Predictors of hyperkinetic seizures.

OBJECTIVE: To identify predisposing factors for hyperkinetic seizure occurrence in a representative cohort of surgically treated patients with drug-resistant focal epilepsy. METHODS: We retrospectively recruited all seizure-free patients after epilepsy surgery with a postoperative follow-up ≥12 months. Patients were classified as presenting with hyperkinetic seizures if at least 2 episodes occurred during their disease history, based on clear-cut anamnestic description and/or video-EEG/stereo-EEG recordings. We performed univariable and multivariable logistic regression models to study the association between the occurrence of hyperkinetic seizures and some predictors. RESULTS: From a pool of 1758 consecutive patients who underwent surgery from 1996 to 2017, we identified 974 seizure-free cases. Considering at least 1-year follow-up, 937 cases were included (511 males, 91 patients with hyperkinetic seizures). Variables significantly associated with an increased risk of hyperkinetic seizure occurrence were (1) presence of epilepsy with sleep-related seizures (SRE) (P < 0.001); (2) histological diagnosis of type II focal cortical dysplasia (FCD) (P < 0.001); (3) resection including the frontal lobe (P = 0.002) (4) duration of epilepsy at surgery (P < 0.001) and (5) high seizure frequency at surgery (weekly: P = 0.02 - daily: P = 0.05). A resection including the occipital lobe reduced the risk of hyperkinetic seizures (P = 0.05). About 63% of patients had hyperkinetic seizure onset before 12 years and it was rarely reported before 5 years of age. SIGNIFICANCE: Our findings underlie the role of SRE, type II FCD and frontal epileptogenic zone as predictors of hyperkinetic seizure occurrence and highlight an age-dependent effect in favoring hyperkinetic manifestations.

Neural networks underlying hyperkinetic seizures: A quantitative PET and SEEG study.

OBJECTIVE: Hyperkinetic seizures (HKS) are characterized by complex movements that commonly occur during seizures arising from diverse cortical structures. A common semiology network may exist and analyzing the anatomo-electrical mechanisms would facilitate presurgical evaluation. Here, quantitative positron emission tomography (PET) and stereoelectroencephalography (SEEG) analysis was used to explore the underlying mechanism of HKS. METHODS: We retrospectively collected patients with epilepsy with HKS between 2014 and 2019. The interictal PET data of patients with epilepsy with HKS were compared with those of 25 healthy subjects using statistical parametric mapping to identify regions with significant hypometabolism. Then, regions of interest (ROI) for SEEG analysis were identified based on the results of PET analysis. Patients in which the ROIs were covered by intracerebral electrodes were selected for further analysis. Stereoelectroencephalography -clinical correlations with latency measurements were analyzed, and we also performed coherence analysis among ROIs both before and during HKS. RESULTS: Based on the inclusion criteria, 27 patients were analyzed. In the PET analysis, significant hypometabolism was observed in the ipsilateral dorsoanterior insular lobe, bilateral mesial frontal lobes (supplementary motor area/middle cingulate cortex, SMA/MCC), and the bilateral heads of the caudate nuclei in patients with HKS compared with the control group (p < 0.001). We selected dorsoanterior insula and SMA/MCC as ROIs for SEEG analysis. Eight patients with 23 HKS events were selected for further analysis. There was a linear correlation between the ictal involvement of both the dorsoanterior insula and SMA/MCC with the onset of HKS. Stereoelectroencephalography analysis indicated alpha range activity seemed more often associated with dorsoanterior insula and SMA/MCC involvement during HKS. CONCLUSIONS: The dorsoanterior insular lobe, mesial frontal lobes (SMA/MCC), and the bilateral heads of the caudate nuclei were probably involved in the generation of HKS. The SEEG analysis further indicated that the occurrence of HKS might be partly associated with synchronized rhythmical alpha activity between dorsoanterior insula and SMA/MCC.

Quantitative analysis of hyperkinetic seizures and correlation with seizure onset zone.

OBJECTIVE: Hyperkinetic epileptic seizures (HKS) are difficult to characterize and localize according to semiologic features. We propose a multicriteria scale to help visual analysis and report results of cerebral localization. METHODS: We assessed seizures from 37 patients with HKS, explored with stereoelectroencephalography during presurgical evaluation. We used a multicriteria scale (hyperkinetic seizure scale [HSS]) with 10 semiologic features, scored independently by two neurologists. The item scores were used to group seizures using the k-means method. Semiologic features were correlated with the seizure onset zone (SOZ) localization (temporal, prefrontal dorsolateral, prefrontal ventromesial, parietal, insular). RESULTS: Fifty-five seizures were analyzed, and each item of the HSS was compared between the two examiners with good interrater agreement (85.3%). Dystonia, integrated behavior, and bilateral or unilateral hyperkinetic movements were statistically significant according to localization. Three clusters were identified according to the HSS and correlated with different patterns of anatomic localization of SOZ. Cluster 1 was characterized clinically by asymmetric hyperkinetic movements associated with marked dystonia and vocalization. It mainly included parietal seizures. Cluster 2 was characterized by bilateral and symmetrical stereotyped hyperkinetic movements without dystonia. It represented half of temporal seizures and one-third of prefrontal seizures (dorsolateral). Cluster 3 was characterized by seizures with strong emotionality and vocalization with bilateral and symmetrical hyperkinetic movements and integrated behavior. It involved half of temporal seizures and a majority of prefrontal (ventromesial) seizures. SIGNIFICANCE: We propose a first attempt to quantify clinical patterns of HKS. The HSS may help to predict SOZ localization according to three main groups of hyperkinetic seizures.

Clinical features of sleep-related hypermotor epilepsy in relation to the seizure-onset zone: A review of 135 surgically treated cases.

OBJECTIVES: Sleep-related hypermotor epilepsy (SHE), formerly nocturnal frontal lobe epilepsy, is characterized by abrupt and typically sleep-related seizures with motor patterns of variable complexity and duration. They seizures arise more frequently in the frontal lobe than in the extrafrontal regions but identifying the seizure onset-zone (SOZ) may be challenging. In this study, we aimed to describe the clinical features of both frontal and extrafrontal SHE, focusing on ictal semiologic patterns in order to increase diagnostic accuracy. METHODS: We retrospectively analyzed the clinical features of patients with drug-resistant SHE seen in our center for epilepsy surgery. Patients were divided into frontal and extrafrontal SHE (temporal, operculoinsular, and posterior SHE). We classified seizure semiology according to four semiology patterns (SPs): elementary motor signs (SP1), unnatural hypermotor movements (SP2), integrated hypermotor movements (SP3), and gestural behaviors with high emotional content (SP4). Early nonmotor manifestations were also assessed. RESULTS: Our case series consisted of 91 frontal SHE and 44 extrafrontal SHE cases. Frontal and extrafrontal SHE shared many features such as young age at onset, high seizure-frequency rate, high rate of scalp electroencephalography (EEG) and magnetic resonance imaging (MRI) abnormalities, similar histopathologic substrates, and good postsurgical outcome. Within the frontal lobe, SPs were organized in a posteroanterior gradient (SP1-4) with respect to the SOZ. In temporal SHE, SP1 was rare and SP3-4 frequent, whereas in operculoinsular and posterior SHE, SP4 was absent. Nonmotor manifestations were frequent (70%) and some could provide valuable localizing information. SIGNIFICANCE: Our study shows that the presence of certain SP and nonmotor manifestations may provide helpful information to localize seizure onset in patients with SHE.

Frontal lobe epilepsy and mild malformation with oligodendroglial hyperplasia: Further observations on electroclinical and imaging phenotypes, and surgical perspectives.

OBJECTIVE: Mild malformation with oligodendroglial hyperplasia (MOGHE) is a recently described clinicopathologic entity, associated with drug-resistant epilepsy and extensive epileptogenic networks. Knowledge is accumulating about particular electroclinical phenotypes, correlations with imaging, and potential prognostic significance for surgical outcomes. The study adds relevant information by documenting the presence of a hyperkinetic frontal lobe seizure phenotype in adolescents and an epileptic encephalopathy phenotype in young children. METHODS: Five cases were subjected to a structured presurgical evaluation protocol, including EEG-FMRI, chronic and acute invasive EEG, subjected to frontal lobe surgery with postoperative follow-up between 15 months and 7 years. RESULTS: In the two adult cases, surface EEG demonstrated lateralized widespread frontal lobe epileptogenicity and hyperkinetic semiological features. MRI demonstrated cortical white matter blurring and deeper white matter abnormalities. EEG-FMRI suggested concordant frontal lobe involvement. iEEG demonstrated a widespread frontal lobe epilepsy network. The three young children demonstrated a diffuse epileptic encephalopathy phenotype, with nonlocalizing, nonlateralizing surface EEG, and "spasms" as the main seizure type. MRI demonstrated extensive frontal lobe subcortical gray and white matter abnormalities, consistent with MOGHE literature for this age, while EEG-FMRI, in 2/3, demonstrated concordant frontal lobe involvement. They did not undergo chronic iEEG, and the resection was assisted by acute intraoperative ECoG. All cases were subjected to extensive frontal lobectomies with Engel class IA (2/5), IB (1/5), and IIB (2/5) outcomes. SIGNIFICANCE: The study confirms the presence of frontal lobe epilepsy and epileptic encephalopathy phenotypes, in accordance with epilepsy phenotypes already described in MOGHE literature. Presurgical evaluation studies, including EEG-FMRI, can provide strong lateralizing and localizing evidence of the epileptogenic networks involved. All responded favorably to extensive frontal lobe resections, despite widespread epileptic activity recorded by surface and intracranial EEG pre- and postoperatively; an epileptic encephalopathy phenotype, in the first years of life, should not discourage such a resection.