The choice of antiepileptic drugs in newly diagnosed epilepsy: a national French survey

The choice of an antiepileptic drug (AED) in patients with epilepsy is mainly based on efficacy and safety of each drug. However, these criteria of drug selection should be further evaluated according to the epileptic syndromes, and adjusted to the sex and age of the patient. Unfortunately, very few studies have been conducted based on these latter criteria. We conducted a survey on the management of epilepsy treatment in adults. This survey was undertaken in France, and led to the establishment of a French consensus on antiepileptic drug treatment in adult patients with newly diagnosed epilepsy. Patients were grouped into 18 categories according to the epileptic syndrome (absence epilepsy, juvenile myoclonic epilepsy, undetermined idiopathic generalized epilepsy, symptomatic or cryptogenic partial epilepsy and unclassified epilepsy), and to the patient's gender and age. Our survey suggests that there is a consensus among French epileptologists for the choice of AEDs, mainly based on the epilepsy syndrome. Gender also plays a crucial role. Sodium valproate and lamotrigine are the two drugs of choice for generalized epilepsies, as well as for undetermined epilepsies. Lamotrigine is often prefered for women of childbearing age. First line AEDs in partial epilepsy are carbamazepine (particularly for men), lamotrigine (particularly for women), and gabapentin (in the elderly). In cases of failure and/or intolerance to one of these AED, the principal alternatives are oxcarbazepine, sodium valproate and topiramate.

PET evidence for a role of the basal ganglia in patients with ring chromosome 20 epilepsy

BACKGROUND

Studies in animal models and epileptic patients have suggested that circuits of the basal ganglia may control epileptic seizures and that striatal dopaminergic transmission plays a key role in seizure interruption. Ring chromosome 20 (r[20]) epilepsy is a very homogenous type of epilepsy and is clinically characterized by long-lasting seizures suggesting a dysfunction in the seizure control system. The hypothesis that these long-lasting seizures are associated with a reduction of striatal dopamine was addressed in the present study in drug-resistant patients with r(20) epilepsy using PET.

METHOD

The authors performed [18F]fluoro-l-DOPA PET in 14 patients with r(20) epilepsy and compared uptake constants in the putamen and the caudate with those of 10 controls. In addition, the authors examined the correlation between these constants and the percentage of cells with r(20) mosaicism.

RESULTS

[18F]fluoro-l-DOPA uptake was significantly decreased bilaterally in the putamen and in the caudate nucleus of patients. This reduction was equal for both nuclei and was not correlated to the percentage of cells with r(20).

CONCLUSION

Striatal dopamine is modulated in r(20) epilepsy; dysfunction of this neurotransmission may impair the mechanisms that interrupt seizures.

[Cost-effectiveness of epilepsy surgery in a cohort of patients with medically intractable partial epilepsy--preliminary results]

OBJECTIVE

Patients with medically intractable epilepsy are potential candidates for surgery if the epileptogenic tissue is localized and resectable. Surgical therapy can eliminate seizures but is very expensive. We followed a prospective adult cohort of intractable epileptic patients in order to perform a cost-effectiveness analysis.

POPULATION AND METHODS

Adult patients with a suspected partial medically intractable and operable epilepsy were eligible for evaluation, explorations and/or surgery. Clinical and economical data were collected at the inclusion and every 6 months over at least two years. Two patient groups were analyzed: some underwent a surgery, others did not. Clinical data were compared between both groups. As the data collection was not yet complete, we compared the surgery to a continuation of the preoperative medical management in a cost-effectiveness analysis. Direct medical and nonmedical costs were evaluated according to a societal perspective. The effectiveness was defined as one year without seizure. We assessed the incremental cost-effectiveness ratio (ICER) for the first two years after the surgery. We also modeled long-term costs and effectiveness and extrapolated the results over the patients' lifetime with a Markov model. We computed the ICER and performed a sensitivity analysis. Indirect costs were measured in physical units and intangible costs were assessed with quality-of-life measures (QOLIE-31, SEALS). Data were compared before and after surgery.

RESULTS

Among the 286 patients included, 119 did not enter in the analysis: 7 were not eligible, 44 not operable, 31 did not present a follow-up, 37 still underwent exams. Finally, 89 underwent a surgical treatment, and 78 were medically treated. Disease was more severe in surgical patients than in medical patients: seizures frequency, depressive disorders and cognitive impairment were greater. One year after the surgery, 83% patients were seizure free. During the year before inclusion and the year after surgery, direct costs were mainly due to hospitalization. During the second year after surgery, the cost of antiepileptic drugs predominated. One additional year without seizure costs 23 531 euro one year after surgery and 9533 euro two years after surgery. In a long-term perspective, the surgery became cost-effective between 7 and 8 years after the surgery.

CONCLUSION

Surgical therapy is a cost-effective treatment in a middle-term even without indirect costs consideration.

Metabolic changes and electro-clinical patterns in mesio-temporal lobe epilepsy: a correlative study

Interictal hypometabolism is commonly found in mesio-temporal lobe epilepsy (MTLE), but its pathophysiology remains incompletely understood. We hypothesized that metabolic changes reflect the preferential networks involved by ictal discharges. We analysed the topography of interictal hypometabolism according to electro-clinical patterns in 50 patients with unilateral hippocampal sclerosis (HS) and consistent features of MTLE. Based on electro-clinical correlations, we identified four groups: (i) mesial group (13 cases) characterized by mesial seizure onset without evidence of early spread beyond the temporal lobe; (ii) anterior mesio-lateral group (AML; 18 cases) with early anterior spread involving the anterior lateral temporal cortex and insulo-fronto-opercular areas; (iii) widespread mesio-lateral group (WML; 15 cases) with wide spread (involving both anterior and posterior lateral temporal and perisylvian areas); and (iv) bitemporal (BT) group (four cases) with early contralateral temporal spread. Results of [18F]fluorodeoxyglucose-PET imaging in each group were compared with those of 10 control subjects using statistical parametric mapping software (SPM99). MRI data and surgical outcome in each group were compared with metabolic findings. Hypometabolism was limited to hippocampal gyrus, temporal pole and insula in the mesial group. Gradual involvement of lateral temporal cortex, insula and perisylvian areas was observed in the AML and WML groups. The BT group differed from the others with mild bitemporal involvement, bilateral insular hypometabolism and longer epilepsy duration. MRI structural abnormalities outside of the mesial formations were detected in 65% of the cases. Neither the severity of HS nor temporal atrophy appeared related to the topography of hypometabolism. However, temporal hypometabolism was more extended when temporo-polar signal changes were detected. Among operated patients (n = 43), seizure-free outcome was obtained in 82%. Surgical outcome appeared more favourable in the mesial group. However, the difference between the four groups was not significant. Our results suggest that hypometabolism in MTLE may be related to ictal discharge generation and spread pathways, even if structural changes and epilepsy duration may also play a role.

Functional anatomy of the insula: new insights from imaging

Little is known about the functional anatomy of the insula. Several experimental data suggest that the organization of the insular connections from the different insular cytoarchitectonic regions is related to different functional domains within the insula, and recent electrophysiological and neuroimaging studies have shown the existence of an anterior-posterior organization within the insular cortex. To further investigate this point, we carried out a positron emission tomography (PET) study using fluorodeoxyglucose ((18)F-FDG) in patients with medial temporal lobe epilepsy who experienced emotional or visceral symptoms that are supposed to be elicited in the insula. The aim of our study was to assess the existence of a functional insular somatotopic organization. FDG-PET studies were carried out in 18 epileptic patients. Data were analyzed using statistical parametric mapping (SPM96). The results showed that the emotional symptoms were correlated with hypometabolism in the anterior part of the ipsilateral insular cortex, while visceral symptoms were correlated with hypometabolism in the posterior part ( p=0.001). This neuroimaging study demonstrates that the anterior part of the insular cortex corresponding to the agranular cortex subserves emotional functions while the posterior part of the insular cortex corresponding to the granular cortex subserves ascending visceral symptoms.

Early and late seizures after cryptogenic ischemic stroke in young adults

OBJECTIVES

To assess the incidence and predictive factors of early and late seizures after ischemic stroke in young adults.

METHODS

A total of 581 patients (aged 18 to 55 years) with recent cryptogenic ischemic stroke were prospectively enrolled at 30 neurology departments and followed for 37.8 +/- 9.7 months. Early seizures (occurring within 7 days of stroke) were assessed by chart review and late seizures were prospectively recorded at each follow-up visit. Clinical and brain imaging findings were reviewed by two neurologists and two neuroradiologists who were blinded to the occurrence of seizures.

RESULTS

Fourteen of the 581 patients (2.4%) developed early seizures, 71% of which occurred within the first 24 hours. Rankin scale >or=3 (odds ratio [OR] 3.9, 95% CI 1.2 to 12.7) and cortical involvement (OR 7.7, 95% CI 1.0 to 61.1) were independently associated with early seizures. Late seizures occurred only in patients with hemispheric stroke (n = 20). The risk of first late seizure was 3.1% (95% CI 1.4 to 4.8) within 1 year and 5.5% (95% CI 3.1 to 7.9) within 3 years. The mean delay between stroke and first late seizure was 12.9 months (0.3 to 33.9). Late seizures were associated with early seizure (hazard ratio [HR] 5.1, 95% CI 1.8 to 14.8), cortical signs (HR 4.5, 95% CI 1.6 to 13.1), and size of infarct superior to one-half hemisphere (HR 9.7, 95% CI 3.1 to 30.8). Eleven of the 20 patients with late seizure experienced recurrences (multiple in eight) on antiepileptic drug treatment. Most of them were seizure free at the end of the follow-up.

CONCLUSION

Epilepsy is rarely a major problem in young cryptogenic ischemic stroke survivors. Early seizures are associated with stroke disability and cortical involvement. Early seizures, cortical signs, and large infarct are independent risk factors for late seizures.

Temporal pole hypometabolism may be linked to a reduction of grey matter in temporal lobe epilepsy

In order to gain further insight into the pathophysiology of temporal pole hypometabolism, we decided to perform a voxel-based automated analysis of structural MRI in epileptic patients with or without temporal pole hypometabolism. After fully automated segmentation of cerebral grey matter from structural T1-weighted MRI scans, we applied the automated technique of statistical parametric mapping (SPM) to the analysis of grey matter of nine control subjects, and 18 patients with right medial temporal lobe epilepsy with (n = 13) or without (n = 5) significant temporal pole hypometabolism. Group comparisons between subject controls and epileptic patients with temporal pole hypometabolism showed a reduction of grey matter located into the superior part of the right temporal pole, the right hippocampus and the left parahippocampal gyrus. Epileptic patients without temporal pole hypometabolism did not exhibit temporal pole grey matter abnormalities. These findings suggest that a reduction of temporal pole neocortical grey matter might contribute to temporal pole hypometabolism in temporal lobe epilepsy.

PET imaging in epilepsy: basal ganglia and thalamic involvement

Positron emission tomography imaging has revealed basal ganglia and thalamic abnormalities in cerebral blood flow, metabolism and neurotransmission in patients with partial epilepsy. Although these changes remain of uncertain significance, this involvement could be associated with the initiation, propagation or control of seizures. This paper will review the imaging data obtained using positron emission tomography in patients with partial and generalized epilepsy.

Temporoporal metabolic abnormalities in temporal lobe epilepsies

Positron emission tomography (PET) may be used to map regional cerebral glucose metabolism using 18F-deoxyglucose-PET in patients with partial epilepsy. An area of reduced glucose metabolism, that is commonly more extensive than the underlying anatomical abnormality, is reported in most of the patients with medically refractory partial epilepsy. These functional changes are useful in the delineation of the epileptogenic focus prior to surgery. Nevertheless, in patients with mesial temporal lobe epilepsy (MTLE) without mass lesion, the hypometabolism involves a large area of the temporal lobe, including the mesial structures, the temporal pole and part of the lateral temporal cortex. In such patients with MTLE, subcortical structures and extratemporal lobe areas are also often hypometabolic. The reasons for this large hypometabolism remain debated. In MTLE patients, the most severe hypometabolism is found in the temporo-polar region. The clinical significance of this temporo-polar hypometabolism is unknown. The pathophysiology of interictal hypometabolism probably involves several mechanisms, such as neuronal loss, deafferentation, postictal depression, and others epilepsy-related phenomena. The relationship between interictal temporo-polar hypometabolism and seizure onset or seizure spread remain speculative.

Correlation between PET and SISCOM in temporal lobe epilepsy

The subtraction of interictal from ictal SPECT coregistered to 3-dimensional (3D) MRI (SISCOM) and (18)F-FDG PET are 2 techniques that are involved in the definition of the epileptogenic zone in refractory partial temporal lobe epilepsy (TLE). The aim of this study was compare, region by region, the functional patterns obtained by both strategies, SISCOM and PET, in patients with unilateral TLE.

METHODS

Perfusion data using SISCOM and metabolic data using (18)F-FDG PET scans were acquired from 17 patients with unilateral TLE. The functional metabolism and perfusion maps were overlaid onto a 3D rendering of the patient's anatomic MRI scans.

RESULTS

The functional patterns that were observed with PET and SISCOM were found mainly in the ipsilateral and contralateral temporal lobes, in the orbitofrontal and insular cortices. Despite the high rate of concordance, in some cases discrepancies could be observed between PET and SISCOM abnormalities: In the mesial regions, as in the anterior neocortex, PET abnormalities were found more frequently than SISCOM changes. SISCOM abnormalities were found more frequently in the posterior temporal neocortex. In the extratemporal cortex, SISCOM abnormalities were more widespread.

CONCLUSION

The marked rate of concordance between PET and SISCOM abnormalities observed in relatively extensive regions shows that, in TLE, seizures were generated and spread in metabolically abnormal regions.

Is amygdalohippocampectomy really selective in medial temporal lobe epilepsy? A study using positron emission tomography with (18)fluorodeoxyglucose

PURPOSE

Selective amygdalohippocampectomy (SAH) is a surgical technique effective for the treatment of medial temporal lobe epilepsy, which selectively removes the epileptogenic hippocampus and amygdala but spares the temporal neocortex. However, the benefit of SAH in terms of functional outcome is debated. In this study, we aimed to assess the metabolic consequences of SAH.

METHODS

Volumetric magnetic resonance imaging (MRI) and fluorodeoxyglucose positron emission tomography (PET) studies were performed in nine patients with medial temporal lobe epilepsy associated with hippocampal sclerosis before and after SAH. Regions of interest were delineated on MRIs and then replaced on PET images using an automatic 3D image registration. We calculated absolute metabolic rates of glucose and normalized metabolic values in each region of interest.

RESULTS

The comparison between preoperative and postoperative metabolic values showed a statistically significant worsening of the hypometabolism on the ipsilateral temporal pole on the superior and the hippocampal levels (p < 0.05 and 0.0045, respectively). A postoperative increase of the metabolic activity also was noted in the contralateral anterior hippocampus (p < 0.05) and the orbitofrontal cortex bilaterally (p < 0.002 and 0.001, respectively)

CONCLUSIONS

SAH functional benefit is controversial. SAH worsened significantly the hypometabolism of a temporal structure that was not surgically removed (i.e., the temporal pole), and it improved postoperatively the metabolic activity in the contralateral hippocampus and the orbitofrontal cortex. Whether this postoperative improvement is linked to the selectivity of the surgical procedure must be further clarified.

Accurate prediction of postoperative outcome in mesial temporal lobe epilepsy: a study using positron emission tomography with 18fluorodeoxyglucose

BACKGROUND

Recent studies suggest that positron emission tomography may be a reliable predictive indicator of clinical outcome following surgical treatment for epilepsy.

OBJECTIVE

We evaluated 30 patients with documented medial temporal lobe epilepsy to determine if prediction of postoperative outcome is improved with the use of positron emission tomography with (18)fluorodeoxyglucose.

PATIENTS AND METHODS

We performed a discriminant analysis to determine the combination of metabolic asymmetry indexes in temporal and extratemporal regions defined by magnetic resonance imaging that best predicted the postoperative outcome. Seizure outcome was assessed at least 2 years after surgery: patients were classified as seizure free (n = 14, group A), mostly improved (n = 10, group B), or as having persistent seizures (n = 6, group C).

RESULTS

Discriminant analysis was first performed in groups A and C. The temporal pole seemed to be the only temporal region for which metabolism was a significant predictor of the postoperative outcome (F(1,18) = 10.19; P =.005). The predictive value of positron emission tomography with (18)fluorodeoxyglucose was considerably improved by the multivariate analysis (F(4,15) = 7.21; P =.002), which correctly predicted the 2 -year prognosis in 100% of the patients using 4 regions: the temporal pole, the medial temporal region, the anterior part of the lateral temporal neocortex, and the basofrontal region. As a validation, we performed this 4-region analysis in the patients in group B. The difference among the 3 groups was highly significant (F = 15.5, P<.001).

CONCLUSION

These findings suggest that the interictal metabolic pattern reliably predicts the 2-year prognosis after surgery in patients with medial temporal lobe epilepsy.

Gamma knife surgery for mesial temporal lobe epilepsy

PURPOSE

Gamma knife radiosurgery (GK) allows precise and complete destruction of chosen target structures containing healthy and/or pathologic cells, without significant concomitant or late radiation damage to adjacent tissues. All the well-documented radiosurgery of epilepsy cases are epilepsies associated with tumors or arteriovenous malformations (AVMs). Results prompted the idea to test radiosurgery as a new way of treating epilepsy without space-occupying lesions.

METHODS

To evaluate this new method, we selected seven patients with drug-resistant "mesial temporal lobe epilepsy" (MTLE). The preoperative evaluation program was the one we usually perform for patients selected for microsurgery of TLE [video-EEG analysis of seizures, foramen ovale electrode recording, magnetic resonance imaging (MRI) positron emission tomography (PET) scan, neuropsychological testing]. In lieu of microsurgery, the amygdalohippocampectomy was performed by using GK radiosurgery.

RESULTS

Morphologic (MRI) signs of destruction of the target took place at 9 months after GK surgery. Since the treatment day, the first patient has been seizure free. Seizure improvement came more gradually for the following patients, and complete cessation of seizures occurred around the tenth month (range, 8-15 months). MRI shows that the amygdaloentorhinohippocampal target was selectively injured. No significant side effect (except one case of homologous quadrantanopia) or morbidity and no mortality was observed. The current follow-up is 24-61 months, and all (but one) patients are seizure free.

CONCLUSIONS

This initial experience proves clearly the short-to middle-term efficiency and safety of GK for MTLE surgery. These results need further confirmation of long-term efficiency, but the introduction of GK surgery into epilepsy surgery can reduce dramatically its invasiveness and morbidity.

Association of ipsilateral motor automatisms and contralateral dystonic posturing: a clinical feature differentiating medial from neocortical temporal lobe epilepsy

BACKGROUND

Clinical features that may help to differentiate medial temporal lobe epilepsy (MTLE) from neocortical temporal lobe epilepsy (NTLE) are lacking.

OBJECTIVE

To investigate the localizing and lateralizing value of the association of ipsilateral motor automatisms and contralateral dystonic posturing in patients with medically refractory temporal lobe epilepsy.

PATIENTS AND METHODS

Videotapes of 60 patients with well-defined MTLE, NTLE, or both were reviewed to assess the presence and the localizing value of unilateral dystonic posturing associated with motor automatisms.

RESULTS

Twenty-eight of the 60 patients exhibited unilateral dystonic posturing. This sign was observed in patients with MTLE and NTLE. It was mostly contralateral to the seizure focus in patients with MTLE and exclusively ipsilateral in patients with NTLE. Unilateral motor automatisms occurred in 26 of the 60 patients with MTLE or NTLE. It was predominantly ipsilateral to the seizure focus in patients with MTLE and exclusively contralateral in patients with NTLE. The association of ipsilateral motor automatisms and contralateral dystonic posturing was found in 14 patients with MTLE but in none of the patients with NTLE. Two patients who had medial and neocortical seizure onset also exhibited this clinical feature. This association was not significantly correlated with the postoperative outcome in patients with MTLE.

CONCLUSIONS

The association of ipsilateral motor automatisms and contralateral dystonic posturing may help to differentiate MTLE from NTLE with a reliable lateralizing value. This clinical association may reflect a specific pattern in the spread of the ictal discharge.

In vivo imaging of muscarinic cholinergic receptors in temporal lobe epilepsy with a new PET tracer: [76Br]4-bromodexetimide

Muscarinic acetyl cholinergic receptors (mAChRs) may be involved in the pathophysiology of partial epilepsy. Previous experimental and imaging studies have reported medial temporal abnormalities of mAChR in patients with medial temporal lobe epilepsy (MTLE). Suitable radiotracers for mAChR are required to evaluate these disturbances in vivo using PET. Dexetimide is a specific mAChR antagonist that has been labeled recently with 76Br. This first study in humans focused on regional distribution and binding kinetics of [76Br]4-bromodexetimide (BDEX) in patients with MTLE.

METHODS

Ten patients with well-lateralized MTLE had combined MRI, 18F-fluorodeoxyglucose (FDG) PET and 76Br-BDEX PET studies. Time-activity curves were generated in PET-defined regions of interest, including the medial, polar and lateral regions of the temporal lobe; the basal ganglia; the external and medial occipital cortex; and the white matter.

RESULTS

The highest radioactivity concentration was observed in the basal ganglia and in the cortical regions, whereas radioactivity was lower in the white matter. On late images of PET studies, 76Br-BDEX uptake was statistically significantly decreased only in the medial temporal region ipsilateral to the seizure focus (1.37 +/-0.28, P < 0.01) as determined by FDG PET imaging, anatomic MRI and electroencephalogram correlation, compared with the contralateral medial temporal region (1.46 +/- 0.31).

CONCLUSION

76Br-BDEX concentration is reduced in the temporal lobe ipsilateral to the seizure focus in patients with MTLE. This preliminary study suggests that 76Br-BDEX is a suitable radiotracer for studies of mAChR in humans. Further studies are required to investigate the potential value of 76Br-BDEX PET in other neurological disorders with muscarinic disturbances.

Radiosurgery for trigeminal neuralgia and epilepsy

The role of Gamma Knife surgery in the field of functional surgery recently has evolved dramatically. For treatment of trigeminal neuralgia, Gamma Knife surgery is the least invasive procedure, with a low rate of hypesthesia. If a rate of complete relief similar to that of other surgical techniques could be achieved, this approach will become one of the main techniques used to treat the disease initially. The authors present their experience with a group of 16 patients with mesial temporal lobe epilepsy who have been treated successfully (15 completely seizure-free and 1 with rare, nondisabling seizures) without significant complication. After additional follow-up to demonstrate the absence of long-term consequences, this fascinating new approach could change epilepsy surgery practice dramatically.

Early and delayed MR and PET changes after selective temporomesial radiosurgery in mesial temporal lobe epilepsy

We report a patient with medically refractory mesial temporal lobe epilepsy treated by gamma knife radiosurgery. In lieu of a microsurgical procedure, an entorhinoamygdalohippocampectomy was performed with a gamma knife and low marginal doses (25 Gy). The clinical and imaging studies, including CT, MR imaging, 18F-fluorodeoxyglucose positron emission tomography (FDG-PET), and long-term follow-up MR examinations, are reported. The patient has been seizure-free since the day of treatment, with no clinical complications. MR studies accurately depicted the effect on the target structures and the transient secondary changes around them. FDG-PET scans showed decreased metabolism after gamma knife surgery throughout the anteromesial part of the epileptogenic temporal lobe. This metabolic decrease was reversible in the lateral temporal cortex. Our case suggests that gamma knife surgery is a promising tool for use as a minimally invasive approach to the treatment of epilepsy.

Is the underlying cause of epilepsy a major prognostic factor for recurrence?

BACKGROUND

We investigated the prognostic value of the type of epilepsies and epileptic syndromes for seizure recurrence. In patients with partial epilepsy, we focused on the prognostic value of any structural brain abnormality and of the location of the epileptogenic region.

METHODS

A total of 2,200 adult outpatients were included in a hospital-based observational survey, with a follow-up of 1 to 7 years. Twenty-two percent of the patients exhibited generalized epilepsy, 62% partial epilepsy, and 16% undetermined epilepsy.

RESULTS

Seizure control (>1 year without seizure) was achieved in 82% of patients who had idiopathic generalized epilepsy, 35% of those with symptomatic partial epilepsy, 45% of those with cryptogenic partial epilepsy, and 11% of those with partial epilepsy associated with hippocampal sclerosis (HS). Temporal lobe epilepsy (TLE) was the most refractory partial epilepsy, with only 20% of such patients remaining seizure free, compared with 36% of extra-TLE patients. In partial epilepsy, HS, cerebral dysgenesis, and dual pathology (HS and another lesion) were associated with a low rate of seizure-free patients (11%, 24%, and 3%, respectively). No significant difference in seizure control was found between patients with extra-TLE and those with TLE and no HS.

CONCLUSIONS

In adults, partial epilepsy is more difficult to treat than idiopathic generalized epilepsy. In patients who have partial epilepsy, the location of the epileptogenic zone does not seem to be a determining factor. Brain abnormalities--especially HS, either alone or associated with another lesion--are a major prognostic factor.

The underlying pathophysiology of ictal dystonia in temporal lobe epilepsy: an FDG-PET study

BACKGROUND

Unilateral dystonic posturing of limbs occurs frequently in medial temporal lobe epilepsy (MTLE) but its underlying anatomic basis is still unknown.

OBJECTIVE

To investigate the pathophysiology of dystonic posturing, we examined the relation between the occurrence of dystonia and interictal cerebral metabolic abnormalities using fluorodeoxyglucose (FDG)-PET in MTLE patients.

METHODS

Video recordings of 30 patients with documented MTLE were reviewed to assess the presence of ictal dystonic posturing. Interictal FDG-PET was performed in all patients.

RESULTS

Eighteen patients exhibited dystonic posturing--contralateral to the seizure focus in 16 cases, bilateral in one, and ipsilateral in one. Dystonia was statistically associated with more severe hypometabolism in the striatal and in the orbitofrontal regions ipsilateral to the seizure focus.

CONCLUSION

Hypometabolism observed in the striatal region of patients with ictal dystonic posturing suggests that the basal ganglia are involved in the generation of ictal dystonic posturing in MTLE.

Hippocampal developmental changes in patients with partial epilepsy: magnetic resonance imaging and clinical aspects

Developmental disorders of the hippocampal formation (HF) have been described in epileptic syndromes associated with lissencephaly, but HF malformations can be found without widespread cortical changes. We report 19 patients with partial epilepsy and abnormal HF patterns on magnetic resonance imaging (MRI). The changes consisted of incomplete folding with abnormal medial location along the choroid fissure, globular shape and/or verticalization, and were observed in the following three contexts: (1) diffuse disorder of neuronal migration (n=1); (2) temporal lobe malformation (n=5), including heterotopia, abnormal gyration, and, in 2 cases, reduced HF volume; and (3) apparently isolated HF changes (n=13, bilateral in 3 cases). The clinical features were heterogeneous in terms of severity of epilepsy and, when the focus could be determined, in localization (temporal or extratemporal). In 4 patients with apparently isolated HF changes, MRI was suggestive of both abnormal development and hippocampal sclerosis. In these patients, presurgical investigation and postoperative results suggested multiple epileptogenic foci, involving the frontal lobes in 2 cases. One HF specimen was large enough for the observation of developmental abnormalities corresponding to the changes seen on MRI. HF changes in shape and/or position should be included among the structural abnormalities associated with partial epilepsies. They may represent the visible part of a more extensive or more distant disorder of brain development.

Gabapentin add-on therapy with adaptable dosages in 610 patients with partial epilepsy: an open, observational study. The French Gabapentin Collaborative Group

The objectives were to evaluate gabapentin add-on therapy in a large population under conditions close to real practice and to determine the therapeutic doses as reached with adaptable dosages. A 6-month multicentre, open-label study, involved addition of gabapentin to pre-existing treatment at the initial dosage of 1200 mg and subsequent adjustment between 900 and 2400 mg/day according to efficacy and tolerability. A study group of 610 adult patients, with partial epilepsy, persistent seizures and a median seizure frequency with a baseline of 7.2 per month were recruited; one-third had less than four seizures per month. Polypharmacy was frequent, with a mean of 2.3 concomitant drugs. After 6 months, 368 patients (62%) continued on gabapentin, at a mean dosage of 1739 mg/day with 44% of responders. On an intention-to-treat basis, median reduction in frequency was 21.2%, and the responder rate was 33.9%. The responder rate increased to 40.7% in the less severe subgroup receiving only one concomitant drug. Seventy-nine patients (13.4%) remained without seizures during the last evaluation period, versus nine (1.5%) during the baseline. Most of them had initially less than four seizures per month. The most frequent adverse effects, somnolence (29.3%), asthenia (14.6%), nausea (7.9%), ataxia (7.7%) and vertigo (7.2%), occurred rapidly after initial titration to 1200 mg/day, and were usually transitory. Weight gain (8.8%) seemed to be related to gabapentin dose. The combination of two recent drugs, vigabatrin and gabapentin, in 190 patients led to similar efficacy levels, with a tendency for more frequent somnolence and asthenia.

[Strategy of evaluation and surgical results in medial temporal lobe epilepsy]

To analyse the presurgical evaluation process of mediotemporal lobe epilepsy (MTLE) in relation to electroclinical characteristics of the patients, we reviewed the presurgical data (clinical, EEG, neuropsychological, MRI, FDG-PET and sometimes intracranial EEG) and the post-operative results of 53 consecutive cases treated by antero-medial temporal resection for MTLE (without lesion other than mediotemporal sclerosis). Forty one patients (77 p. 100) had a typical and well-lateralised presentation and were operated without invasive procedure. Twelve patients (23 p. 100) presented less pure data: unusual or absent auras, divergent scalp EEG features (bitemporal, widespread or extratemporal) or absence of MRI-based hippocampal sclerosis or FDG-PET hypometabolism. They were explored by invasive monitoring which confirmed the medial temporal origin of seizures. Outcome (follow-up: 30 months) was excellent in 88 p. 100 of the pure cases (Engel's class I) and less favorable in the more difficult ones (50 p. 100 of class I). In conclusion, the diagnosis and surgical treatment of MTLE can be performed without invasive investigations in the majority of cases owing to the strong contribution of brain imaging and video EEG monitoring. Some patients however present a less pure presentation suggesting more complex epileptogenic networks and associated to relatively less favorable postsurgical results.

Temporal lobe epilepsy with varying severity: MRI study of 222 patients

MRI was performed in 222 consecutive adult patients with temporal lobe epilepsy of varying severity from January 1991 to May 1993. The diagnosis of hippocampal sclerosis was established visually by three independent observers. The accuracy of visual assessment of hippocampal asymmetry was compared with volumetric measurements. Neuropathological correlations were obtained in 63 patients with refractory seizures. Temporal lobe abnormalities were observed in 180 patients (81%) as follows: hippocampal sclerosis in 122 (55%); developmental abnormalities in 16 (7.2%); tumours in 15 (6.8%); scars in 11 (5%); cavernous angiomas in 10 (4.5%); miscellaneous lesions in 6. MRI was normal or showed unrelated changes in 42 patients (19%). Visual assessment correctly lateralised hippocampal sclerosis in 79 of the 84 patients measured (94%). Temporal lobectomy confirmed the MRI data (side and aetiology) in all 63 operated patients. Patients with normal MRI had an older age of seizure onset and were more often drug-responsive than patients with hippocampal sclerosis. MRI showed temporal lobe abnormalities in 81% of epileptic patients with varying severity with good neuropathological correlation. Patients with normal MRI had a less severe form of the disease.

Progressive facial hemiatrophy and epilepsy: a common underlying dysgenetic mechanism

Progressive facial hemiatrophy (PFH), a rare disorder characterized by progressive and self-limited atrophy of the skin and the subcutaneous tissues, is often associated with epilepsy but the link between these two conditions is poorly understood. The cause of PFH remains unclear. We report four patients with PFH associated with partial epilepsy in whom brain MRI showed cerebral dysgenesis. The four patients (two men, two women; age range: 24 to 73 years) developed parasagittal PFH in their second decade. Seizures started before the age of 20 years in three patients and were refractory simple, or complex partial seizures. All the patients had focal MRI showing cortical dysgenesis, ipsilateral to PFH, consisting of cortex thickening, gyral effacement, and blurring of the white-gray interface. The underlying white matter was hyperintense on T2-weighted sequences, with nodular areas in two patients. These areas were stable over time, without contrast enhancement, and were consistent with the MRI characteristics of cystic encephalomalacia. These neuroradiologic features suggest a localized cerebral hemispheric defect of congenital origin. Because cells participating in the formation of the fronto-nasal bud derive from common progenitors with the cells that give rise to the cerebral hemisphere, we suggest that an early malformative process affecting one side of the rostral neural tube could underlie both cerebral dysgenesis and facial hemiatrophy.

[Therapeutic options provided by new antiepileptic drugs]

The introduction on the French market of vigabatrin, gabapentin and lamotrigine has considerably diversified our conventional therapeutical schemes in epilepsies, as will be as amplified by the arrivals of topiramate, tiagabine and oxcarbazepine. Compared to the conventional drugs, these new products present more favorable pharmacokinetics, no or very weak interactions and a better tolerability, specially regarding the cognitive field. They should be used according to their spectrum of activity, function of their modes of action. In add-on trials on partial epilepsy patients all these new products have shown efficacy on partial and secondarily generalized seizures. Seizure frequency is reduced by at least 50 p. 100 in 30 to 50 p. 100 of the patients. A substantial number of patients can be rendered seizure-free with vigabatrin. Lamotrigine has a broader spectrum, as it is also efficacious on the different seizure types of generalized, symptomatic or idiopathic epilepsies. Main adverse events are non-specific central nervous system disturbances such as dizziness, drowsiness, ataxia, tremor or diplopia. More specifically, vigabatrin may induce weight gain and requires closer supervision in case of psychiatric history; lamotrigine which has also probable antidepressant properties, may induce skin rashs, rarely severe. Further data are needed for gabapentin which is now used at daily dosages which are two to three times those used in the initial studies. Gabamimetic agents may be worsening in some cases of generalized epilepsies, more specially on absence and myoclonic seizures. The most obvious benefits, some patients becoming seizure-free, are obtained in cases of intermediate severity, with a bitherapy including one of these new drugs. Developments in children are often delayed. Nevertheless the prognosis, including cognitive outcome, is considerably improved in infantile spasms with vigabatrin and in Lennox-Gastaut syndrome with lamotrigine and felbamate, the latter being highly toxic. For the moment in France, authorities have limited the use of all these new antiepileptic drugs to adjunctive therapy in epilepsies resisting to conventional drugs. But recent monotherapy data show similar efficacy with better tolerability. Once the pivotal, controlled studies have enabled to obtain regulatory approval, all these compounds must undergo a large-scale evaluation phase in order to better define dosages, long-term tolerability, indications and eventual contra-indications in the various epileptic syndromes, including children.

[Magnetic resonance imaging of temporal lobe epilepsy]

MR has gained more and more importance in the evaluation of patients with temporal lobe epilepsy (TLE). Until recently, hippocampal sclerosis (which is the most frequent cause of temporal lobe epilepsy, accounting for 50-70% of the cases) could not be identified reliably. Using optimized magnetic resonance imaging techniques, hippocampal sclerosis can now be evidenced in a large proportion of patients with TLE. Tumors (10-15%), developmental abnormalities (5-7%), vascular malformations (mostly cavernous angiomas, 1-5%), and traumatic scars (5-10%) represent the other structural lesions associated with TLE. Studies of large series of patients with intractable epilepsy or with varying severity have shown that in only 8.5% and 20%, respectively, a specific imaging abnormality was not found. Specific MR sequences increase the diagnostic value of MR (coronal images perpendicular to the axis of the hippocampal formations, three-dimensional T1 weighted images, inversion recovery images, volumetry or more specific processes such as T1 and T2 relaxometry or spectroscopy). MR also helps guide placement of intra-cerebral and subdural electrodes in surgically relevant cases. All these results have given greater importance to MR in the definition of the epileptic syndrome of TLE and should probably be integrated in the criteria of international classifications.

Variability of presentation in medial temporal lobe epilepsy: a study of 30 operated cases

INTRODUCTION

To evaluate the homogeneity of patients operated on for MTLE.

MATERIAL AND METHODS

30 consecutive patients prospectively investigated with clinical, EEG, neuropsychology, MRI, FDG-PET criteria and eventually intracranial EEG, who underwent antero-medial temporal resection (follow-up: 24 months).

RESULTS

Clear and well-lateralised MTLE was non-invasively ascertained in 22 patients (73%). Eight patients (27%) had a less pure presentation due to divergent scalp EEG features (bitemporal, widespread or extratemporal), unusual auras or absence of MRI-based hippocampal sclerosis or FDG-PET hypometabolism. They were explored by invasive monitoring which confirmed medial temporal origin of seizures. Outcome was excellent in 95% of the pure cases (Engel's class I) and less favorable in the more difficult ones (65% of class I).

CONCLUSIONS

MTLE criteria, including the strong contribution of brain imaging, permit to select accurately a large percentage of patients. However a consistant number of patients present a less pure presentation suggesting more complex epileptogenic networks.

Is interictal temporal hypometabolism related to mesial temporal sclerosis? A positron emission tomography/magnetic resonance imaging confrontation

The mechanism of interictal glucose hypometabolism remains unclear, but this abnormality occurs more frequently in temporal lobe epilepsy (TLE) than in other types of partial epilepsy. Therefore temporal hypometabolism has been suggested to reflect mesial temporal sclerosis (MTS). To investigate this, we selected 22 patients with refractory partial epilepsy of mesial temporal lobe origin (MTLE) who had hippocampal atrophy based on magnetic resonance imaging (MRI) volumetric analysis. We then analyzed the metabolic correlates of unilateral hippocampal atrophy. Thirteen temporal regions of interest (ROI) were defined on MRI scans for each individual and then applied to high-resolution FDG-positron emission tomography (PET) images obtained parallel to the long axis of the hippocampus. The most hypometabolic regions were the temporal pole and the hippocampal region. When we analyzed ensembles of temporal regions grouped into related networks, the temporolimbic network, which included the hippocampal region and the temporal pole, was abnormal in 95% of the patients at a 3-SD threshold. PET hypometabolism was highly correlated with the degree of hippocampal atrophy in this network, but not in other parts of the temporal lobe, which were less frequently hypometabolic. These data indicate that hypometabolism is a consequence of MTS in the temporolimbic region but not necessarily in the other parts of the temporal lobe. Our results also suggest that the combination of PET and MRI may facilitate the noninvasive diagnosis of MTLE.

Carbamazepine and its epoxide: an open study of efficacy and side effects after carbamazepine dose increment in refractory partial epilepsy

We evaluated the efficacy, development of adverse effects, and possible correlation between the plasma concentration of carbamazepine (CBZ) and its major metabolite, carbamazepine-10,11-epoxide (CBZ-E), in a group of epileptic patients in whom selective increases in CBZ doses were made. Eighteen patients with refractory partial epilepsy participated in an open trial. Five were on monotherapy and 13 on polytherapy. All the patients were on CBZ before the trial and had plasma levels within the therapeutic range (17-42 mumol/L). After a baseline period, CBZ doses were progressively increased either to reach a 50% reduction in seizure frequency for 2 months or until side effects appeared. Thirty-nine percent of the patients had a 50% decline in seizure frequency, but only 17% improved for > 6 months. Mild or moderate side effects were observed in 78% of the patients. Side effects were correlated with CBZ plasma levels but not with CBZ-E plasma levels. Correlation between CBZ and CBZ-E plasma levels were found in the monotherapy group, but not in the polytherapy group. Our results confirm that higher doses of CBZ can successfully be used in some patients with refractory partial epilepsy. Furthermore, the plasma level of CBZ-E does not seem to be a useful indicator of toxicity in CBZ-treated ambulatory epileptic patients.

Hippocampal formations imaging with axial sections parallel to their longitudinal axis

The complex shape of hippocampal formation (HF) and its obliquity make its morphological analysis difficult using brain imaging techniques. Adapted planes of section are required. The hippocampal axial plane (HAP) parallel to the hippocampus long axis is able to provide a complete and comprehensive view of the structure. HF has a rostrocaudal extent and is divided into three parts, head, body, and tail. Histological sections in the HAP display very well the pattern of the cell layers, with their transversal folding at the head and the tail. At more ventral levels, HF sections consist of parts of the CA1 field and the subicular complex. These are completely embedded in the temporal lobe and separated from its medial surface by the white matter and the cortical plate of the parahippocampal gyrus. More dorsal sections allow the study of the amygdala, uncus and fimbria. Functional images of HF can be accurately defined by combining magnetic resonance imaging (MRI), positron emission tomography (PET), or single photon emission computed tomography (SPECT) in this plane. According to the small dorsal-ventral dimension of the structures, a few slices can cover the whole HF and precise regions of interest may be outlined.