New stimulation procedures for language mapping in stereo-EEG.

OBJECTIVE: Cortical intracerebral electrical stimulation is an important tool for language mapping in the presurgical work-up of patients with drug-resistant focal epilepsy. Language mapping with stereo-electroencephalography (EEG) is usually performed by high-frequency stimulations (HFS: 50 Hz), whereas low-frequency stimulations (LFS: 1 Hz) are usually considered useful for primary cortices mapping. Little is known in literature about "intermediate" frequencies (IFS: 6-15 Hz). Our objective is to explore the clinical usefulness of IFS in language mapping and identify factors, beyond the electrical parameters, that impact the mapping. METHODS: We studied 23 patients submitted to stereo-EEG for presurgical evaluation. Language mapping was performed in the anterior, posterior and/or basal language region of the dominant hemisphere for language. We included all contact positions within these regions stimulated by HFS (50 Hz, 5 s, 1-3 mA) and IFS (6-15 Hz, 15 s, 5 mA). We compared the capability of both stimulation methods to induce a language deficit without afterdischarges (ADs), and we analyzed factors related to clinical examination, region, and stimulation technique by multivariate analysis. RESULTS: A total of 211 stimulations (98 HFS, 113 IFS) in 70 cortical sites within the anterior (84 stimulations), posterior (137), and basal language region (60) were included. IFS induced more frequently language deficits not associated to AD compared to HFS (37.1% vs 25.7%, p = .0043), whereas HFS provoked more diffuse AD (34.7% vs 15.0%, p = .001). Investigating multiple language functions increased the probability of revealing a deficit (odds ratio [OR] 3.16, p = .0016), independently of the stimulation method. SIGNIFICANCE: IFS are valuable for language mapping, thereby improving the probability of inducing a clinical deficit not accompanied by an AD. The completeness of the clinical examination independently affects the sensitivity of the mapping. IFS are a new tool with potential usefulness for the cortical mapping of other associative cortical regions.

Language lateralization mapping (reversibly) masked by non-dominant focal epilepsy: a case report.

Language lateralization in patients with focal epilepsy frequently diverges from the left-lateralized pattern that prevails in healthy right-handed people, but the mechanistic explanations are still a matter of debate. Here, we debate the complex interaction between focal epilepsy, language lateralization, and functional neuroimaging techniques by introducing the case of a right-handed patient with unaware focal seizures preceded by aphasia, in whom video-EEG and PET examination suggested the presence of focal cortical dysplasia in the right superior temporal gyrus, despite a normal structural MRI. The functional MRI for language was inconclusive, and the neuropsychological evaluation showed mild deficits in language functions. A bilateral stereo-EEG was proposed confirming the right superior temporal gyrus origin of seizures, revealing how ictal aphasia emerged only once seizures propagated to the left superior temporal gyrus and confirming, by cortical mapping, the left lateralization of the posterior language region. Stereo-EEG-guided radiofrequency thermocoagulations of the (right) focal cortical dysplasia not only reduced seizure frequency but led to the normalization of the neuropsychological assessment and the "restoring" of a classical left-lateralized functional MRI pattern of language. This representative case demonstrates that epileptiform activity in the superior temporal gyrus can interfere with the functioning of the contralateral homologous cortex and its associated network. In the case of presurgical evaluation in patients with epilepsy, this interference effect must be carefully taken into consideration. The multimodal language lateralization assessment reported for this patient further suggests the sensitivity of different explorations to this interference effect. Finally, the neuropsychological and functional MRI changes after thermocoagulations provide unique cues on the network pathophysiology of focal cortical dysplasia and the role of diverse techniques in indexing language lateralization in complex scenarios.

Intermediate stimulation frequencies for language mapping using Stereo-EEG.

OBJECTIVE: Identification of eloquent cortices is a prerequisite for the surgical plan but may be challenging, in particular for language areas (LAs), considering the complexity of language function and organization. Electrical intracerebral stimulations (ES) during Stereo-electroencephalography are an essential tool in the localization of LAs and high frequency ES (HFS, 50 Hz) are current gold standard. Low frequencies (1 Hz) are not effective. We aim to investigate different ES frequencies for establishing their utility in localizing LAs. METHODS: We implemented an observational and prospective study evaluating frequencies lower than 50 and higher than 1 Hz; indicated as "intermediate" frequencies (IFS) performed at 6, 9 and 12 Hz and lasting 15 seconds. We included ten patients and carried out a standardized protocol comparing IFS to HFS. RESULTS: Eighty-six ES were carried out in LAs, positive for a language interference in 61.6% without noteworthy difference between IFS and HFS. Among these, 53.3% IFS vs 21.7% HFS yielded no after-discharge. CONCLUSIONS: IFS were similarly effective as HFS, with lower incidence of ADs. Their longer duration facilitated more accurate clinical testing. SIGNIFICANCE: Our results are promising, suggesting that IFS can be useful in the study of LAs.

Tonic somatosensory responses and deficits of tactile awareness converge in the parietal operculum.

Although clinical neuroscience and the neuroscience of consciousness have long sought mechanistic explanations of tactile-awareness disorders, mechanistic insights are rare, mainly because of the difficulty of depicting the fine-grained neural dynamics underlying somatosensory processes. Here, we combined the stereo-EEG responses to somatosensory stimulation with the lesion mapping of patients with a tactile-awareness disorder, namely tactile extinction. Whereas stereo-EEG responses present different temporal patterns, including early/phasic and long-lasting/tonic activities, tactile-extinction lesion mapping co-localizes only with the latter. Overlaps are limited to the posterior part of the perisylvian regions, suggesting that tonic activities may play a role in sustaining tactile awareness. To assess this hypothesis further, we correlated the prevalence of tonic responses with the tactile-extinction lesion mapping, showing that they follow the same topographical gradient. Finally, in parallel with the notion that visuotactile stimulation improves detection in tactile-extinction patients, we demonstrated an enhancement of tonic responses to visuotactile stimuli, with a strong voxel-wise correlation with the lesion mapping. The combination of these results establishes tonic responses in the parietal operculum as the ideal neural correlate of tactile awareness.

Temporal lobe epilepsy: A never-ending story.

INTRODUCTION: Semiology and anatomo-electroclinical correlations remain invaluable for maintaining the level of excellence in temporal lobe epilepsy (TLE) surgery, in parallel to the constantly evolving technical progress. The aim of this study was to address semiological frequent and not so frequent signs, rarities and red flags in a long follow-up surgical series of patients suffering from TLE. METHODS: Patients operated within the boundaries of the TL at our center, with presurgical video-EEG recorded seizures and seizure free after a postoperative follow-up of at least 24 months were included. Ictal semiology was systematically described and new red flags were explored by comparing with a second group of patients with the same inclusion criteria but whose outcome had been unfavorable (Engel II-IV). RESULTS: Sixty-two patients were included, 46 seizure free and 16 with outcome Engel II-IV. Most seizure-free patients had a classical semiological presentation including aura (69.6%, abdominal the most frequent), followed by loss of responsiveness (90.2%) oral automatisms (90.7%), ipsilateral gestural automatisms (53.5%), contralateral upper limb dystonia (37.5%) or immobility (39.1%), and early ipsilateral non-versive head orientation (33.3%). More infrequent presentations were also present in the group of seizure-free patients: ictal language disturbance (13%), maintenance of responsiveness during seizures (9.8%), and contralateral rhythmic non manipulative automatism (6.9%). The presence of an isolated viscerosensory and/or psychic aura was significantly more frequent in the seizure-free group (p = 0.017), as well as oroalimentary automatisms (p = 0.005). Two signs were only present in the group with outcome Engel II-IV, constituting possible red flags (0.06 < p < 0.07): inferior limbs stepping-like automatisms and postictal dysarthria. CONCLUSION: An adequate clinical exam during seizures and a careful analysis of video recordings allow to recognize infrequent but well-characterized ictal signs that are part of the range of semiology in TLE, together with the most frequent and classical ictal presentations. Special attention to the localization hypothesis must be paid in the absence of oroalimentary automatisms or when the signs classified as possible red flags emerge.

Praxis induction and its relationship with cognition in genetic generalized epilepsy.

INTRODUCTION: Praxis induction (PI) is a reflex trait defined as the precipitation of epileptic discharges (ED) or seizures by cognition-guided tasks that often involve visuomotor coordination and decision-making. This is a characteristic of genetic generalized epilepsy (GGE), and especially of juvenile myoclonic epilepsy (JME). Additionally, several studies have described dysexecutive traits in these patients. Our objective was to analyze PI in the different syndromes of GGE and explore the relationship between PI and cognitive performance. METHODS: Sixty-one adult patients with GGE underwent video-electroencephalograph (EEG) during which a neuropsychological activation protocol (NPAP) was performed: reading, writing, calculations, crosswords, and tangram. Praxis induction was defined by the presence of ED during the NPAP with a persistence of at least twice seen on the basal EEG. All patients also underwent a comprehensive cognitive evaluation. RESULTS: We observed PI in 22 out of 61 patients (36%). Grouped by syndrome, PI was more frequent in adult patients with persistent childhood or juvenile absence epilepsy (JAE, 60%), followed by JME (42.1%) and in a lesser grade in patients with only tonic-clonic generalized seizures (9%). Patients classified as having PI did not obtain worse results in the cognitive evaluation. The presence of ED during the performance of a test was associated with a trend to lower results in that specific test. SIGNIFICANCE: Our study showed a relevant presence of PI in patients whose absence epilepsy persists into adulthood, and not only in JME, the syndrome classically associated with PI. According to our results, PI as a reflex trait does not imply necessarily a poorer cognitive phenotype, but the induction of frequent ED during the tasks could be associated with transient cognitive impairment.

Cost of status epilepticus (SE): Effects of delayed treatment and SE duration.

BACKGROUND: The health expenditure related to status epilepticus (SE) is high because of lengthy hospitalization requirements and possible sequelae. We aimed to study the factors associated with this cost including the different timings of the treatment and SE duration. METHODS: We evaluated retrospectively all SE recorded in 2 hospitals. The factors studied included the mean cost of hospitalization, demographics, clinical data, duration of hospitalization, in-hospital/out-of-hospital debut, time from onset to treatment, duration of SE, and destination at discharge. RESULTS: Three hundred five patients were evaluated (December/2012-July/2017), 195 with out-of hospital and 110 with in-hospital debut. The cost of SE with out-of-hospital onset was significantly lower (6559€ vs 15,174€; p = 0.0001). In out-of-hospital cases, the factors independently related to expenditure were the level of consciousness (p < 0.001), presence of complications (p = 0.005), a potentially fatal etiology (p = 0.008), and duration of the episode (p = 0.003). Duration was significantly higher in patients discharged to a convalescence center (p = 0.006); this variable was significantly related to the time SE onset-arrival to hospital, and SE onset-administration of the treatment. In the in-hospital cases, cost was related to male sex (p = 0.002), the development of complications (p = 0.003), and the etiology (p = 0.016) but was not directly related to the SE duration or to the time onset-treatment. CONCLUSIONS: The duration of SE and the speed with which proper management is applied have a direct impact on the healthcare expenditure resulting from out-of-hospital SE. In contrast, the etiology and development of complications are the main factors responsible for expenditure related to in-hospital SE.

The cognitive phenotype of idiopathic generalized epilepsy.

OBJECTIVE: Dysexecutive traits have been described in idiopathic generalized epilepsy (IGE), but studies mainly focused on juvenile myoclonic epilepsy (JME). To better understand the neuropsychology of IGE, more research is needed on syndromes other than JME, controlling potential confounding factors as the cognitive effects of valproate and epileptic discharges (ED). We describe the neuropsychological profile of a group of patients with different syndromes of IGE including simultaneous video electroencephalography (EEG). METHODS: We performed a comprehensive cognitive and neuropsychiatric evaluation with video-EEG on 61 adults with IGE (JME 19; IGE with generalized tonic-clonic seizures [GTCS] alone [IGE-GTCS] 22; childhood absence epilepsy [CAE] or juvenile absences epilepsy [JAE] persisting in adulthood 20). We compared results between patients (globally and by syndrome) and a control group of 21 individuals (similar age, educational level); p-values were adjusted for multiple testing according to a 0.05 false discovery rate. RESULTS: Patients obtained significantly lower results than controls on visuospatial working memory, processing speed, cognitive flexibility and strategy, abstract visuospatial reasoning, arithmetic, and acquired knowledge. While CAE/JAE showed the lowest scores on cognitive assessment and highest anxiety index, IGE-GTCS showed the most favorable scores. Most tests were not influenced by valproate intake, and the dose did not correlate with cognitive performance in the test that yielded differences between patients and controls. Epileptic discharges during assessment were not frequent (10 patients, 1-4 tests). SIGNIFICANCE: Our findings suggest that patients with IGE have significantly lower abilities in various executive functions and acquired knowledge, compared to population of same age and education. The low frequency of ED on simultaneous video-EEG and absence of correlation of scores with valproate dose reinforce that the obtained results are due to a cognitive phenotype in IGE. This phenotype may be influenced by syndrome, and patients with CAE/JAE persisting in the adult may have a wider neuropsychiatric impairment.

Praxis-induced myoclonia: From the neurophysiologist to the patient perspective.

PURPOSE: To characterize semiology and EEG features of praxis-induced (PI) myoclonia and to describe the subjective perception of juvenile myoclonic epilepsy (JME) patients with this reflex trait. METHODS: Patients with JME who presented myoclonia during a Video-EEG Neuropsychological Protocol were selected. We analyzed the semiology of upper limbs myoclonia and the ictal EEG patterns on Video-EEG. We explored the subjective aspects of PI by performing a semi-structured interview to each patient. RESULTS: 15 patients experienced 59 upper limbs myoclonia. Jerks were more frequently asymmetric or unilateral (32/59); a bilaterally symmetric pattern of all myoclonia was observed in only five patients. Ictal pattern was polyspike-wave (PSW) in 31/59 myoclonic seizures and spike-and-wave (SW) in 28/59. Six patients started perceiving myoclonia while learning a new skill or practicing a previously learned skill in a more stressful context. For most patients, PI-myoclonia were a source of anxiety. PI persisted despite antiepileptic medications in 10 patients. CONCLUSIONS: Electroclinical features of PI-myoclonia were more heterogeneous than traditionally described. Ictal pattern of SW was almost as frequent as classical PSW. Patients described the influence of learning new skills and anxiety on PI. Their subjective perception let us understand the impact of this reflex trait.

The relevance of timing in nonconvulsive status epilepticus: A series of 38 cases.

BACKGROUND: Timing in the management of nonconvulsive status epilepticus (NCSE) seems to be one of the most important modifiable prognostic factors. We aimed to determine the precise relationship between timing in NCSE management and its outcome. METHODS: We performed a cross-sectional study in which clinical data were prospectively obtained from all consecutive adults with NCSE admitted to our hospital from 2014 to 2016. Univariate and multivariable regression analyses were performed to identify clinical and timing variables associated with NCSE prognosis. RESULTS: Among 38 NCSE cases, 59.9% were women, and 39.5% had prior epilepsy history. The median time to treatment (TTT) initiation and the median time to assessment by a neurologist (TTN) were 5h, and the median time to first electroencephalography assessment was 18.5h; in the cases with out-of-hospital onset (n=24), the median time to hospital (TTH) arrival was 2.8h. The median time to NCSE control (TTC) was 16.5h, and it positively correlated with both the TTH (Spearman's rho: 0.439) and the TTT (Spearman's rho: 0.683). In the multivariable regression analyses, the TTC was extended 1.7h for each hour of hospital arrival delay (p=0.01) and 2.7h for each hour of treatment delay (p<0.001). Recognition delay was more common in the episodes with in-hospital onset, which also had longer TTN and TTC, and increased morbidity. CONCLUSIONS: There were pervasive delays in all phases of NCSE management. Delays in hospital arrival or treatment initiation may result in prolonged TTC. Recognition of in-hospital episodes may be more delayed, which may lead to poorer prognosis in these cases.

Lacosamide for refractory generalized tonic-clonic seizures of non-focal origin in clinical practice: A clinical and VEEG study.

•7 of 9 patients with GGE reduced ≥ 50% their tonic-clonic seizure frequency on LCM.•All 7 patients remained seizure free for > 1 year, and 2 of them for > 5 years.•In 2 of the 9 patients, both with Juvenile Absence Epilepsy, absences aggravated.•One aggravation consisted on a myoclonia and absence status, in a patient with no history of myoclonia.•VEEG paralleled clinical improvement but didn't change in a case of absence worsening.

Greater Occipital Nerve Blockade: A Safe and Effective Option for the Acute Treatment of Hemiplegic Aura.

BACKGROUND: Prolonged auras such as those of hemiplegic migraine or migraine with brainstem aura may be extremely disabling. The availability of effective treatments is limited, but two case reports described cessation of the aura symptoms after a greater occipital nerve (GON) blockade. CASE: A 26-year-old woman with a history of hemiplegic migraine with prolonged auras came to our office with an episode of motor and sensory aura 1 hour after onset. Both muscle strength and sensory function started to improve immediately after a GON anesthetic blockade, and the patient was fully relieved in 50 minutes. CONCLUSION: GON blockade may be an effective option for the acute treatment of hemiplegic aura or other prolonged migraine auras.

Extreme delta brush in a patient with anti-NMDAR encephalitis.

Anti-N-methyl-D-aspartate receptor encephalitis is a severe, potentially treatable, disorder and prognosis depends on early recognition and prompt immunotherapy. We report a case of anti-N-methyl-D-aspartate receptor encephalitis with atypical age and gender, and a characteristic electroencephalographic pattern that supported the diagnosis. A 66-year-old male presented with psychiatric disturbances and focal seizures with alteration of consciousness, and progressed to a state of akinetic mutism. Auxiliary tests were negative or non-specific for anti-NMDAR encephalitis. Electroencephalographic monitoring revealed a unique pattern; the extreme delta brush. The patient improved with immunotherapy and was asymptomatic at six months of follow-up. Ancillary testing was positive for anti-N-methyl-D-aspartate receptor antibodies. Extreme delta brush is a recently described electroencephalographic pattern presenting in only one third of patients with anti-N-methyl-D-aspartate receptor encephalitis. The identification of this pattern, as in our case, may guide early diagnosis and treatment of anti-N-methyl-D-aspartate receptor encephalitis.