Search PubMed⌕ Search

Biomedical subjects

S Noachtar

Publications and source records attributed to S Noachtar.

At least 55 records · Page 3Linked to original sources
PubMed1999

18F-FDG PET studies in patients with extratemporal and temporal epilepsy: evaluation of an observer-independent analysis.

UNLABELLED: The aim of this study was to evaluate an observer-independent analysis of 18F-fluorodeoxyglucose (FDG) PET studies in patients with temporal or extratemporal epilepsy. METHODS: Twenty-seven patients with temporal epilepsy and 22 patients with extratemporal epilepsy were included in the study. All patients with temporal epilepsy and 7 patients with extratemporal epilepsy underwent surgical treatment. In patients who showed significant postoperative improvement (temporal, n = 23; extratemporal, n = 6), the epileptogenic focus was assumed to be located in the area of surgical resection. In extratemporal epilepsy patients who did not undergo surgery, the focus localization was determined using a combination of semiology, ictal and interictal electroencephalography, [99mTc]ethyl cysteinate dimer SPECT, MRI and [11C]flumazenil PET. Visual analysis was performed by two experienced and two less experienced blinded observers using sagittal, axial and coronal images. In the automated analysis after anatomic standardization and generation of three-dimensional stereotactic surface projections (SSPs), a pixelwise comparison of 18F-FDG uptake with an age-matched reference database (n = 20) was performed, resulting in z score images. Pixels with the maximum deviation were detected, summarized and attached to one of 20 predefined surface regions of interest. For comparison with 18F-FDG PET and MR images, three-dimensional overlay images were generated. RESULTS: In patients with temporal epilepsy, the sensitivity was comparable for visual and observer-independent analysis (three-dimensional SSP 86%, experienced observers 86%-90%, less experienced observers 77%-86%). In patients with extratemporal epilepsy, three-dimensional SSP showed a significantly higher sensitivity in detecting the epileptogenic focus (67%) than did visual analysis (experienced 33%-38%, each less experienced 19%). In temporal lobe epilepsy, there was moderate to good agreement between the localization found with three-dimensional SSP and the different observers. In patients with extratemporal epilepsy, there was a high interobserver variability and only a weak agreement between the localization found with three-dimensional SSP and the different observers. Although three-dimensional SSP detected multiple lesions more often than visual analysis, the determination of the highest deviation from the reference database allowed the identification of the epileptogenic focus with a higher accuracy than subjective criteria, especially in extratemporal epilepsy. CONCLUSION: Three-dimensional SSP increases sensitivity and reduces observer variability of the analysis of 18F-FDG PET images in patients with extratemporal epilepsy and is, therefore, a useful tool in the evaluation of this patient group. The benefit of this analytical approach in patients with temporal epilepsy is less apparent.

Adolescent↗
PubMed1998

[Semiologic classification of epileptic seizures].

Recent advances in epileptology and epilepsy surgery require revision of the currently used International Classification of Epileptic Seizures, which was published 1981. We present a classification of epileptic seizures which is based purely on the clinical seizure semiology. The advantages of a semiological seizure classification are stressed.

Brain Mapping↗
PubMed1998

Ictal technetium-99m ethyl cysteinate dimer single-photon emission tomographic findings and propagation of epileptic seizure activity in patients with extratemporal epilepsies.

Although ictal single-photon emission tomography (SPET) with technetium-99m ethyl cysteinate dimer (ECD) has a well-established role in the diagnostic evaluation of patients with temporal lobe epilepsy who are being considered for epilepsy surgery, its use in cases of extratemporal epilepsy is still limited. We investigated the influence of the propagation of extratemporal epileptic seizure activity on the regional increase in cerebral blood flow, which is usually associated with epileptic seizure activity. Forty-two consecutive patients with extratemporal epilepsies were prospectively evaluated. All patients underwent ictal SPET studies with simultaneous electroencephalography (EEG) and video recordings of habitual seizures and imaging studies including cranial magnetic resonance imaging and positron emission tomography with 2-[18F]-fluoro-2 deoxy-d-glucose. Propagation of epilptic seizure activity (PESA) was defined as the absence of hyperperfusion on ictal ECD SPET in the lobe of seizure onset, but its presence in another ipsilateral or contralateral lobe. Observers analysing the SPET images were not informed of the other results. PESA was observed in 8 of the 42 patients (19%) and was ipsilateral to the seizure onset in five (63%) of these eight patients. The time between clinical seizure onset and injection of the ECD tracer ranged from 14 to 61 s (mean 34 s). Seven patients (88%) with PESA had parieto-occipital epilepsy and one patient had a frontal epilepsy. PESA was statistically more frequent in patients with parieto-occipital lobe epilepsies (58%) than in the remaining extratemporal epilepsy syndromes (3%) (P<0.0002). These findings indicate that ictal SPET studies require simultaneous EEG-video recordings in patients with extratemporal epilepsies. PESA should be considered when interpreting ictal SPET studies in these patients. Patients with PESA are more likely to have parieto-occipital lobe epilepsy than seizure onset in other extratemporal regions.

Adolescent↗
PubMed1998

Gabapentin and carbamazepine affect eye movements and posture control differently: a placebo-controlled investigation of acute CNS side effects in healthy volunteers.

This prospective study examined the effects of the new antiepileptic drug (AED) gabapentin (GBP) compared to the standard AED carbamazepine (CBZ) and placebo (PLA) on eye movements, posture and finger force control in 12 healthy volunteers who received single doses of 600 mg GBP and 400 mg CBZ in a placebo-controlled, double-blind, cross-over, randomized trial. CBZ and GBP reduced almost equally (8% vs. 10%) the mean peak saccade velocity as compared to PLA (P < 0.05). CBZ, but not GBP, significantly prolonged the duration of saccades as compared to placebo (14-24%) (P < 0.05). GBP produced a greater maximal increase of body sway than CBZ with eyes open (P < 0.01) and eyes closed (P < 0.001). CBZ and GBP did not significantly influence control of grip force. CBZ effects were better correlated with plasma levels. Subjective side effects were more pronounced with CBZ than GBP. Although CBZ and GBP cause similar CNS side effects, the effects on eye movements and body sway were different. CBZ predominantly affects saccadic eye movements, whereas GBP had more impact on posture control. Thus, electro-oculography seems to be more appropriate in the detection of CBZ-induced side effects and posturography appears to be more sensitive in the detection of side effects associated with GBP.

Acetates↗
PubMed1998

Semiological seizure classification.

We propose an epileptic seizure classification based exclusively on ictal semiology. In this semiological seizure classification (SSC), seizures are classified as follows: a. Auras are ictal manifestations having sensory, psychosensory, and experiential symptoms. b. Autonomic seizures are seizures in which the main ictal manifestations are objectively documented autonomic alterations. c. "Dialeptic" seizures have as their main ictal manifestations an alteration of consciousness that is independent of ictal EEG manifestations. The new term "dialeptic" seizure has been coined to differentiate this concept from absence seizures (dialeptic seizures with a generalized ictal EEG) and complex partial seizures (dialeptic seizures with a focal ictal EEG). d. Motor seizures are characterized mainly by motor symptoms and are subclassified as simple or complex. Simple motor seizures are characterized by simple, unnatural movements that can be elicited by electrical stimulation of the primary and supplementary motor area (myoclonic, tonic, clonic and tonic-clonic, versive). Complex motor seizures are characterized by complex motor movements that resemble natural movements but that occur in an inappropriate setting ("automatisms"). e. Special seizures include seizures characterized by "negative" features (atonic, astatic, hypomotor, akinetic, and aphasic seizures). The SSC identifies in detail the somatotopic distribution of the ictal semiology as well as the seizure evolution. The advantages of a pure SSC, as opposed to the current classification of the International League Against Epilepsy (ILAE), which is actually a classification of electroclinical syndromes, are discussed.

Electroencephalography↗
PubMed1998

Platelet activation, epinephrine, and blood pressure in obstructive sleep apnea syndrome.

OBJECTIVE: There is an increased risk of patients with obstructive sleep apnea syndrome (OSAS) to have stroke or cardiac infarcts. Besides hypertension, epinephrine-induced platelet activation could be a further reason for the increased cardiovascular morbidity and mortality in OSAS. METHODS: During a 4-month period (August 1994 to December 1994) we recruited prospectively 76 patients referred for polysomnograms because of a suspected sleep disorder such as OSAS. RESULTS: Fifty patients had no respiratory events during sleep (non-OSAS), 19 patients had more than five but less than 50 obstructive apneas or hypopneas per hour of total sleep time (mild-to-moderate OSAS group), and seven patients had an apnea hypopnea index of more than 50 per hour of total sleep time (severe OSAS group). Blood pressure, plasma epinephrine levels, and P-selectin expression (as a marker for platelet activation) were measured in every patient at 9 PM and 6 AM (before and after the polysomnogram). There was a significant correlation of the apnea hypopnea index with 9 PM and 6 AM systolic and diastolic blood pressure, with 9 PM platelet activation, and with 6 AM epinephrine levels mainly due to high values in the severe OSAS group. CONCLUSIONS: Our results suggest that platelet activation, epinephrine, and high blood pressure play a role in the high prevalence of cerebrovascular and cardiovascular events in patients with OSAS.

Adult↗
PubMed1997

Ipsilateral median somatosensory evoked potentials recorded from human somatosensory cortex.

Somatosensory evoked potentials (SEP) to ipsilateral and contralateral median nerve stimulations were recorded from subdural electrode grids over the perirolandic areas in 41 patients with medically refractory focal epilepsies who underwent evaluation for epilepsy surgery. All patients showed clearly defined, high-amplitude contralateral median SEPs. In addition, four patients showed ipsilateral SEPs. Compared with the contralateral SEPs, ipsilateral SEPs were very localized, had a different spatial distribution, were of considerably lower amplitude, had a longer latency (1.2-17.8 ms), did not show an initial negativity, and were markedly attenuated during sleep. Stimulation of the subdural electrodes overlying the sensory hand area was associated with contralateral hand paresthesias, but no ipsilateral hand paresthesias, occurred. It was concluded that subdurally recorded cortical SEPs to ipsilateral stimulation of the median nerve (M) reflect unconscious sensory input from the hand possibly serving fast bimanual hand control. The anatomical pathway of these ipsilateral short-latency MSEPs is not yet known. Transcallosal transmission seems unlikely because of the short delay between the ipsilateral and contralateral responses in selected cases. The infrequent occurrence of ipsilateral subdurally recorded SEPs and their low amplitude and limited distribution suggest that they contribute very little to the short-latency ipsilateral median SEPs recorded on the scalp.

Adolescent↗
PubMed1997

Localization of epileptic auras induced on stimulation by subdural electrodes.

PURPOSE: This study evaluates the localization of stimulation-induced auras (SIA) and tries to determine whether the SIA can help to define the boundaries of resection in epilepsy surgery. METHODS: Using subdural grid electrodes, 31 patients with drug resistant focal epilepsy were examined in a retrospective and prospective study lasting 2 years. RESULTS: On stimulation by subdural electrodes, we elicited habitual auras in 16 patients (52%). The zone of SIA overlapped the epileptogenic lesion in 12 patients (75%), the EEG seizure onset zone in 12 patients (75%), and the irritative zone of interictal spikes in eight patients (50%). Postoperative results showed a significant correlation with the complete removal of the epileptogenic lesion (p < 0.001). Because the number of patients in the study was small, we could not find a significant correlation with the complete removal of the SIA zone, EEG seizure onset zone, and irritative zone. CONCLUSIONS: Our study confirms previous analyses which indicate that complete resection of the epileptogenic lesion is essential to achieve a good outcome. Frequent overlap of the SIA zone with the epileptogenic lesion and the EEG seizure onset zone indicates proximity of the SIA with the epileptogenic zone. Nevertheless, this study does not support the concept that the SIA zone and the EEG seizure onset zone have additional value in defining the boundaries of resection in epilepsy surgery. Three case presentations suggest that SIA result from facilitated pathways between the stimulated cortex, the epileptogenic zone around the lesion, and the symptomatogenic zone. Functional reorganization in the vicinity of the cortical lesion cannot be ruled out but was not seen in our patients. Thus, SIA often do not reflect the normal function of the stimulated underlying cortex.

Adolescent↗
PubMed1997

Epileptic negative myoclonus. Subdural EEG recordings indicate a postcentral generator.

We report a patient with epileptic negative myoclonus (ENM) presenting as status epilepticus of the right arm. The etiology was a cortical malformation in the contralateral postcentral gyrus. Electrical stimulation of the right median nerve revealed giant surface somatosensory evoked potentials. Subdural recordings, performed to plan epilepsy surgery, demonstrated that the epileptogenic zone was in the left postcentral gyrus. Repetitive left postcentral spikes were consistently followed by an EMG silent period in the right arm with a latency of about 20 to 30 msec. The silent period in the EMG reflected the negative myoclonus and lasted 30 to 340 msec, mostly between 100 and 200 msec. Spikes in other regions of the cortex did not elicit ENM. The amplitude and duration of the spikes correlated with the EMG silent period: the more cortex involved in the spike generation, the longer the duration of the silent period. This suggests that epileptic activation of postcentral cortex leads to an inhibition of tonic activity of motor neurons. Focal ENM may be related to a hyperexcitability of the postcentral cortex.

Adult↗
PubMed1996

[Costs of drug treatment of neurologic diseases: Parkinson disease, dystonia, epilepsy].

AIM: The costs of drug treatment were evaluated for Parkinson's disease, focal dystonias and epilepsy. METHODS: Retrospective analysis over a period of 12 months of 785 patients who visited regularly a neurological out-patient department. RESULTS: Drug treatment caused a mean annual expenditure of DM 3,920.- (US-($) 2590, pounds 1690) for Parkinson's disease (n = 409), DM 3,620.- (US-($) 2390; pounds 1550) for focal dystonias (n = 140) and DM 660.- (US-($) 435, pounds 280) for hemifacial spasm (n = 35) per patient.- In Parkinson's disease costs are dependent on the extent of the disease, the type involved and the presence or absence of motor fluctuations. In Hoehn and Yahr stage I we calculated costs of DM 2,230.- (US-($) 1470; pounds 960), in contrast to DM 11,870.- (US-($) 7830; pounds 5100) in Hoehn and Yahr stage V. The occurrence of fluctuations in motor ability increased annual costs to DM 6,010.- (US-($) 3970, pounds 2580); patients' treatment without motor fluctuations was cheaper (DM 2,700.-; US-($) 1780, pounds 1160).- The annual treatment costs of focal dystonias and facial hemispasm varied due to the location of the involuntary movement and the extent of symptoms: DM 4,900.- (US-($) 3300; pounds 2100) were calculated for the treatment of cervical dystonias, DM 1,480.- (US-($) 930; pounds 600) for the treatment of blepharo-spasm (oromandibular dystonia: DM 1,710.-; US-($) 1200; pounds 800) and DM 600.- (US-($) 470; pounds 300) for the treatment of facial hemispasm.- The drug treatment of epilepsy caused mean costs of DM 1,740.- (US-($) 1160; pounds 750) per year. There were marked differences concerning the different epileptic syndromes and types of seizure. CONCLUSION: Costs of drug treatment varied considerably in the three diseases depending on the course, the type and the different forms of the respective disease.

Adolescent↗
PubMed1996

Systematic testing of medical intractability for carbamazepine, phenytoin, and phenobarbital or primidone in monotherapy for patients considered for epilepsy surgery.

PURPOSE: To assess medical intractability in patients considered for restrictive epilepsy surgery. METHODS: Seventy-four patients received single drug treatment with carbamazepine (CBZ), phenytoin (PHT), and either phenobarbital (PB) or primidone (PRM). Medical intractability was established if seizure control was not obtained despite maximum tolerable doses of the drug. In all, 120 single drug treatments were administered with the drugs that has not been administered at maximal doses in monotherapy before the study. RESULTS: Complete seizure control was not achieved in any patient. However, 7 patients (9.5%) had significant seizure reduction of at least 80%. In 4 patients, only the third antiepileptic drug (AED) proved effective. CONCLUSION: The poor result of AED monotherapy in our patients may be attributed to the patients' long-standing chronic epilepsies and high seizure frequencies. Our findings suggest that despite the failure of one or two major AEDs in controlling seizures completely, further single drug treatment may still improve the quality of life in some patients who are candidates for epilepsy surgery.

Adolescent↗
PubMed1995

Palatal tremor of cortical origin presenting as epilepsia partialis continua.

Palatal tremor (PT) is frequently caused by brainstem lesions. The inferior olive plays a major role in the pathophysiologic mechanisms involved. We report a case of PT of cortical origin presenting as epilepsia partialis continua. EEG showed continuous left frontocentral epileptiform discharges and both single photon emission computed tomography (SPECT) and positron emission tomography (PET) showed focal hypoperfusion and hypometabolism in the corresponding location.

Adolescent↗
PubMed1995

Automatisms with preserved responsiveness: a lateralizing sign in psychomotor seizures.

This is a report of a 1-year prospective study to investigate how often automatisms occur with preserved responsiveness in psychomotor seizures. Responsiveness is usually impaired or lost when automatisms occur during psychomotor seizures. However, there are several anecdotal reports in the literature of patients who have automatisms with preserved responsiveness (APRs). We evaluated 123 patients with temporal lobe epilepsy (57 patients [46%] left-sided, 48 patients [39%] right-sided, and 18 patients [15%] bitemporal) with video/EEG monitoring, testing responsiveness by asking the patient to respond verbally and to follow motor commands. Seven patients (5.6%) had preserved responsiveness in the presence of prominent automatisms (lip smacking, swallowing). In 15 seizures, the responsiveness was adequately tested (3.6 questions per period of automatism). Average seizure duration was 71.6 +/- 14.8 seconds (range, 45 to 100 seconds). Average duration of automatisms was 59.5 +/- 13.5 seconds (range, 40 to 80 seconds). Ictal EEG was localized over the right temporal area in nine seizures, over the right hemisphere in five, and was nonlocalizable in one seizure. APRs never occurred in left-sided psychomotor seizures and occurred in 10% of the right temporal cases. In conclusion, APRs reliably lateralized to the right side in temporal lobe epilepsy.

Adult↗