Predictive factors for postoperative outcome in temporal lobe epilepsy according to two different classifications

PURPOSE

The determination of prognostic factors is important for predicting outcome after epilepsy surgery. We investigated the factors related to surgical outcome within a homogeneous group of patients suffering from pathologically proven mesial temporal lobe epilepsy with hippocampal sclerosis (MTLE-HS), and compared Engel's outcome classification system with the latest one proposed by the ILAE.

METHOD

We included 109 patients with MTLE-HS who were followed-up for at least 1 year after epilepsy surgery. A retrospective chart review was performed to extract patients' demographic details, and potential pre-postoperative risk factors. Outcome of surgery was defined by the Engel's and ILAE classifications. In addition, the course of prognosis was determined according to the changes in ILAE classifications on an annual basis. Univariate and multivariate logistic regression analyses were used for the latest available outcomes and two different courses of prognosis.

RESULTS

The average duration of follow up was 4.78+/-2.55 years in the 109 patients with MTLE-HS. The univariate and multiple logistic regression analyses showed that the occurrence of seizures during the first month after surgery was a significant risk factor for a poor outcome. A history of trauma was also significant for patients with late recurrence of postsurgical seizures after at least 1-year seizure remission.

CONCLUSION

The occurrence of seizures during the first month after surgery is a significant prognostic factor in patients with MTLE-HS. Ignoring early postoperative seizures in classification systems may result in difficulty in identifying the course of epilepsy after surgery.

Surgical outcome of patients with mesial temporal lobe epilepsy related to hippocampal sclerosis

Seizure outcome in mesial temporal lobe epilepsy related to hippocampal sclerosis (MTLE-HS) that was evaluated according to a noninvasive protocol was assessed in 165 patients and reported using both Engel's and ILAE classifications. The mean postoperative follow-up was 5.0 +/- 2.7 years. At the end of first year, 77.1% of patients were in Engel-I, and 52.7% were in ILAE-I. Antiepileptic drugs (AEDs) were discontinued in 41 patients (42.7%), all remained seizure-free for >or= 2 years that could be accepted as "cure." Thirty-six patients had recurrences, 19 had running-down phenomena. Anterior temporal lobectomy (ATL) was performed in 27 patients with a better outcome when compared to patients operated by selective anterior hippocampectomy. Clinical risk factors for better and worse outcome, which show some similarity in different reports, seem to veil the main reason, which is the accurate delineation of epileptogenic zone considering the presence of different subgroups and underlying developmental pathologies.

Tractography of the parahippocampal gyrus and material specific memory impairment in unilateral temporal lobe epilepsy

INTRODUCTION

Temporal lobe epilepsy (TLE) is associated with disrupted memory function. The structural changes underlying this memory impairment have not been demonstrated previously with tractography.

METHODS

We performed a tractography analysis of diffusion magnetic resonance imaging scans in 18 patients with unilateral TLE undergoing presurgical evaluation, and in 10 healthy controls. A seed region in the anterior parahippocampal gyrus was selected from which to trace the white matter connections of the medial temporal lobe. A correlation analysis was carried out between volume and mean fractional anisotropy (FA) of the connections, and pre-operative material specific memory performance.

RESULTS

There was no significant difference between the left and right sided connections in controls. In the left TLE patients, the connected regions ipsilateral to the epileptogenic region were found to be significantly reduced in volume and mean FA compared with the contralateral region, and left-sided connections in control subjects. Significant correlations were found in left TLE patients between left and right FA, and verbal and non-verbal memory respectively.

CONCLUSION

Tractography demonstrated the alteration of white matter pathways that may underlie impaired memory function in TLE. A detailed knowledge of the integrity of these connections may be useful in predicting memory decline in chronic temporal lobe epilepsy.

Pediatric epilepsy surgery in focal lesions and generalized electroencephalogram abnormalities

Generalized abnormalities on scalp electroencephalograms (EEG) are not uncommon in children with partial epilepsy in whom a dominant focus of interictal and ictal abnormalities concordant to the brain lesion usually clarifies surgical candidacy. Children with exclusively generalized or multiregional EEG abnormalities and mental retardation are usually not considered surgical candidates, even when brain lesions are seen on imaging. Of 176 pediatric epilepsy surgeries at our center, we describe 10 children with exclusively generalized and multiregional interictal and ictal EEG abnormalities who had resection of a focal lesion seen on brain MRI. Surgical decisions were strengthened by clinical data. Surgery was offered as a last resort because of catastrophic epilepsy and treatment failures. At 26 months' mean postoperative follow-up, eight had no seizures, and two had infrequent seizures. Six months after surgery, generalized electroencephalographic abnormalities had resolved in all. We conclude that generalized and multiregional EEG abnormalities in the absence of dominant focus may not preclude epilepsy surgery in children with a congenital or acquired lesion seen on MRI. Generalized EEG abnormalities are likely secondary phenomena that resolve after surgery. Maladaptive neural plasticity and secondary epileptogenesis are potential mechanisms that mask an epileptogenic lesion with generalized EEG abnormalities.

Outcome measurement after vagal nerve stimulation therapy: proposal of a new classification

PURPOSE

Vagal nerve stimulation (VNS) is an adjunctive palliative therapy for refractory epilepsy. Effects of treatment are varied and some, such as the use of an external magnet for seizure termination, are unique to VNS. No accepted standard exists for outcome measurement after VNS treatment. We present a novel classification for outcome, which includes assessment of both seizure frequency and severity in VNS-treated patients.

METHODS

We devised a classification system modeled on the Engel classification for surgically treated patients, but tailored for use in VNS therapy, which incorporates five classes of outcome. We retrospectively reviewed VNS-treated patients in our centre, and used the data to illustrate our system and compare it with the Engel model.

RESULTS

With this system, 48 patients (mean age, 30 years) were followed up over a median of 18 months. Seventy-eight percent had partial epilepsy. Sixteen and a half percent experienced class I outcome (>80% seizure-frequency reduction). Twenty percent had class II improvement (50-79% seizure-frequency reduction). One-third had no improvement (class V). The remaining patients comprised class III (seizure-frequency reduction <50%) or class IV (magnet benefit alone) outcomes. Class I-III outcomes were further subdivided according to effects on ictal or postictal severity.

CONCLUSIONS

We propose a new classification, which can be used for all epilepsies and which reflects outcome measures beyond seizure-frequency reduction alone. Use of this system would allow greater comparison between future studies of VNS therapy.

Evaluation of quantitative magnetic resonance imaging contrasts in MRI-negative refractory focal epilepsy

PURPOSE

Conventional optimal MRI is unremarkable in 20%-30% of patients with intractable focal epilepsy. These MRI-negative patients are the most challenging in surgical programs. Our aim was to evaluate the yield and utility of quantitative MRI with novel contrasts in MRI-negative patients with refractory focal epilepsy, who were potential surgical candidates.

METHODS

Ninety-three consecutive potential surgical candidates with refractory focal epilepsy, 44 with temporal lobe epilepsy, and 49 with frontal lobe epilepsy as determined with ictal scalp video-EEG; and normal optimal conventional MRI, including hippocampal volumes and T2 measures were investigated with quantitative MRI contrasts. The contrasts comprised fast fluid attenuated inversion recovery based T2 measurement (FFT2), double inversion recovery (DIR), magnetization transfer ratio (MTR), and voxel-based morphometry of gray matter (VBM). Voxel-based analyses of whole brain data were used to compare each patient with a control group.

RESULTS

In patients with a putative single focus on scalp video-EEG telemetry, 16% had concordant FFT2 abnormalities, as did 16% with DIR, 5% with MTR and 9% with VBM. The greatest agreement in the localization of abnormalities was between FFT2 and DIR. Altogether, 31% patients had a focal abnormality with at least one contrast in the lobe of seizure onset. Signal changes outside the lobe of the putative focus were found with FFT2 in 36% patients, with DIR in 42%, with MTR in 6% and with VBM in 7%.

DISCUSSION

Quantitative analysis of MRI contrasts had a low yield of identifying focal abnormalities concordant with putative epileptic foci in patients with unremarkable conventional MRI. Specificity was low for FFT2 and DIR. With the low specificity, data must be interpreted with caution, but in some patients may assist in creating a hypothesis for testing with intracranial electrodes.

Clinical seizure lateralization in frontal lobe epilepsy

PURPOSE

We systematically analyzed the lateralizing value of clinical seizure semiology in patients with frontal lobe epilepsy (FLE).

METHODS

We studied the incidence, positive predictive value (PPV), and the lateralizing significance of various clinical symptoms in 228 seizures (s) of 31 patients (p) with medically refractory FLE (17 with left-sided and 14 with right-sided seizure onset). Seizures recorded during prolonged video-EEG monitoring were assessed by two independent reviewers blinded for the patient's clinical data. Analysis was performed both for patients and seizures.

RESULTS

Version [16 p (52%); PPV, 94%; p=0.001; 47 s (21%); PPV, 75%; p=0.001], unilateral clonic movements [16 p (52%); PPV, 81%; p=0.021; 32 s (14%); PPV, 81%; p=0.001], unilateral dystonic posturing [eight p (26%); PPV, 75%; p=0.289; 46 s (20%); PPV, 80%; p=0.001], unilateral tonic posturing [10 p (32%); PPV, 80%; p=0.109; 19 s (7.4%); PPV, 79%; p=0.019], and unilateral grimacing [10 p (32%); PPV, 100%; p=0.002; 19 s (8%); PPV, 100%; p=0.001] were of lateralizing significance, indicating a contralateral seizure onset. Asymmetric ending [five p (16%); PPV, 80%; p=0.375; nine s (4%); PPV, 89%; p=0.039] after secondarily generalized tonic-clonic seizures was significantly associated with an ipsilateral seizure onset. Pure ictal vocalizations occurred significantly more frequently in seizures of right hemispheric onset [13 p (42%); PPV, 62%; p=0.581; 63 s (28%); PPV, 73%; p=0. 001], whereas in individual patients, this symptom showed no lateralizing significance. The remaining clinical symptoms (figure 4 sign, unilateral hand automatisms, early head turning, postictal nose wiping, and unilateral eye blinking) were not of lateralizing significance in our patients. The results of clinical seizure lateralization corresponded with the final lateralization of the seizure-onset zone in 81% of our patients.

CONCLUSIONS

Clinical seizure semiology can provide correct information on the lateralization of the seizure-onset zone in >80% of patients with medically refractory frontal lobe epilepsy.

Correlation of quantitative MRI and neuropathology in epilepsy surgical resection specimens--T2 correlates with neuronal tissue in gray matter

Newer MRI methods can detect cerebral abnormalities not identified on routine imaging in patients with focal epilepsy. Correlation of MRI with histopathology is necessary to understand the basis of MRI abnormalities and subsequently predict histopathology from in vivo MRI. The aim of this study was to determine if particular quantitative MR parameters were associated with particular histological features.

Nine patients with temporal lobe epilepsy were imaged at 1.5 T using standard presurgical volumetric and quantifiable sequences: magnetization transfer and FFT2. The resected temporal lobe was registered with the volumetric MRI data according to our previously described method to permit correlation of the modalities. Stereologically measured neuronal densities and field fraction of GFAP, MAP2, synaptophysin and NeuN immunohistochemistry were obtained. Analyses were performed in the middle temporal gyrus and compared with quantitative MRI data from the equivalent regions.

There was a significant Spearman Rho negative correlation between NeuN field fraction and the T2 value in gray matter (correlation coefficient − 0.72, p = 0.028). There were no significant correlations between any neuropathological and MR measures in white matter.

These preliminary findings suggest that T2 in gray matter is sensitive to the proportion of neuronal tissue. Novel quantitative MRI measures acquired with higher field strength magnets, and so with superior signal to noise ratios, may generate data that correlate with histopathological measures. This will enable better identification and delineation of the structural causes of refractory focal epilepsy, and will be of particular benefit in patients in whom current optimal MRI does not identify a relevant abnormality.

The efficacy and tolerability of levetiracetam in pharmacoresistant epileptic dogs

Twenty-two dogs with idiopathic epilepsy which were pharmacoresistant to phenobarbitone and bromide were treated with levetiracetam as an add-on medication. Records of eight dogs were used retrospectively to determine a safe, efficient levetiracetam dosage. Fourteen dogs were entered into a prospective, open label, non-comparative study. After 2 months of levetiracetam oral treatment (10 mg/kg TID), 8/14 dogs responded significantly to the treatment and seizure frequency was reduced by 50%. In dogs that remained refractory, the dosage was increased to 20 mg/kg TID for 2 months. One further dog responded to levetiracetam treatment. Levetiracetam responders had a significant decrease in seizure frequency of 77% (7.9+/-5.2 to 1.8+/-1.7 seizures/month) and a decrease in seizure days per month of 68% (3.8+/-1.7 to 1.2+/-1.1 seizure days/month). However, 6/9 responders experienced an increase in seizure frequency and seizure days after 4-8 months continuing with the levetiracetam treatment at the last effective dosage. Levetiracetam was well tolerated by all dogs and sedation was the only side-effect reported in just one of the 14 dogs.

Prediction of postoperative outcome with special respect to removal of hemosiderin fringe: A study in patients with cavernous haemangiomas associated with symptomatic epilepsy

PURPOSE

In this study 30 patients with symptomatic epilepsy caused by cavernomas were investigated in a postoperative follow up study to assess predictors for postoperative outcome with respect to indications, time and approach of surgery.

METHODS

Thirty patients with cavernomas refractory to medical treatment were scheduled for surgery based on the findings of high-resolution MR imaging and intensive EEG-video monitoring. Postoperative outcome of epilepsy was assessed by follow-up examinations based on the basis of classification by Engel and the International League against epilepsy (ILAE).

RESULTS

The following variables were associated with good postoperative outcome: (1) complete resection of hemosiderin fringe surrounding the cavernoma was correlated to less postoperative seizure frequency versus incomplete resection of the hemosiderin fringe according to the outcome protocol of ILAE. (2) Lower duration of epilepsy at the time of operation was correlated to a better postoperative outcome with a benefit for recovery. (3) Absence of hemorrhage before surgery and unifocal seizure onset was a predictor for a favorable outcome, whereas bilateral or multifocal seizure onset zones showed poorer postoperative outcomes. (4) In patients with dual pathology (hippocampal sclerosis in addition to a cavernoma), lesionectomy plus hippocampectomy as opposed to lesionectomy only, had a better outcome than single lesionectomy.

CONCLUSION

Postoperative outcome in patients with cavernomas should be the topic of further prospective multicenter studies involving a large number of patients. In addition to the ideal operation time and handling of dual pathology the role of extended resection including perilesional hemorrhages should be taken into account.

Intestinal expression of cytochrome P450 enzymes and ABC transporters and carbamazepine and phenytoin disposition

OBJECTIVES

Interindividual variability in intestinal absorption and bioavailability might contribute to inadequate control of seizures under treatment with carbamazepine and phenytoin. We therefore correlated intestinal expression levels and genetics of CYP3A4, CYP2C9/19, MDR1 and MRP2 with dose requirement and plasma levels of carbamazepine and phenytoin.

MATERIALS AND METHODS

Epileptic patients on carbamazepine (n = 29) or phenytoin (n = 15) were stratified into a 'high'-dose (carbamazepine > or =800 mg/day, phenytoin > or =300 mg/day) and a 'low'-dose group (carbamazepine < or =600 mg/day, phenytoin < or =200 mg/day). Duodenal biopsies and DNA were obtained for Western blotting and genotyping studies.

RESULTS

Low carbamazepine plasma levels showed a trend towards higher intestinal MDR1 expression (P = 0.06). Furthermore, carbamazepine dose was positively correlated with MRP2 expression (P = 0.1). Moreover, MDR1 expression and carbamazepine and phenytoin dose requirement was influenced by the genotype in position 2677 and 3435 of the MDR1 gene.

CONCLUSION

Differences in intestinal MDR1 and MRP2 expression may influence carbamazepine and phenytoin disposition and may account for interindividual pharmacokinetic variability.

Psychiatric disorders in temporal lobe epilepsy patients over the first year after surgical treatment

OBJECTIVE

To evaluate the psychiatric disorders over a 1-year period in a group of TLE patients who underwent surgery.

METHODS

Prospective, open study in a sample of 70 TLE patients. Psychiatric disorders' assessment was made before surgery, and at 1, 6 and 12 months after surgery, with the structured clinical diagnostic interview for DSM-IV axis I diagnoses (SCID). Presurgical psychiatric and neurological variables were compared with the outcomes of surgery and the course of psychiatric pathology over the follow-up through parametric and non-parametric tests.

RESULTS

Depression decreased from 17.2% before surgery to 4.3% at 12 months after surgery (chi(2)=5.41, d.f.=1, p=0.071), anxiety disorders decreased from 21.5% before surgery to 14.2% at 12 months after surgery (chi(2)=10.309, d.f.=1, p<0.005). Patients with no presurgical psychiatric condition had lower postsurgical rate of psychiatric disorders than those with psychiatric history (X(2)=9.87, gl=1, p< or =0.001), with psychiatric disorders in the presurgical evaluation (X(2)=12.02, gl=1, p< or =0.001), or with both conditions (chi(2)=15.28, d.f.=1, p<0.001). No association was found between psychiatric disorders and the outcomes after surgery. No association was found between the course of psychiatric disorders before and after surgery and neurological or neurosurgical variables.

CONCLUSIONS

Surgery in TLE patients does not worsen the global psychopathological status. Presurgical psychiatric morbidity was found to be related to the presence of psychiatric disorders after surgery. Specific psychiatric assessment should be made before and after surgery.

The seizure outcome after amygdalohippocampectomy and temporal lobectomy

The aim of this study was to compare the seizure outcome of two different types of epilepsy surgery, selective amygdalohippocampectomy (AHE) and anterior temporal lobectomy (ATLE) in patients with temporal lobe epilepsy. We included 114 patients who had mesio-temporal lobe epilepsy and hippocampal sclerosis or gliosis on histology. Patients had ATLE if the non-dominant hemisphere was affected or if the whole temporal lobe was atrophic. Patients had AHE if the dominant hemisphere was affected. Standardized seizure outcome at 1 year following surgery was used. Overall 40% of the 114 patients who had temporal lobe epilepsy surgery were seizure-free at 1-year (Engel's class Ia). A good outcome (Engel's classes I and II) was significantly more frequent in ATLE than in AHE. (66% and 44%, respectively, P = 0.03). ATLE had a better seizure outcome than AHE.

Correlation of health-related quality of life after surgery for mesial temporal lobe epilepsy with two seizure outcome scales

PURPOSE

The objective of this study was to correlate health-related quality of life (HRQOL) after surgery for mesial temporal lobe epilepsy, as revealed by a postoperative screening tool, to different modalities of seizure outcome classification (Engel, International League Against Epilepsy (ILAE)).

METHOD

One hundred twenty-eight of one hundred forty consecutive patients returned a HRQOL questionnaire at a mean of 36 months after selective amygdalohippocampectomy. Patients answered in two ways: with an absolute estimation (values 1-4) and with a self-rated relative change (-1, 0, +1) after surgery.

RESULTS

Eighty patients were seizure- and aura-free (63.3% ILAE 1), 16 continued to have auras (12.5% ILAE 2), and 13 experienced 1-3 seizure days per year after surgery (10.2% ILAE 3). Ninety-two patients were classified seizure-free (71.9% Engel I), and 17 had two or fewer seizures per year (13.3% Engel II). Of 110 patients in ILAE 1-3, 100 (91%) stated good or even very good postoperative HRQOL, and 99 (90.0%) reported improvements in HRQOL. Only 9 of the remaining 18 (50%) reported good or very good HRQOL after surgery (P=0.01). Corresponding results were obtained with Engel classes I and II, suggesting a trend toward ILAE 1-3 and Engel I and II as overall satisfactory outcomes. A more detailed HRQOL assessment yielded lowest scores in the cognitive domain, and a significant correlation of self-rated changes in cognitive functioning with seizure control (P=0.01). Changes in physical capabilities and mood were significantly better with satisfactory seizure outcome (P=0.006 and P<0.001, respectively), whereas the social aspects were not significantly dependent on seizure outcome (P=0.06).

CONCLUSION

Correlation of HRQOL and seizure control suggested that ILAE 1-3 and Engel I and II most likely represent overall satisfactory outcome. Subdomain analyses revealed cognitive abilities as the most critical feature associated with seizure control, whereas social aspects remained mainly stable.

Toward the substitution of invasive electroencephalography in epilepsy surgery

The authors compared the localization accuracy of interictal magnetoencephalography (MEG) with ictal and interictal invasive video electroencephalography (VEEG) in identifying the epileptogenic zone in epilepsy surgery candidates. Forty-one patients, 29 with temporal lobe epilepsy (TLE) and 12 with extratemporal lobe epilepsy (ETLE), participated. Only patients with interictal changes during the MEG recordings were included. A comparison of the accuracy of invasive VEEG and MEG seizure zone identification was based on the degree of overlap between the location of the actual surgical resection and the zone identified by each method, and the success of surgery in reducing seizure activity. No statistical differences were observed between the accuracy of invasive VEEG and MEG in determining the location of the seizure zone across TLE and ETLE cases. Invasive VEEG and MEG localization judgments were correct in 54% and 56% of the cases, respectively. Separate group analyses suggested that MEG may be less beneficial relative to invasive VEEG in ETLE than TLE cases. MEG is of statistically equivalent accuracy to invasive VEEG, despite the fact that its use has not reached optimal conditions. The authors predict the replacement of the more invasive procedure with MEG in the near future for TLE cases, subsequent to the optimization of the conditions under which preoperative MEG is performed.

Postsurgical treatment of epilepsy

In people with localization-related epilepsy who do not respond well to medication and continue to have seizures despite having been evaluated and treated by an epilepsy specialist, current recommendations are to consider surgery as an alternative to continued trials of different antiepileptic drugs (AEDs).

1H-MRS imaging in intractable frontal lobe epilepsies characterized by depth electrode recording

Presurgical evaluation of frontal lobe epilepsy (FLE) remains a challenging issue and frequently requires invasive depth electrode recording. In this study, we aimed at evaluating the potential usefulness of a non-invasive technique such as proton magnetic resonance spectroscopic imaging ((1)H-MRSI) in the presurgical evaluation of FLE and at investigating the potential electrophysiological correlates of the metabolic disturbances as defined by (1)H-MRSI. We compared the distribution of (1)H-MRSI abnormalities with the electrophysiological abnormalities defined by stereo-electroencephalography (SEEG) recording in 12 patients presenting with several subtypes of FLE. We also used 12 control subjects in order to obtain normative (1)H-MRSI data. We used a multilevel (1)H-MRSI protocol to better sample the principal regions of the frontal lobe. We also applied a metabolic mapping technique allowing a visual display of metabolic data. A significant decrease of both N-acetyl-aspartate/phosphocreatine-creatine and N-acetyl-aspartate/(choline-compounds + phosphocreatine-creatine) ratios was observed in regions involved in the epileptogenic zone (EZ) and/or the irritative zone (IZ) compared to regions without electrical abnormalities in the same patients (P = 0.044 and P = 0.018, respectively), and also compared to controls (P = 0.004 and P = 0.0001, respectively). No significant differences in metabolic ratios were observed between those regions involved in the EZ and those involved in the IZ only. Our results suggest a link between the relative decrease of N-acetyl-aspartate and the EZ as well as the IZ in FLE. Thus, multilevel (1)H-MRSI protocol may add pertinent information during the non-invasive presurgical evaluation of FLE.

Occipital lobe epilepsy secondary to ulegyria

OBJECTIVE

To analyse clinical and therapeutic aspects of epilepsy secondary to ulegyria in adults.

PATIENTS

Out of 1,020 consecutive patients studied at a tertiary care epilepsy centre, eight cases of ulegyria were identified. All patients had comprehensive clinical evaluation, neuropsychological testing, interictal EEG, and brain magnetic resonance imaging (MRI). In addition, five patients had video-EEG monitoring. Ulegyria was confirmed by histological analysis in two patients who had successful epilepsy surgery.

RESULTS

All patients had a history of perinatal asphyxia. In four of them there was psychomotor developmental delay. Mean age at onset of seizures was 5.8 years (range first week to 21 years). Brain MRI demonstrated predominant involvement of occipito-parietal cortical and subcortical areas. This posterior distribution of lesions was also supported by the presence of auras with occipital and parietal semiology in six patients, and signs of visuospatial dysfunction in five. Four patients had medically refractory epilepsy and two of them had significant improvement with surgical treatment.

CONCLUSIONS

In this group of adult epileptic patients with ulegyria brain MRI, ictal semiology, and neurological examination are consistent with occipital lobe epilepsy. Most patients have severe epilepsy, but in some of them epilepsy can be controlled with antiepileptic drugs, while in others surgical treatment can be effective. Brain MRI criteria of ulegyria are well established, and in two cases it was possible to confirm their diagnosis with histological analysis.

The chance of cure following surgery for drug-resistant temporal lobe epilepsy. What do we know and do we need to revise our expectations?

Although surgery is often seen as a curative treatment for patients with drug-resistant temporal lobe epilepsy, little information is available how many cases can be considered cured after surgery, i.e. are seizure-free for several years without taking antiepileptic drugs (AEDs). In our review, 13 retrospective and five prospective clinical observations published since 1980 provided data on long-term seizure control off AEDs in a total of 1658 patients. No randomized studies were found. Following temporal lobe surgery, approximately one in four adult patients and approximately one in three children or adolescents can currently shown to be seizure-free for 5 years without AEDs (25%, mean of eight studies in adults, 95% CI: 21-30%, and 31%, mean of three studies in children, 95% CI: 20-41%). The rate of seizure control off AEDs seemed to be stable after 2 years of follow-up. However, as 55% of patients free of disabling seizures preferred not to discontinue their medication completely as late as 5 years after surgery, it is impossible to know if they are cured or not. No features predictive of surgical cure were detected except for better cure outcome in children versus adults with hippocampal sclerosis and in patients with typical versus atypical Ammonshorn's sclerosis or tumor in one small study each. In conclusion, the available evidence on seizure outcome off AEDs after temporal lobe surgery is based on non-randomized studies and, in part, data were collected retrospectively. A randomized controlled trial is needed to determine if, in fact only one in three to four patients with temporal lobe epilepsy undergoing surgery can be considered cured.

Early seizures after temporal lobectomy predict subsequent seizure recurrence

Patients are understandably anxious if seizures occur immediately after temporal lobectomy. Such "neighborhood" seizures are commonly regarded as irrelevant to seizure outcome and discounted in outcome measurement. We conducted an in-depth examination of early postoperative seizures (<28 days) and outcome. The risk of recurrence at one postoperative year was calculated using Poisson regression, and statistical adjustments were made for preoperative pathology. Of 321 patients, 69 (22%) experienced early postoperative seizures. These early seizures were associated with subsequent seizure recurrence (rate ratio [RR] 5.9; 95% confidence interval [CI], 4.1-8.4). Among patients with early seizures, the only significant factor was the presence of seizure precipitants, which was associated with a lower recurrence risk. However, when compared with patients with no early seizures, those with precipitants to early seizures had a higher risk of recurrence (RR, 3.0; 95% CI, 1.8-5.2). The risk was higher again for patients without precipitants to early seizures (RR, 7.6; 95% CI, 5.0-11.5). Early seizures and other seizure recurrences in the first postoperative year did not differ in their effect on subsequent outcome (X(2) [3] = 3.4, p = 0.33). We conclude that early postoperative seizures are associated with subsequent seizure recurrence. These findings have implications for patient counseling and the measurement of outcome.

Vagus Nerve Stimulation Therapy after Failed Cranial Surgery for Intractable Epilepsy: Results from the Vagus Nerve Stimulation Therapy Patient Outcome Registry

OBJECTIVE:

To determine the effectiveness of vagus nerve stimulation (VNS) therapy among patients with persistent or recurrent seizures after lobar resection, callosotomy, and other cranial operations for intractable epilepsy.

METHODS:

Data were obtained from the VNS therapy patient outcome registry, which was established after United States Food and Drug Administration approval of the VNS device in 1997 as a means of capturing open-label clinical data outside of protocol. The integrity of the systems for collecting and processing registry data was authenticated by an independent auditing agency. The effect of potential selection bias, however, remains uncertain.

RESULTS:

Two nonconsecutive cohorts were compared: patients tracked in the registry who had previously undergone cranial surgery for epilepsy (CS group, n = 921) and those who had not (non-CS group, n = 3822). For the CS group, the median reduction in seizure frequency was 42.5% after 3 months of VNS therapy, 42.9% at 6 months, 45.7% at 12 months, 52.0% at 18 months, and 50.5% at 24 months. For the non-CS group, analogous rates were 47.0%, 52.9%, 60.0%, 62.7%, and 66.7%, respectively. In the CS group, seizures were reduced by at least 50% in 55.1% of patients, at least 75% in 31.4% of patients, at least 90% in 17.3% of patients, and 100% in 5.1% of patients after 24 months of VNS therapy. Response rates were more pronounced in the non-CS group: at least 50% in 62.2% of patients, at least 75% in 43.7% of patients, at least 90% in 26.8% of patients, and 100% in 8.3% of patients. Patients in both groups experienced marked improvements in quality of life parameters.

CONCLUSION:

The effectiveness of VNS is maintained during prolonged stimulation, and overall seizure control continues to improve with time. Patients in whom prior cranial surgery had failed did not respond as favorably as all other patients receiving VNS therapy. Nonetheless, many of the former group improved substantially. Thus, on the basis of these open-label data, VNS therapy represents a potentially palliative treatment option for patients with refractory seizures after failed cranial surgery.

Neuropsychological Outcome after Selective Amygdalohippocampectomy with Transsylvian versus Transcortical Approach: A Randomized Prospective Clinical Trial of Surgery for Temporal Lobe Epilepsy

PURPOSE

Selective amygdalohippocampectomy (SAH) is a surgical treatment option for patients with medically intractable mesial temporal lobe epilepsy. In contrast to standard anterior temporal lobectomy, resection of unaffected tissue is limited, although it achieves equal seizure outcomes in selected patients. In SAH, the mesial structures can be approached by different routes, the transsylvian approach and the transcortical approach. Advantages or disadvantages with respect to postoperative cognitive outcome are still a matter of debate.

METHODS

Eighty randomized patients were included in the analyses. In 41 patients, the transsylvian approach, and in 39 patients, the transcortical approach was performed. All patients received comprehensive neuropsychological testing of verbal and nonverbal memory, attention, and executive functions before and 6 months or 1 year after SAH.

RESULTS

Seventy-five percent of patients became completely seizure free with no difference depending on the chosen approach. Repeated measures multivariate analysis of variance (MANOVA) showed that cognitive outcomes after both approaches were essentially the same. The only exception was phonemic fluency, which was significantly improved after transcortical but not after transsylvian SAH.

CONCLUSIONS

The results indicate that either surgical approach can be chosen independent of cognitive outcome criteria. Improvement in phonemic fluency after transcortical SAH may reflect selective normalization of cognitive function after epilepsy surgery, whereas frontal lobe manipulation might have hindered recovery of this function after transsylvian SAH.

Genital Automatisms: A Video-EEG Study in Patients with Medically Refractory Seizures

PURPOSE

Genital automatisms (GAs) are rare clinical phenomena during or after epileptic seizures. They are defined as repeated fondling, grabbing, or scratching of the genitals. The anatomic correlates of GAs have been discussed controversially. The aim of this investigation was to assess the localizing and lateralizing value of GAs.

METHODS

The authors studied 207 consecutive patients with intractable seizures referred to a University Hospital for presurgical evaluation between 1998 and 2002: 135 had temporal lobe epilepsy (TLE); 23, frontal lobe epilepsy (FLE); 29, generalized epilepsies (GEs); and 20 had extratemporal or multifocal epilepsy.

RESULTS

Twenty-three (11%) of 207 patients showed GAs in 42 (3%) of 1,299 seizures. GAs occurred significantly more often in men (17 of 93, 18%) than in women (six of 114, 5%; p = 0.0037). Twenty-one (16%) of 135 patients with TLE performed GAs, one (4%) of 23 with FLE and one (3%) of 29 with GE. GAs were associated with unilateral hand automatisms in 16 (70%) of 23 and with periictal urinary urge in five (22%) of 23. All patients had amnesia for the performance of GAs.

CONCLUSIONS

GAs appear in the ictal or postictal period with impaired consciousness. Men exhibit GAs significantly more often than do women. GAs do not localize or lateralize per se, but may localize seizure onset in the presence of periictal urinary urge or unilateral hand automatisms. They show a tendency to occur more often in TLE.

Long-term seizure outcome following resective surgery at National Epilepsy Center in Shizuoka, Japan

We analyzed the seizure outcome of 357 patients who were followed for at least 2 years after resective surgeries; 282 underwent temporal lobe resection and 75 had extratemporal lobe resection. This study confirmed that resective surgery provides sustained, positive benefits with a high seizure-free rate of nearly 80% for most medically refractory patients. In patients with no MRI-detectable lesion who underwent extratemporal lobe resection, however, Engel's class I-II (seizure-free or rare seizures) was achieved in less than 50% of patients. High-resolution MRI should be performed at the early stage of disease in all patients with partial epilepsies. The findings would certainly urge clinicians to actively select surgical intervention.

Clinical outcome of epilepsy surgery

PURPOSE OF REVIEW

The outcome from current surgical methods of treating drug-resistant epilepsy will be considered, looking at changes in classical resective surgery and new methodology being introduced in the functional treatment of these patients.

RECENT FINDINGS

There is now class I evidence that temporal lobe surgery is effective. Sophisticated and appropriate magnetic resonance imaging sequences, together with an assessment of the electroclinical syndrome, allow patients to be assessed for resective surgery. The concept of 'surgically remediable syndromes' determines the type of procedure that is effective for particular patients. Technical advances such as neuronavigation techniques and intra-operative magnetic resonance imaging have improved the effectiveness of these procedures. Other techniques of disconnection, such as multiple subpial transection, and stimulation both indirectly using the vagus nerve and directly using various intracranial targets, are currently effective and have potential for future development.

SUMMARY

This review will demonstrate that current surgical techniques are safe and effective in relieving drug-resistant epilepsy.

Preoperative clinical evaluation, outline of surgical technique and outcome in temporal lobe epilepsy

Temporal lobe epilepsy (TLE) is the most common type of refractory epilepsy. The mechanisms of epileptogenesis and seizure semiology of the mesial and neocortical temporal lobe epilepsy are discussed. The evaluation and selection of patients for TLE surgery requires team work: the different clinical aspects of neuropsychological evaluation, magnetic resonance and functional imaging (positron emission tomography, single photon emission computed tomography and magnetoenephalography) are reviewed. In our programme of epilepsy surgery at Kuopio University Hospital, Finland, we have performed 230 temporal resections from 1988 until 2002. Preoperative diagnostic EEG-videotelemetry often required intracranial monitoring and it has proved to be safe and efficient. The indications and technique for tailored temporal lobe resection with amygdalohippocampectomy used in our institution, as well as the complications, are described. Our analysis of outcome after temporal lobe surgery included 140 consecutive adult patients between 1988 and 1999; one year after the operation in unilateral TLE the Engel I-II outcome was observed in 68% of the patients. Outcome of surgery improved significantly after introduction of the standardised MR imaging protocol from 1993; 74% of patients with unilateral TLE achieved Engel I-II outcome.

Temporal evolution and prognostic significance of postoperative spikes after selective amygdala-hippocampectomy

The purpose of this study was to quantify the temporal evolution and to determine the prognostic significance of spikes on serial postoperative EEGs after selective amygdala-hippocampectomy. The authors performed postoperative EEGs 4 months, 1 year, and 2 years after surgery in 31 patients with unilateral mesial temporal lobe epilepsy. Spike frequency was determined ipsilateral to the resection (group I, no spikes; group II, 1 to 10 spikes; group III, 11 to 20 spikes; group IV, more than 21 spikes during the 30-minute recording). The temporal evolution of postoperative spike frequency was assessed, and these parameters were correlated with surgical outcome. Twenty-two patients showed spikes on postoperative EEG. Spike frequency decreased over time in 14 patients, while no changes or minimal changes occurred in seven patients, and spike frequency increased in one patient. Nine patients had no spikes. There was no correlation between occurrence, frequency, and temporal evolution of spikes with postoperative seizure control. The authors' results demonstrate a progressive decrease of spike frequency during the postoperative period after selective amygdala-hippocampectomy, although occurrence, frequency, and temporal evolution of postoperative spikes had no implications on surgical outcome.

How effective is surgery to cure seizures in drug-resistant temporal lobe epilepsy?

It is well recognized that two-thirds of patients with drug-resistant temporal lobe epilepsy will be free of disabling seizures with continued medical treatment after temporal resection. Seizure recurrence has been noted during a five-year follow-up in approximately one-third of these seizure-free patients mostly but not exclusively following planned complete discontinuation of antiepileptic drugs (AEDs). This leaves one-third of patients without disabling seizures and without AEDs several years after surgery. Despite improvements in seizure frequency or severity, seizures persist in another third of patients undergoing surgery. Although cure (five years without any seizures and off AEDs) is the ultimate aim of epilepsy surgery, the percentage of patients cured by surgery cannot be well defined at the moment. We need a long-term randomized controlled trial on AED discontinuation in seizure-free patients followed by long-term open extension to determine if only one in three adult patients with drug-resistant temporal lobe epilepsy is cured by surgical intervention.

Antiepileptic drug treatment before and after selective amygdalohippocampectomy

Retrospectively, we analyzed pre and postoperative (po) AED treatment in relation to long-term annual seizure outcome in the Zurich selective amygdalohippocampectomy (AHE) series. In 376 patients (hippocampal sclerosis ("HS"), n:185; other lesions ("lesional"), n:191) with a follow-up of more than 1 year, in the last available outcome (lao), 60% were seizure- and aura-free (ILAE Class 1). During the year prior to surgery, in the "HS" group a mean of 2.3 +/- 0.8 AEDs were taken. The percentage of patients without AEDs increases to 36.1% in the po years 1-5 (po year 5: "HS" (n:133) 27.8%; "lesional" (n:111) 45.9%). In po years 7-11 this percentage is between 40 and 43% (po year 10: "HS" (n:75) 29.3%; "lesional" (n:65) 55.4%). In the ILAE Class 1a, at po year 5 63/85 (74.1%) patients have discontinued AED intake. At lao 36.2% of patients were off AEDs and additional 18.9% had a "substantial" reduction (i.e. from polytherapy to monotherapy, or a reduction of the existing monotherapy by at least 66% compared to the year before AHE). The relapse rate is similar for patients who were free of disabling seizures (a) for > or =1 year and without AEDs (17.1%), (b) immediately after surgery with or without AEDs (18.4%), and (c) had a "substantial" AED reduction over the entire follow-up period (18.9%). The rate of re-gained full seizure control, however, is significantly better for group (b) compared to (c) (77% versus 53%). 10.9% of patients showed the "running down phenomenon," i.e. had seizures during the first po year, but then became seizure-free for 1 or more years. The percentage of patients free of "disabling" seizures, who did not follow the medical advice to discontinue/reduce AEDs, is about 30% after the 10th po year. In the 15th po year this figure is 4.2 times higher for "HS" versus "lesional" patients. We conclude that the time of discontinuation of AEDs after AHE should be tailored based on the results of the presurgical evaluation, the early po seizure outcome, the histopathological findings, the intraoperative ECoG findings and the po EEG. In an optimal constellation, "substantial" AED reduction with the goal of a monotherapy can be advised 1 year and discontinuation 2 years after surgery.

Classification of seizures and epilepsy

The management of seizures and epilepsy begins with forming a differential diagnosis, making the diagnosis, and then classifying seizure type and epileptic syndrome. Classification guides treatment, including ancillary testing, management, prognosis, and if needed, selection of the appropriate antiepileptic drug (AED). Many AEDs are available, and certain seizure types or epilepsy syndromes respond to specific AEDs. The identification of the genetics, molecular basis, and pathophysiologic mechanisms of epilepsy has resulted from classification of specific epileptic syndromes. The classification system used by the International League Against Epilepsy is periodically revised. The proposed revision changes the classification emphasis from the anatomic origin of seizures (focal vs generalized) to seizure semiology (ie, the signs or clinical manifestations). Modified systems have been developed for specific circumstances (eg, neonatal seizures, infantile seizures, status epilepticus, and epilepsy surgery). This article reviews seizure and epilepsy classification, emphasizing new data.

Long-term seizure outcomes following amygdalohippocampectomy

OBJECT

Analyses of the results of surgery for epilepsy are hindered by inconsistent classifications of seizure outcome, small numbers of patients, and short postoperative follow-up periods. The authors conducted a retrospective study with a reassessment of the long-term seizure outcomes in patients who underwent selective amygdalohippocampectomy (SelAH) for pharmacotherapy-resistant mesial temporal lobe epilepsy (MTLE) at the Zurich University Hospital from 1975 to 1999.

METHODS

Year-by-year data and the last available data on seizure outcomes were retrospectively assessed for 369 consecutively surgically treated patients who had participated in a follow-up period longer than 1 year as of 1999 and whose outcomes were classified according to the Engel scale and the proposed new International League Against Epilepsy (ILAE) scale. Patients were grouped into nonlesional and lesional MTLE groups depending on whether they harbored a gross anatomical lesion that caused the MTLE. Differentiation was made between curative and palliative operations. Complications related to surgery are reported for 453 patients who underwent SelAH and participated in more than 3 months of follow-up review. The last available outcome data according to the Engel scale were found to be generally similar to those of the new ILAE classification, with 66.9% of patients free from disabling seizures (Engel Class I) compared with 57.1% who were completely seizure and aura free (ILAE Class 1). The last available data on seizure outcome were not significantly different between patients in the lesional and nonlesional MTLE groups. In the lesional group, seizure outcomes were significantly better when patients underwent surgery early in the course of the disease. Overall, 70% of the patients received reductions in their antiepileptic drug treatment at the time of the last available follow-up review. Complications related to the surgical procedures were rare.

CONCLUSIONS

The authors conclude that SelAH is a safe and effective surgical procedure for MTLE.

EEG and evoked potential recording from the subthalamic nucleus for deep brain stimulation of intractable epilepsy

OBJECTIVES

The substantia nigra in the animal model has been implicated in the control of epilepsy. The substantia nigra pars reticulata (SNpr) receives afferents from the subthalamic nucleus (STN), which thus may have an effect on the control of epilepsy. There is evidence in the animal model of a direct connection from the cortex to the STN. High-frequency STN stimulation is being used in experimental trial for the management of intractable epilepsy. Our primary objective in this study was to determine if there was epileptiform activity recorded from the STN in association with scalp recorded epileptiform activity to support the presence of a pathway from the cortex to the STN in humans as described in animals that may be important for the management of epilepsy. This article describes the interictal and ictal electroencephalographic (EEG) findings as well as evoked potential recordings from the STN in these patients with intractable epilepsy.

METHODS

Four patients (3 males) ranging from 19 to 45 years with intractable focal epilepsy refractory to anti-epileptic drugs were studied. Two patients failed vagal nerve stimulation and one patient had previous epilepsy surgery. Depth electrodes were implanted stereotactically in the STN bilaterally. A comparative analysis of the interictal and ictal activities recorded from the scalp and STN electrodes was performed. Median nerve somatosensory evoked potentials (SEPs) and auditory evoked potentials (AEPs) were also recorded.

RESULTS

Interictal sharp waves recorded in the scalp EEG were always negative in polarity. These sharp waves were always associated with sharp waves recorded at the ipsilateral STN electrode contacts that were always positive in polarity. In addition repetitive spikes were recorded independently at the left or right STN electrode contacts, with no reflection at the scalp. These spikes were extremely stereotyped, of high amplitude and short duration, and were positive or negative in polarity. Focal scalp EEG seizures were also recorded at the ipsilateral STN electrodes. In 3 patients SEPs were recorded from the contralateral STN electrodes corresponding to the P14/N18 far-field complex. In two patients AEPs were recorded, and wave V (near-field) and wave VII (far-field) from the contralateral STN electrodes.

CONCLUSIONS

This study demonstrates that scalp recorded epileptiform activity is reflected at the ipsilateral STN either following or preceding the scalp sharp waves. The STN sharp waves are most probably an expression of the direct cortico-STN glutamatergic pathways that have been demonstrated previously in animals. This pathway in man may be important with regard to a possible mechanism for the treatment of epilepsy with STN stimulation.

Childhood epilepsy in relation to mental handicap and behavioural disorders

Epidemiological studies indicate that there is a high rate of mental retardation and behavioural problems in children with epilepsy. In some cases both the epilepsy and the mental retardation will have a common cause, such as a metabolic disorder or brain trauma. However, in other children, the epilepsy itself may cause either temporary or permanent learning problems. When permanent learning disability can be prevented it is important to treat the epilepsy early and effectively. Children with specific learning difficulties and memory problems can benefit greatly from appropriate management. There are many causes of behavioural disturbance in children with epilepsy. These causes include the epilepsy itself, treatment of the epilepsy, reactions to the epilepsy, associated brain damage/dysfunction and causes that are equally applicable to children who do not have epilepsy. Identifying the cause or causes in each child allows rational management to be provided. Antiepileptic treatment with medication or surgery can either improve the situation or make matters worse. The treatment should be tailored to the needs of the individual child. If surgery is required, there is a strong argument for performing this early in life, both to allow the greatest opportunity for brain plasticity and also to allow the child full benefit from the important developmental and educational years, without the problems that can be associated with the epilepsy. Skilled management of children with epilepsy who have mental retardation and/or behavioural problems can be very rewarding both for the family and for the professionals involved.

Recent advances in the diagnosis and treatment of epilepsy

Recent advances in the diagnosis and treatment of epilepsies are discussed with special consideration of epidemiology and classification, progress in neuroimaging, electrophysiological studies using EEG and MEG, initiation of medical and surgical treatment, the role of new antiepileptic drugs and selected aspects of genetics of idiopathic epilepsies. In addition from conclusions obtained by the review of recent developments suggestions for future work in Europe are discussed. A constructive approach from multicenter studies requires homologous definitions, documentations and standardization of procedures of trials for European multicenter studies.