The impact of anti-seizure medications on electroencephalogram (EEG) results

INTRODUCTION

Despite recent advances in neuroimaging and genetics, electroencephalography (EEG) continues to play a central role in the diagnosis and management of epilepsy. One application of EEG is called pharmaco-EEG. This technique is highly sensitive in detecting the effects of drugs on brain functioning and shows potential in predicting the efficacy and tolerability of anti-seizure medications (ASMs).

AREAS COVERED

In this narrative review, the authors discuss the most salient data concerning the effects of different ASMs on EEG. The authors aim to provide a clear and concise overview of the current state of research in this area, while also identifying opportunities for future investigation.

EXPERT OPINION

To date, pharmaco-EEG does not appear to be clinically reliable for predicting treatment response in epilepsy, as the literature is limited by underreporting of negative results, a lack of controls in many studies and insufficient direct replication of previous findings. Future research should focus on controlled interventional studies, which are currently lacking.

The effect of Perampanel on EEG spectral power and connectivity in patients with focal epilepsy

OBJECTIVE

Quantitative Encephalography (qEEG) depicts synthetically the features of EEG signal and represents a promising tool in the assessment of neurophysiological changes brought about by Anti-Seizure Medications (ASMs). In this study we characterized qEEG alterations related to add-on therapy with Perampanel (PER). PER is the only ASM presenting a direct glutamatergic antagonism, hence the characterization of PER induced EEG changes could help to better understand its large spectrum of efficacy.

METHODS

We analysed standard-19 channel-EEG from 25 People with Epilepsy (PwE) both before (T0) and after (T1) the introduction of PER as add-on treatment. Normal values were obtained in 30 healthy controls (HC) matched for sex and age. EEGs were analysed using Matlab™ and the EEGlab and Brainstorm toolkits. We extracted spectral power and connectivity (Phase locking Value) of EEG signal and then compared these features between T0 and T1 and across groups (PwE, HC), we also evaluated the correlations with clinical features.

RESULTS

PwE showed increased theta power (p = 0.036) after the introduction of PER but no significant change of EEG connectivity. We also found that PwE have reduced beta power (p = 0.012) and increased connectivity in delta (p = 0.013) and theta (p = 0.007) range as compared to HC, but no significant change was observed between T0 and T1 in PwE. Finally, we found that PwE classified as drug responders to PER have greater alpha power both at T0 and at T1 (p = 0.024) suggesting that this parameter may predict response to treatment.

CONCLUSIONS

PER causes slight increase of theta activity and does not alter connectivity as assessed by standard EEG. Moreover, greater alpha power could be a good marker of response to PER therapy, and potentially ASM therapy in general.

SIGNIFICANCE

Our results corroborate the hypothesis that pharmaco-EEG is a viable tool to study neurophysiological changes induced by ASM. Additionally, our work highlights the role of alpha power as a marker of ASM therapeutic response.

Does retigabine affect the development of alcohol dependence?--A pharmaco-EEG study

New antiepileptic drugs have been investigated for their potential role in the treatment of alcohol dependence. One of these drugs is retigabine and this study examines the effect of retigabine co-administered with ethanol on the development of alcohol dependence and the course of acute withdrawal syndrome. A pharmaco-EEG method was used to examine this impact in selected brain structures of rabbits (midbrain reticular formation, hippocampus and frontal cortex). Retigabine was administered p.o. at a dose of 5mg/kg/day with ethanol ad libitum for 6 weeks and then alone for 2 weeks during an abstinence period. Changes in bioelectric activity, which demonstrated the inhibitory effect of alcohol on the brain structures, were already visible after 2 weeks of ethanol administration. In the abstinence period, changes were of a different nature and significant neuronal hyperactivity was observed, particularly in the midbrain reticular formation and the hippocampus. This findings reveal that retigabine decreased ethanol-induced changes during both alcohol administration and abstinence periods. In particular, the modulatory effect of retigabine on the hippocampus may be a significant element of its mechanism of action in alcohol dependence therapy.

Effects of Psychotropic Drugs on Quantitative EEG among Patients with Schizophrenia-spectrum Disorders

OBJECTIVE

We examined how psychotropic medications affected quantitative EEG (qEEG) results among patients with a schizophrenia-spectrum disorder.

METHODS

The drugs were clustered into nine groups depending on their mechanism. We hypothesized that drugs would affect the relative power shown in qEEG results independently and investigated the effect of each drug group on relative power using multiple linear regression analysis and independent samples t-tests.

RESULTS

We found that antipsychotics other than clozapine induced an increase in the relative power of alpha activity. Clozapine markedly increased slow waves and decreased alpha activity in the occipital area. The main findings for antidepressants and antiepileptic drugs were the beta increment and lithium increased the power of delta and theta activity. However, we found no evident changes in power due to benzodiazepine.

CONCLUSION

Our results are generally consistent with previous pharmaco-EEG studies, despite some differences. Therefore, the EEG effect in each drug group could be singled out even under the polypharmacy condition, with the possible exception of benzodiazepines. Our results support using a new methodological approach to identify the qEEG effects of various psychotropic drugs in clinical settings.