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Biomedical subjects

M L Scheuer

Publications and source records attributed to M L Scheuer.

11 recordsLinked to original sources
PubMed2001

Extraction and analysis of early ictal activity in subdural electroencephalogram.

Subdural electroencephalograms (SEEGs) are of great value in localizing primary epileptogenic regions in patients undergoing evaluation for focal resective epilepsy surgery. The data segments which contain a transition from interictal to ictal activity carry the most critical diagnostic information. Computer signal extraction within this transition period represents a challenging signal processing problem. In this work a two-step method is presented to extract early ictal activity. In the first step we employ a nonlinear signal decomposition technique in the wavelet domain to separate SEEG data into ictal and background components. In the second step we use time-frequency analysis and a novel integration algorithm to extract the desired information. Our experiments on clinically recorded data indicate that this method is highly effective allowing us to reveal important hidden features in the data which could not otherwise be observable.

Adult↗
PubMed2000

Planned ictal FDG PET imaging for localization of extratemporal epileptic foci.

PURPOSE: This work demonstrates the feasibility of planned ictal positron emission tomography (PET) with [18F]fluoro-2-deoxy-glucose (FDG) for localization of epileptic activity in patients with frequent partial seizures of extratemporal origin. METHODS: Ictal PET imaging was performed in four patients (two men and two women, ages 28-61) with continuous or very frequent (every 3-15 min) partial seizures. All patients had abnormalities apparent on magnetic resonance (MR) or computed tomographic (CT) imaging, two with extensive brain lesions that precluded precise localization of the seizure focus with interictal PET or single-photon emission tomography (SPECT) imaging. RESULTS: Ictal PET imaging demonstrated a restricted area of focal hypermetabolism concordant with surface electroencephalographic (EEG) recording in all cases. The PET images were registered to MR imaging data for further anatomic localization of hypermetabolic regions in three cases. The ictal PET data were used to guide neurosurgical intervention in one case. CONCLUSIONS: We conclude that planned ictal PET imaging may be a useful and potentially superior approach to ictal SPECT for identifying the epileptic focus in a selected group of patients with continuous or frequent simple partial seizures.

Adolescent↗
PubMed1999

Spike detection II: automatic, perception-based detection and clustering.

OBJECTIVES: We developed perception-based spike detection and clustering algorithms. METHODS: The detection algorithm employs a novel, multiple monotonic neural network (MMNN). It is tested on two short-duration EEG databases containing 2400 spikes from 50 epilepsy patients and 10 control subjects. Previous studies are compared for database difficulty and reliability and algorithm accuracy. Automatic grouping of spikes via hierarchical clustering (using topology and morphology) is visually compared with hand marked grouping on a single record. RESULTS: The MMNN algorithm is found to operate close to the ability of a human expert while alleviating problems related to overtraining. The hierarchical and hand marked spike groupings are found to be strikingly similar. CONCLUSIONS: An automatic detection algorithm need not be as accurate as a human expert to be clinically useful. A user interface that allows the neurologist to quickly delete artifacts and determine whether there are multiple spike generators is sufficient.

Adolescent↗
PubMed1998

Cross-country digital EEG survey 1998.

A survey of digital EEG (DEEG) in clinical practice was recently completed by electroencephalographers in North America. Most had used DEEG for 3 or more years. They clearly preferred digital to analog EEG. The cost of operating DEEG was lower, and DEEG laboratories were more efficient. Reformatting was considered the best single feature of DEEG. However, problems continued to be encountered with equipment, service, and networking.

Electroencephalography↗
PubMed1998

Determination of lamotrigine in biologic materials by a simple and rapid liquid chromatographic method.

Lamotrigine (LTG), a newly introduced antiepileptic drug, appears to have potential therapeutic advantages for the treatment of patients with partial-onset seizures. Increasing clinical application and research of LTG demand a simpler and more rapid analytical procedure to determine LTG concentration in body fluids and tissues. The authors have developed an effective one-step procedure for sample preparation followed by high-performance liquid chromatography (HPLC) to quantitate LTG in plasma, urine, and brain tissues. Body fluids and brain homogenates were treated with cold acetonitrile to precipitate protein. The samples were fractionated on a 250 x 4.6 mm C18 reversed-phase column with an isocratic mobile system consisting of potassium phosphate buffer, acetonitrile, and methanol (70:16:14). The method had a LTG detection limit of 0.02 microg/ml in plasma and 0.03 microg/ml in urine. The coefficients of variation were <2.7% for intraday and 4.2% for interday analyses. The recovery of LTG added to plasma, urine, and brain homogenate ranged from 98% to 100%. The method was applied to a clinical study to determine plasma and urine concentrations of LTG in subjects receiving a single oral dose of LTG. The calculated pharmacokinetic parameters were comparable to those previously reported. The method proved to be simple, fast, reproducible, and useful in clinical investigation and monitoring of LTG concentrations.

Acetonitriles↗
PubMed1997

Recognition and classification of seizures in infants.

PURPOSE: We wished to assess the reliability of the International League Against Epilepsy (ILAE) seizure classification system applied to infantile seizures and to test a proposed new classification. METHODS: We first analyzed 39 seizures in 20 infants (aged 1-26 months) recorded with simultaneous closed-circuit television and EEG (CCTV/EEG). EEGs and videotapes of all seizures were independently analyzed by two epileptologists blinded to clinical histories. Videotapes of each seizure were reviewed without simultaneous EEG (phase 1), and printouts of ictal EEGs were assessed without behavioral correlates (phase II). The observers classified seizures according to ILAE criteria. Interrater agreement was assessed by the kappa statistic. RESULTS: Agreement on EEG features (phase II) was moderate (= 0.54) in identifying focal ictal onsets and substantial (= 0.79) in identifying generalized onsets. In contrast, analysis of videotapes showed substantial disagreement between observers in terms of classifying seizures as partial or generalized. Therefore, agreement between observers for partial was slight (= 0.14) and fair for generalized seizures (= 0.26). Similarly, conclusions of the observers as compared with those of a consensus panel were divergent for both partial (= 0.18) and generalized seizures (= 0.30). We therefore developed an alternative classification scheme and retested interrater agreement in a review of 50 seizures in 25 other infants. With this classification scheme, there was substantial agreement between observers (= 0.72). CONCLUSIONS: With clinical observations and interictal EEGs, seizures in infants cannot be reliably classified by current ILAE criteria. In contrast, a proposed new classification scheme based solely on semiology showed substantial reliability.

Age Factors↗
PubMed1995

Localization of a gene for partial epilepsy to chromosome 10q.

There is strong evidence for a genetic contribution to epilepsy, but it is commonly assumed that this genetic contribution is limited to 'generalized' epilepsies, and that most forms of 'partial' epilepsy are nongenetic. In a linkage analysis of a single family containing 11 affected individuals, we obtained strong evidence for localization of a gene for partial epilepsy. This susceptibility gene maps to chromosome 10q, with a maximum two-point lod score for D10S192 of 3.99 at theta = 0.0. All affected individuals share a single haplotype for seven tightly linked contiguous markers; the maximum lod score for this haplotype is 4.83 at theta = 0.0. Key recombinants place the susceptibility locus within a 10 centimorgan interval.

Adolescent↗
PubMed1995

Outcome after diagnosis of psychogenic nonepileptic seizures.

Information regarding outcome in patients with psychogenic nonepileptic seizures (PNES) is limited. We attempted to contact 72 consecutive patients with PNES confirmed by video-EEG monitoring: 51 of 72 (71%) were reached a mean of 15 months (range 12-27 months) after diagnosis and agreed to answer a structured telephone questionnaire. The questionnaire assessed the number of PNES in the last 6 months, antiepileptic drug (AED) use, occupational status, global self-rating, and extent of psychotherapeutic treatments. PNES had ceased in 18 of 51 (35%), decreased > 80% in 21 of 51 (41%), and decreased < 80% in 12 of 51 (24%). Thirty-three of 51 (65%) were not taking AEDs. Occupational status improved in 20% and did not change in 75%. Overall, 29 of 51 (57%) rated themselves markedly improved and 15 of 51 (29%) rated themselves unchanged or worse. Persisting PNES were associated with longer duration of PNES before diagnosis (p < 0.02) and presence of additional psychiatric disease (p < 0.01). Persisting PNES were not associated with gender, presence of epileptic seizures, or extent of psychotherapeutic treatments after diagnosis. Placebo saline infusion had been administered in some patients to help precipitate PNES. This did not affect the number of psychotherapy visits or outcome. We conclude that PNES cease or significantly decrease in most patients, but occupational status does not improve as often. Earlier diagnosis may improve outcome.

Anticonvulsants↗
PubMed1993

Reliability of seizure classification using a semistructured interview.

Methods for standardized classification of epileptic seizures are important for both clinical practice and epidemiologic research. In this study, we developed a strategy for standardized classification using a semistructured telephone interview and operational diagnostic criteria. We interviewed 1,957 adults with epilepsy ascertained from voluntary organizations. To confirm and expand the seizure history, we also interviewed a first-degree relative for 67% of subjects and obtained medical records for 59%. Three lay reviewers used all available information to classify seizures. To assess reliability, each reviewer classified a sample of subjects assigned to the others. In addition, an expert physician classified a sample of subjects assigned to two of the reviewers. Agreement was "moderate-substantial" for generalized-onset seizures, both for the comparisons between pairs of lay reviewers and for the neurologist versus lay reviewers. Agreement was "substantial-almost perfect" for partial-onset seizures, both for pairs of lay reviewers and for the neurologist versus lay reviewers. These results suggest that seizures can be reliably classified by lay reviewers, using operational criteria applied to symptoms ascertained in a semistructured telephone interview.

Adolescent↗
PubMed1993

Seizures and epilepsy in the elderly.

Recent data indicate that the incidence and prevalence of seizures and epilepsy rise substantially in the elderly. Little well-founded information is available on which to base treatment decisions. This article discusses cause, diagnostic evaluation, and antiepileptic drug pharmacology. Tentative treatment suggestions are offered, emphasizing the limits of available knowledge.

Aged↗