined groups. In addition, mesiobasal TLE tends to have higher concomitant contralateral abnormalities. Our results reveal that 1H-MRS is able to distinguish between mesiobasal and lateral pathologies in patients with TLE and represents a useful tool for noninvasive TLE classification.

Adult↗

PubMed2003

Magnetic brain source imaging of focal epileptic activity: a synopsis of 455 cases.

Epilepsy surgery is based upon the minute assessment of brain tissue generating epileptic activity. A number of diagnostic methods are employed in the process of presurgical evaluation, supplying information on various morphological and functional aspects, ultimately integrated into the general result fundamental to the final treatment decision. Magnetic source imaging (MSI), combining structural (MRI) and functional (MEG) data, has been playing an increasingly important role among the tools of presurgical epilepsy evaluation. However, in spite of a considerable number of publications, the samples used have hardly exceeded 50 cases. Therefore, we present a synopsis of 455 epilepsy patients who underwent MSI investigations. Analysis of this substantial data revealed that the average sensitivity of MEG for specific epileptic activity was 70%. Among 131 patients who underwent surgical therapy in addition to antiepileptic drug medication, MSI identified the lobe to be treated in 89%, with results for extratemporal cases being even superior to those with temporal lobe surgery. Introducing a measure to quantify the contribution of MSI to the general result of presurgical evaluation that was applied to 104 patients, the results showed that MSI supplied additional information in 35% and information crucial to final decision making in 10%. Accuracy as well as contribution findings underlined MSI appropriateness even for extratemporal epilepsies, which otherwise frequently prove difficult with respect to focus localization.

Adolescent↗

PubMed2003

[Is epilepsy in the elderly overlooked? An investigation in a home for the aged].

The symptoms of epileptic seizures in old patients differ from those in younger patients. Therefore, these seizures may be misinterpreted as symptoms of other "typical" diseases in old people. In an old people's home, we assessed whether a standardized questionnaire is able to reveal undiagnosed epilepsy in the elderly. Reported sudden falls, loss of consciousness, and cramps were the criteria for further diagnostic procedures. We found epilepsy in 11 of 389 study participants. In four of them (1% of the total sample), the epilepsy was newly diagnosed; five more cases remained unclear. Therefore, the total number of epileptic patients might have been even higher. Most of the reported sudden falls and unconsciousness (89%) were due to internal medical or other neurological or orthopaedic causes. Once these have been excluded, the diagnosis of epilepsy should be considered. The results of our pilot study suggest that epilepsy in old people's homes is often unrecognised. Early diagnosis and treatment of epilepsy in the elderly is important to improve prognosis and social consequences for affected persons.

Accidental Falls↗

PubMed2003

[Ictal signs--cerebral localization and propagation].

In this manuscript, ictal signs are reported with regard to their relevance concerning cerebral localization. Limitations of so-called silent brain regions in this respect are also discussed. As a simple aid for clinical diagnosis, the nuclear shell structure model is demonstrated.

Action Potentials↗

PubMed2003

Clinical applications of 1H-MR spectroscopy in the evaluation of epilepsies--what do pathological spectra stand for with regard to current results and what answers do they give to common clinical questions concerning the treatment of epilepsies?

Nuclear magnetic resonance spectroscopy (1H-MRS) is a non-invasive method in detecting abnormal spectra of various brain metabolites containing N-acetylaspartate (NAA), Choline (Cho), Creatine (Cr), gamma-Aminobutyric acid (GABA) and Glutamate. Technical processing of the MR-systems, improved automated shimming methods and further development of special shim coils increase the magnetic field homogeneity and lead to a better spectral quality and spectral resolution. The handling of the systems becomes more user-friendly and is more likely to be used in routine diagnostics. The 1H-MRS has become a diagnostic tool for assessing a number of diseases of the central nervous system mainly including epilepsies and brain tumours. The role of 1H-MRS in the assessment of epilepsies will probably increase in future. In the following article, the principles of 1H-MRS and an overview of it in the evaluation and treatment of epilepsies with special regard to temporal lobe epilepsies (TLE) has been illustrated.

Brain↗

PubMed2002

Somatosensory evoked magnetic fields following passive movement compared with tactile stimulation of the index finger.

Cortical processing of passive finger movement was assessed magnetoencephalographically in 12 healthy volunteers and compared with somatosensory evoked magnetic fields (SEF) following tactile stimulation. A new device comprising a clamp-like digit holder facilitated bilateral guidance of the briskly elevated index finger. Both passive movement and tactile stimulation induced activation of the contralateral primary somatosensory (SI) cortex, indicated by six SEF deflections with inter-individually rather consistent peak latencies of 20-230 ms following proprioceptive and 20-300 ms following tactile stimulation. SEF responses to the two stimulus modalities clearly differed with regard to peak latencies, amplitudes and orientations of equivalent current dipoles (ECDs). The strength and orientation of proprioception-related ECDs suggested sequential activation of SI generators, with possible involvement of areas 3a and/or 2 at around 20 ms, area 4 at approximate peak latencies of 65 and 100 ms and area 3b between 150 to 230 ms. Passive movement elicited additional activation of cortical regions outside SI, including the bilateral perisylvian regions and the contralateral cingulate gyrus at latencies of 40-470 and 150-500 ms respectively. The study provides new results with respect to the spatiotemporal analysis of proprioception-related cortical processing and may contribute to a better understanding of the modality-specific organization of the human somatosensory cortex.

Adult↗

PubMed2002

Influence of vagus nerve stimulation on histamine-induced itching.

OBJECTIVE: To investigate whether vagus nerve stimulation (VNS) reduces pruritus in humans. BACKGROUND: Recently, it has been shown that VNS has antinociceptive and antidepressant effects in humans. METHODS: Eleven patients were investigated before (baseline) and during chronic VNS treatment. The experiments were performed at two different stimulation intensities: 2 to 5 days after implantation at a low stimulation intensity (mean intensity 0.7 +/- 0.2 mA, second session) and after 8 to 14 weeks of VNS therapy (mean intensity 1.4 +/- 0.3 mA, third session). Twelve healthy age- and sex-matched subjects were investigated using the same experimental protocol. Itch was induced by histamine-iontophoresis and quantified on a visual analogue scale (VAS). Histamine-induced flare was quantified using laser-Doppler flowmetry. RESULTS: Itch was reduced by VNS from 24 +/- 8% VAS at baseline to 15 +/- 5% VAS at second session, and 19 +/- 8% VAS at third session (p < 0.05 multivariate analysis of variance). In the control group, itch remained unaltered in all three sessions (26 +/- 5% at baseline, 23 +/- 5% in the second session, and 25 +/- 5% in the third session, not significant). The flare was unaltered in both patients and control subjects. CONCLUSIONS: VNS may suppress pruritus in humans.

Adult↗

PubMed2002

Cerebral cavernous malformations: mutations in Krit1.

OBJECTIVE: To find mutations in the recently identified additional exons of the Krit1 gene that causes CCM1, a disease characterized by the formation of cerebral cavernous malformations (CCM). To determine the relative frequency with which Krit1 mutations cause CCM as well as recharacterize the mutations reported in the literature. METHODS: Twenty-seven families and 11 apparently sporadic individuals affected with CCM were screened for mutations in the Krit1 gene. The gene was screened by single stranded conformation polymorphism, and variants were sequenced. Familial segregation of the mutations was determined. RESULTS: In familial samples, two new mutations in the novel upstream exons and six additional mutations in the previously identified exons were identified. No mutation was found in any of the sporadic individuals. CONCLUSIONS: Results demonstrate that the frequency of mutations found in Krit1 is 47% in the families studied and the frequency may increase as more mutations are detected. Mutations are evenly distributed in the gene and do not seem to be limited to structural domains present in Krit1. This is in accordance with the model that Krit1 could be a tumor suppressor gene.

Ankyrin Repeat↗

PubMed2002

Fractionated stereotactically guided radiotherapy of pharmacoresistant temporal lobe epilepsy.

PURPOSE: This prospective study evaluated the efficacy of fractionated stereotactically guided radiotherapy (SRT) as a treatment of pharmacoresistant temporal lobe epilepsy. PATIENTS AND METHODS: Inclusion criteria were patients aged between 17 and 65 years with unilateral temporal focus, without sufficient epilepsy control by antiepileptic drugs or neurosurgery. Two groups of 6 patients each were treated with 21 Gy (7 times 3 Gy) and 30 Gy (15 times 2 Gy). Study end points were change in seizure frequency, intensity, seizure length and neuropsychological parameters. RESULTS: All patients experienced a marked reduction in seizure frequency. The mean reduction of seizures was 37% (range 9-77%, i.e. seizures reduced from a monthly mean number of 11.75 to 7.52) at 18 months following radiation treatment and 46% (23-94%, i.e. 0.2-23 seizures per month) during the whole follow-up time. Seizure length was reduced in 5 out of 11 patients and intensity of seizures in 7 out of 11 patients. CONCLUSION: Radiotherapy was identified as a safe and effective treatment for pharmacoresistant epilepsy since a good reduction of seizure frequency during longer follow-up was observed. SRT means an appropriate alternative for patients with contraindication against neurosurgery or insufficient seizure reduction after neurosurgery.

Adolescent↗

PubMed2002

[Goose flesh and cold sensation. Symptoms of visceral epilepsy].

Goose flesh and cold shiver can be ictal signs of visceral epilepsies. These visceral epilepsies may occur with isolated ictal signs during a simple partial seizure or in combination with other autonomic signs or in complex partial seizures. Because of the unusual features of the ictal symptomatology, these visceral epilepsies often are masked and wrongly diagnosed as nonepileptic events, e.g., somatoform disorders. Five cases are reported with case history, neurological findings, and results of electroencephalography, MEG, and imaging. Interestingly, patients did not suffer from tumoral epilepsies and the epileptic focus was lateralized to the left (dominant) temporal lobe.

Adolescent↗

PubMed2002

Progressive cognitive decline in epilepsy: an indication of ongoing plasticity.

In addition to the identification of epileptic syndromes associated with cognitive decline, the influence of suppression of secondarily generalized seizures on IQ is reviewed. Our own data concerning cognitive function in temporal lobe epilepsy show a decrease of IQ and verbal memory with long duration of epilepsy and frequent tonic-clonic seizures, but not with simple or complex partial seizures. The use of a 'nucleus shell structure model' may be helpful to visualize the dynamic changes ('running up') in seizure structures in the long-term course of epilepsies. In addition to the localization and extent of structural changes, functional monitoring of cognition and pathology of MR spectroscopy is now available for long-term studies in progressive epileptic disorders. Concepts for memory storage and consolidation and mechanisms of plasticity concerning epileptic activity as well as modification of long-term potentiation for plasticity with regard to memory functions are also discussed.

Disease Progression↗

PubMed2002

Ictal onset localization of epileptic seizures by magnetoencephalography.

OBJECTIVES: The aim of this study was to localize the ictal onset zone of focal epileptic seizures by magnetoencephalography (MEG) and to compare the results with interictal MEG localizations, ictal and interictal electroencephalography (EEG) results and magnetic resonance imaging (MRI) in epilepsy surgery candidates. MATERIALS AND METHODS: Data of 13 patients with partial seizures during MEG recording were analysed. Measurements were performed with a Magnes II dual unit system. RESULTS: In six of 13 cases, the ictal onset zone could be localized by MEG, with all interictal MEG findings being confirmed by ictal MEG results. In four cases, the ictal MEG localization results were corresponding to the ictal EEG localization results. In two cases, EEG yielded no comparable information. CONCLUSION: Ictal onset localization is feasible with MEG. Both interical and ictal MEG contribute valuable information to the presurgical assessment of epilepsy patients.

Adult↗

PubMed2002

Autonomic auras: left hemispheric predominance of epileptic generators of cold shivers and goose bumps?

PURPOSE: Autonomic seizures in temporal lobe epilepsies associated with "cold shivers and goose bumps" as a principal ictal sign or aura have only rarely been studied. METHODS: Sixteen patients with autonomic auras [cold shivers or cold sweats (n=11), goose bumps (n=4), one patient showed both ictal signs] were analyzed. RESULTS: Lesions were detected in 12 patients. The etiology was heterogeneous [cryptogenic, arteriovenous (AV)-malformation cyst, trauma, hippocampal sclerosis]. Eight patients underwent epilepsy surgery. The localization and lateralization of the focal epileptic activity in the temporal lobes was determined either by magnetic resonance imaging lesions, EEG, ictal signs, or single-photon emission computed tomography imaging. CONCLUSIONS: The patients with temporal lobe epilepsies associated with "cold shivers and/or goose bumps" showed a left hemispheric predominance of the focal abnormality in the temporal lobe.

Adult↗

PubMed2002

[Pharmacological treatment of epilepsies: progress during the last 10 years].

The pharmacological treatment of epilepsies represents an important domain of neurological therapeutical strategies and is not only important for specialized epilepsy centres, but for all hospital -and office-based neurologists. The choice of the right anticonvulsive drug is not always simple since the development of new drugs during the last 10 years offers a broad range of possibilities. Therefore, pharmacological treatment has become more sophisticated than it was with relatively few anticonvulsive drugs before. The new drugs are better tolerated and have less side effects, but more knowledge is required about the specific aspects of each drug. Pharmacology, pharmacocinetics, indication, dosage and side effects of the substances will be summarized and discussed.

Anticonvulsants↗