Topiramate effects on the EEG and alertness in healthy volunteers: a different profile of antiepileptic drug neurotoxicity

In vivo laser speckle contrast imaging of 4-aminopyridine- or pentylenetetrazole-induced seizures

Clinical and preclinical studies on epileptic seizures are closely linked to the study of neurovascular coupling. Obtaining reliable information about cerebral blood flow (CBF) in the area of epileptic activity through minimally invasive techniques is crucial for research in this field. In our studies, we used laser speckle contrast imaging (LSCI) to gather information about the local blood circulation in the area of epileptic activity. We used two models of epileptic seizures: one based on 4-aminopyridine (4-AP) and another based on pentylenetetrazole (PTZ). We verified the duration of an epileptic seizure using electrocorticography (ECoG). We applied the antiepileptic drug topiramate (TPM) to both models, but its effect was different in each case. However, in both models, TPM had an effect on neurovascular coupling in the area of epileptic activity, as shown by both LSCI and ECoG data. We demonstrated that TPM significantly reduced the amplitude of 4-AP-induced epileptic seizures (4-AP+TPM: 0.61 ± 0.13 mV vs 4-AP: 1.08 ± 0.19 mV; p < 0.05), and it also reduced gamma power in ECoG in PTZ-induced epileptic seizures (PTZ+TPM: 38.5% ± 11.9% of the peak value vs PTZ: 59.2% ± 3.0% of peak value; p < 0.05). We also captured the pattern of CBF changes during focal epileptic seizures induced by 4-AP. Our data confirm that the system of simultaneous cortical LSCI and registration of ECoG makes it possible to evaluate the effectiveness of pharmacological agents in various types of epileptic seizures in in vivo models and provides spatial and temporal information on the process of ictogenesis.

Einfluss von Medikamenten auf das EEG: Eine Übersicht

Eine Vielzahl von Präparaten mit Einfluss auf das zentrale Nervensystem, insbesondere Medikamente, die zur Standard-Therapie auf neurologischen Intensiv- und Überwachungsstationen gehören, haben einen Einfluss auf den elektroenzephalograhischen (EEG) Befund. Diese Effekte reichen von geringen Einflüssen auf Grundrhythmus und EEG-Amplituden bis zur Auslösung von epileptiformer Aktivität und Anfallsmustern. Kenntnisse über die zu erwartenden Veränderungen sind daher relevant, um neben krankheitsassoziierten Auffälligkeiten im Rahmen der Differentialdiagnostik auch medikamentöse Ursachen bedenken zu können und etwaige therapeutische Konsequenzen einzuleiten. In dem vorliegenden Übersichtartikel werden neben Einflüssen von Analgosedierung und antikonvulsiven Medikamenten auch Effekte von Neuroleptika, Antidepressiva, Immunsuppressiva sowie Antibiotika auf das EEG diskutiert.

Why It Is Important to Consider the Effects of Analgesics on Sleep: A Critical Review

We review the known physiological mechanisms underpinning all of pain processing, sleep regulation, and pharmacology of analgesics prescribed for chronic pain. In particular, we describe how commonly prescribed analgesics act in sleep-wake neural pathways, with potential unintended impact on sleep and/or wake function. Sleep disruption, whether pain- or drug-induced, negatively impacts quality of life, mental and physical health. In the context of chronic pain, poor sleep quality heightens pain sensitivity and may affect analgesic function, potentially resulting in further analgesic need. Clinicians already have to consider factors including efficacy, abuse potential, and likely side effects when making analgesic prescribing choices. We propose that analgesic-related sleep disruption should also be considered. The neurochemical mechanisms underlying the reciprocal relationship between pain and sleep are poorly understood, and studies investigating sleep in those with specific chronic pain conditions (including those with comorbidities) are lacking. We emphasize the importance of further work to clarify the effects (intended and unintended) of each analgesic class to inform personalized treatment decisions in patients with chronic pain. © 2021 American Physiological Society. Compr Physiol 11:1-31, 2021.

Perampanel Increases Cortical EEG Fast Activity in Child and Adult Patients Affected by Epilepsy: A Quantitative EEG Study

OBJECTIVE

Quantitative EEG (qEEG) is an established technique used as objective measure for evaluating the effect of antiseizure medications (ASMs) on EEG background activity and monitoring cognitive effects of ASMs. Perampanel (PER) has been associated with relatively more tolerable cognitive effects in patients with epilepsy. The primary aim of the present study was to verify the effect of PER as first add-on ASM on qEEG in child and adult patients affected by epilepsy. The secondary aim of this study was to verify the effectiveness of the drug as first add-on treatment in both child and adult patients with epilepsy.

METHODS

We collected data from 17 adults and 10 children treated with PER as first add-on treatment, who underwent qEEG analysis before starting PER and at 3-month follow-up under stable treatment.

RESULTS

PER resulted with significant effectiveness in reducing seizures in both children and adults. Considering qEEG analysis, we observed at follow-up the significant increase in beta1 and beta total bands both in children and adult patients. In particular, children showed the significant increase of beta band frequencies predominantly in the occipital regions, whereas adults showed a widespread increase of beta activity. Moreover, we documented in both child and adult patients the global reduction of delta bands activity.

CONCLUSIONS

This qEEG study documented the relative increase of cortical EEG fast activity in both children and adult patients affected by epilepsy and treated by PER. This result may suggest a potential less negative impact of PER on cognition in patients affected by epilepsy, other than demonstrating effectiveness of the drug when used as first add-on treatment in both children and adult patients.

Effects of perampanel on cognition and quantitative electroencephalography in patients with epilepsy

Antiepileptic drugs are well known for their effects on cognition and electrophysiologic changes. However, perampanel is yet to be evaluated for its effects on cognitive function and electroencephalography (EEG). The purpose of the present study was to identify the effect of perampanel on neuropsychological (NP) tests and quantitative EEG (QEEG) and their relationship with the level of the drug in blood. Seventeen patients with epilepsy were enrolled in the study. Electroencephalographic recordings were obtained, and NP tests were conducted before perampanel intake and 6 months after treatment. The relative frequency band power, peak alpha frequency, and NP test scores were compared before and after drug administration. The serum concentration of perampanel was correlated with the QEEG changes. Delayed recall of the Rey Complex Figure showed significant improvement (20.03 vs. 22.94; P = 0.004) following perampanel administration. Other cognitive function tests showed no significant differences before and after drug administration. Theta frequency band power increased in all brain regions (P = 0.001-0.01), and alpha frequency power decreased in all brain regions (P = 0.006-0.03). The theta/alpha ratio, which represents background EEG slowing, increased in all brain areas (P = 0.003-0.02). The peak frequency of the alpha rhythm decreased after perampanel intake (t = 2.45, P = 0.03). Difference of relative alpha power in the central region positively correlated with the blood level of perampanel (r = 0.53, P = 0.03). Perampanel induced electrophysiological slowing, but cognitive decline was not observed. Because the controls were not compared in the study, the results of cognitive function tests should be interpreted conservatively. Background EEG slowing correlated with the serum concentration of perampanel. Our results show the effect of perampanel on cognitive function and background EEG in adult patients with epilepsy.

An association between resting state EEG parameters and the severity of topiramate-related cognitive impairment

INTRODUCTION

Many commonly prescribed drugs cause cognitive deficits. We investigated whether parameters of the resting-state electroencephalogram (rsEEG) are related to the severity of cognitive impairments associated with administration of the antiseizure drug topiramate (TPM) and the benzodiazepine lorazepam (LZP).

METHODS

We conducted a double-blind, randomized, placebo-controlled crossover study. After a baseline visit, subjects completed three sessions at which they received either a single dose of TPM, LZP, or placebo. Four-hours after drug administration and at baseline, subjects completed a working memory (WM) task after their rsEEG was recorded. After quantifying drug-related behavioral (WM accuracy (ACC)/reaction time (RT)) and electrophysiological (alpha, theta, beta (1,2), gamma power) change for each subject, we constructed drug-specific mixed effects models of change for each WM and EEG measure. Regression models were constructed to characterize the relationship between baseline rsEEG measures and drug-related performance changes.

RESULTS

Linear mixed effects models showed theta power increases in response to TPM administration. The results of the regression models revealed a number of robust relationships between baseline rsEEG parameters and TPM-related, but not LZP-related, WM impairment.

CONCLUSIONS

We showed for the first time that parameters of the rsEEG are associated with the severity of TPM-related WM deficits; this suggests that rsEEG measures may have novel clinical applications in the future.

Effects of antiepileptic drugs on electroencephalography (EEG): Insights and applicability

OBJECTIVE

The objective of the study was to assess the effects of antiepileptic drugs (AEDs) on posterior alpha rhythm and determine whether they produce pathological slow waves in patients with epilepsy.

METHODS

Outpatient electroencephalographs (EEGs) in alert patients were selected. The three compared groups include 1) patients with an interested AED (monotherapy or combined with other AEDs); 2) patients with AEDs other than the interested AED; and 3) patients who did not take AEDs. Outcomes were frequency of posterior alpha rhythm and presence of generalized continuous (CSWs) and generalized intermittent slow waves (ISWs). Analysis of variance was used to assess which AED was associated with slower posterior alpha rhythm. Chi-square and logistic regression were employed to assess association and odds ratio (OR) with 95% confidence interval (CI) between pathological generalized slow waves and each AED.

RESULTS

Among 1050 EEG tracings, 638 EEGs met our criteria. Electroencephalographs requested because of cognitive decline and psychiatric symptoms were excluded, leaving 616 EEGs for analysis. Four hundred thirty-seven patients received at least one AED, whereas the remaining 179 patients did not take AED. Conventional AEDs [carbamazepine (CBZ), p = 0.024; phenobarbital (PB), p = 0.013; phenytoin (PHT), p = 0.001] except valproic acid (VPA) were associated with slower alpha frequency. Carbamazepine [adjusted OR: 5.74 (95% CI: 2.07, 15.94)] and PB [adjusted OR: 2.58 (95% CI: 1.15, 5.78)] were significantly associated with generalized ISWs. None were associated with generalized CSWs.

CONCLUSIONS

Phenytoin, CBZ, and PB are associated with slower posterior alpha frequency. The latter 2 AEDs also produced pathological generalized ISWs. Valproic acid, benzodiazepines, and new-generation AEDs are not associated with either outcome. The presence of generalized ISWs in patients taking CBZ or PB should be cautiously interpreted since there can be drug effects. Association with cognitive side effects of these slow waves should be further studied.

Eslicarbazepine Acetate Modulates EEG Activity and Connectivity in Focal Epilepsy

Introduction: Eslicarbazepine acetate (ESL) is an antiepileptic drug approved as monotherapy or add-on for the treatment of epilepsy with seizures of focal onset. ESL owns a good profile in terms of efficacy and tolerability, but its effects on EEG activity and connectivity are unknown. The purpose of this study was to investigate EEG activity and connectivity changes after ESL treatment in persons with focal epilepsy (PFE).

Material and Methods: We performed a multicentre, longitudinal, retrospective, quantitative EEG study on a population of 22 PFE, and a group of 40 controls. We investigated the ESL-related changes of EEG power spectral activity and global connectivity [phase locking value (PLV), amplitude envelope correlation (AEC) and amplitude envelope correlation of orthogonalized signals (Ortho-AEC)] for standard frequency bands (delta to gamma). Seizure frequency was evaluated to assess ESL efficacy in our cohort.

Results: ESL significantly enhanced both global power spectral density and connectivity for all frequency bands, similarly for all connectivity measures. When compared to the control group, Post-ESL power was significantly higher in theta and gamma band. Pre-ESL connectivity values were significantly lower than control for all frequency bands. Post-ESL connectivity increased and the gap between the two groups was no longer significant. ESL induced a 52.7 ± 41.1% reduction of seizure frequency, with 55% of clinical responders (reduction of seizures ≥50%).

Discussion: ESL therapy induces significant enhancement of brain activity and connectivity. Post-ESL connectivity profile of epilepsy patients was similar to the one of healthy controls.

Quantitative EEG and Current Source Density Analysis of Combined Antiepileptic Drugs and Dopaminergic Agents in Genetic Epilepsy: Two Case Studies

Two adolescent females with absence epilepsy were classified, one as attention deficit and the other as bipolar disorder. Physical and cognitive exams identified hypotension, bradycardia, and cognitive dysfunction. Their initial electroencephalograms (EEGs) were considered slightly slow, but within normal limits. Quantitative EEG (QEEG) data included relative theta excess and low alpha mean frequencies. A combined treatment of antiepileptic drugs with a catecholamine agonist/reuptake inhibitor was sequentially used. Both patients' physical and cognitive functions improved and they have remained seizure free. The clinical outcomes were correlated with statistically significant changes in QEEG measures toward normal Z-scores in both anterior and posterior regions. In addition, low resolution electromagnetic tomography (LORETA) Z-scored source correlation analyses of the initial and treated QEEG data showed normalized patterns, supporting a neuroanatomic resolution. This study presents preliminary evidence for a neurophysiologic approach to patients with absence epilepsy and comorbid disorders and may provide a method for further research.

Cognitive dysfunction in patients with epilepsy: focus on clinical variables

ABSTRACT 

A variety of factors can affect cognitive functions in patients with epilepsy, with the majority of cognitive problems having a multifactorial origin. In routine clinical practice, it can be difficult to dissect out the contribution of all of the different variables, because they are often interlinked together. In this article, all of the major variables implicated in cognitive dysfunction in epilepsy are discussed. In general terms, it is widely accepted that cognitive dysfunction in epilepsy can be trait dependent or state dependent. The former is a permanent condition due to the underlying brain damage or disorder, while the latter is a potentially reversible condition due to modifiable factors, such as antiepileptic drugs, seizure frequency and pattern and psychiatric comorbidity. Neuropsychological deficits also represent an important sequela in epilepsy surgery. Visual naming and visual memory loss have been clearly associated with temporal lobe surgery. It seems that the laterality of resection is not a major determinant, while the extension of resection is relevant for visual naming.

Topiramate and cognitive impairment: evidence and clinical implications

Topiramate is an antiepileptic drug (AED) with multiple mechanisms of action that has been shown to be effective in a number of neuropsychiatric disorders. However, cognitive dysfunction is frequently observed in such patients, often representing a relevant challenge in their management. Moreover, there is a long-held recognition that AEDs may profoundly affect cognitive functions. This paper reviews available data on cognitive adverse events in patients with neurological disorders treated with topiramate, discussing the role of different contributing factors such as the pharmacological properties of the drug, the specific features of the brain disorder, and other variables pertinent to the discussion. All studies agree that up to 10% of patients may complain of treatment-emergent adverse events on cognition. Such problems occur early during treatment (i.e. within 6 weeks) and emerge in a dose-dependent fashion, suggesting that such prevalence may be significantly reduced using the drug in monotherapy and adopting individualized doses and titration schedules. The magnitude of the problem is generally mild to moderate and the subjective perception of the patient needs to be taken into account. In fact, apart from language problems, data are not conclusive. Comparisons with new AEDs are limited to levetiracetam and lamotrigine, in both cases generally disfavoring topiramate, while data regarding first-generation AEDs show clear differences only for verbal fluency.

Patient considerations in the management of focal seizures in children and adolescents

Focal epilepsy accounts for approximately one-half to two-thirds of new-onset epilepsy in children. Etiologies are diverse, and range from benign epilepsy syndromes with normal neuroimaging and almost certain remission to focal malformations of cortical development or hippocampal sclerosis with intractable seizures persisting lifelong. Other important etiologies in children include pre-, peri-, or postnatal brain injury, low-grade neoplasms, vascular lesions, and neuroimmunological disorders. Cognitive, behavioral, and psychiatric comorbidities are commonly seen and must be addressed in addition to seizure control. Given the diverse nature of focal epilepsies in children and adolescents, investigations and treatments must be individualized. First-line therapy consists of prophylactic antiepileptic drugs; however, prognosis is poor after failure of two to three drugs for lack of efficacy. Refractory cases should be referred for an epilepsy surgery workup. Dietary treatments and neurostimulation may be considered in refractory cases who are not good candidates for surgery.

Dominant frequencies of resting human brain activity as measured by the electrocorticogram

The brain's spontaneous, intrinsic activity is increasingly being shown to reveal brain function, delineate large scale brain networks, and diagnose brain disorders. One of the most studied and clinically utilized types of intrinsic brain activity are oscillations in the electrocorticogram (ECoG), a relatively localized measure of cortical synaptic activity. Here we objectively characterize the types of ECoG oscillations commonly observed over particular cortical areas when an individual is awake and immobile with eyes closed, using a surface-based cortical atlas and cluster analysis. Both methods show that [1] there is generally substantial variability in the dominant frequencies of cortical regions and substantial overlap in dominant frequencies across the areas sampled (primarily lateral central, temporal, and frontal areas), [2] theta (4-8 Hz) is the most dominant type of oscillation in the areas sampled with a mode around 7 Hz, [3] alpha (8-13 Hz) is largely limited to parietal and occipital regions, and [4] beta (13-30 Hz) is prominent peri-Rolandically, over the middle frontal gyrus, and the pars opercularis. In addition, the cluster analysis revealed seven types of ECoG spectral power densities (SPDs). Six of these have peaks at 3, 5, 7 (narrow), 7 (broad), 10, and 17 Hz, while the remaining cluster is broadly distributed with less pronounced peaks at 8, 19, and 42 Hz. These categories largely corroborate conventional sub-gamma frequency band distinctions (delta, theta, alpha, and beta) and suggest multiple sub-types of theta. Finally, we note that gamma/high gamma activity (30+ Hz) was at times prominently observed, but was too infrequent and variable across individuals to be reliably characterized. These results should help identify abnormal patterns of ECoG oscillations, inform the interpretation of EEG/MEG intrinsic activity, and provide insight into the functions of these different oscillations and the networks that produce them. Specifically, our results support theories of the importance of theta oscillations in general cortical function, suggest that alpha activity is primarily related to sensory processing/attention, and demonstrate that beta networks extend far beyond primary sensorimotor regions.

Effect of oxcarbazepine on background EEG activity and cognition in epilepsy

BACKGROUND AND PURPOSE

Cognitive dysfunction related to antiepileptic drugs (AEDs) is an important issue in the management of patients with epilepsy. The aim of the present study was to evaluate relative long-term effects of oxcarbazepine (OXC) on cognition in drug-naive patients with epilepsy.

METHODS

Fifteen drug-naïve epilepsy patients were enrolled. Electroencephalogram (EEG) recordings and neuropsychological (NP) tests were performed before and after OXC monotherapy. The relative power of the discrete frequency bandwas obtained. In addition, interhemispheric and intrahemispheric spectral coherence was also calculated.

RESULTS

NP tests showed significant improvement in visuo-spatial, memory and executive function after OXC treatment. However, neither spectral power nor coherence changed significantly with OXC treatment.

CONCLUSIONS

Our study supports the notion that OXC has no significant cognitive side effect in patients with epilepsy.

The effect of topiramate plasma concentration on linguistic behavior, verbal recall and working memory

This is the first study of the effect of topiramate on linguistic behavior and verbal recall using a computational linguistics system for automated language and speech analysis to detect and quantify drug-induced changes in speech recorded during discourse-level tasks. Healthy volunteers were administered a single, 100-mg oral dose of topiramate in two double-blind, randomized, placebo-controlled, crossover studies. Subjects' topiramate plasma levels ranged from 0.23 to 2.81 μg/mL. We found a significant association between topiramate levels and impairment on measures of verbal fluency elicited during a picture description task, correct number of words recalled on a paragraph recall test, and reaction time recorded during a working memory task. Using the tools of clinical pharmacology and computational linguistics, we elucidated the relationship between the determinants of a drug's disposition as reflected in plasma concentrations and their impact on cognitive functioning as reflected in spoken language discourse.

Alpha frequency estimation in patients with epilepsy

We report comparison and assessment of the clinical utility of different automated methods for the estimation of the alpha frequency in electroencephalograph (EEG) and compare them with visual evaluation. A total of 56 consecutive patients, aged 17 to 78 years, who had a routine EEG recording, were included, and they were grouped as patients with epilepsy (Ep) and without epilepsy (nEp). Five different methods were used for alpha frequency estimation: visually guided manual counting and visually guided Fourier transform, and 3 methods were fully automated: time domain estimation of alpha (automatic assessment of alpha waves in time domain [ATD]) and 2 fast Fourier transform (FFT)-based methods, a segmented (automatic assessment of EEG segments by FFT) and one full FFT (automatic assessment of whole EEG by one FFT of the full recording [AWF]). The AWF discriminated significantly between Ep and nEp. Visually guided manual counting showed an almost significant difference independently in the 2 occipital electrodes. The ATD underestimated high frequencies and returned a too low mean frequency. This study shows that AWF is the best suited method for automatic assessment of the alpha frequency.

Cognitive and neurodevelopmental effects of antiepileptic drugs

This article primarily represents the contributions of two young investigators to the understanding of the neuropsychological consequences of epilepsy and its treatment. The authors have reviewed two key areas of importance: the complex relationship between cognitive dysfunction and epilepsy and the risks of cognitive dysfunction in children as a consequence of in utero exposure to antiepileptic drug treatment. The work of two young investigators is presented and future research needs are outlined.

Reduced movement-related β desynchronisation in juvenile myoclonic epilepsy: a MEG study of task specific cortical modulation

OBJECTIVE

We investigated differences in task induced responses in occipital and sensorimotor cortex between patients with juvenile myclonic epilepsy (JME) and healthy controls .

METHODS

Twelve patients with JME and 12 age-matched non-epilepsy volunteers performed visual and motor tasks during MEG. We used synthetic aperture magnetometry to localise areas of task-related oscillatory modulations, performed time-frequency analyses on the locations of peak task related power changes and compared power and frequency modulation at these locations between patients and controls.

RESULTS

Patients with JME had significantly reduced pre-movement beta event-related desynchronisation in the motor task compared to controls. No significant differences were seen in other motor-related responses, or visual oscillatory responses.

CONCLUSIONS

Altered beta event-related desynchronisation may represent network specific dysfunction in JME possibly through GABAergic dysfunction.

SIGNIFICANCE

Characterising task specific cortical responses in epilepsy offers the potential to understand the patho-physiological basis of seizures and provide a window on disease and treatment effects.

Increased EEG current-source density in the high Beta frequency band induced by levetiracetam adjunctive therapy in refractory partial epilepsy

Background and Purpose

Levetiracetam (LEV) is an antiepileptic drug (AED) that has favorable effects on cognition. Although neuropsychological studies have demonstrated these favorable outcomes on cognition, there are few electrophysiologic data describing the functional changes exerted by LEV. The purpose of this study was to determine the effects of LEV adjunctive therapy on the current-source density (CSD) in the high beta frequency band (22-30 Hz) of EEG background activity in refractory partial epilepsy (RPE).

Methods

We conducted a 24-week, open-label, prospective study in 24 patients with RPE. Scalp electroencephalography and neuropsychological tests (NPTs) were conducted twice, once before the LEV trial and then again after 24 weeks of medication.

Results

The CSD in the 22-30 Hz band of EEG background activity increased in the bilateral anterior cingulate gyri, left parahippocampal gyrus, and a small area of the right anterior parahippocampal gyrus after the LEV trial. Neither seizure freedom nor the dosage increment of LEV elicited meaningful CSD changes. Verbal memory and executive function were improved after the 24-week LEV trial.

Conclusions

To our knowledge, this is the first study to examine the changes in CSD induced by LEV adjunctive therapy in RPE patients. The CSD changes and NPT results suggest that LEV enhances the activities of the neuronal networks in the prefrontal cortex and left hippocampus.