Britta Wandschneider

Frontal lobe function and structure in juvenile myoclonic epilepsy: A comprehensive review of neuropsychological and imaging data

Juvenile myoclonic epilepsy is the most common idiopathic epilepsy syndrome and is considered a benign seizure disorder that responds well to antiepileptic drug treatment, in particular sodium valproate. By definition, routine brain imaging shows no abnormalities, but advanced imaging studies have identified functional and structural abnormalities in the frontal cortex and thalamus. Neuropsychological studies revealed subtle cognitive deficits in patients with JME, mainly implicating the frontal lobes. These findings are in keeping with anecdotal reports of behavioral problems in JME. Cognitive dysfunction in otherwise healthy siblings of patients with JME and a high heritability support the concept of a genetically determined thalamo‐frontocortical network dysfunction, accounting for the cognitive impairment and cognitively triggered “motor seizures.”

Levetiracetam reduces abnormal network activations in temporal lobe epilepsy

Objective: We used functional MRI (fMRI) and a left-lateralizing verbal and a right-lateralizing visual-spatial working memory (WM) paradigm to investigate the effects of levetiracetam (LEV) on cognitive network activations in patients with drug-resistant temporal lobe epilepsy (TLE). Methods: In a retrospective study, we compared task-related fMRI activations and deactivations in 53 patients with left and 54 patients with right TLE treated with (59) or without (48) LEV. In patients on LEV, activation patterns were correlated with the daily LEV dose. Results: We isolated task- and syndrome-specific effects. Patients on LEV showed normalization of functional network deactivations in the right temporal lobe in right TLE during the right-lateralizing visual-spatial task and in the left temporal lobe in left TLE during the verbal task. In a post hoc analysis, a significant dose-dependent effect was demonstrated in right TLE during the visual-spatial WM task: the lower the LEV dose, the greater the abnormal right hippocampal activation. At a less stringent threshold (p < 0.05, uncorrected for multiple comparisons), a similar dose effect was observed in left TLE during the verbal task: both hippocampi were more abnormally activated in patients with lower doses, but more prominently on the left. Conclusions: Our findings suggest that LEV is associated with restoration of normal activation patterns. Longitudinal studies are necessary to establish whether the neural patterns translate to drug response. Classification of evidence: This study provides Class III evidence that in patients with drug-resistant TLE, levetiracetam has a dose-dependent facilitation of deactivation of mesial temporal structures.

Structural imaging biomarkers of sudden unexpected death in epilepsy

The mechanisms underlying sudden unexpected death in epilepsy (SUDEP) remain unclear. Wandschneider et al. reveal increased amygdalo-hippocampal volume in cases of SUDEP and in individuals at high risk, compared to individuals at low risk and people without epilepsy. Findings are consistent with histopathological reports in sudden infant death syndrome.

Risk-taking behavior in juvenile myoclonic epilepsy.

Patients with juvenile myoclonic epilepsy (JME) often present with risk‐taking behavior, suggestive of frontal lobe dysfunction. Recent studies confirm functional and microstructural changes within the frontal lobes in JME. This study aimed at characterizing decision‐making behavior in JME and its neuronal correlates using functional magnetic resonance imaging (fMRI).

Motor co-activation in siblings of patients with juvenile myoclonic epilepsy: an imaging endophenotype?

In juvenile myoclonic epilepsy (JME), myoclonic jerks are often triggered by cognitive effort. Wandschneider et al. report co-activation of the motor and prefrontal cognitive networks in unaffected siblings, similar to that previously reported in patients themselves. This co-activation could constitute a heritable marker for further genetic studies of JME.

Concepts and controversies of juvenile myoclonic epilepsy: still an enigmatic epilepsy

Juvenile myoclonic epilepsy (JME) is a clinically and genetically heterogenous, generalized epilepsy syndrome usually starting in adolescence. An age-related, predominantly frontocortical-subcortical network dysfunction is likely to be the substrate of bilateral myoclonic seizures occurring at full consciousness within hours after awakening, which are the clinical hallmark of JME. Although essential features of JME were recognized by Herpin more than 140 years ago, it is still an enigmatic epilepsy syndrome in many ways; advanced imaging techniques reveal multi-focal abnormalities in this paradigmatic generalized epilepsy syndrome; clinical studies reveal a major role of genetics in etiology, but the underlying molecular changes are likely to be highly heterogeneous; many JME patients have psycho-social issues, even though their intelligence is normal; antiepileptic drugs (AEDs), notably valproic acid, achieve seizure remission in two thirds of patients, but more patients seem to relapse after stopping AEDs than in any other epilepsy syndrome. This pessimistic outlook has been challenged in recent population-based studies and needs to be assessed in randomized AED withdrawal trials. This review summarizes recent focus neuroimaging, genetic, and behavioral aspects of JME and re-appraises the entrenched view that remission off AEDs is exceptionally rare in JME.

Effect of topiramate and zonisamide on fMRI cognitive networks

Objective: To investigate the effects of topiramate (TPM), zonisamide (ZNS), and levetiracetam (LEV) on cognitive network activations in patients with focal epilepsy using an fMRI language task. Methods: In a retrospective, cross-sectional study, we identified patients from our clinical database of verbal fluency fMRI studies who were treated with either TPM (n = 32) or ZNS (n = 51). We matched 62 patients for clinical measures who took LEV but not TPM or ZNS. We entered antiepileptic comedications as nuisance variables and compared out-of-scanner psychometric measures for verbal fluency and working memory between groups. Results: Out-of-scanner psychometric data showed overall poorer performance for TPM compared to ZNS and LEV and poorer working memory performance in ZNS-treated patients compared to LEV-treated patients. We found common fMRI effects in patients taking ZNS and TPM, with decreased activations in cognitive frontal and parietal lobe networks compared to those taking LEV. Impaired deactivation was seen only with TPM. Conclusions: Our findings suggest that TPM and ZNS are associated with similar dysfunctions of frontal and parietal cognitive networks, which are associated with impaired performance. TPM is also associated with impaired attenuation of language-associated deactivation. These studies imply medication-specific effects on the functional neuroanatomy of language and working memory networks. Classification of evidence: This study provides Class III evidence that in patients with focal epilepsy, TPM and ZNS compared to LEV lead to disruption of language and working memory networks.

Pharmaco fMRI: Determining the functional anatomy of the effects of medication

Functional MRI studies have helped to elucidate underlying mechanisms in complex neurological and neuropsychiatric disorders. Disease processes often involve complex large-scale network interactions, extending beyond the presumed main disease focus. Given both the complexity of the clinical phenotype and the underlying dysfunctional brain circuits, so called pharmaco-fMRI (ph-MRI) studies probe pharmacological effects on functional neuro-anatomy, and can help to determine early treatment response, mechanisms of drug efficacy and side effects, and potentially advance CNS drug development. In this review, we discuss recent ph-MRI research in three major neuropsychiatric and neurological disorders and associated network alterations, namely selective serotonin and noradrenergic reuptake inhibitors in affective disorders and emotional processing circuits; antiepileptic drugs in epilepsy and cognitive networks; and stimulants in attention-deficit/hyperactivity disorder and networks of attention control. We conclude that ph-MRI studies show consistent and reproducible changes on disease relevant networks, and prove sensitive to early pharmacological effects on functional anatomy associated with disease. Further CNS drug research and development would benefit greatly from improved disease phenotyping, or biomarkers, using advanced imaging techniques.

Retinal nerve fibre layer thinning is associated with drug resistance in epilepsy

Objective Retinal nerve fibre layer (RNFL) thickness is related to the axonal anterior visual pathway and is considered a marker of overall white matter ‘integrity’. We hypothesised that RNFL changes would occur in people with epilepsy, independently of vigabatrin exposure, and be related to clinical characteristics of epilepsy. Methods Three hundred people with epilepsy attending specialist clinics and 90 healthy controls were included in this cross-sectional cohort study. RNFL imaging was performed using spectral-domain optical coherence tomography (OCT). Drug resistance was defined as failure of adequate trials of two antiepileptic drugs to achieve sustained seizure freedom. Results The average RNFL thickness and the thickness of each of the 90° quadrants were significantly thinner in people with epilepsy than healthy controls (p<0.001, t test). In a multivariate logistic regression model, drug resistance was the only significant predictor of abnormal RNFL thinning (OR=2.09, 95% CI 1.09 to 4.01, p=0.03). Duration of epilepsy (coefficient −0.16, p=0.004) and presence of intellectual disability (coefficient −4.0, p=0.044) also showed a significant relationship with RNFL thinning in a multivariate linear regression model. Conclusions Our results suggest that people with epilepsy with no previous exposure to vigabatrin have a significantly thinner RNFL than healthy participants. Drug resistance emerged as a significant independent predictor of RNFL borderline attenuation or abnormal thinning in a logistic regression model. As this is easily assessed by OCT, RNFL thickness might be used to better understand the mechanisms underlying drug resistance, and possibly severity. Longitudinal studies are needed to confirm our findings.

Effects of carbamazepine and lamotrigine on functional magnetic resonance imaging cognitive networks

To investigate the effects of sodium channel–blocking antiepileptic drugs (AEDs) on functional magnetic resonance imaging (fMRI) language network activations in patients with focal epilepsy.