Musical components important for the Mozart K448 effect in epilepsy.

There is growing evidence for the efficacy of music, specifically Mozart's Sonata for Two Pianos in D Major (K448), at reducing ictal and interictal epileptiform activity. Nonetheless, little is known about the mechanism underlying this beneficial "Mozart K448 effect" for persons with epilepsy. Here, we measured the influence that K448 had on intracranial interictal epileptiform discharges (IEDs) in sixteen subjects undergoing intracranial monitoring for refractory focal epilepsy. We found reduced IEDs during the original version of K448 after at least 30-s of exposure. Nonsignificant IED rate reductions were witnessed in all brain regions apart from the bilateral frontal cortices, where we observed increased frontal theta power during transitions from prolonged musical segments. All other presented musical stimuli were associated with nonsignificant IED alterations. These results suggest that the "Mozart K448 effect" is dependent on the duration of exposure and may preferentially modulate activity in frontal emotional networks, providing insight into the mechanism underlying this response. Our findings encourage the continued evaluation of Mozart's K448 as a noninvasive, non-pharmacological intervention for refractory epilepsy.

Asymmetric Frequency-Specific Feedforward and Feedback Information Flow between Hippocampus and Prefrontal Cortex during Verbal Memory Encoding and Recall.

Hippocampus and prefrontal cortex (PFC) circuits are thought to play a prominent role in human episodic memory, but the precise nature, and electrophysiological basis, of directed information flow between these regions and their role in verbal memory formation has remained elusive. Here we investigate nonlinear causal interactions between hippocampus and lateral PFC using intracranial EEG recordings (26 participants, 16 females) during verbal memory encoding and recall tasks. Direction-specific information theoretic analysis revealed higher causal information flow from the hippocampus to PFC than in the reverse direction. Crucially, this pattern was observed during both memory encoding and recall, and the strength of causal interactions was significantly greater during memory task performance than resting baseline. Further analyses revealed frequency specificity of interactions with greater causal information flow from hippocampus to the PFC in the delta-theta frequency band (0.5-8 Hz); in contrast, PFC to hippocampus causal information flow were stronger in the beta band (12-30 Hz). Across all hippocampus-PFC electrode pairs, propagation delay between the source and target signals was estimated to be 17.7 ms, which is physiologically meaningful and corresponds to directional signal interactions on a timescale consistent with monosynaptic influence. Our findings identify distinct asymmetric feedforward and feedback signaling mechanisms between the hippocampus and PFC and their dissociable roles in memory recall, demonstrate that these regions preferentially use different frequency channels, and provide novel insights into the electrophysiological basis of directed information flow during episodic memory formation in the human brain.SIGNIFICANCE STATEMENT Hippocampal-PFC circuits play a critical role in episodic memory in rodents, nonhuman primates, and humans. Investigations using noninvasive fMRI techniques have provided insights into coactivation of the hippocampus and PFC during memory formation; however, the electrophysiological basis of dynamic causal hippocampal-PFC interactions in the human brain is poorly understood. Here, we use data from a large cohort of intracranial EEG recordings to investigate the neurophysiological underpinnings of asymmetric feedforward and feedback hippocampal-PFC interactions and their nonlinear causal dynamics during both episodic memory encoding and recall. Our findings provide novel insights into the electrophysiological basis of directed bottom-up and top-down information flow during episodic memory formation in the human brain.

Comparison of efficiency between VNS and ANT-DBS therapy in drug-resistant epilepsy: A one year follow up study.

Vagus nerve stimulation (VNS) and anterior thalamic deep brain stimulation (ANT-DBS) have both been used for treatments of drug-resistant epilepsy (DRE). However, there is no comparative study on the effectiveness of two methods from one single center. 17 patients with DRE who underwent VNS therapy and 18 patients who underwent DBS were enrolled. A retrospective study was performed starting from baseline before operation extending to 12 months after operation. The seizure types, duration of epilepsy, age at implantation, failed numbers of antiepileptic drugs (AEDs) before operation, history of craniotomy, stimulation parameters and response rate were described. The analysis of liner regression on the age of onset, duration of epilepsy, numbers of AEDs, and the seizure reduction at 12 months after operation was applied. The mean seizure reduction in patients with DBS at 3, 6, 9 and 12 months after the operation was 57.22%, 61.61%, 63.94% and 65.28%, and that in cases with VNS was 36.06%, 39.94%, 45.24% and 48.35%, respectively. At 1 year after the operation, the patients with older operation age, focal seizures and older age of onset responded better to VNS; and those older operation age, focal generalized seizures, history of craniotomy and longer duration of disease responded better to DBS. The efficiency of ANT-DBS was higher than that of VNS at each follow up time point. Patients can choose the appropriate treatment according to the individual clinical characteristics.

Prestimulus dynamics blend with the stimulus in neural variability quenching.

Neural responses to the same stimulus show significant variability over trials, with this variability typically reduced (quenched) after a stimulus is presented. This trial-to-trial variability (TTV) has been much studied, however how this neural variability quenching is influenced by the ongoing dynamics of the prestimulus period is unknown. Utilizing a human intracranial stereo-electroencephalography (sEEG) data set, we investigate how prestimulus dynamics, as operationalized by standard deviation (SD), shapes poststimulus activity through trial-to-trial variability (TTV). We first observed greater poststimulus variability quenching in those real trials exhibiting high prestimulus variability as observed in all frequency bands. Next, we found that the relative effect of the stimulus was higher in the later (300-600ms) than the earlier (0-300ms) poststimulus period. Lastly, we replicate our findings in a separate EEG dataset and extend them by finding that trials with high prestimulus variability in the theta and alpha bands had faster reaction times. Together, our results demonstrate that stimulus-related activity, including its variability, is a blend of two factors: 1) the effects of the external stimulus itself, and 2) the effects of the ongoing dynamics spilling over from the prestimulus period - the state at stimulus onset - with the second dwarfing the influence of the first.

Global and Parallel Cortical Processing Based on Auditory Gamma Oscillatory Responses in Humans.

Gamma oscillations are physiological phenomena that reflect perception and cognition, and involve parvalbumin-positive γ-aminobutyric acid-ergic interneuron function. The auditory steady-state response (ASSR) is the most robust index for gamma oscillations, and it is impaired in patients with neuropsychiatric disorders such as schizophrenia and autism. Although ASSR reduction is known to vary in terms of frequency and time, the neural mechanisms are poorly understood. We obtained high-density electrocorticography recordings from a wide area of the cortex in 8 patients with refractory epilepsy. In an ASSR paradigm, click sounds were presented at frequencies of 20, 30, 40, 60, 80, 120, and 160 Hz. We performed time-frequency analyses and analyzed intertrial coherence, event-related spectral perturbation, and high-gamma oscillations. We demonstrate that the ASSR is globally distributed among the temporal, parietal, and frontal cortices. The ASSR was composed of time-dependent neural subcircuits differing in frequency tuning. Importantly, the frequency tuning characteristics of the late-latency ASSR varied between the temporal/frontal and parietal cortex, suggestive of differentiation along parallel auditory pathways. This large-scale survey of the cortical ASSR could serve as a foundation for future studies of the ASSR in patients with neuropsychiatric disorders.

The thalamus-precentral gyrus functional connectivity changes in epilepsy patients following vagal nerve stimulation.

Vagal nerve stimulation (VNS) is an effective treatment for patients with drug-resistant epilepsy who are unsuitable for surgical epilepsy treatment. However, the mechanism of action of VNS remains unclear, and the efficacy of VNS treatment regarding seizure frequency reduction cannot be assessed before surgery. This study measured changes in functional connectivity between thalamus and precentral gyrus which are activated as vital targets of deep brain stimulation (DBS) and transcranial magnetic stimulation (TMS) using resting-state functional MRI to evaluate the effects of VNS. 16 epilepsy patients who underwent VNS were collected and scanned by resting-state functional MRI before and after operation. The functional connections (regions of interest: thalamus, precentral gyrus) were examined. After three months of stimulation, there were eight responders (≥50 % seizure reduction) and eight non-responders to VNS. No significant difference in thalamus-precentral gyrus functional connectivity was found between responders and nonresponders before operation. Enhanced functional connections were observed between bilateral thalamus and bilateral precentral gyrus in responders, which decreased in nonresponders, while functional connections between bilateral thalamus decreased in both responders and nonresponders. Short-term stimulation may cause thalamus-precentral gyrus functional connectivity changes in DRE patients, and control seizures by enhancing functional connections between bilateral thalamus and bilateral precentral gyrus.

Relation between coffee consumption and risk of seizure-related respiratory dysfunction in patients with drug-resistant focal epilepsy.

OBJECTIVE: Caffeine is an antagonist of the adenosine pathway, which is involved in regulation of breathing. Extracellular concentrations of adenosine are increased in the immediate aftermath of a seizure. Seizure-related overstimulation of adenosine receptors might promote peri-ictal apnea. However, the relation between caffeine consumption and risk of seizure-related respiratory dysfunction in patients with drug-resistant focal epilepsy remains unknown. METHODS: We performed a cross-sectional analysis of data collected in patients included in the SAVE study in Lyon's epilepsy monitoring unit at the Adult Epilepsy Department of the Lyon University Hospital between February 2016 and October 2018. The video-electroencephalographic recordings of 156 patients with drug-resistant focal epilepsy included in the study were reviewed to identify those with ≥1 focal seizure (FS), valid pulse oximetry (SpO2 ) measurement, and information about usual coffee consumption. This latter was collected at inclusion using a standardized self-questionnaire and further classified into four groups: none, rare (≤3 cups/week), moderate (4 cups/week to 3 cups/day), and high (≥4 cups/day). Peri-ictal hypoxemia (PIH) was defined as SpO2 < 90% for at least 5 s occurring during the ictal period, the post-ictal period, or both. RESULTS: Ninety patients fulfilled inclusion criteria, and 323 seizures were analyzed. Both the level of usual coffee consumption (p = .033) and the level of antiepileptic drug withdrawal (p = .004) were independent risk factors for occurrence of PIH. In comparison with FS in patients with no coffee consumption, risk of PIH was four times lower in FS in patients with moderate consumption (odds ratio [OR] = .25, 95% confidence interval [CI] = .07-.91, p = .036) and six times lower in FS in patients with high coffee consumption (OR = .16, 95% CI = .04-.66, p = .011). However, when PIH occurred, its duration was longer in patients with moderate or high consumption than in those with no coffee consumption (p = .042). SIGNIFICANCE: Coffee consumption may be a protective factor for seizure-related respiratory dysfunction, with a dose-dependent effect.

Distributed source modeling of intracranial stereoelectro-encephalographic measurements.

Intracranial stereoelectroencephalography (sEEG) provides unsurpassed sensitivity and specificity for human neurophysiology. However, functional mapping of brain functions has been limited because the implantations have sparse coverage and differ greatly across individuals. Here, we developed a distributed, anatomically realistic sEEG source-modeling approach for within- and between-subject analyses. In addition to intracranial event-related potentials (iERP), we estimated the sources of high broadband gamma activity (HBBG), a putative correlate of local neural firing. Our novel approach accounted for a significant portion of the variance of the sEEG measurements in leave-one-out cross-validation. After logarithmic transformations, the sensitivity and signal-to-noise ratio were linearly inversely related to the minimal distance between the brain location and electrode contacts (slope≈-3.6). The signa-to-noise ratio and sensitivity in the thalamus and brain stem were comparable to those locations at the vicinity of electrode contact implantation. The HGGB source estimates were remarkably consistent with analyses of intracranial-contact data. In conclusion, distributed sEEG source modeling provides a powerful neuroimaging tool, which facilitates anatomically-normalized functional mapping of human brain using both iERP and HBBG data.

Electrophysiology of the Human Superior Temporal Sulcus during Speech Processing.

The superior temporal sulcus (STS) is a crucial hub for speech perception and can be studied with high spatiotemporal resolution using electrodes targeting mesial temporal structures in epilepsy patients. Goals of the current study were to clarify functional distinctions between the upper (STSU) and the lower (STSL) bank, hemispheric asymmetries, and activity during self-initiated speech. Electrophysiologic properties were characterized using semantic categorization and dialog-based tasks. Gamma-band activity and alpha-band suppression were used as complementary measures of STS activation. Gamma responses to auditory stimuli were weaker in STSL compared with STSU and had longer onset latencies. Activity in anterior STS was larger during speaking than listening; the opposite pattern was observed more posteriorly. Opposite hemispheric asymmetries were found for alpha suppression in STSU and STSL. Alpha suppression in the STS emerged earlier than in core auditory cortex, suggesting feedback signaling within the auditory cortical hierarchy. STSL was the only region where gamma responses to words presented in the semantic categorization tasks were larger in subjects with superior task performance. More pronounced alpha suppression was associated with better task performance in Heschl's gyrus, superior temporal gyrus, and STS. Functional differences between STSU and STSL warrant their separate assessment in future studies.

Thalamus and focal to bilateral seizures: A multiscale cognitive imaging study.

OBJECTIVE: To investigate the functional correlates of recurrent secondarily generalized seizures in temporal lobe epilepsy (TLE) using task-based fMRI as a framework to test for epilepsy-specific network rearrangements. Because the thalamus modulates propagation of temporal lobe onset seizures and promotes cortical synchronization during cognition, we hypothesized that occurrence of secondarily generalized seizures, i.e., focal to bilateral tonic-clonic seizures (FBTCS), would relate to thalamic dysfunction, altered connectivity, and whole-brain network centrality. METHODS: FBTCS occur in a third of patients with TLE and are a major determinant of disease severity. In this cross-sectional study, we analyzed 113 patients with drug-resistant TLE (55 left/58 right), who performed a verbal fluency fMRI task that elicited robust thalamic activation. Thirty-three patients (29%) had experienced at least one FBTCS in the year preceding the investigation. We compared patients with TLE-FBTCS to those without FBTCS via a multiscale approach, entailing analysis of statistical parametric mapping (SPM) 12-derived measures of activation, task-modulated thalamic functional connectivity (psychophysiologic interaction), and graph-theoretical metrics of centrality. RESULTS: Individuals with TLE-FBTCS had less task-related activation of bilateral thalamus, with left-sided emphasis, and left hippocampus than those without FBTCS. In TLE-FBTCS, we also found greater task-related thalamotemporal and thalamomotor connectivity, and higher thalamic degree and betweenness centrality. Receiver operating characteristic curves, based on a combined thalamic functional marker, accurately discriminated individuals with and without FBTCS. CONCLUSIONS: In TLE-FBTCS, impaired task-related thalamic recruitment coexists with enhanced thalamotemporal connectivity and whole-brain thalamic network embedding. Altered thalamic functional profiles are proposed as imaging biomarkers of active secondary generalization.

Antiseizure drug efficacy and tolerability in established and novel drug discovery seizure models in outbred vs inbred mice.

OBJECTIVE: Initial identification of new investigational drugs for the treatment of epilepsy is commonly conducted in well-established mouse acute and chronic seizure models: for example, maximal electroshock (MES), 6 Hz, and corneal kindling. Comparison of the median effective dose (ED50) of approved antiseizure drugs (ASDs) vs investigational agents in these models provides evidence of their potential for clinical efficacy. Inbred and outbred mouse strains exhibit differential seizure susceptibility. However, few comparisons exist of the ED50 or median behaviorally impairing dose (TD50) of prototype ASDs in these models in inbred C57Bl/6 vs outbred CF-1 mice, both of which are often used for ASD discovery. METHODS: We defined the strain-related ED50s and TD50s of several mechanistically distinct ASDs across established acute seizure models (MES, 6 Hz, and corneal-kindled mouse). We further quantified the strain-related effect of the MES ED50 of each ASD on gross behavior in a locomotor activity assay. Finally, we describe a novel pharmacoresistant corneal-kindling protocol that is suitable for moderate-throughput ASD screening and demonstrates highly differentiated ASD sensitivity. RESULTS: We report significant strain-related differences in the MES ED50 of valproic acid (CF-1 ED50: 90 mg/kg [95% confidence interval (CI) 165-214] vs C57Bl/6: 276 mg/kg [226-366]), as well as significant differences in the ED50 of levetiracetam in the pharmacoresistant 6 Hz test (CF-1: 22.5 mg/kg [14.7-30.2] vs C57Bl/6: >500 mg/kg [CI not defined]). There were no differences in the calculated TD50 of these ASDs between strains. Furthermore, the MES ED50 of phenobarbital significantly enhanced locomotor activity of outbred CF-1, but not C57Bl/6, mice. SIGNIFICANCE: Altogether, this study provides strain-related information to differentiate investigational agents from ASD standards-of-care in commonly employed preclinical discovery models and describes a novel kindled seizure model to further explore the mechanisms of drug-resistant epilepsy.

Nine-year prospective efficacy and safety of brain-responsive neurostimulation for focal epilepsy.

OBJECTIVE: To prospectively evaluate safety and efficacy of brain-responsive neurostimulation in adults with medically intractable focal onset seizures (FOS) over 9 years. METHODS: Adults treated with brain-responsive neurostimulation in 2-year feasibility or randomized controlled trials were enrolled in a long-term prospective open label trial (LTT) to assess safety, efficacy, and quality of life (QOL) over an additional 7 years. Safety was assessed as adverse events (AEs), efficacy as median percent change in seizure frequency and responder rate, and QOL with the Quality of Life in Epilepsy (QOLIE-89) inventory. RESULTS: Of 256 patients treated in the initial trials, 230 participated in the LTT. At 9 years, the median percent reduction in seizure frequency was 75% (p < 0.0001, Wilcoxon signed rank), responder rate was 73%, and 35% had a ≥90% reduction in seizure frequency. We found that 18.4% (47 of 256) experienced ≥1 year of seizure freedom, with 62% (29 of 47) seizure-free at the last follow-up and an average seizure-free period of 3.2 years (range 1.04-9.6 years). Overall QOL and epilepsy-targeted and cognitive domains of QOLIE-89 remained significantly improved (p < 0.05). There were no serious AEs related to stimulation, and the sudden unexplained death in epilepsy (SUDEP) rate was significantly lower than predefined comparators (p < 0.05, 1-tailed χ2). CONCLUSIONS: Adjunctive brain-responsive neurostimulation provides significant and sustained reductions in the frequency of FOS with improved QOL. Stimulation was well tolerated; implantation-related AEs were typical of other neurostimulation devices; and SUDEP rates were low. CLINICALTRIALSGOV IDENTIFIER: NCT00572195. CLASSIFICATION OF EVIDENCE: This study provides Class IV evidence that brain-responsive neurostimulation significantly reduces focal seizures with acceptable safety over 9 years.

External trigeminal nerve stimulation for drug resistant epilepsy: A randomized controlled trial.

BACKGROUND: External trigeminal nerve stimulation (ETNS) is an emergent, non-invasive neurostimulation therapy delivered bilaterally with adhesive skin electrodes. In previous studies, ETNS was associated to a decrease in seizure frequency in patients with focal drug-resistant epilepsy (DRE). OBJECTIVE: To determine the long-term efficacy and tolerability of ETNS in patients with focal DRE. Moreover, to explore whether its efficacy depends on the epileptogenic zone (frontal or temporal), and its impact on mood, cognitive function, quality of life, and trigeminal nerve excitability. METHODS: Forty consecutive patients with frontal or temporal DRE, unsuitable for surgery, were randomized to ETNS or usual medical treatment. Participants were evaluated at 3, 6 and 12 months for efficacy, side effects, mood scales, neuropsychological tests and trigeminal nerve excitability. RESULTS: Subjects had a median of 15 seizures per month and had tried a median of 12.5 antiepileptic drugs. At 12 months, percentage of responders was 50% in ETNS group and 0% in control group. Seizure frequency in ETNS group decreased by -43.5% from baseline. Temporal epilepsy subgroup responded better than frontal epilepsy subgroup (55.56% vs. 45.45%, respectively). Median stimulation intensity was 6.2 mA. ETNS improved quality of life, but not anxiety or depression. Long-term ETNS affected neither neuropsychological function, nor trigeminal nerve excitability. No relevant adverse events were observed. CONCLUSIONS: ETNS is an effective and well-tolerated therapy for focal DRE. Patients with temporal epilepsy showed a better response than those with frontal epilepsy. Future studies with larger populations may define its role compared to other neurostimulation techniques. CLASSIFICATION OF EVIDENCE: This study provides Class II evidence that ETNS reduces seizure frequency in patients with focal DRE.

Mesial temporal resection following long-term ambulatory intracranial EEG monitoring with a direct brain-responsive neurostimulation system.

OBJECTIVE: To describe seizure outcomes in patients with medically refractory epilepsy who had evidence of bilateral mesial temporal lobe (MTL) seizure onsets and underwent MTL resection based on chronic ambulatory intracranial EEG (ICEEG) data from a direct brain-responsive neurostimulator (RNS) system. METHODS: We retrospectively identified all patients at 17 epilepsy centers with MTL epilepsy who were treated with the RNS System using bilateral MTL leads, and in whom an MTL resection was subsequently performed. Presumed lateralization based on routine presurgical approaches was compared to lateralization determined by RNS System chronic ambulatory ICEEG recordings. The primary outcome was frequency of disabling seizures at last 3-month follow-up after MTL resection compared to seizure frequency 3 months before MTL resection. RESULTS: We identified 157 patients treated with the RNS System with bilateral MTL leads due to presumed bitemporal epilepsy. Twenty-five patients (16%) subsequently had an MTL resection informed by chronic ambulatory ICEEG (mean = 42 months ICEEG); follow-up was available for 24 patients. After MTL resection, the median reduction in disabling seizures at last follow-up was 100% (mean: 94%; range: 50%-100%). Nine patients (38%) had exclusively unilateral electrographic seizures recorded by chronic ambulatory ICEEG and all were seizure-free at last follow-up after MTL resection; eight of nine continued RNS System treatment. Fifteen patients (62%) had bilateral MTL electrographic seizures, had an MTL resection on the more active side, continued RNS System treatment, and achieved a median clinical seizure reduction of 100% (mean: 90%; range: 50%-100%) at last follow-up, with eight of fifteen seizure-free. For those with more than 1 year of follow-up (N = 21), 15 patients (71%) were seizure-free during the most recent year, including all eight patients with unilateral onsets and 7 of 13 patients (54%) with bilateral onsets. SIGNIFICANCE: Chronic ambulatory ICEEG data provide information about lateralization of MTL seizures and can identify additional patients who may benefit from MTL resection.

A perspective on cannabinoids for treating epilepsy: Do they really change the landscape?

With the licensing of cannabidiol for drug resistant seizures in Dravet and Lennox Gastaut syndromes in the United states in 2018, interest in the potential for cannabis-based-medicinal products to meet currently unmet needs for people with epilepsy continues to grow. This review summarizes current knowledge and discusses the implications for future research and practice. Both cannabidiol and tetrahydrocannabinol, the main components, have been extensively studied in animal models, with multimodal mechanisms of action proposed. Only pure cannabidiol formulations have been rigorously evaluated in controlled trials thus far, with modest but significant improvements in motor seizures. Adverse effects include diarrhoea, somnolence and reduced appetite, with mostly acceptable tolerability, but a not insignificant (up to 1 in 23) risk of serious adverse events. Recognized drug interactions include with valproate (increased risk of hepatotoxicity) and clobazam (contributing to somnolence, increased secretions, probably chest infections, and potentially efficacy). Whilst there is public (and producer) interest in products also containing tetrahydrocannabinol, clinicians have justifiable concerns about exposing a group already vulnerable to mental health and neurobehavioural comorbidities to the associated additional risks in these domains. Artisanal preparations, with often inconsistent/unknown constituents are frequently used but not recommended. A gulf exists between the actual evidence, including a lack of comparative studies and public beliefs, fuelled by media and anecdote. Continued education of the public, policymakers, researchers and healthcare providers about what is and isn't yet known, together with on-going good quality research is essential to mitigate against future potential risks, particularly in relation to vulnerable populations. This article is part of the special issue entitled 'New Epilepsy Therapies for the 21st Century - From Antiseizure Drugs to Prevention, Modification and Cure of Epilepsy'.

Responsive neurostimulation for regional neocortical epilepsy.

OBJECTIVE: Surgical resection of seizure-producing brain tissue is a gold standard treatment for drug-resistant focal epilepsy. However, several patient-specific factors can preclude resective surgery, including a spatially extensive ("regional") seizure-onset zone (SOZ). For such patients, responsive neurostimulation (RNS) represents a potential treatment, but its efficacy has not been investigated in this population. METHODS: We performed a multicenter retrospective cohort study of patients (N = 30) with drug-resistant focal epilepsy and a regional neocortical SOZ delineated by intracranial monitoring who were treated with the RNS System for at least 6 months. RNS System leads were placed at least 1-cm apart over the SOZ, and most patients were treated with a lead-to-lead stimulation pathway. Five patients underwent partial resection of the SOZ concurrent with RNS System implantation. We assessed change in seizure frequency relative to preimplant baseline and evaluated correlation between clinical outcome and stimulation parameters. RESULTS: Median follow-up duration was 21.5 months (range 6-52). Median reduction in clinical seizure frequency was 75.5% (interquartile range [IQR] 40%-93.9%). There was no significant difference in outcome between patients treated with and without concurrent partial resection. Most patients were treated with low charge densities (1-2.5 µC/cm2 ), but charge density, interlead distance, and duration of treatment were not significantly correlated with outcome. SIGNIFICANCE: RNS is a feasible and effective treatment in patients with drug-resistant regional neocortical seizures. Prospective studies in larger cohorts are necessary to determine optimal lead configuration and stimulation parameters, although our results suggest that lead-to-lead stimulation and low charge density may be effective in some patients.

Transcutaneous Auricular Vagus Nerve Stimulation.

Invasive vagus nerve stimulation (VNS) is an approved treatment for drug-resistant epilepsy. Besides recognized clinical efficacy in about 60% of patients, there are major drawbacks such as invasiveness and common side effects including hoarseness, sore throat, shortness of breath, and coughing. Invasive VNS applies electrical stimulation to the left cervical branch of the vagus nerve and excites thick-myelinated afferent nerve fibers. Peripheral vagus nerve afferent volley initiates brainstem activity in the nucleus of the solitary tract and provokes typical brainstem and cerebral activation patterns that mediate the anticonvulsive mode of action. Whereas invasive VNS is an established neuromodulatory treatment in drug-resistant epilepsy, transcutaneous VNS (tVNS) of the auricular branch of the vagus nerve is suggested to be an alternative access path to the same neuronal network without invasiveness. Preclinical and clinical studies indicate that especially the cymba conchae of the auricle is selectively supplied by the auricular branch of the vagus nerve. Recent anatomical data demonstrate existence and quantity of thick-myelinated afferent nerve fibers of the left auricular branch of the vagus nerve that carries 21% of thick-myelinated afferent nerve fibers counted in the left thoracic vagus nerve in humans. Projection of auricular branch of the vagus nerve afferents from the auricle to the nucleus of the solitary tract is known from histochemical and electrophysiological experiments in rodents and confirmed in humans by functional imaging. Cerebral activation patterns triggered by invasive and tVNS resemble each other in appearance. Clinical trials in patients address safety and performance of tVNS and provide evidence for application in drug-resistant epilepsy.

Decreased electrodermal activity in patients with epilepsy.

OBJECTIVE: Biofeedback therapy using electrodermal activity (EDA) is a new noninvasive therapy for intractable epilepsy. However, the characteristics of EDA in patients with epilepsy are little known; therefore, we assessed the EDA characteristics in patients with epilepsy. METHODS: A cross-sectional observational study was conducted in 22 patients with epilepsy and 24 healthy individuals. We collected information on demographic characteristics, EDA, and state anxiety from both groups, and epilepsy diagnosis, seizure number per month, disease duration, and number of antiepileptic drugs (AED) from the epilepsy group. A wristband device was used to measure resting EDA from both wrists for 10 min under controlled temperature and humidity. We compared the EDA levels between the epilepsy group and the control group and examined correlations between EDA and epilepsy-associated factors in the epilepsy group. RESULTS: A decreasing trend in EDA was observed during the first 1 min from the start of the measurement in 22 patients with epilepsy (with or without seizures) compared with healthy controls (P = 0.12). However, a significant decrease in EDA was found in 18 patients with epilepsy with seizures compared with healthy controls (-0.48 versus -0.26; P = 0.036). Furthermore, seizure frequency showed a significant inverse correlation with EDA in the epilepsy group (ρ = -0.50, P = 0.016). However, neither disease duration nor the number of drugs prescribed correlated with EDA in the epilepsy group . SIGNIFICANCE: Marginally decreased EDA was observed in patients with epilepsy, and significantly decreased EDA was found in patients with a higher seizure frequency. The present findings shed light on the appropriateness of EDA-biofeedback therapy in epilepsy.

Early polytherapy for benzodiazepine-refractory status epilepticus.

The transition from single seizures to status epilepticus (SE) is associated with malaptive trafficking of synaptic gamma-aminobutyric acid (GABAA) and glutamate receptors. The receptor trafficking hypothesis proposes that these changes are key events in the development of pharmacoresistance to antiepileptic drugs (AEDs) during SE, and that blocking their expression will help control drug-refractory SE (RSE). We tested this hypothesis in a model of SE induced by very high-dose lithium and pilocarpine (RSE), and in a model of SE induced by sc soman. Both models are refractory to benzodiazepines when treated 40 min after seizure onset. Our treatments aimed to correct the loss of inhibition because of SE-associated internalization of synaptic GABAA receptors (GABAAR), using an allosteric GABAAR modulator, sometimes supplemented by an AED acting at a nonbenzodiazepine site. At the same time, we reduced excitation because of increased synaptic localization of NMDA and AMPA (?-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid and N-methyl-D-aspartate) receptors (NMDAR, AMPAR (?-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor, N-methyl-D-aspartate receptors)) with an NMDAR channel blocker, since AMPAR changes are NMDAR-dependent. Treatment of RSE with combinations of the GABAAR allosteric modulators midazolam or diazepam and the NMDAR antagonists dizocilpine or ketamine terminated RSE unresponsive to high-dose monotherapy. It also reduced RSE-associated neuronal injury, spatial memory deficits, and the occurrence of spontaneous recurrent seizures (SRS), tested several weeks after SE. Treatment of soman-induced SE also reduced seizures, behavioral deficits, and epileptogenesis. Addition of an AED further improved seizure outcome in both models. Three-dimensional isobolograms demonstrated positive cooperativity between midazolam, ketamine, and valproate, without any interaction between the toxicity of these drugs, so that the therapeutic index was increased by combination therapy. The midazolam-ketamine-valproate combination based on the receptor trafficking hypothesis was far more effective in stopping RSE than the midazolam-fosphenytoin-valproate combination inspired from clinical guidelines for the treatment of SE. Furthermore, sequential administration of midazolam, ketamine, and valproate was far less effective than simultaneous treatment with the same drugs at the same dose. These data suggest that treatment of RSE should be based at least in part on its pathophysiology. The search for a better treatment should focus on the cause of pharmacoresistance, which is loss of synaptic GABAAR and gain of synaptic glutamate receptors. Both need to be treated. Monotherapy addresses only half the problem. Improved pharmacokinetics will not help pharmacoresistance because of loss of receptors. Waiting for one drug to fail before giving the second drugs gives pharmacoresistance time to develop. Future clinical trials should consider treating both the failure of inhibition and the runaway excitation which characterize RSE, and should include an early polytherapy arm. This article is part of the Special Issue "Proceedings of the 7th London-Innsbruck Colloquium on Status Epilepticus and Acute Seizures".

The Role of Anterior Thalamic Deep Brain Stimulation as an Alternative Therapy in Patients with Previously Failed Vagus Nerve Stimulation for Refractory Epilepsy.

Deep brain stimulation (DBS) has provided new treatment options for refractory epilepsy; however, treatment outcomes of DBS in refractory epilepsy patients previously treated with vagus nerve stimulation (VNS) have not been clarified. Herein, treatment outcomes of DBS of the anterior nucleus of the thalamus (ANT-DBS) in patients who had previously experienced VNS failure are reported. Seven patients who had previously experienced VNS failure underwent ANT-DBS device implantation. VNS was turned off before DBS device implantation. Monthly seizure counts starting from baseline to 12-18 months after DBS were analyzed. Five (71.3%) of the 7 patients experienced a >50% reduction of seizure counts after DBS; 1 responder reached a seizure-free status after DBS therapy. Of the 2 nonresponders, 1 subject showed improvement in seizure strength and duration, which lessened the impact of the seizures on the patient's quality of life. This is the first study in which favorable outcomes of ANT-DBS surgery were observed in individual patients with refractory epilepsy who had not responded to prior VNS. Further studies with a larger number of subjects and longer follow-up period are needed to confirm the feasibility of ANT-DBS in patients who have previously experienced VNS failure.