How valid are proxy assessment of mental health and sleep comorbidities of patients with epilepsy using standardized questionnaires?

BACKGROUND

The study aimed to determine the level of agreement between patients with epilepsy and their proxies when assessing psychiatric comorbidities, sleep disorders, and medication adherence using standardized questionnaires.

METHODS

This agreement study is an ancillary analysis of the PRERIES study, a matched case-control study exploring SUDEP risk factors. Controls aged 15 years and older, with active epilepsy or in remission for less than 5 years were recruited between 01/01/2011 and 03/31/2019. An interview was carried out by a trained psychologist on both the patient and a proxy-respondent. During these independent interviews, the following comorbidities were explored: psychiatric comorbidities using the MINI, the STAI- Y2 and NDDI-E scales, sleep disorders with the SDQ-SA and Epworth scales and medication adherence. Level of agreement between patient and their proxy was estimated using Gwet's AC1&2.

RESULTS

Among the 107 patient-proxy dyads recruited, proxy respondents were mainly family members (65.4%) or spouses (30.8%). Exploration of present major depression showed excellent agreement at 0.81 [0.65;0.97], as well as exploration of dysthymia at 0.96 [0.61;1]. Suicidal risk evaluation had a lesser agreement at 0.77 [0.60;0.94]. Agreement on anxiety was moderate 0.5 [0.38;0.62]. For sleep disorder, SDQ-SA presented a better agreement than the Epworth questionnaire with respectively 0.73 [0.51;0.95] and 0.45 [0.26;0.63]. For medication adherence, the overall agreement rate was excellent (0.90 [0.78;1]).

CONCLUSION

Exploration of potential risk factors through families can give valuable and relatively robust information, especially if the respondent lives with the patient, and should be retrieved, when possible, in usual clinical setting.

Early identification of seizure freedom with medical treatment in patients with mesial temporal lobe epilepsy and hippocampal sclerosis

BACKGROUND

Mesial temporal lobe epilepsy with hippocampal sclerosis (MTLE-HS) is usually associated with a poor response to antiseizure medications. We focused on MTLE-HS patients who were seizure free on medication to: (1) determine the clinical factors associated with seizure freedom and (2) develop a machine-learning classifier to better earlier identify those patients.

METHODS

We performed a retrospective, multicentric study comparing 64 medically treated seizure-free MTLE-HS patients with 200 surgically treated drug-resistant MTLE-HS patients. First, we collected medical history and seizure semiology data. Then, we developed a machine-learning classifier based on clinical data.

RESULTS

Medically treated seizure-free MTLE-HS patients were seizure-free for at least 2 years, and for a median time of 7 years at last follow-up. Compared to drug-resistant MTLE-HS patients, they exhibited: an older age at epilepsy onset (22.5 vs 8.0 years, p < 0.001), a lesser rate of: febrile seizures (39.0% vs 57.5%, p = 0.035), focal aware seizures (previously referred to as aura)(56.7% vs 90.0%, p < 0.001), autonomic focal aware seizures in presence of focal aware seizure (17.6% vs 59.4%, p < 0.001), dystonic posturing of the limbs (9.8% vs 47.0%, p < 0.001), gestural (27.4% vs 94.0%, p < 0.001), oro-alimentary (32.3% vs 75.5%, p < 0.001) or verbal automatisms (12.9% vs 36.0%, p = 0.001). The classifier had a positive predictive value of 0.889, a sensitivity of 0.727, a specificity of 0.962, a negative predictive value of 0.893.

CONCLUSIONS

Medically treated seizure-free MTLE-HS patients exhibit a distinct clinical profile. A classifier built with readily available clinical data can identify them accurately with excellent positive predictive value. This may help to individualize the management of MTLE-HS patients according to their expected pharmacosensitivity.

Assessment of an under-mattress sensor as a seizure detection tool in an adult epilepsy monitoring unit

OBJECTIVE

Because of SUDEP (Sudden and unexpected death in epilepsy) and other direct consequences of generalized tonic-clonic seizures, the use of efficient seizure detection tool may be helpful for patients, relatives and caregivers. We aimed to evaluate an under-mattress detection tool (EMFIT®) in real-life hospital conditions, in particular its sensitivity and false alarm rate (FAR), as well as its impact on patient care.

METHODS

We carried out a retrospective study on a cohort of patients with epilepsy admitted between September 2017 and June 2021 to Amiens University Hospital for a video-EEG of at least 24 h, during which at least one epileptic seizure was recorded. All video-EEGs records were analyzed visually in order to assess the sensitivity of the under-mattress tool (triggering of the alarm) and to classify the seizure type (convulsive/non convulsive). We also considered whether nurses intervened during the seizure, and the time of their intervention if applicable. An additional prospective survey was conducted over 272 days to analyze the FAR of the tool.

RESULTS

A total of 220 seizures were included in the study, from 55 patients, including 23 convulsive seizures from 15 patients and 197 non-convulsive seizures. Sensitivity for convulsive seizure detection was 69.6%. As expected, none of the non-convulsive seizures was detected. The false alarm rate was 0.007/day. Median trigger time was 74 s, decreasing to 5 s for generalized tonic-clonic seizure. The frequency of nurses' intervention during convulsive seizures was significantly greater in case of the alarm triggering (100% vs 57%, p<0.02).

SIGNIFICANCE

These results suggest that EMFIT® sensor is able to detect convulsive seizures with good sensitivity and low FAR, and allows caregivers to intervene more often in the event of a nocturnal seizure. This would be an interesting complementary tool to better secure the patients with epilepsy during hospitalization or at home.

Stratifying sudden death risk in adults with drug-resistant focal epilepsy: The SUDEP-CARE score

BACKGROUND AND PURPOSE

A clinical risk score for sudden unexpected death in epilepsy (SUDEP) in patients with drug-resistant focal epilepsy could help improve prevention.

METHODS

A case-control study was conducted including (i) definite or probable SUDEP cases collected by the French National Sentinel Mortality Epilepsy Network and (ii) control patients from the French national research database of epilepsy monitoring units. Patients with drug-resistant focal epilepsy were eligible. Multiple logistic regressions were performed. After sensitivity analysis and internal validation, a simplified risk score was developed from the selected variables.

RESULTS

Sixty-two SUDEP cases and 620 controls were included. Of 21 potential predictors explored, seven were ultimately selected, including generalized seizure frequency (>1/month vs. <1/year: adjusted odds ratio [AOR] 2.6, 95% confidence interval [CI] 1.25-5.41), nocturnal or sleep-related seizures (AOR 4.49, 95% CI 2.68-7.53), current or past depression (AOR 2.0, 95% CI 1.19-3.34) or the ability to alert someone of an oncoming seizure (AOR 0.57, 95% CI 0.33-0.98). After internal validation, a clinically usable score ranging from -1 to 8 was developed, with high discrimination capabilities (area under the receiver operating curve 0.85, 95% CI 0.80-0.90). The threshold of 3 has good sensitivity (82.3%, 95% CI 72.7-91.8), whilst keeping a good specificity (82.7%, 95% CI 79.8-85.7).

CONCLUSIONS

These results outline the importance of generalized and nocturnal seizures on the occurrence of SUDEP, and show a protective role in the ability to alert someone of an oncoming seizure. The SUDEP-CARE score is promising and will need external validation. Further work, including paraclinical explorations, could improve this risk score.

New onset refractory status epilepticus: State of the art

NORSE (new onset refractory status epilepticus) has recently been defined as a clinical presentation, not a specific diagnosis, in a patient without active epilepsy or other preexisting relevant neurological disorder, with new onset of refractory status epilepticus without a clear acute or active structural, toxic or metabolic cause. It includes the concept of FIRES described in children with a similar condition but preceded by a 2-14-day febrile illness. NORSE constitutes the acute phase of an entity preceded by a prodromal phase which may be accompanied by numerous manifestations (febrile episode, behavioural changes, headache, …), and followed by a chronic phase marked by long-term neurological sequelae, cognitive impairment, epilepsy and functional disability. There are many causes of NORSE: autoimmune, infectious, genetic, toxic, … but in half of the cases, despite an exhaustive assessment, the cause remains undetermined. Paraneoplastic and non-paraneoplastic autoimmune encephalitis remains by far the leading cause of NORSE. For these reasons, immunotherapy should be considered rapidly in parallel with the treatment of the status epilepticus, including in cryptogenic NORSE. Good communication with the family is important because the management of the acute phase is long and difficult. Although mortality remains high (11-22%), and sequelae can be severe, the majority of survivors can have a good or fair outcome.

A brain atlas of axonal and synaptic delays based on modelling of cortico-cortical evoked potentials

Epilepsy presurgical investigation may include focal intracortical single-pulse electrical stimulations with depth electrodes, which induce cortico-cortical evoked potentials at distant sites because of white matter connectivity. Cortico-cortical evoked potentials provide a unique window on functional brain networks because they contain sufficient information to infer dynamical properties of large-scale brain connectivity, such as preferred directionality and propagation latencies.

 Here, we developed a biologically informed modelling approach to estimate the neural physiological parameters of brain functional networks from the cortico-cortical evoked potentials recorded in a large multicentric database. Specifically, we considered each cortico-cortical evoked potential as the output of a transient stimulus entering the stimulated region, which directly propagated to the recording region. Both regions were modelled as coupled neural mass models, the parameters of which were estimated from the first cortico-cortical evoked potential component, occurring before 80 ms, using dynamic causal modelling and Bayesian model inversion. This methodology was applied to the data of 780 patients with epilepsy from the F-TRACT database, providing a total of 34 354 bipolar stimulations and 774 445 cortico-cortical evoked potentials. The cortical mapping of the local excitatory and inhibitory synaptic time constants and of the axonal conduction delays between cortical regions was obtained at the population level using anatomy-based averaging procedures, based on the Lausanne2008 and the HCP-MMP1 parcellation schemes, containing 130 and 360 parcels, respectively. To rule out brain maturation effects, a separate analysis was performed for older (>15 years) and younger patients (<15 years). In the group of older subjects, we found that the cortico-cortical axonal conduction delays between parcels were globally short (median = 10.2 ms) and only 16% were larger than 20 ms. This was associated to a median velocity of 3.9 m/s. Although a general lengthening of these delays with the distance between the stimulating and recording contacts was observed across the cortex, some regions were less affected by this rule, such as the insula for which almost all efferent and afferent connections were faster than 10 ms. Synaptic time constants were found to be shorter in the sensorimotor, medial occipital and latero-temporal regions, than in other cortical areas. Finally, we found that axonal conduction delays were significantly larger in the group of subjects younger than 15 years, which corroborates that brain maturation increases the speed of brain dynamics.

To our knowledge, this study is the first to provide a local estimation of axonal conduction delays and synaptic time constants across the whole human cortex in vivo, based on intracerebral electrophysiological recordings.

Cardiac Autonomic Dysfunction and Risk of Sudden Unexpected Death in Epilepsy

OBJECTIVE

We aimed to test whether patients who died of sudden unexpected death in epilepsy (SUDEP) had an abnormal cardiac autonomic response to sympathetic stimulation by hyperventilation.

METHODS

We conducted a retrospective, observational, case-control study of a group of patients who died of SUDEP and controls who were matched to the patients for epilepsy type, drug resistance, sex, age at EEG recording, age at onset of epilepsy, and duration of epilepsy. We analyzed the heart rate (HR) and HR variability (HRV) at rest and during and after hyperventilation performed during the patient's last EEG recording before SUDEP. In each group, changes over time in HRV indexes were analyzed with linear mixed models.

RESULTS

Twenty patients were included in each group. In the control group, the HR increased and the root mean square of successive RR-interval differences (RMSSD) decreased during the hyperventilation and then returned to the baseline values. In the SUDEP group, however, the HR and RMSSD did not change significantly during or after hyperventilation. A difference in HR between the end of the hyperventilation and 4 minutes after its end discriminated well between patients with SUDEP and control patients (area under the receiver operating characteristic curve 0.870, sensitivity 85%, specificity 75%).

CONCLUSION

Most of patients with subsequent SUDEP have an abnormal cardiac autonomic response to sympathetic stimulation through hyperventilation. An index reflecting the change in HR on hyperventilation might be predictive of the risk of SUDEP and could be used to select patients at risk of SUDEP for inclusion in trials assessing protective measures.

Prise en charge des états de mal épileptiques en préhospitalier, en structure d’urgence et en réanimation dans les 48 premières heures (à l’exclusion du nouveau‑né et du nourrisson)

La Société de réanimation de langue française et la Société française de médecine d’urgence ont décidé d’élaborer denouvelles recommandations sur la prise en charge de l’état de mal épileptique (EME) avec l’ambition de répondre leplus possible aux nombreuses questions pratiques que soulèvent les EME : diagnostic, enquête étiologique, traitementnon spécifique et spécifique. Vingt‑cinq experts ont analysé la littérature scientifique et formulé des recommandationsselon la méthodologie GRADE. Les experts se sont accordés sur 96 recommandations. Les recommandations avecle niveau de preuve le plus fort ne concernent que l’EME tonicoclonique généralisé (EMETCG) : l’usage des benzodia‑zépines en première ligne (clonazépam en intraveineux [IV] direct ou midazolam en intramusculaire) est recommandé,répété cinq minutes après la première injection (à l’exception du midazolam) en cas de persistance clinique. En casde persistance cinq minutes après cette seconde injection, il est proposé d’administrer la deuxième ligne thérapeu‑tique : valproate de sodium, (fos‑)phénytoïne, phénobarbital ou lévétiracétam. La persistance avérée de convulsions30 minutes après le début de l’administration du traitement de deuxième ligne signe l’EMETCG réfractaire. Il est alorsproposé de recourir à un coma thérapeutique au moyen d’un agent anesthésique intraveineux de type midazolam oupropofol. Des recommandations spécifiques à l’enfant et aux autres EME sont aussi énoncées.

Recommandations Formalisées d’Experts SRLF/SFMU : Prise en charge des états de mal épileptiques en préhospitalier, en structure d’urgence et en réanimation dans les 48 premières heures (A l’exclusion du nouveau-né et du nourrisson)

La Société de réanimation de langue française et la Société française de médecine d’urgence ont décidé d’élaborer de nouvelles recommandations sur la prise en charge de l’état mal épileptique (EME) avec l’ambition de répondre le plus possible aux nombreuses questions pratiques que soulèvent les EME : diagnostic, enquête étiologique, traitement non spécifique et spécifique. Vingt-cinq experts ont analysé la littérature scientifique et formulé des recommandations selon la méthodologie GRADE. Les experts se sont accordés sur 96 recommandations. Les recommandations avec le niveau de preuve le plus fort ne concernent que l’EME tonico-clonique généralisé (EMTCG) : l’usage des benzodiazépines en première ligne (clonazépam en intraveineux direct ou midazolam en intramusculaire) est recommandé, répété 5 min après la première injection (à l’exception du midazolam) en cas de persistance clinique. En cas de persistance 5 min après cette seconde injection, il est proposé d’administrer la seconde ligne thérapeutique : valproate de sodium, (fos-)phénytoïne, phénobarbital ou lévétiracétam. La persistance avérée de convulsions 30 min après le début de l’administration du traitement de deuxième ligne signe l’EMETCG réfractaire. Il est alors proposé de recourir à un coma thérapeutique au moyen d’un agent anesthésique intraveineux de type midazolam ou propofol. Des recommandations spécifiques à l’enfant et aux autres EME sont aussi énoncées.

Usefulness of head-up tilt test combined with video electroencephalogram to investigate recurrent unexplained atypical transient loss of consciousness

BACKGROUND

Convulsive syncope and epileptic seizure share many similar clinical features. Early diagnosis is critical for choosing the appropriate management strategy.

AIM

Our aim was to evaluate the diagnostic yield of an innovative diagnostic strategy - combined head-up tilt test (HUT)/video electroencephalogram (EEG) monitoring - in patients with unexplained seizure-like transient loss of consciousness (T-LOC).

METHODS

Combined HUT/video EEG was performed in patients with unexplained atypical T-LOC with both syncope and seizure characteristics remaining undiagnosed after a first-line investigation. T-LOC diagnosis was achieved in case of reproduction of usual symptoms. Events were classified as vasovagal, psychogenic or epilepsy. The link between EEG abnormalities and T-LOC was determined by an epilepsy specialist. Clinical follow-up was performed to assess T-LOC recurrence.

RESULTS

Hundred and one consecutive patients were prospectively enrolled (median age 26 [19; 46] years; 72% female) and underwent combined HUT/video EEG between 2007 and 2015. Antiepileptic drugs were being prescribed in 42% of patients. Combined HUT/video EEG was diagnostic in 67% of patients, leading to diagnosis of vasovagal syncope in 59 patients and psychogenic pseudosyncope in nine cases. Antiepileptic drugs were discontinued in 18 patients without epilepsy. Independent predictors of a definitive diagnosis were the presence of prodromal symptoms (odds ratio 5.97, 95% confidence interval 1.37-26; P=0.017) and a history of myoclonic jerks during T-LOC (odds ratio 4.36, 95% confidence interval 1.71-11.15; P=0.002).

CONCLUSIONS

Combined HUT/video EEG is useful for investigating recurrent unexplained atypical seizure-like T-LOC, especially in patients with a history of myoclonic jerks or with documented interictal non-specific EEG abnormalities.

Experiences of self-conscious emotions in temporal lobe epilepsy

Self-conscious emotions (SCEs) with a negative valence (such as shame and guilt) or a positive valence (such as pride) are moral emotions that emerge from self-reflection and self-evaluation processes in social contexts. In some neurologic and psychiatric disorders, experiences of SCEs are dysregulated. The objectives of the present study were to (i) evaluate whether patients with temporal lobe epilepsy (TLE) experience SCEs in the same way as nonclinical (control) participants and (ii) probe the relationships between experiences of SCEs on the one hand and the psychological symptoms frequently diagnosed in patients with TLE (anxiety and depression), the patients' clinical characteristics, and their functional outcomes in everyday life on the other. Sixty-one patients with TLE and 61 matched controls completed a self-questionnaire (the Positive and Negative Affect Schedule (PANAS)) that enabled us to evaluate the extent to which they experienced shame, guilt, and pride. Demographic data, cognitive data, the severity of anxiety symptoms, and the severity of depressive symptoms were recorded for all participants. In patients with TLE, data of clinical characteristics and quality of life were also evaluated. Relative to controls, patients with TLE were more likely to experience negative-valence SCEs to a higher extent and positive SCEs to a lesser extent. The patients who experienced negative-valence SCEs to a higher extent (rather than to a lesser extent) had a higher frequency of seizures, more severe anxiety and depressive symptoms, and a greater prevalence of anxiety and depressive disorders. Furthermore, patients who experienced positive-valence SCEs to a lesser extent (rather than to a higher extent) displayed a higher level of anxiety. Lastly, differences in experiences of SCEs by patients with TLE were associated with a lower quality of life. In conclusion, experiences of SCEs can be dysregulated in patients with TLE. This dysregulation is linked to the patients' clinical and psychological symptoms and quality of life. In this context, SCEs might be a target of interest in the management of epilepsy.

Probabilistic functional tractography of the human cortex revisited

In patients with pharmaco-resistant focal epilepsies investigated with intracranial electroencephalography (iEEG), direct electrical stimulations of a cortical region induce cortico-cortical evoked potentials (CCEP) in distant cerebral cortex, which properties can be used to infer large scale brain connectivity. In 2013, we proposed a new probabilistic functional tractography methodology to study human brain connectivity. We have now been revisiting this method in the F-TRACT project (f-tract.eu) by developing a large multicenter CCEP database of several thousand stimulation runs performed in several hundred patients, and associated processing tools to create a probabilistic atlas of human cortico-cortical connections. Here, we wish to present a snapshot of the methods and data of F-TRACT using a pool of 213 epilepsy patients, all studied by stereo-encephalography with intracerebral depth electrodes. The CCEPs were processed using an automated pipeline with the following consecutive steps: detection of each stimulation run from stimulation artifacts in raw intracranial EEG (iEEG) files, bad channels detection with a machine learning approach, model-based stimulation artifact correction, robust averaging over stimulation pulses. Effective connectivity between the stimulated and recording areas is then inferred from the properties of the first CCEP component, i.e. onset and peak latency, amplitude, duration and integral of the significant part. Finally, group statistics of CCEP features are implemented for each brain parcel explored by iEEG electrodes. The localization (coordinates, white/gray matter relative positioning) of electrode contacts were obtained from imaging data (anatomical MRI or CT scans before and after electrodes implantation). The iEEG contacts were repositioned in different brain parcellations from the segmentation of patients' anatomical MRI or from templates in the MNI coordinate system. The F-TRACT database using the first pool of 213 patients provided connectivity probability values for 95% of possible intrahemispheric and 56% of interhemispheric connections and CCEP features for 78% of intrahemisheric and 14% of interhemispheric connections. In this report, we show some examples of anatomo-functional connectivity matrices, and associated directional maps. We also indicate how CCEP features, especially latencies, are related to spatial distances, and allow estimating the velocity distribution of neuronal signals at a large scale. Finally, we describe the impact on the estimated connectivity of the stimulation charge and of the contact localization according to the white or gray matter. The most relevant maps for the scientific community are available for download on f-tract. eu (David et al., 2017) and will be regularly updated during the following months with the addition of more data in the F-TRACT database. This will provide an unprecedented knowledge on the dynamical properties of large fiber tracts in human.

Stereoelectroencephalography and surgical outcome in polymicrogyria-related epilepsy: A multicentric study

OBJECTIVE

We aimed to (1) assess the concordance between various polymicrogyria (PMG) types and the associated epileptogenic zone (EZ), as defined by stereoelectroencephalography (SEEG), and (2) determine the postsurgical seizure outcome in PMG-related drug-resistant epilepsy.

METHODS

We retrospectively analyzed 58 cases: 49 had SEEG and 39 corticectomy or hemispherotomy.

RESULTS

Mean age at SEEG or surgery was 28.3 years (range, 2-50). PMG was bilateral in 9 (16%) patients and unilateral in 49, including 17 (29%) unilobar, 12 (21%) multilobar, 15 (26%) perisylvian, and only 5 (9%) hemispheric. Twenty-eight (48%) patients additionally had schizencephaly, heterotopia, or focal cortical dysplasia. The SEEG-determined EZ was fully concordant with the PMG in only 8 (16%) cases, partially concordant in 74%, and discordant in 10%. The EZ included remote cortical areas in 21 (43%) cases and was primarily localized in those in 5 (10%), all related to the mesial temporal structures. All but 1 PMG patient with corticectomy or hemispherotomy had a unilateral PMG. At last follow-up (mean, 4.6 years; range, 1-16), 28 (72%) patients remained seizure free. Shorter epilepsy duration to surgery was an independent predictor of seizure freedom.

INTERPRETATION

PMG-related drug-resistant epilepsy warrants a comprehensive presurgical evaluation, including SEEG investigations in most cases, given that the EZ may only partially overlap with the PMG or include solely remote cortical areas. Seizure freedom is feasible in a large proportion of patients. PMG extent should not deter from exploring the possibility of epilepsy surgery. Our data support the early consideration of epilepsy surgery in this patient group. Ann Neurol 2017;82:781-794.

Stereo-electroencephalography identifies N2 sleep and spindles in human hippocampus

OBJECTIVES

To describe the hippocampal stereo-electroencephalogram during sleep according to sleep stages (including N2 sleep) and cycles, together with the hippocampal spindles.

METHODS

All patients with drug-resistant focal epilepsy undergoing intra-hippocampal implantation between August 2012 and June 2013 at Nancy University Hospital were screened. Six patients with explored hippocampus devoid of pathological features were analyzed. During one night, we identified continuous periods of successive N2, N3 and REM sleep for two full cycles. We performed a spectral analysis of the hippocampal signal for each labeled sleep period.

RESULTS

N2, N3 and REM sleeps were individualized according to their spectral powers, for each frequency band and sleep cycle. Hippocampal spindles showed dynamic intrinsic properties, the 11.5-16Hz frequency band being mainly dominant, whereas the 9-11.5Hz frequency band heightening during the beginning and the end of the transient. For N3 and REM sleep stages, the power of the hippocampal signal was significantly decreased between the first and the second sleep cycle.

CONCLUSION

Distinct N2 sleep, fast spindles and homeostatic profile are all common properties shared by hippocampus and cortex during sleep.

SIGNIFICANCE

The close functional link between hippocampus and cortex may have various sleep-related substrates.

Ictal changes in parasympathetic tone: Prediction of postictal oxygen desaturation

OBJECTIVE

To measure changes in parasympathetic tone before, during, and after temporal seizures, and to determine whether changes in high-frequency heart rate variability are correlated with postictal oxygen desaturation.

METHODS

We recorded the electrocardiogram and peripheral oxygen saturation during 55 temporal lobe seizures and calculated a high-frequency variability index (HFVI) as a marker of parasympathetic tone for periods of 20 minutes (centered on seizure onset). We then compared HFVI values in seizures with and without postictal hypoxemia, and looked for correlations between HFVI changes and the risk of sudden unexpected death in epilepsy (SUDEP) (as assessed with the SUDEP-7 Inventory).

RESULTS

Parasympathetic tone decreased rapidly at the onset of temporal lobe seizures, reached its minimum value at the end of the seizure, and then gradually returned to its preictal value. Changes in parasympathetic tone were more intense and longer-lasting in older patients with a longer duration of epilepsy. The HFVI was significantly lower during seizures with hypoxemia, and remained significantly lower 5 minutes after the end of the seizure. The change in the HFVI slope over the first 30 seconds of the seizure was predictive of postictal oxygen desaturation. Postictal autonomic changes were correlated with the SUDEP-7 scores.

CONCLUSION

Our results showed that ictal autonomic dysfunction is correlated with postictal hypoxemia. A prolonged impairment of parasympathetic tone might expose a patient to a greater risk of postictal sudden unexpected death. The real-time measurement of parasympathetic tone in patients with epilepsy may be of value to medical staff as an early warning system.

Risk factors of postictal generalized EEG suppression in generalized convulsive seizures

OBJECTIVE

To identify the clinical determinants of occurrence of postictal generalized EEG suppression (PGES) after generalized convulsive seizures (GCS).

METHODS

We reviewed the video-EEG recordings of 417 patients included in the REPO2MSE study, a multicenter prospective cohort study of patients with drug-resistant focal epilepsy. According to ictal semiology, we classified GCS into 3 types: tonic-clonic GCS with bilateral and symmetric tonic arm extension (type 1), clonic GCS without tonic arm extension or flexion (type 2), and GCS with unilateral or asymmetric tonic arm extension or flexion (type 3). Association between PGES and person-specific or seizure-specific variables was analyzed after correction for individual effects and the varying number of seizures.

RESULTS

A total of 99 GCS in 69 patients were included. Occurrence of PGES was independently associated with GCS type (p < 0.001) and lack of early administration of oxygen (p < 0.001). Odds ratio (OR) for GCS type 1 in comparison with GCS type 2 was 66.0 (95% confidence interval [CI 5.4-801.6]). In GCS type 1, risk of PGES was significantly increased when the seizure occurred during sleep (OR 5.0, 95% CI 1.2-20.9) and when oxygen was not administered early (OR 13.4, 95% CI 3.2-55.9).

CONCLUSION

The risk of PGES dramatically varied as a function of GCS semiologic characteristics. Whatever the type of GCS, occurrence of PGES was prevented by early administration of oxygen.

Arousal in response to neutral pictures is modified in temporal lobe epilepsy

The objectives of the present study were to (i) better characterize visual emotional experience in patients with temporal lobe epilepsy (TLE), (ii) identify clinical risk factors that might be predictive of a change in emotional experience, and (iii) study the relationships between emotional experience and psychobehavioral/quality-of-life factors. Fifty patients with TLE and fifty matched controls evaluated the emotional content of unpleasant, pleasant, and neutral pictures with respect to their valence (unpleasant-to-pleasant) and arousal (low-to-high) levels. Demographic, cognitive, and psychobehavioral data were recorded for all participants, and clinical data and factors related to quality of life were also collected for patients with TLE. There were no significant differences between the group with TLE and the control group in terms of valence evaluations. However, arousal scores for neutral pictures were significantly higher in patients with TLE than in controls. There was also a nonsignificant trend towards lower arousal scores for pleasant pictures in patients with TLE than in controls. Although none of the recorded clinical factors were found to be related to emotional experience, the level of apathy was predictive of greater arousal experience for neutral pictures in patients with TLE. In conclusion, emotional experience appears to be modified in TLE and might be related to apathy. Changes in emotional experience should be taken into account in studies in which neutral stimuli are used to establish a baseline level when assessing emotional and cognitive processing.

Continuous EEG monitoring in adults in the intensive care unit (ICU)

Continuous EEG monitoring in the ICU is different from planned EEG due to the rather urgent nature of the indications, explaining the fact that recording is started in certain cases by the clinical team in charge of the patient's care. Close collaboration between neurophysiology teams and intensive care teams is essential. Continuous EEG monitoring can be facilitated by quantified analysis systems. This kind of analysis is based on certain signal characteristics, such as amplitude or frequency content, but raw EEG data should always be interpreted if possible, since artefacts can sometimes impair quantified EEG analysis. It is preferable to work within a tele-EEG network, so that the neurophysiologist has the possibility to give an interpretation on call. Continuous EEG monitoring is thus useful in the diagnosis of non-convulsive epileptic seizures or purely electrical discharges and in the monitoring of status epilepticus when consciousness disorders persist after initial treatment. A number of other indications are currently under evaluation.

EEG guidelines in the diagnosis of brain death

In France, for the determination and diagnostic validation of brain death the law requires either two EEG recordings separated by a 4-hour observation period, both showing electrocerebral inactivity; or cerebral angiography examination. Since EEG is available in most hospitals and clinics, it is often used in this indication, at the patient's bedside, especially in the context of organ donation. However, very precise methodology must be followed. The last French guidelines date back to 1989, before the development of digital EEG recording. We present the new guidelines from the Société de Neurophysiologie Clinique de Langue Française. Electrocerebral inactivity may be confirmed when a 30-minute good quality EEG recording shows complete electrocerebral silence, defined as no cerebral activity greater than 2 uV, having first ruled out the possible influence of sedative drugs, metabolic disorders or hypothermia. In the presence of sedative drugs, CT brain angiography will be the gold standard test for this diagnosis. In the newborn, the utmost caution is indicated since electrocerebral inactivity can be observed in the absence of cerebral death. In the infant, the criterion for the observation period to be respected between both EEG recordings needs to be more clearly refined.

Study on the Relationships between Intrinsic Functional Connectivity of the Default Mode Network and Transient Epileptic Activity

Rationale: Simultaneous recording of electroencephalogram and functional MRI (EEG–fMRI) is a powerful tool for localizing epileptic networks via the detection of hemodynamic changes correlated with interictal epileptic discharges (IEDs). fMRI can be used to study the long-lasting effect of epileptic activity by assessing stationary functional connectivity during the resting-state period [especially, the connectivity of the default mode network (DMN)]. Temporal lobe epilepsy (TLE) and idiopathic generalized epilepsy (IGE) are associated with low responsiveness and disruption of DMN activity. A dynamic functional connectivity approach might enable us to determine the effect of IEDs on DMN connectivity and to better understand the correlation between DMN connectivity changes and altered consciousness.

Method: We studied dynamic changes in DMN intrinsic connectivity and their relation to IEDs. Six IGE patients (with generalized spike and slow-waves) and 6 TLE patients (with unilateral left temporal spikes) were included. Functional connectivity before, during, and after IEDs was estimated using a sliding window approach and compared with the baseline period.

Results: No dependence on window size was observed. The baseline DMN connectivity was decreased in the left hemisphere (ipsilateral to the epileptic focus) in TLEs and was less strong but remained bilateral in IGEs. We observed an overall increase in DMN intrinsic connectivity prior to the onset of IEDs in both IGEs and TLEs. After IEDs in TLEs, we found that DMN connectivity increased before it returned to baseline values. Most of the DMN regions with increased connectivity before and after IEDs were lateralized to the left hemisphere in TLE (i.e., ipsilateral to the epileptic focus).

Conclusion: Results suggest that DMN connectivity may facilitate IED generation and may be affected at the time of the IED. However, these results need to be confirmed in a larger independent cohort.

Characterization and prediction of theory of mind disorders in temporal lobe epilepsy

OBJECTIVE

Patients with temporal lobe epilepsy (TLE) have impaired theory of mind (ToM). However, ToM involves a variety of processes, such as understanding a person's intentions ("cognitive" ToM) and emotional states ("affective" ToM). The objectives of the present study were to characterize ToM disorders in TLE patients, identify patients at risk of ToM disorders, and study the relationships between psychobehavioral and quality of life factors and ToM disorders.

METHOD

Fifty TLE patients and 50 controls performed ToM tasks assessing their understanding of verbal clumsiness (faux pas), sarcastic remarks, and mentalistic actions. Demographic, cognitive, and psychobehavioral data, and (for TLE patients) clinical and quality of life factors, were recorded.

RESULTS

Compared with controls, TLE patients showed impairments in all ToM tasks: 84% misunderstood faux pas, and around 50% misunderstood sarcasm. A long duration of epilepsy and young age at onset were risk factors for ToM impairments. In TLE patients, ToM impairments were associated with impaired empathy and anhedonia. Their affective states were less positively and more negatively valenced than in controls. Low positive affectivity was predictive of greater cognitive and affective ToM impairments for the faux pas task, and high negative affectivity was predictive of greater cognitive ToM abilities for the sarcasm task. The lack of social support was correlated with impaired ToM but was not a predictive factor.

CONCLUSIONS

Both cognitive and affective ToM processes are impaired in TLE patients. Impaired ToM has an impact on empathy abilities and is related to affective disturbances in TLE patients.

Attention impairment in temporal lobe epilepsy: a neurophysiological approach via analysis of the P300 wave

PURPOSE

Attention is often impaired in temporal lobe epilepsy (TLE). The P300 wave (an endogenous, event-related potential) is a correlate of attention which is usually recorded during an "oddball paradigm," where the subject is instructed to detect an infrequent target stimulus presented amongst frequent, standard stimuli. Modifications of the P300 wave's latency and amplitude in TLE have been suggested, but it is still not known whether the source regions also differ. Our hypothesis was that temporal lobe dysfunction would modify the P3 source regions in TLE patients.

METHODS

A comparative, high density, 128-channel electroencephalographic analysis of the characteristics of P300 (P3b latency and amplitude) was performed in 10 TLE patients and 10 healthy controls during auditory and visual oddball paradigms. The P3b sources were localized on individual 3D MR images using the LORETA method and intergroup statistical comparisons were performed using SPM2(R) software.

RESULTS

Our main results (in both individual analyses and intergroup comparisons) revealed a reduction in temporal (and more particularly mesiotemporal) sources and, to a lesser extent, frontal sources in TLE patients, compared with controls.

DISCUSSION

This reduction may reflect direct, local cortical dysfunction caused by the epileptic focus or more complex interference between epileptic networks and normal attentional pathways.