Chronic temporal lobe epilepsy: spatial extent and degree of metabolic dysfunction studied with magnetic resonance spectroscopy (MRS)

INTRODUCTION

Proton magnetic resonance spectroscopy ((1)H MRS) has been proposed as a lateralizing method for the presurgical evaluation of patients with medically intractable temporal lobe epilepsy (TLE). Studies have shown correlations between temporal lobe (TL) NAA and seizure frequency, and TL NAA/Cr and the duration of epilepsy in patients with TLE. This latter finding may suggest that progressive neuronal dysfunction may occur in both temporal lobes in patients with TLE, even when the seizures originate in only one temporal lobe. We analyzed our data in an attempt to find a possible correlation between extension of neuronal dysfunction based on NAA measures and duration of epilepsy.

METHODS

We studied 45 consecutive patients with the diagnosis of TLE, who were referred for presurgical evaluation. Duration of epilepsy was defined as the interval between the age of seizure onset and the time of the MRS examination. All studies were performed in the inter-ictal state, prior to intracranial monitoring or resection. We performed two-tailed Pearson correlation analysis between ipsilateral NAA/Cr and extension of the abnormality (voxels involved) and the duration of the seizure disorder in years.

RESULTS

The average duration of epilepsy in this group was 20 years. No significant correlation was found between duration of epilepsy and mean hippocampal NAA/Cr (r=-.131, p=.390); nor was a correlation found between duration of epilepsy in years or the extent of metabolic lesion (voxels involved) (r=-.264, p=.079).

CONCLUSIONS

Hippocampal NAA/Cr does not correlate with duration of epilepsy in TLE. Our findings suggest that cross-sectional group measures of hippocampal neuronal function do not suggest damage progression.

Self-report of cognitive abilities in temporal lobe epilepsy: cognitive, psychosocial, and emotional factors

Self-report of cognitive functioning using the Multiple Abilities Self-Report Questionnaire (MASQ) was examined in 57 left (LTLE) and 36 right (RTLE) temporal lobe epilepsy patients. The MASQ is a 38-item self-report measure assessing five domains of self-perceived cognitive functioning: Language, Visual-Perceptual Abilities, Verbal Memory, Visual-Spatial Memory, and Attention/Concentration. Overall, LTLE patients self-reported more cognitive difficulties across all domains. Language was the only domain to emerge as a robust indicator of seizure lateralization (LTLE patients reporting more problems). Neuropsychological test performance did not emerge as a significant predictor for any domain, whereas measures of psychosocial and emotional functioning accounted for a significant but modest amount of variance in all of them. The results suggest caution in using such self-report measures as an ecological extension of objective testing, but suggest a role in assessing self-appraisal of deficits.

Eclampsia, hippocampal sclerosis, and temporal lobe epilepsy: Accident or association?

BACKGROUND

Up to 30% of patients with temporal lobe epilepsy (TLE) have no identifiable risk factors.

OBJECTIVE

S: To report nine patients with TLE who had a history of eclampsia as the only risk factor for epilepsy and to investigate whether this possible association existed in a larger cohort of women with surgically treated TLE.

METHODS

The clinical data, video-EEG, neuroimaging, and neuropathology of 195 consecutive women undergoing anterior temporal lobectomy (ATL) were reviewed. Risk factors for TLE, age at epilepsy onset, and occurrence of pregnancy were identified in each patient.

RESULTS

Twenty-six women had no identifiable risk factors or seizures following a pregnancy. Nine of the 26 women had a history of eclampsia. The median age at the time of eclampsia was 16 years, and the latent period between the occurrence of eclampsia and onset of epilepsy ranged from 1 month to 2 years. The clinical, EEG, MRI, and neuropathologic findings were typical of hippocampal sclerosis (HS) and other than age at onset were no different from those of noneclampsia ATL patients. At mean follow-up of 57 months, seven patients were seizure-free and the other two markedly improved.

CONCLUSION

Eclampsia may be a risk factor for TLE and HS.

Long-term tolerability of lamotrigine: data from a 6-year continuation study

This open-label, 6-year continuation study of several short-term clinical trials was conducted to assess the long-term tolerability and efficacy of lamotrigine when used as adjunctive therapy or monotherapy for partial seizures in adult patients (> or =16 years) with epilepsy. Study visits occurred every 24 weeks throughout the treatment period. Of the 527 patients enrolled in the long-term continuation study, 508 were exposed to lamotrigine for at least 6 months (including their exposure in the primary clinical study), and 248 were exposed to lamotrigine for at least 5 years. Of the 527 patients, 75 received initial lamotrigine exposure during this study. Investigators judged that overall clinical status at the end of the study or at time of discontinuation (whichever occurred first) was improved moderately or markedly relative to prelamotrigine clinical status for 36% of patients. The most common treatment-emergent adverse events (regardless of suspected cause) were dizziness, diplopia, and headache. The only serious treatment-emergent adverse event occurring at a frequency exceeding 2% was accidental injury (2.7% of patients). Adverse events prompted 28 patients to discontinue from the study. The most common adverse events leading to discontinuation were dizziness (1.3%), headache (0.8%), rash (0.8%), and somnolence (0.6%). All adverse events resolved without sequelae. Lamotrigine administered as monotherapy or adjunctive therapy during a 6-year open-label continuation study was associated with a low incidence of adverse events in adult patients with epilepsy.

Confirmatory Factor Analysis of the California Verbal Learning Test in Patients With Epilepsy: Relationship to Clinical and Neuropathological Markers of Temporal Lobe Epilepsy

Latent constructs involved in California Verbal Learning Test (D. C. Delis, J. H. Kramer, E. Kaplan, & B. A. Ober, 1987) performance were examined using confirmatory factor analysis in 388 epilepsy surgery candidates. Eight factor models were compared. A single-factor model was examined, along with 7 models accommodating constructs of auditory attention, inaccurate recall, and delayed recall in different combinations. The retained model consisted of 3 correlated factors: Auditory Attention. Verbal Learning, and Inaccurate Recall. Validity of this factor structure was examined in a subsample of patients with left and right temporal lobe epilepsy. All 3 factors were related to seizure focus and magnetic resonance imaging hippocampal volume. Only Verbal Learning was related to hippocampal neuropathology, supporting the distinction between learning and attention in the factor structure.

Treatment of refractory primary generalized epilepsy

Although complete seizure control is achievable in 54% to 82% of patients with primary (idiopathic) generalized epilepsy syndromes, there remains a substantial group with inadequate control. Valproate has been considered the drug of choice but is not always effective and might produce unacceptable adverse effects. Several newer drugs have emerged as potential alternatives to valproate, including lamotrigine, levetiracetam, topiramate, and zonisamide. Sedation and tolerance limit the utility of benzodiazepines. For severely refractory patients, drug combinations, vagal nerve stimulation, or felbamate might be considered. Only a few controlled clinical trials have been conducted for these syndromes; more are needed.

Frequency of epilepsy in patients with psychogenic seizures monitored by video-EEG

This study examined the frequency of epilepsy in a consecutive series of patients who received a definitive diagnosis of psychogenic nonepileptic seizures (PNES) after completing inpatient video-EEG (VEEG) monitoring. Of the 1,590 patients receiving definitive diagnosis, 514 (32.3%) were diagnosed with PNES. Twenty-nine (5.3%) of these patients were found to have both PNES and epilepsy. When strict diagnostic criteria are applied, there is little overlap between epileptic seizures and PNES among patients referred for VEEG monitoring.

Clinical presentations and phenomenology of myoclonus

The term "myoclonus" has been used to describe heterogeneous phenomena involving sudden movements, but there is no generally accepted, precise definition of myoclonus. Myoclonus can often be classified based on electroencephalographic (EEG) and/or electromyographic (EMG) data. Some myoclonic epilepsy syndromes, including juvenile myoclonic epilepsy, may frequently be misdiagnosed because of failure to obtain a complete patient history and/or failure to appreciate characteristic EEG changes. A good understanding of the features associated with myoclonic disorders (particularly the myoclonic epilepsies) and of features associated with other neurologic disorders that are often confused with myoclonic disorders is an invaluable aid in obtaining an accurate diagnosis and will ultimately help in determining the best course of treatment for patients.

Clinical trials for treatment of primary generalized epilepsies

PURPOSE

To review the current state of knowledge of the treatment of primary (idiopathic) generalized epilepsy syndromes based on the efficacy results of clinical trials, to highlight obstacles in the design of these trials, and to suggest solutions for future research.

METHODS

Published reports of controlled clinical trials, as well as large or significant uncontrolled trials of treatments for these syndromes, were reviewed. Trials were selected for discussion based on their importance or their illustration of design issues.

RESULTS

Only a few randomized, controlled trials of therapy for these syndromes exist. Conclusions based on this Class I data include efficacy in absence epilepsies for ethosuximide, valproate, and lamotrigine, and for eight drugs for primary generalized tonic-clonic seizures. Many commonly accepted therapeutic strategies are not based on formal data. No controlled data exist for uncommon syndromes.

CONCLUSIONS

More clinical trials of therapies for primary generalized epilepsies are needed. To overcome design obstacles, better funding, multicenter cooperation, inclusion of children, study designs requiring fewer patients, equivalent-control designs, use of EEG and video seizure counting, and better syndrome identification will be required.

Health-related quality of life in senior adults with epilepsy: what we know from randomized clinical trials and suggestions for future research

OBJECTIVE

The goal of this work was to review the randomized controlled trial (RCT) literature on antiepileptic medication effects on health-related quality of life in seniors with epilepsy.

METHODS

Studies published from 1998 to June 2002 were identified by searching through Medline and the Cochrane Clinical Trials Register. Pre-1998 RCTs identified by Baker et al. [Epilepsia 41 (2003) 1357] were also examined for relevance to the present review. Studies were reviewed if they included a RCT design and included epilepsy patients over the age of 60.

RESULTS

A total of 85 clinical trials were reviewed. Of the 85 studies reviewed only 37 RCT studies included patients over the age of 60. However, formal quality-of-life outcome assessment was not performed in any of the RCTs that included senior adults, and only six studies provided formal quantitative analyses of AED effects in the form of adverse events incidence and participant withdrawal rates. For the most part, early study withdrawal rates were substantial for seniors and adverse events were very common. Two studies reporting on the cognitive and behavioral effects of study AEDs indicated only modest impact when AED monotherapy was kept at therapeutic levels.

CONCLUSIONS

Despite growing appreciation for quality-of-life, issues in the management of epilepsy little current empirical guidance is available for elderly with epilepsy. There exists virtually no information on elderly patient preferences and goals for epilepsy treatment outcomes, and available data primarily concerns younger adults. Despite some encouraging preliminary evidence from this review suggesting that conservative AED treatment may have a more favorable quality of life-related outcome, more conclusive statements await further systematic investigation.

A past psychiatric history may be a risk factor for topiramate-related psychiatric and cognitive adverse events

OBJECTIVES

Topiramate (TPM) is a new antiepileptic drug (AED) that has been found to be associated with a high prevalence of cognitive adverse events (CAEs). The prevalence of psychiatric adverse events (PAEs) has yet to be established. The purpose of this study was to determine the prevalence of PAEs related to TPM when used in polytherapy regimens in a large cohort of adult patients with epilepsy, to identify any association between the occurrences of CAEs and PAEs and to identify predictors of PAEs and CAEs.

METHODS

Investigators from 16 epilepsy centers (PADS group) prospectively obtained postmarketing safety and efficacy data on 596 patients aged 16 years and older. All data were recorded on standardized data retrieval forms, completed at the initial visit, while follow-up data were obtained every 6 months or at the time of discontinuation.

RESULTS

PAEs were identified in 75 (12.6%) patients: 30 (5%) experienced symptoms of depression and 34 (5.7%) of aggressive behavior and irritability, while 9 patients experienced symptoms of psychosis (1.5%). CAEs were reported by 247 (41.5%) patients. There was a significant association between the occurrences of CAEs and PAEs. A past psychiatric history was a predictor of CAEs, while older age and past psychiatric history were predictors of PAEs.

CONCLUSIONS

The use of TPM in polytherapy regimens can cause PAEs and CAEs and their occurrence is significantly correlated. Patients with a past psychiatric history may be at a higher risk for experiencing PAEs and CAEs.

Significance of fornix atrophy in temporal lobe epilepsy surgery outcome

BACKGROUND

Previous magnetic resonance imaging (MRI) studies have shown concurrent fornix atrophy in a large proportion of patients with hippocampal atrophy. The contribution of the fornix as an independent preoperative determinant of surgical outcome is unknown.

OBJECTIVE

To evaluate the contribution of the fornix as a determinant of surgical outcome in patients with preoperatively determined temporal lobe epilepsy.

METHODS

We selected 78 patients who had undergone anterior temporal lobectomy for intractable temporal lobe epilepsy at the University of Alabama at Birmingham Epilepsy Center during a 24-month period. All patients underwent standard presurgical investigations and intracranial investigations when needed. Magnetic resonance imaging volumetric studies were performed prior to surgery using previously published techniques. Patients were assessed regularly for postoperative seizure control. Outcome after at least 3 years was evaluated using Engel's classification for epilepsy. The chi2 test was used to compare categorical data.

RESULTS

Seventy-eight patients were included in this study. Eight patients were excluded because of inadequate follow-up. Thirty-five patients (44.9%) had unilateral isolated hippocampal atrophy exclusively on MRI volumetry, 29 (37.2%) had unilateral hippocampal atrophy with ipsilateral fornix atrophy, and 6 (7.7%) had isolated fornix atrophy without hippocampal atrophy. Twenty-eight patients (80%) in the unilateral hippocampal atrophy group were seizure free (ie, Engel class 1: patients who are completely seizure free with no aura and who do not receive antiepileptic drugs) compared with 21 patients (73%) in the fornix and hippocampal atrophy group (P =.57). All 6 patients with isolated fornix atrophy achieved an Engel's class 1 outcome.

CONCLUSIONS

These findings suggest that identification of fornix atrophy with or without associated hippocampal atrophy is not an important preoperative determinant of surgical outcome. However, in the presence of a normal hippocampus, fornix atrophy may be valuable in predicting seizure-free outcome.

Neurotoxicity following addition of intravenous valproate to lamotrigine therapy

Reversible neurotoxic symptoms were observed in three adult patients with absence status epilepticus on lamotrigine (LTG) therapy after administration of an IV bolus followed by oral valproic acid (VPA). Neurotoxicity was likely related to elevated serum LTG levels, as improvement correlated with discontinuing or reducing LTG dosage.

Temporal lobectomy in congenital porencephaly associated with hippocampal sclerosis

BACKGROUND

Clinical and neuroimaging features of patients with epilepsy and coexisting extratemporal porencephaly and hippocampal sclerosis have been previously described.

OBJECTIVE

To present the clinical characteristics and surgical outcome of 6 patients with intractable epilepsy and coexisting extratemporal porencephaly and hippocampal sclerosis.

PATIENTS AND METHODS

Twenty-four patients with porencephaly and epilepsy were studied. Of these, 6 had an epileptogenic focus in the temporal region. All patients underwent video electroencephalogram monitoring, magnetic resonance imaging studies, and neuropsychological evaluation. Of the subset of patients with temporal lobe epilepsy, 1 patient underwent intracranial electroencephalogram monitoring. Temporal lobe resection was performed in 5 patients. Outcomes were evaluated using the Engel classification.

RESULTS

Freedom from seizures was achieved in all patients. Pathologic analysis of the resected tissue confirmed the presurgical diagnosis of mesial temporal sclerosis.

CONCLUSION

Patients with extratemporal porencephaly and intractable seizures should be evaluated early and be considered for temporal lobectomy if clinical, magnetic resonance imaging, and electroencephalogram findings support the diagnosis of temporal lobe onset seizures.

Determining reliable cognitive change after epilepsy surgery: development of reliable change indices and standardized regression-based change norms for the WMS-III and WAIS-III

PURPOSE

Reliable change indices (RCIs) and standardized regression-based (SRB) change scores norms were established for the recently revised Wechsler Adult Intelligence Scale-III (WAIS-III) and Wechsler Memory Scale-III (WMS-III) in patients with complex partial seizures. Establishment of such standardized change scores can be useful in determining the effects of epilepsy surgery on cognitive functioning independent of test-retest artifacts including practice effects.

METHODS

Forty-two nonoperated-on adult patients with complex partial seizures (primarily of temporal lobe onset) were administered the WMS-III and WAIS-III on two occasions (mean 7-month interval). All patients were receiving stable antiepileptic drug (AED) treatment at both testings. RCI and SRB change scores were calculated. Confidence interval cutoff scores (90% and 80%) and standardized regression equations were calculated for each of the WAIS-III and WMS-III Primary Indices and individual subtests. Age, gender, education, test-retest interval, preoperative test performance, seizure onset, and seizure duration were predictor variables for the SRB equations.

RESULTS

Test-retest reliabilities for the WAIS-III and WMS-III Primary Indices were within acceptable ranges, although considerable individual subtest variability was found. Preoperative performance was the single largest contributor to each of the predictive regression equations. Age, gender, education, seizure onset, and seizure duration contributed modest variance to several of the regression equations.

CONCLUSIONS

We calculated both RCI and SRB change score indices for the recently revised Wechsler instruments. These formulas help control for test-retest methodologic artifacts and provide a standardized method with which to examine both individual and group level cognitive change after epilepsy surgery.

Magnitude of the placebo effect in randomized trials of antiepileptic agents

Placebo-controlled randomized trials ideally produce unbiased estimates of the treatment effect after accounting for nonpharmacological effects (regression to the mean, Hawthorne, and placebo effects). Recognizing that the magnitude of these effects may help understand why investigators need to control for them, we sought to measure this magnitude. We reviewed published meta-analyses of randomized, placebo-controlled add-on trials of antiepileptic medications versus placebo, included in the Cochrane Library. In randomized trials of antiepileptic agents for epilepsy, 9.3-16.6% of patients in the placebo arm had a >50% reduction in seizure frequency. This effect represents 20-50% of the effect observed with active agents. Because patients with epilepsy in the placebo arm of randomized trials experience a large clinical benefit due to nonpharmacological effects, randomized controlled trials are necessary to gauge the true magnitude of the treatment effect of new antiepileptic agents.

Risk to verbal memory following anterior temporal lobectomy in patients with severe left-sided hippocampal sclerosis

BACKGROUND

Previous investigations indicate low risk for memory loss following anterior temporal lobectomy (ATL) in patients with severe hippocampal sclerosis (HS) compared with patients with mild HS. However, these conclusions have been established primarily with group-level analyses.

OBJECTIVE

To investigate individual base rate risk for verbal memory loss following ATL in patients who have pathologically verified mild, moderate, or severe HS.

PATIENTS AND METHODS

One hundred fifteen patients with unilateral temporal lobe epilepsy (68 with left-sided and 47 with right-sided epilepsy) were included. Acquisition, retrieval, and recognition components of verbal memory, as measured by the California Verbal Learning Test, were assessed before and after ATL. Postoperatively, the degree of neuronal loss and reactive gliosis of the hippocampus was assessed via a 3-tiered rating system establishing mild, moderate, and severe pathologic features. Patients with preoperative magnetic resonance imaging-based evidence of lesions outside the mesial temporal area (side of surgical resection) were excluded.

RESULTS

Neither seizure laterality nor severity of HS was associated with preoperative verbal memory performance. Postoperatively, the left-sided ATL group demonstrated significant decline across the acquisition (P<.01), retrival (P<.001), and recognition (P<.001) verbal memory components compared with the right-sided ATL group. Patients who underwent left-sided ATL and had mild HS displayed the largest magnitude and percentage proportion of postoperative decline across all verbal memory components. However, 28 (48%) of the 58 patients who underwent left-sided ATL and who had moderate and severe HS displayed statistically reliable declines on retrieval aspects of verbal memory. Most patients undergoing right-sided ATL, regardless of the extent of hippocampal pathologic features, displayed no postoperative memory change.

CONCLUSIONS

Substantial individual heterogeneity of memory outcome exists across groups of patients undergoing ATL, with various degrees of pathologically verified HS. Patients undergoing left-sided ATL who have mild HS seem at greatest risk for broad-spectrum verbal memory decline. However, when examining outcome on a patient-by-patient basis, many patients undergoing left-sided ATL who have moderate to severe HS were also vulnerable to verbal memory loss. This risk seems selective to a retrieval-based aspect of verbal memory.

A double-blind, placebo-controlled study of remacemide hydrochloride in patients with refractory epilepsy following pre-surgical assessment

This multicentre, randomised, double-blind, placebo-controlled, parallel-group study investigated the efficacy, safety and pharmacokinetics of remacemide hydrochloride in adult patients ( n= 59) with refractory epilepsy, undergoing reduced or discontinued antiepileptic drug (AED) usage, as part of an evaluation for epilepsy surgery. On discontinuation or reduction of maintenance AEDs, patients received remacemide hydrochloride, up to 600 mg daily, or placebo, for up to ten days or until they experienced a fourth complex partial (CPS) or a generalised tonic-clonic (GTC) seizure. Pre- and post-study blood and urine samples were taken for analysis. Remacemide hydrochloride showed a significantly ( P= 0.045) longer median time to fourth seizure compared with placebo (6.8 vs. 3.8 days). Median nine-day seizure counts were significantly ( P= 0.0327) lower with remacemide hydrochloride than placebo (6.2 vs. 12.8). Eleven remacemide hydrochloride patients and six placebo patients completed ten days' treatment. Remacemide and desglycinyl metabolite levels were lower in patients receiving concomitant carbamazepine or phenytoin than in those receiving non-inducing AEDs or remacemide hydrochloride alone. No serious adverse events occurred; all patients receiving remacemide hydrochloride completed the study. Remacemide hydrochloride was well tolerated and showed significant therapeutic activity in this patient population.