Patrick Tugendhaft

Statistical parametric mapping of regional glucose metabolism in mesial temporal lobe epilepsy.

We investigated statistical parametric mapping (SPM) use for positron emission tomography (PET) with [(18)F]fluorodeoxyglucose (FDG) data analysis in mesial temporal lobe epilepsy. The study involved 14 patients with temporal lobe epilepsy ultimately treated by anterior temporal lobectomy. Surgical outcome in terms of seizure control was favorable in 12 patients. Two different SPM approaches were designed to analyze each FDG-PET scan: a direct comparison with a control group (n = 27) and a search for significant interhemispheric asymmetry considering the asymmetry existing in the control group. Statistical inference was performed, first, without correction for multiple comparisons (making the hypothesis of temporal hypometabolism) and, second, after correction for multiple comparisons. Search for temporal interhemispheric asymmetry under the hypothesis of temporal hypometabolism was the most reliable SPM approach: hypometabolism was identified on the side chosen for resection in most cases (sensitivity, 71%; specificity, 100%) and was predictive of favorable postsurgical outcome in 90% of the patients. There was no false-positive result within the control group using this approach. After correction for multiple comparisons, SPM also identified in some patients temporal hypermetabolic areas as well as extratemporal cortical and subcortical hypometabolic areas on the side of resection but also on the contralateral side. In a further step, SPM was used for a group analysis of patients with favorable outcome after reversing scans when needed to set an identical lateralization in all patients. This analysis identified multiple ipsilateral temporal and extratemporal hypometabolic regions; when temporal metabolic changes were specifically assessed, the contralateral mesiotemporal region was found hypermetabolic, possibly as a manifestation of compensatory mechanisms in the presence of a unilateral epileptogenic lesion.

Usefulness of prolonged video–EEG monitoring and provocative procedure with saline injection for the diagnosis of non epileptic seizures of psychogenic origin

ObjectivesTo assess the usefulness of long term video–EEG monitoring (VEEGM) and intravenous injection of saline solution (IVISS) for the diagnosis of non epileptic seizures of psychogenic origin (PNES).Background PNES are common among patients referred to an epilepsy center. Long term VEEGM remains the gold standard method for assessing the correct diagnosis. However, spontaneous PNES do not always occur during VEEGM, and a provocative test is often required. Although IVISS is the most commonly performed method, its usefulness is still debated.MethodsWe performed a long term VEEGM and an IVISS test the last day of the monitoring to each patient admitted to the Epilepsy Monitoring Unit of Erasme Hospital, Brussels, between October 2001 and February 2005 for suspicion of PNES. Patient charts were retrospectively reviewed.ResultsOf a total of 138 patients admitted to our center, 28 (20.3%) were referred for suspicion of PNES. There were 7 men and 21 women with a mean age of 35 years. Twenty–one patients (75%) had PNES during the VEEGM. Ten patients (36 %) had spontaneous PNES and positive IVISS.Nine patients (32 %) had no spontaneous PNES but a positive IVISS. Two patients (7 %) had spontaneous PNES and a negative IVISS.Among patients with PNES, 8 had also epileptic findings.ConclusionIVISS is a useful diagnostic tool since it was the only way to confirm the diagnosis of PNES in 32% of our patients. We suggest that investigation for the diagnosis of PNES should always include both a prolonged VEEGM and an IVISS test.

Long-term outcome of surgical disconnection of the epileptic zone as an alternative to resection for nonlesional mesial temporal epilepsy.

Background Pharmacoresistant epilepsy can be treated by either resection of the epileptic focus or functional isolation of the epileptic focus through complete disconnection of the pathways of propagation of the epileptic activity. Objective To evaluate long-term seizure outcome and complications of temporal lobe disconnection (TLD) without resection for mesial temporal lobe epilepsy (MTLE). Methods Data of 45 patients operated on for intractable MTLE using a functional disconnection procedure have been studied. Indication of TLD surgery was retained after a standard preoperative evaluation of refractory epilepsy and using the same criteria as for standard temporal resection. Results Mean follow-up duration was 3.7 years. At the last follow-up, 30 patients (67%) were completely seizure-free (Engel-Ia/International League Against Epilepsy class 1) and 39 patients (87%) remained significantly improved (Engel-I or -II) by surgery. Actuarial outcome displays a 77.7% probability of being seizure-free and an 85.4% probability of being significantly improved at 5 years. No patient died after surgery and no subdural haematoma or hygroma occurred. Permanent morbidity included hemiparesis, hemianopia and oculomotor paresis found in three, five and one patient, respectively, after TLD. Conclusions TLD is acceptable alternative surgical technique for patients with intractable MTLE. The results of TLD are in the range of morbidity and long-term seizure outcome rates after standard surgical resection. We observed a slightly higher rate of complications after TLD in comparison with usual rates of morbidity of resection procedures. TLD may be used as an alternative to resection and could reduce operating time and the risks of subdural collections.

Febrile seizures, early onset of temporal epilepsy and mesial temporal sclerosis

D. Schmidt et a1 (1) commenting on the peculiar incidence of febrile convulsions (FC) among intractable temporal epileptics suggest that such a figure may arise “possibly through the development of mesial temporal sclerosis” (MTS). A close look at the scarce clinical series in the literature certainly gives the same impression. The cumulative incidence of FC in the general population in the USA and Europe can be estimated as between 2.4% (2) and 3.6% (3). In the sub-population of epileptic patients this figure is increased to 19% (4) to 40% (5). In various selected groups of temporal lobe epileptics this incidence might even be higher, since Falconer and his colleagues reported in three successive operative series 23% (6, 7, 8), 17% (9) and 50% (lo) of FC lasting more than 30 min (without mentioning the others) whereas Ounsted et a1 described 32% of their patients starting in status associated with fever (11). When taking into account FC of any duration the incidence was 38% in the surgical series operated by Paillas (12) as well as in the medical series described by Hassan et a1 (13). Finally the incidence of initial febrile seizures among patients whose pathologic examination discloses mesial temporal sclerosis is as high as 40%, 30% and 82% for Falconer’s series (and pertaining only to prolonged FC). Falconer’s patients were intractable and since a major part of his three series was formed by mesial temporal sclerosis patients (47%, 47% and 55%) it is likely that this pathological subgroup represents the bias through which FC are overrepresented in intractable temporal epileptic groups. When febrile convulsions amidst temporal epileptics are acknowledged as a clinical clue for mesial temporal sclerosis it is indeed to be expected that, on a statistical basis, Schmidt’s patient, with such antecedents had an earlier onset of epilepsy. Cavanagh & Meyer (14) stated as early as 1956 that patients with “Ammon’s horn sclerosis” had an earlier onset of seizures than those without this histological feature. Taylor & Ounsted (15) stated that “the age of onset in cases proven to have mesial temporal sclerosis was almost entirely limited to the first decade of life and largely to the first quinquennium”, whereas onsets in other pathology groups were more or less randomly distributed over five decades. These authors (I]) , commenting on Cavanagh & Meyer’s study, report that “the group with Ammon’s horn sclerosis showed a remarkably high incidence (64%) of status epilepticus in the first few years of life, whereas the group without a history of status were generally of late onset and were not found to have Ammon’s horn sclerosis. Cavanagh & Meyer state that the initial status epilepticus was commonly in the setting of an acute febrile episode that is to say, it was a severe febrile convulsion”. These data, and others, tend to delineate a nosological entity closely associating antecedents of febrile convulsions, early onset of complex partial seizures and mesial temporal sclerosis eventually disclosed after temporal lobectomy or autopsy. This could be of some relevance in the preoperative evaluation of intractable temporal epileptics, since MTS patients are known to benefit on a large scale from surgery.

Evaluation of Anoxic Brain Damage

Patients successfully resuscitated from cardiorespiratory arrest endure anoxic and ischaemic insult of the central nervous system. The extent of brain damage determines the chances and qualitiy of survival of those patients whose hemodynamic state can be restored. Anoxic neuronal lesions occur predominantly in the cerebral and cerebellar cortex because neurons in those areas are more sensitive to anoxia. This selective vulnerability of neurons to anoxia and relative sparing of brainstem structures is probably the reason why the vegetative state more frequently follows anoxia than any other cause of nontraumatic coma [6]. The prognosis of patients in vegetative state with spontaneous eye epening, normal brainstem reflexes but without cognition is difficult to ascertain within the first days of coma [2]. Thus in contrast to brain death, a widely accepted criterion of death in medical, legal and public opinion today many medical, judicial and moral questions concerning the vegetative state remain unsolved.