[Show abstract][Hide abstract] ABSTRACT: Methohexital has replaced amobarbital during Wada testing at many centers. The objective of our study was to compare the use of methohexital and amobarbital during Wada testing regarding language and memory lateralization quotients as well as speech arrest times.
A chart review of 582 consecutive patients undergoing 1041 Wada-procedures was performed (left=60, right=63, bilateral=459). Language lateralization was calculated based on duration of speech arrest using a laterality index, defined as (L-R)/(L+R). Memory lateralization was expressed as percentage of retained objects and laterality quotient.
Language and memory lateralization revealed a similar distribution with amobarbital and methohexital. Speech arrest after left and right-sided injection was significantly longer in the amobarbital group as compared to the methohexital group. Language lateralization did not differ in the two groups. Percentage of retained memory items was higher in the methohexital group and there were fewer presented test items in the methohexital group.
Language and memory testing during the Wada test can successfully be performed with methohexital instead of amobarbital. The shorter half-life of methohexital allows repeated injections and shorter interhemispheric testing intervals, but also shortens the testing window.
[Show abstract][Hide abstract] ABSTRACT: Memory asymmetry scores are used in intracarotid amobarbital procedure (IAP) to predict memory outcome after anterior temporal lobectomy (ATL) in patients with temporal lobe epilepsy (TLE). Reversed asymmetry (RA) of memory scores occurs in a minority of patients, with better memory performance observed following contralateral injection. Left ATL patients with RA are reported to have poorer postoperative verbal memory outcome. Studies also suggest that dysphasia during language dominant left hemisphere injection may contribute to lower right-sided memory scores seen in RA.
To examine the role of dysphasia in RA and investigate the relationship between RA scores and memory outcome after ATL.
IAP asymmetry scores and duration of speech arrest following bilateral IAP injection were examined in 50 patients with unilateral left TLE. Postoperative memory outcome was examined in a subset of patients (n=31).
Thirty-nine percent of patients had RA on IAP. The duration of speech arrest after left injection was significantly longer in the RA group compared to the expected asymmetry (EA) group. RA was not associated with negative postoperative memory outcome.
In left TLE patients, RA of IAP memory scores does not preclude good postoperative memory outcome. Prolonged speech arrest after left injection may lower right side memory scores contributing to misleading RA. Memory asymmetry patterns are sensitive to IAP protocol effects; therefore, RA may not be a robust predictor of memory outcome following left ATL.
[Show abstract][Hide abstract] ABSTRACT: Dejerine and Benson and Geschwind postulated disconnection of the dominant angular gyrus from both visual association cortices as the basis for pure alexia, emphasizing disruption of white matter tracts in the dominant temporooccipital region. Recently functional imaging studies provide evidence for direct participation of basal temporal and occipital cortices in the cognitive process of reading. The exact location and function of these areas remain a matter of debate.
To confirm the participation of the basal temporal region in reading.
Extraoperative electrical stimulation of the dominant hemisphere was performed in three subjects using subdural electrodes, as part of presurgical evaluation for refractory epilepsy.
Pure alexia was reproduced during cortical stimulation of the dominant posterior fusiform and inferior temporal gyri in all three patients. Stimulation resulted in selective reading difficulty with intact auditory comprehension and writing. Reading difficulty involved sentences and words with intact letter by letter reading. Picture naming difficulties were also noted at some electrodes. This region is located posterior to and contiguous with the basal temporal language area (BTLA) where stimulation resulted in global language dysfunction in visual and auditory realms. The location corresponded with the visual word form area described on functional MRI.
These observations support the existence of a visual language area in the dominant fusiform and occipitotemporal gyri, contiguous with basal temporal language area. A portion of visual language area was exclusively involved in lexical processing while the other part of this region processed both lexical and nonlexical symbols.
[Show abstract][Hide abstract] ABSTRACT: [March 2008-Cleveland Case Report]. There is a well-described association between the occurrence of developmental tumors and the presence of cortical dysplasia in the neighboring brain tissue. The main surgical approaches in the treatment of medically refractory epilepsy related to such developmental tumors include a lesionectomy versus a tailored cortical resection, often guided by an invasive evaluation. This case report describes the surgical management of a 26-year-old female with olfactory auras evolving into automotor seizures and convulsions, occurring in the context of a right temporo-parietal developmental lesion. It illustrates the pros and cons of various surgical approaches, and discusses some pathophysiological aspects of developmental tumors, dysplasia and epilepsy. [Published with video sequences].
Full-text · Article · Apr 2008 · Epileptic disorders: international epilepsy journal with videotape
[Show abstract][Hide abstract] ABSTRACT: In evaluation of patients with complex partial seizures who are candidates for surgical treatment, exact definition of the epileptogenic focus is essential for a good surgical outcome. We report a new technique which permits detailed mapping of the epileptogenic activity in the basal temporal lobe and the convexity of the temporal lobe. The technique consists of placement of at least 16 basal temporal electrodes and an additional 64 electrodes covering the temporal convexity. This extensive coverage permits accurate definition of the limits of the epileptogenic focus and also of adjacent functional areas and therefore allows more significant determination than have previous techniques of the ideal extent of the surgical resection. This accuracy cannot be achieved with depth electrodes or the limited coverage provided by previously reported epidural or subdural electrode techniques.RÉSUMÉDans le bilan de patients présentant des crises partielles complexes et qui sont candidats à un traitement chirurgical, une définition exact du foyer épileptogène est essentielle dans la perspective d'un bon résultat post-opératoire. Les auteurs rappor-tent une nouvelle technique qui permet d'établir une topographie détaillée de l'activité paroxystique dans la région basale et la convexité du lobe temporal. Cette technique consiste à placer un minimum de 16 électrodes temporales basales et 64 électrodes supplémentaires sur la convexité temporale. Cette large couverture permet de défiinir précisément les limites du foyer ṕileptogene et des régions fonctionnelles adjacentes; elle permet done de déterminer avec une précision supérieure à celle des techniques antérieures l'extension idéale de la résection chirurgicale. Cette précision ne peut être obtenue par des électrodes pro-fondes ou par la couverture limitée fournie par les techniques antérieurement décrites utilisant des électrodes épi- ou sous-durales.RESUMENEn la evaluación de enfermos con ataques parciales comple-jos, considerados como candidates para tratamiento quirúrgico, resulta esencial la definicióm del foco epileptogénico para consequir unos resultados quirúrgicos de buena calidad. Se presenta una técnica nueva que permite conseguir un mapa detallado de la actividad epileptogénica en la región basal y en la convexidad del lóbulo temporal. Esta técnica consiste en la colocación de, al menos, 16 electrodos basales temporales y de 64 electrodos que cubren la convexidad del lóbulo temporal. Esta ámplia cobertura permite una válida definición de los límites de los focos epilep-togénicos y también de las áreas funcionales adyacentes que, por lo tan to, permite determinar con precisión, más fiable que con técnicas previas, la amplitud ideal de la resección quirúrgica. Esta exactitud no puede consequirse con electrodos profundos ni con el emplazamiento de electrodos epi o subdurales como ha sido previamente publicado.ZUSAMMENFASSUNGBei der Untersuchung der Patienten mit komplexen Partialan-fllen, die möglicherweise für eine chirurgische Behandlung in Frage kommen, ist eine genaue Abgrenzung des epileptogenen Fokus' unabdingbar für einen guten Operationserfolg. Wir be-richten über eine neue Technik, welche ein detailliertes Mapping der epileptogenen Aktivitt über der Basis und der Konvexitt des Temporallappens erlaubt. Die Technik umfaβt die Plazierung von wenigstens 16 basalen Elektroden und Weiteren 64 Konvex-ittselektroden. Diese dichte Besetzung erlaubt die akkurate Abgrenzung der Fokusregion sowie angrenzender funktioneller Ge-biete. Damit lβt sich mit signifikant besserer Zuverlssigkeit das Ausmaβ der vorgesehenen Resektion fest bestimmen. Die Genauigkeit kann weder mit Tiefenelektroden noch mit be-grenzten Ableitungen–wie kürzhch berichtet–durch epi- oder subdurale Elektroden-Technik erreicht werden.
[Show abstract][Hide abstract] ABSTRACT: Ictal asystole (IA) is a rare event mostly seen in patients with temporal lobe epilepsy (TLE) and a potential contributor to sudden unexplained death in epilepsy (SUDEP). Clinical and video-electroencephalographic findings associated with IA have not been described, and may be helpful in screening for high risk patients.
A database search was performed of 6,825 patients undergoing long-term video-EEG monitoring for episodes of IA.
IA was recorded in 0.27% of all patients with epilepsy, eight with temporal (TLE), two with extratemporal (XTLE), and none with generalized epilepsy. In 8 out of 16 recorded events, all occurring in patients with TLE, seizures were associated with a sudden atonia on average 42 seconds into the typical semiology of a complex partial seizure. The loss of tone followed after a period of asystole usually lasting longer than 8 seconds and was associated with typical EEG changes seen otherwise with cerebral hypoperfusion. Clinical predisposing factors for IA including cardiovascular risk factors or baseline ECG abnormalities were not identified.
Ictal asystole is a rare feature of patients with focal epilepsy. Delayed loss of tone is distinctly uncommon in patients with temporal lobe seizures, but may inevitably occur in patients with ictal asystole after a critical duration of cardiac arrest and cerebral hypoperfusion. Further cardiac monitoring in patients with temporal lobe epilepsy and a history of unexpected collapse and falls late in the course of a typical seizure may be warranted and can potentially help to prevent sudden unexplained death in epilepsy.
[Show abstract][Hide abstract] ABSTRACT: Frontal lobe epilepsy (FLE) surgery is the second most common surgery performed to treat pharmacoresistant epilepsy. Yet, little is known about long-term seizure outcome following frontal lobectomy. The aim of this study is to investigate the trends in longitudinal outcome and identify potential prognostic indicators in a cohort of FLE patients investigated using modern diagnostic techniques. We reviewed 70 patients who underwent a frontal lobectomy between 1995 and 2003 (mean follow-up 4.1 +/- 3 years). Data were analysed using survival analysis and multivariate regression with Cox proportional hazard models. A favourable outcome was defined as complete seizure-freedom, allowing for auras and seizures restricted to the first post-operative week. The estimated probability of complete seizure-freedom was 55.7% [95% confidence interval (CI) = 50-62] at 1 post-operative year, 45.1% (95% CI = 39-51) at 3 years, and 30.1% (95% CI = 21-39) at 5 years. Eighty per cent of seizure recurrences occurred within the first 6 post-operative months. Late remissions and relapses occurred, but were rare. After multivariate analysis, the following variables retained their significance as independent predictors of seizure recurrence: MRI-negative malformation of cortical development as disease aetiology [risk ratio (RR) = 2.22, 95% CI = 1.40-3.47], any extrafrontal MRI abnormality (RR = 1.75, 95% CI = 1.12-2.69), generalized/non-localized ictal EEG patterns (RR = 1.83, 95% CI = 1.15-2.87), occurrence of acute post-operative seizures (RR = 2.17, 95% CI = 1.50-3.14) and incomplete surgical resection (RR = 2.56, 95% CI = 1.66-4.05) (log likelihood-ratio test P-value < 0.0001). More than half of patients in favourable prognostic categories were seizure-free at 3 years, and up to 40% were seizure-free at 5 years, compared to <15% in those with unfavourable outcome predictors. These data underscore the importance of appropriate selection of potential surgical candidates.
[Show abstract][Hide abstract] ABSTRACT: To assess short- and long-term seizure freedom, the authors reviewed 371 patients who underwent anterior temporal lobectomy to treat pharmacoresistant epilepsy. The mean follow-up duration was 5.5 years (range 1 to 14.1 years). Fifty-three percent of patients were seizure free at 10 years. The authors identified multiple predictors of recurrence. Results of EEG performed 6 months postoperatively correlated with occurrence and severity of seizure recurrence, in addition to breakthrough seizures with discontinuation of antiepileptic drugs.
[Show abstract][Hide abstract] ABSTRACT: The purpose of this study was to determine the validity of abbreviated EEG montages for seizure detection during polysomnography. Three electroencephalographers reviewed files containing seizures or nonepileptic events using 8- and 18-channel montages. Files were rated as to whether they contained seizures and assigned a "probability of seizure" score from 0% to 100% reflecting the confidence that it was a seizure. Readers then localized seizures as temporal, frontal, parieto-occipital, or nonlocalized and provided a probability of correct localization with 0% to 100% confidence. Data were analyzed using the Adjusted McNemar Test method of Obochuwski. The probability of seizure score was measured using the receiver operating characteristic curve. Observed agreement was 78% and 84% for 8- and 18-channel montages, respectively. Readers were better able to distinguish seizures from nonepileptic events using the 18-channel montage (P = 0.004). Seizures localized to the temporal and parieto-occipital regions were more likely to be correctly identified and localized. Readers were able to correctly localize 27% and 49% of seizures using the 8- and 18-channel montages, respectively (P < 0.001). Abbreviated EEG montages are inadequate in the differentiation of seizures and nonepileptic events arising from sleep during polysomnography. This seems to be particularly true in frontal lobe epilepsy.
No preview · Article · Feb 2006 · Journal of Clinical Neurophysiology
[Show abstract][Hide abstract] ABSTRACT: Purpose: To study the correlation between histopathology and epileptogenicity, as measured by seizure frequency and electrocorticography (EcoG), in patients with cortical dysplasia (CD) as compared with control patients with gangliogliomas or gliomas.
Methods: The influence of the histopathological classification and the presence of balloon cells in CD on the frequency and extension of five predefined patterns of ECoG spiking, seizure frequency, age of seizure onset and 6-month postoperative outcome were analyzed in 32 patients with focal epilepsy undergoing presurgical evaluation with chronically implanted subdural electrodes.
Results: Comparison of patients with CD, gangliogliomas, and gliomas showed that the seizure frequency was greatest in patients with CD and ECoG spiking and was most extensive in patients with gangliogliomas. The onset of epilepsy was earlier in patients with CD and with gangliogliomas. None of these differences was significant. However, in patients with CD, the presence of balloon cells was associated with significantly greater seizure frequency (p = 0.009), and a significantly greater number of electrodes recording continuous frequent spiking (p = 0.03). The presence of continuous very frequent spiking correlated with the duration of the epilepsy and the number of seizures recorded during monitoring. No significant correlation was detected between histopathology, seizure frequency, or ECoG activity and postoperative outcome, which was relatively favorable in patients with balloon cells.
Conclusions: CD refers to a variety of histopathological patterns associated with different epileptogenicity. In CD, increased clinical and ECoG epileptogenicity correlates with the presence of balloon cells. This finding confirms that balloon cells should be considered in the histopathological classification of CD. The predefined ECoG were not specific for any of the histopathologies investigated.
[Show abstract][Hide abstract] ABSTRACT: To determine outcome after epilepsy surgery in patients with normal preoperative magnetic resonance imaging (MRI).
24 adult and paediatric patients with normal preoperative MRIs were studied. They underwent epilepsy surgery between 1994 and 2001 and had at least one year of follow up.
At the most recent follow up, nine patients (37%) were seizure-free and 18 (75%) had at least a 90% reduction in seizure frequency with weekly or monthly seizures. Seizure freedom was not significantly different after resections in frontal (5/9) or temporal regions (4/13) (p = 0.24, Fisher's exact test), or among patients with or without localising features on EEG, PET, or ictal SPECT. Subdural grids, used in 15 of 24 patients, helped tailor resections but were not associated with differences in outcome. Histopathology showed cortical dysplasia in 10 patients (42%), non-specific findings in 13 (54%), and hippocampal sclerosis in one (4%). Cortical dysplasia was seen in seven patients with frontal resection (78%) and non-specific findings in nine (69%) with temporal resection. Seizure outcome did not differ on the basis of location of resection or histopathology.
While these results were less favourable than expected for patients with focal epileptogenic lesions seen on MRI, they represented worthwhile improvement for this patient population with high preoperative seizure burden. In this highly selected group, no single test or combination of tests further predicted postoperative seizure outcome.
Full-text · Article · Jun 2005 · Journal of Neurology Neurosurgery & Psychiatry
[Show abstract][Hide abstract] ABSTRACT: To characterize non-epileptic seizures (NES) in the elderly and compare their features with NES of a younger control group.
The database of the epilepsy monitoring unit of the Cleveland Clinic Foundation (CCF) was searched for patients aged 60 years and older having undergone long-term video-/EEG monitoring between 1994 and 2002, with the subsequent diagnosis of NES. Videotapes of all events were evaluated by independent observers. NES were classified based on the clinical manifestations recorded on video, EEG and imaging data, and compared with a control group of younger adults with NES.
Thirty-nine elderly patients were included. Seventeen of them (44%) had NES only, six (15%) had both epilepsy and NES. The control group consisted of 20 patients, two of them had NES and epilepsy. The NES were classified as physiological in 10 elderly patients (43%) and one control patient. They included TIA, syncope, movement disorders and sleep disorders. Psychogenic NES were found in 13 elderly and 19 control patients and were associated with somatoform disorders, anxiety disorders, mood disorders and reinforced behavior pattern. Psychogenic NES consisted of predominant motor activity in 8 (61%) elderly and 13 (68%) control patients, unresponsiveness in 4 (31%) elderly and 2 (11%) control patients and subjective symptoms in 1 (8%) elderly and 4 (21%) control patients. Twelve (71%) of the patients of each group without evidence for epilepsy were on anticonvulsant drugs at the time of admission.
NES are a frequent problem in elderly patients referred to a comprehensive epilepsy center. In contrast to a younger control group, physiological and psychogenic NES are equally frequent in the elderly. Loss of responsiveness was seen in only 20% of patients with psychogenic NES. Although most of the patients did not have any evidence for epilepsy, more than two thirds of these patients had been placed on anticonvulsive drugs.
No preview · Article · Jul 2004 · Journal of Neurology
[Show abstract][Hide abstract] ABSTRACT: To describe the seizure semiology of patients older than 60 years and to compare it with that of a control group of younger adults matched according to the epilepsy diagnosis.
Available videotapes of all patients aged 60 years and older who underwent long-term video-EEG evaluation at the Cleveland Clinic Foundation (CCF) between January 1994 and March 2002 were analyzed by two observers blinded to the clinical data. A younger adult control group was matched according to the epilepsy diagnosis, and their seizures also were analyzed.
Fifty-four (3.3%) of the 1,633 patients were 60 years or older at the time of admission. For 21 of them, at least one epileptic seizure was recorded. Nineteen patients had focal epilepsy (nine temporal lobe, two frontal lobe, two parietal lobe, eight nonlocalized), and two patients had generalized epilepsy. Seventy-three seizures of the elderly patients and 85 seizures of the 21 control patients were analyzed. In nine elderly patients and 14 control patients, at least one of their seizures started with an aura. Eleven elderly patients and 19 control patients lost responsiveness during their seizures. Approximately two thirds of the patients in both groups had automatisms during the seizures. Both focal and generalized motor seizures (e.g., clonic or tonic seizures) were seen less frequently in the elderly.
Only a small percentage of the patients admitted to a tertiary epilepsy referral center for long-term video-EEG monitoring are older than 60 years. All seizure types observed in the elderly also were seen in the younger control group, and vice versa. Simple motor seizures were seen less frequently in the elderly.
[Show abstract][Hide abstract] ABSTRACT: A 55 year old left handed man with left hemisphere subcortical encephalomalacia, seizures, language impairment, and right hemiparesis from a motor vehicle accident at age five was evaluated for epilepsy surgery. The patient continued to speak and followed commands during a left intracarotid amobarbital test (IAT). Left functional hemispherectomy resulted in expressive aphasia. Based on postoperative outcome, language was bilateral. The injury after primary development of language function, the predominantly subcortical lesion, and the late timing of surgical intervention well past development and plasticity may have been factors in the emergence of postoperative aphasia.
Full-text · Article · Feb 2004 · Journal of Neurology Neurosurgery & Psychiatry
[Show abstract][Hide abstract] ABSTRACT: This chapter provides an overview of “eloquent cortex” and discusses the different aspects of cortical mapping. The important variables that ensure a safe and meaningful study of cortical function include the selection of electrodes, electrode placement, and electrical stimulus that can be reliably delivered to a discrete focal cortical area, and careful and objective recording of responses with clearly specified guidelines. Several mechanisms that could give rise to speech arrest during a stimulation study include stimulation of a positive area, stimulation of a negative motor area, stimulation of the cortex that elicits other distracting symptoms, alteration of consciousness, and stimulation of a language area. Electrical stimulation of the Broca's area may result in the impairment of speech output manifested as speech arrest, slowing of speech, alexia, agraphia, anomia, or paraphasia. These effects can be observed in isolation or in combination from one or more electrodes within the area. Electrical stimulation of Wernicke's area leads to comprehension deficits for auditory and visual stimuli. There are no associated negative motor responses in this area, thus suggesting that Wernicke's area appears to be an exclusive language center and that it is not involved in the organization of voluntary movement.
No preview · Article · Dec 2003 · Handbook of Clinical Neurophysiology
[Show abstract][Hide abstract] ABSTRACT: There is an extremely intimate relationship between sleep and epilepsy. In this manuscript I will review the influence that sleep has on epilepsy. Sleep is a potent activator of interictal epileptiform discharges. Sharp waves are infrequent during wakefulness in benign focal epilepsy of childhood, but may occur in runs of several discharges per page in sleep. The interictal discharges become almost continuous in non-REM sleep in the syndrome of encephalopathy with electrical status epilepticus during slow wave sleep. In some patients with West syndrome a hypsarrhythmia pattern may only appear in sleep whereas in others there may be an increase in discharges in a semiperiodic fashion resulting in a burst-suppression like pattern. Seizures appear to have a very close relationship with sleep in certain epilepsy syndromes. In benign focal epilepsy of childhood the seizures occur almost exclusively in sleep, while supplementary sensorimototor area seizures tend to occur in clusters during sleep. Juvenile myoclonic epilepsy has a close relationship with the sleep-wake cycle with seizures tending to occur predominantly on awakening. I also discuss the role of sleep and sleep deprivation in the EEG evaluation of epilepsy.
No preview · Article · Jan 2003 · Journal of Clinical Neurophysiology