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S Knake

Publications and source records attributed to S Knake.

13 recordsLinked to original sources
PubMed2006

The value of multichannel MEG and EEG in the presurgical evaluation of 70 epilepsy patients.

OBJECTIVE: To evaluate the sensitivity of a simultaneous whole-head 306-channel magnetoencephalography (MEG)/70-electrode EEG recording to detect interictal epileptiform activity (IED) in a prospective, consecutive cohort of patients with medically refractory epilepsy that were considered candidates for epilepsy surgery. METHODS: Seventy patients were prospectively evaluated by simultaneously recorded MEG/EEG. All patients were surgical candidates or were considered for invasive EEG monitoring and had undergone an extensive presurgical evaluation at a tertiary epilepsy center. MEG and EEG raw traces were analysed individually by two independent reviewers. RESULTS: MEG data could not be evaluated due to excessive magnetic artefacts in three patients (4%). In the remaining 67 patients, the overall sensitivity to detect IED was 72% (48/67 patients) for MEG and 61% for EEG (41/67 patients) analysing the raw data. In 13% (9/67 patients), MEG-only IED were recorded, whereas in 3% (2/67 patients) EEG-only IED were recorded. The combined sensitivity was 75% (50/67 patients). CONCLUSION: Three hundred and six-channel MEG has a similarly high sensitivity to record IED as EEG and appears to be complementary. In one-third of the EEG-negative patients, MEG can be expected to record IED, especially in the case of lateral neocortical epilepsy and/or cortical dysplasia.

Adolescent↗
PubMed2006

[Suggestion for a new, patient-oriented epilepsy classification].

The recent proposal by the ILAE Task Force for Epilepsy Classification is a multiaxial, syndrome-oriented approach. Epilepsy syndromes--at least as defined by the ILAE Task Force--group patients according to multiple, usually poorly defined parameters. As a result, these syndromes frequently show significant overlap and may change with patient age. We propose a five-dimensional and patient-oriented approach to epilepsy classification. This approach shifts away from syndrome orientation, using independent criteria in each of the five dimensions similarly to the diagnostic process in general neurology. The main dimensions of this new classification consist of (1) localizing the epileptogenic zone, (2) semiology of the seizure, (3) etiology, (4) seizure frequency, and (5) related medical conditions. These dimensions characterize all information necessary for patient management, are independent parameters, and include information more pertinent than the ILAE axes with regard to patient management. All cases can be classified according to this five-dimensional system, even at initial encounter when no detailed test results are available. Information from clinical tests such as MRI and EEG are translated into the best possible working hypothesis at the time of classification, allowing increased precision of the classification as additional information becomes available.

Epilepsy↗
PubMed2005

Right hemispheric language dominance in a right-handed male with a right frontal tumor shown by functional transcranial Doppler sonography.

BACKGROUND: A 38-year-old, right-handed man with late-onset right frontal epilepsy due to a ganglioglioma and atypical right hemispheric language dominance is described. METHODS: Language dominance was investigated with functional transcranial Doppler sonography (fTCD), and language localization with functional magnetic resonance imaging (fMRI). RESULTS: During a word generation task, fTCD showed atypical right hemispheric language dominance, which was confirmed by fMRI using a semantic word comparison and a word stem completion task. This information helped to guide the resective procedure, which left the patient seizure-free and did not induce new deficits. CONCLUSION: Functional TCD appears to be a useful and reliable screening tool for determining hemispheric language dominance, even in patients with atypical language representation. Functional MRI may be used to confirm fTCD results and further localize eloquent cortex.

Adult↗
PubMed2005

3T phased array MRI improves the presurgical evaluation in focal epilepsies: a prospective study.

BACKGROUND: Although detection of concordant lesions on MRI significantly improves postsurgical outcomes in focal epilepsy (FE), many conventional MR studies remain negative. The authors evaluated the role of phased array surface coil studies performed at 3 Tesla (3T PA MRI). METHODS: Forty patients with medically intractable focal epilepsies were prospectively imaged with 3T PA-MRI including high matrix TSE T2, fluid attenuated inversion recovery, and magnetization prepared rapid gradient echo. All patients were considered candidates for epilepsy surgery. 3T PA-MRIs were reviewed by a neuroradiologist experienced in epilepsy imaging with access to clinical information. Findings were compared to reports of prior standard 1.5T MRI epilepsy studies performed at tertiary care centers. RESULTS: Experienced, unblinded review of 3T PA-MRI studies yielded additional diagnostic information in 48% (19/40) compared to routine clinical reads at 1.5T. In 37.5% (15/40), this additional information motivated a change in clinical management. In the subgroup of patients with prior 1.5T MRIs interpreted as normal, 3T PA-MRI resulted in the detection of a new lesion in 65% (15/23). In the subgroup of 15 patients with known lesions, 3T PA-MRI better defined the lesion in 33% (5/15). CONCLUSION: Phased array surface coil studies performed at 3 Tesla read by an experienced unblinded neuroradiologist can improve the presurgical evaluation of patients with focal epilepsy when compared to routine clinical 1.5T studies read at tertiary care centers.

Adolescent↗
PubMed2005

Motor cortex excitability in focal epilepsies not including the primary motor area--a TMS study.

It is unclear whether focal epilepsies chronically influence the processing of cortex distant to the epileptogenic zone. Therefore, motor cortex excitability was analysed in patients with temporal and extratemporal epilepsies whose epileptogenic zones did not include the primary motor area. Single and paired-pulse transcranial magnetic stimulation (TMS) was applied to the primary motor cortex in 20 healthy controls and 23 patients with focal epilepsy (39.4 +/- 13.2 years; 12 left, 11 right; 14 temporal, nine extratemporal: six frontal, three parieto-occipital) ipsi- and contralateral to the epileptogenic zone. In all patients, the epileptogenic zone did not include the primary motor cortex. The resting motor threshold (RMT), the cortical silent period (CSP), the intracortical inhibition [ICI; combined interstimulus intervals (ISI) 2 and 3 ms] and the intracortical facilitation (ICF; combined ISI 10 and 15 ms) were determined. The measures obtained ipsilateral to the epileptogenic zone were compared with those elicited in contralateral hemispheres and, in exploratory analyses, with controls using non-parametric tests, including Hodges-Lehmann estimates of median differences (HLE) with 95% confidence intervals (CI). In the patient group, the CSP elicited in the ipsilateral motor cortex (median 162.3 ms) was shortened compared with the contralateral CSP (median 174.6 ms; HLE 15.9 ms; CI 6.2, 27.0 ms; P = 0.002). This interhemispheric difference was more pronounced in extratemporal epilepsies (HLE 23.4 ms; CI -3.2, 67.6 ms) compared with temporal epilepsies (HLE 14.3 ms; CI 4.7, 26.2 ms). Patients with parieto-occipital epilepsies showed the greatest interhemispheric differences in CSP (HLE 33.5 ms) and patients with mesial temporal epilepsies the smallest (HLE 9.9 ms). No significant differences were found between ipsi- and contralateral RMT, ICI or ICF. In analyses of subgroups, the CSP was shorter in epileptic hemispheres of patients with extratemporal epilepsies (141.4 ms) than in controls (173.4 ms; HLE 40.0 ms; CI 3.2, 83.4 ms; P = 0.029). ICF was increased in epileptic hemispheres of extratemporal epilepsies (147.6%) compared with temporal epilepsies (114.6%; HLE 33.0%; CI 4.1, 68.3%; P = 0.038). The results suggest that focal epilepsies influence chronically distant cortex, leading to decreased inhibition and increased facilitation in the ipsilateral motor cortex even when the epileptogenic zone is apart from it. This alteration may be due to synaptic reorganization and appears to be more pronounced in extratemporal and neocortical temporal than in mesial temporal epilepsies. This may have diagnostic implications.

Adult↗
PubMed2003

Electrophysiology of focal clonic seizures in humans: a study using subdural and depth electrodes.

Focal clonic seizures are a frequent epileptic phenomenon. However, there are few data about their pathogenesis. Eleven patients with focal epilepsy who experienced focal clonic seizures during prolonged video-EEG monitoring were included in this study. Nine patients had subdural electrodes on the precentral gyrus and one patient had additional bilateral subthalamic nucleus (STN) depth electrodes. In five patients, the EEG was co-registered with the EMG of muscles which were involved in the clonic seizures. The frequency, pattern and evolution of the ictal EEG were analysed and their relationship to STN and EMG activity was studied. Focal clonic seizures were always associated with a polyspike-wave pattern in the EEG of the primary motor area (frequency range 1.6-3.4 Hz), while neighbouring electrodes not overlying the precentral gyrus showed different EEG patterns. At seizure onset, the ictal EEG derived from the precentral gyrus consisted of repetitive spiking for 8-28 s (median 19.5 s), accompanied by a continuous increase in muscle tone. This evolved to a pattern of polyspike-wave complexes which were associated with clinical clonus and lasted for 14-202 s (median 30.5 s). The clonic muscle contractions consisted of bursts of compound muscle action potentials (CMAPs) which occurred synchronously in agonistic and antagonistic muscles and were separated by periods of complete muscle relaxation. Each series of CMAPs followed the polyspikes in the EEG with a latency of 17-50 ms. The periods of muscle relaxation occurred during the EEG slow waves. Only some of the cortical spikes were followed by ipsilateral STN spikes. CMAPs followed the cortical polyspikes independently of whether or not STN spikes were seen. The study suggests that focal clonic seizures are focal tonic-clonic seizures. The epileptic clonus consisted of simultaneous contractions of agonistic and antagonistic muscles at regular intervals and was generated by localized polyspike-wave activity in cortical primary motor areas. Activation of the STN did not appear to be an essential component of clonic seizures.

Action Potentials↗
PubMed2001

[Lateralizing and localizing signs and symptoms of epileptic seizures: significance and application in clinical practice].

This report reviews the lateralising and localising signs of epileptic seizures in respect to the differential diagnosis of epilepsy. The lateralising value of epileptic signs and symptoms can frequently be derived from the neuroanatomy. Focal clonic, focal tonic, and versive seizures as well as ictal unilateral dystonia are associated with a seizure onset zone in the contralateral hemisphere. Postictal nose wiping is performed with the hand ipsilateral to the epileptogenic zone. Similarly, unilateral blinking points to an ipsilateral seizure onset. Automatisms with preserved consciousness, ictal speech, and vomiting correlate to an epileptogenic zone in the non-dominant hemisphere, while postictal dysphasia is produced by seizures arising from the dominant hemisphere. Lateralising and localising signs and symptoms of epileptic seizures are of great help in the differential diagnosis of epilepsy from the first diagnosis of epileptic events to presurgical video-EEG monitoring.

Brain↗
PubMed2001

Incidence of status epilepticus in adults in Germany: a prospective, population-based study.

PURPOSE: To determine the incidence and case-fatality rate of status epilepticus (SE) in adults in Hessen, Germany, we performed a prospective, population-based study from July 1997 through June 1999. METHODS: All adult patients residing within the zip-code area 35 (area-35) with SE were included. Area-35 had 743.285 adult inhabitants, including 123.353 adult inhabitants of the primary service area of the University Hospital Marburg (PS-area). Patients were reported by 16 hospitals in the area and were prospectively identified and carefully reviewed within 5 days by one of the authors. Based on the crude annual incidence of SE and a rate of underascertainment of 10% determined for the PS-area, the corrected, age-adjusted incidence of SE in area 35, more representative of the population of Germany, was calculated. RESULTS: The crude annual incidence in the PS-area was 15.8/100,000 [95% confidence interval (CI), 11.2-21.6]. The calculated, corrected, age-adjusted incidence of SE in area 35 was 17.1/100,000. It was higher for men compared with women (26.1 vs. 13.7) and for those aged 60 years and older (54.5 vs. 4.2/100,000, p < 0.0001). The etiology was mainly remote symptomatic due to cerebrovascular disease. Epilepsy was previously diagnosed in only 50% of the patients. The case-fatality rate was 9.3%. CONCLUSIONS: Based on our data, at least 14,000 patients would be affected by SE in Germany, associated with approximately 1,300 deaths annually. The incidence of SE in Germany is similar to that found in the white United States population. Furthermore, this study confirms the higher incidence of SE in male patients and in the elderly population. This may be due to a higher incidence of cerebrovascular disease in these subpopulations.

Adult↗
PubMed2000

Valproate-induced hyperammonemic encephalopathy in the presence of topiramate.

Two adult patients with focal epilepsy who tolerated valproate (VPA) well in different combinations of anticonvulsants developed hyperammonemic encephalopathy when treated with VPA in combination with topiramate (TPM). Topiramate may contribute to the increased ammonia level by its inhibition of carbonic anhydrase and cerebral glutamine synthetase, thereby facilitating VPA/TPM hyperammonemic encephalopathy. Recovery occurred after withdrawal of VPA or TPM.

Adult↗
PubMed2000

Autonomic seizures versus syncope in 18q- deletion syndrome: a case report.

PURPOSE: The 18q- deletion syndrome (18qDS) is frequently associated with cardiac anomalies. Patients with this syndrome may also have epilepsy, which presents certain diagnostic difficulties. This case report aims to illustrate these diagnostic problems, document the usefulness of heart rate-based seizure detection algorithms in this setting, and define the epilepsy syndrome associated with 18qDS. METHODS: Closed-circuit video electroencephalogram (EEG) monitoring using a heart rate-based seizure detection software was used to identify the event in question and to establish the diagnosis of epilepsy. Chromosomal analysis and magnetic resonance imaging (MRI) were used to further define the epilepsy syndrome. RESULTS: We report on a patient with an atrial septal defect, enlargement of the right heart, and incomplete right bundle branch block, who developed episodes of tachycardia, loss of consciousness, and pallor, for which he was amnesic. Chromosomal analysis demonstrated karyotype 46,XY,del(18)(q21.3). ish del(18)(wcp18+,D18Z1+) with a loss of the gene for myelin basic protein. MRI revealed multifocal dysmyelination. Video-EEG monitoring using an electrocardiogram (ECG)-triggered seizure detection software proved to be indispensable in detecting an autonomic seizure and establishing the correct diagnosis; the procedure also allowed for the definition of the epilepsy syndrome. The patient was treated with carbamazepine and remained seizure-free. CONCLUSIONS: Video-EEG monitoring using a heart rate-based seizure detection software can be helpful in diagnostically differentiating autonomic seizures from syncope. Dysmyelination due to loss of the myelin basic protein gene on 18q and cortical dysgenesis may be of pathogenic relevance.

Adult↗
PubMed1999

Tiagabine-induced absence status in idiopathic generalized epilepsy.

Several medications such as baclofen, amitriptyline and even antiepileptic drugs such as carbamazepine or vigabatrin are known to induce absence status epilepticus in patients with generalized epilepsies. Tiagabine (TGB) is effective in patients with focal epilepsies. However, TGB has also been reported to induce non-convulsive status epilepticus in several patients with focal epilepsies and in one patient with juvenile myoclonic epilepsy. In animal models of generalized epilepsy, TGB induces absence status with 3-5 Hz spike-wave complexes. We describe a 32-year-old patient with absence epilepsy and primary generalized tonic-clonic seizures since 11 years of age, who developed her first absence status epilepticus while treated with 45 mg of TGB daily. Administration of lorazepam and immediate reduction in TGB dosage was followed by complete clinical and electroencephalographic remission. This case demonstrates that TGB can induce typical absence status epilepticus in a patient with primary generalized epilepsy.

Adult↗