A computational biomarker of juvenile myoclonic epilepsy from resting-state MEG

ObjectiveFor people with idiopathic generalized epilepsy, functional networks derived from their resting-state scalp electrophysiological recordings have shown an inherent higher propensity to generate seizures than those from healthy controls when assessed using the concept of brain network ictogenicity (BNI). Herein we tested whether the BNI framework is applicable to resting-state magnetoencephalography (MEG) from people with juvenile myoclonic epilepsy (JME).MethodsThe BNI framework consists in deriving a functional network from apparently normal brain activity, placing a mathematical model of ictogenicity into the network and then computing how often such network generates seizures in silico. We considered data from 26 people with JME and 26 healthy controls.ResultsWe found that resting-state MEG functional networks from people with JME are characterized by a higher propensity to generate seizures (i.e., higher BNI) than those from healthy controls. We found a classification accuracy of 73%.ConclusionsThe BNI framework is applicable to MEG and was capable of differentiating people with epilepsy from healthy controls.SignificanceThe BNI framework may be applied to resting-state MEG to aid in epilepsy diagnosis.     

Neuromagnetic coherence of epileptic activity: An MEG study

PurposeThis study was undertaken to test the hypothesis that patients with epilepsy have abnormal imaginary coherence compared with control subjects.MethodsThirty patients with seizures underwent magnetoencephalography (MEG) recording using a whole cortex MEG system. Conventional equivalent current dipoles (ECDs) and synthetic aperture magnetometry (SAM) were used to analyze MEG data. Neural synchronization was studied using imaginary coherence to analyze resting-state MEG data. The ECDs, SAM, and MEG results were then compared with intra/extra-operative EEG.ResultsAbnormal imaginary coherence was identified in all patients (30/30, 100%). The locations of abnormal imaginary coherence were in agreement with the ECDs locations of spikes in 23 patients (23/30, 76.7%). The ECD locations in 5 patients were scattered or located bilaterally. The locations of abnormal imaginary coherence were in agreement with SAM locations in 26 patients (26/30, 86.7%). One case of imaginary coherence was located in two lobes. The ECDs fit locations were in agreement with SAM locations in 21 patients (21/30, 70.0%). The locations of abnormal imaginary coherence, ECDs, and SAM were in agreement with intra/extra-operative EEG in 23 patients (23/30, 76.7%), 17 patients (17/30, 56.7%), and 20 patients (20/30, 66.7%), respectively. The results of ECDs location, SAM location, imaginary coherence, and intracranial EEG (iEEG) were consistent in 15 patients (15/30, 50%).ConclusionsThe results show that patients with epilepsy have abnormal imaginary coherence, and suggest that the location and coherence of epileptic activity could be quantitatively identified and analyzed using neuromagnetic signals.     

MEG-based identification of the epileptogenic zone in occult peri-insular epilepsy

IntroductionPresurgical work-ups of patients with pharmacoresistant epileptic seizures can require multiple diagnostic methods if magnetic resonance imaging (MRI) combined with video-EEG monitoring fails to show an epileptogenic lesion. Yet, the added value of available methods is not clear. In particular, only a minority of epilepsy centres apply magnetoencephalography (MEG). This study explores the potential of MEG for patients whose previous sophisticated work-ups missed deep-seated, peri-insular epileptogenic lesions.Patients and methodsThree patients with well documented, frequent, stereotypical hypermotor seizures without clear focus hypotheses after repeated presurgical work-ups including video-EEG-monitoring, 3 Tesla (3 T) magnetic resonance imaging (MRI), morphometric MRI analysis, PET and SPECT were referred to MEG source localisation.ResultsIn two out of three patients, MEG source localisation identified very subtle morphological abnormalities formerly missed in MRI or classified as questionable pathology. In the third patient, MEG was not reliable due to insufficient detection of epileptic patterns. Here, a 1 mm × 1 mm × 1 mm 3 T fluid-attenuated inversion recovery (FLAIR) MRI revealed a potential epileptogenic lesion. A minimal invasive work-up via lesion-focused depth electrodes confirmed the intralesional seizure onset in all patients, and histology revealed dysplastic lesions. Seizure outcomes were Engel 1a in two patients, and Engel 1d in the third.DiscussionMEG can contribute to the identification of epileptogenic lesions even when multiple previous methods failed, and when the lesions are located in deep anatomical structures such as peri-insular cortex. For epilepsy centres without MEG capability, referral of patients with cryptogenic focal epilepsies to centres with MEG systems may be indicated.     

Simultaneous MEG and EEG to detect ripples in people with focal epilepsy

ObjectiveWe studied ripples (80–250 Hz) simultaneously recorded in electroencephalography (EEG) and magnetoencephalography (MEG) to evaluate the differences.MethodsSimultaneous EEG and MEG were recorded in 30 patients with drug resistant focal epilepsy. Ripples were automatically detected and visually checked in virtual channels throughout the cortex. The number and location of ripples in EEG and MEG were compared to each other and to a region of interest (ROI) defined by clinically available information.ResultsEleven patients showed ripples in both MEG and EEG, 11 only in EEG and one only in MEG. Twenty-four percent of the ripples occurred simultaneously in EEG and MEG, 71% only in EEG, and 5% only in MEG. Three patients without spikes in EEG showed EEG ripples. Ripple localization was concordant with the ROI in 80% of patients with MEG ripples, as opposed to 62% full or partial concordance for EEG ripples. With the optimal threshold for localizing the ROI, sensitivity and specificity were more than 80%.ConclusionsRipples in MEG are less frequent but more specific and sensitive for the region of interest than ripples in EEG. Ripples in EEG can exist without spikes in the EEG.SignificanceRipples in MEG and EEG provide complementary information.     

Two magneto-encephalographic epileptic foci did not coincide with the electrocorticographic ictal onset zone in a patient with temporal lobe epilepsy

Abstract

To evaluate the usefulness and limitations of magneto-encephalography (MEG) for epilepsy surgery, we compared 'interictal' epileptic spike fields on MEG with ictal electrocorticography (ECoG) using invasive chronic subdural electrodes in a patient with intractable medial temporal lobe epilepsy (MTLE) associated with vitamin K deficiency intracerebral hemorrhage. A 19-year-old male with an 8-year history of refractory complex partial seizures, secondarily generalized, and right hemispheric atrophy and porencephaly in the right frontal lobe on MRI, was studied with MEG to define the interictal paroxysmal sources based on the single-dipole model. This was followed by invasive ECoG monitoring to delineate the epileptogenic zone. MEG demonstrated two paroxysmal foci, one each on the right lateral temporal and frontal lobes. Ictal ECoG recordings revealed an ictal onset zone on the right medial temporal lobe, which was different from that defined by MEG. Anterior temporal lobectomy with hippocampectomy was performed and the patient has been seizure free for two years. Our results indicate that interictal MEG does not always define the epileptogenic zone in patients with MTLE. [Neurol Res 2001; 23: 830-834]     

脑磁图与神经导航结合在癫痫外科的应用

目的探讨脑磁图定位和神经导航方法二者结合在癫痫外科的应用价值。方法选择12例顽固性癫痫手术,术前脑磁图确定皮质癫痫灶及中央后回感觉皮质范围,然后与神经外科导航系统结合应用于手术当中。结果脑磁图癫痫灶定位与术中皮质脑电图定位符合率100％。按Engel分级作为癫痫疗效标准,术后癫痫发作完全停止9例(1级),发作减少90％以上2例(2或3级),发作减少不到90％1例(4级)。无一例出现手术后神经功能障碍。结论脑磁图是无创确定癫痫灶和功能区皮质空间位置关系的重要工具,脑磁图定位结合神经导航方法的应用可使癫痫外科手术更精确,侵袭更小。     

Classification of schizophrenia with spectro-temporo-spatial MEG patterns in working memory

ObjectiveTo investigate whether temporo-spatial patterns of brain oscillations extracted from multichannel magnetoencephalogram (MEG) recordings in a working memory task can be used successfully as a biometric marker to discriminate between healthy control subjects and patients with schizophrenia.MethodsFive letters appearing sequentially on a screen had to be memorized. The letters constituted a word in one condition and a pronounceable non-word in the other. Power changes of 248 channel MEG data were extracted in frequency sub-bands and a two-step filter and search algorithm was used to select informative features that discriminated patients and controls.ResultsThe discrimination between patients and controls was greater in the word condition than in the non-word condition. Furthermore, in the word condition, the most discriminant patterns were extracted in delta (1–4 Hz), alpha (12–16 Hz) and beta (16–24 Hz) frequency bands. These features were located in the left dorso-frontal, occipital and left fronto-temporal, respectively.ConclusionThe analysis of the oscillatory patterns of MEG recordings in the working memory task provided a high level of correct classification of patients and controls.SignificanceWe show, using a newly developed algorithm, that the temporo-spatial patterns of brain oscillations can be used as biometric marker that discriminate schizophrenia patients and healthy controls.     

Surgical management of intractable epilepsy associated with cerebral neurocytoma

Neuronal neoplasms of the CNS constitute a rarely encountered group of tumors. This report concerns the surgical management of seizures encountered in four cases (ranging from 2 to 10 years-of-age at onset; consisting of two males and two females) of a recently recognized morphologically unique tumor, called 'cerebral neurocytoma'. All patients were associated solely with intractable complex partial seizures. The tumor involved the temporal lobe in two cases, and the frontal in two. Magnetoencephalography (MEG) clearly demonstrated an accumulation of equivalent current dipoles originating from the interictal spikes on the cortex around the tumor. On intra-operative electrocorticography (ECoG), the epileptogenic zone was topographically distinct from the region of the tumor. No definite ECoG activities were observed at the tumor site, although this tumor did consist of small mature neuronal cells. Either a complete or a subtotal resection of the tumor and the epileptogenic cortex was performed and, post-operatively, universal freedom from seizures was demonstrated in all patients. A histological examination of the epileptogenic cortex revealed the presence of minute cortical dysplasia or tumor involvement in the hippocampus. A resection of the epileptogenic cortex along with the tumor was thus found to improve the seizure outcome in patients with neurocytoma-associated epilepsy without inducing any identifiable neurological deficits attributable to the incremental resection.     

Electro- and magneto-encephalographic spike source localization of small focal cortical dysplasia in the dorsal peri-rolandic region

ObjectiveSmall focal cortical dysplasia (FCD) may be ambiguous or overlooked on magnetic resonance (MR) imaging. Source localization of EEG and magnetoencephalography (MEG) spikes was evaluated to confirm the diagnosis of small FCD.MethodsThis study included 6 epilepsy patients with a single small lesion on MR imaging suggesting FCD within a single gyrus among 181 consecutive epilepsy patients admitted to our epilepsy monitoring unit over 27 months. Stereotypical interictal spikes were detected on simultaneous EEG and MEG recordings and the onset-related source of averaged spikes was estimated.ResultsAll 6 patients had unique clinical characteristics as follows: leg sensori-motor seizures in 5 patients and eye version in 1 patient; a small MR imaging lesion suggesting FCD in the dorsal peri-rolandic region, which had been overlooked until our evaluation; and both EEG and MEG dipoles were estimated adjacent to the MR imaging lesion.ConclusionsSource localization of EEG and MEG spikes can confirm the diagnosis of FCD based on a single small MR imaging lesion, which was overlooked by previous examination of MR images.SignificanceExamination of MR images should be based on spike source localization as well as seizure semiology to identify subtle MR imaging abnormalities.     

Complementary use of video-electroencephalography and magnetoencephalography in frontal lobe epilepsy

PurposeThe aim of this study was to compare magnetoencephalography (MEG) and video-electroencephalography (VEEG) source localization in frontal lobe epilepsy (FLE) and determine if these methods can be complementary to each other in clinical practice.MethodThirty patients with pharmaco-resistant FLE who underwent epilepsy surgery were retrospectively enrolled. Video EEG was recorded using an IT-med system using 10/20 system. Regional localization of spikes in VEEG was defined as spikes discharged from adjacent electrodes and no further propagation to a large and/or contralateral area. Magnetoencephalography was recorded for the purpose of focus assessment. Magnetoencephalography spikes were detected for dipole localization of the epileptogenic cortex and the epileptogenic area was classified as mono- or multi-focal.ResultsRegional spike discharges were identified in the interictal VEEG of 20 patients and in the ictal VEEG of 17 patients. Thirteen patients had regional spikes in both interictal and ictal VEEG. Mono-focal localization was identified in the MEG of 20 patients. Fourteen of these patients had regional spike discharges in VEEG. In the remaining six patients, sources localization was only identified by MEG and there were no regional spike discharges either interictal or ictal VEEG.ConclusionIn clinical practice, VEEG is the routine procedure in the presurgical evaluation of FLE. However, we found six cases in which VEEG failed to locate the epileptogenic area that was identified by MEG. We therefore propose that combining VEEG and MEG will optimize the noninvasive presurgical evaluation of epileptiform activities in FLE.     

Functional Plasticity of the Motor Cortical Structures Demonstrated by Navigated TMS in Two Patients with Epilepsy

BackgroundRecently, navigated transcranial magnetic stimulation (nTMS) has been suggested to be useful in preoperative functional localization of motor cortex in patients having tumors close to the somatomotor cortex. Resection of tumors in anatomically predicted eloquent areas without adverse effects have emphasized functional plasticity elicited by intracranial pathology.ObjectiveTo describe functional plasticity of motor cortex indicated by nTMS in two patients with epilepsy.MethodsnTMS, functional MRI (fMRI), diffusion-tensor (DT)-tractography and magnetoencephalography (MEG) were utilized to preoperatively localize motor cortical areas in the workup for epilepsy surgery. The localizations were compared with each other, with the cortical anatomical landmarks, and in one patient with invasive electrical cortical stimulation (ECS).ResultsIn two out of 19 studied patients, nTMS identified motor cortical sites that differed from those indicated by anatomical landmarks. In one patient, nTMS activated preferentially premotor cortex rather than pathways originating from the precentral gyrus. MEG and fMRI localizations conformed with nTMS whereas ECS localized finger motor function into the precentral gyrus. Resection of the area producing motor responses in biphasic nTMS did not produce a motor deficit. In the other patient, nTMS indicated abnormal ipsilateral hand motor cortex localization and confirmed the functionality of aberrant motor cortical representations of the left foot also indicated by fMRI and DT-tractography.ConclusionnTMS may reveal the functional plasticity and shifts of motor cortical function. Epileptic foci may modify cortical inhibition and the nTMS results. Therefore, in some patients with epilepsy, the nTMS results need to be interpreted with caution with regard to surgical planning.     

Orbitofrontal epilepsy: Case series and review of literature

BackgroundOrbitofrontal epilepsy (OFE) is less known and is poorly characterized in comparison with temporal lobe epilepsy, partly because it is rare and possibly because it is unrecognized and therefore underestimated.ObjectiveThis paper aimed to better characterize seizure semiology, presurgical findings, and surgical outcomes in patients with OFE.MethodsWe retrospectively reviewed all confidently established OFE cases from six Canadian epilepsy monitoring units between 1988 and 2014, and in the literature between 1972 and 2017. Inclusion criteria were identification of an epileptogenic lesion localized in the OFC or if the patient was seizure-free after surgical removal of the OFC in nonlesional cases.ResultsSixteen cases were identified from our databases. Fifty percent had predominantly sleep-related seizures; 56% had no aura (the remaining had nonspecific or vegetative auras), and 62.5% featured hypermotor (mostly hyperkinetic) behaviors. Interictal epileptiform discharges over frontal and temporal derivations always allowed lateralization. Magnetic resonance imaging (MRI) identified an orbitofrontal lesion in 8/16, positron emission tomography (PET) identified a hypometabolism extending outside the orbital cortex in 4/9, ictal single-photon emission computed tomography (SPECT) identified an orbital hyperperfusion in 1/5, magnetoencephalography (MEG) identified lateral orbital sources in 2/4, and intracranial electroencephalography (EEG) identified an orbitofrontal onset in 9/10. Fourteen patients underwent surgery, all reaching a favorable outcome (71.4% Engel 1; 28.6% Engel 2; mean FU = 5.6 years). Pre- and postoperative neuropsychological assessments revealed heterogeneous findings. Our review of literature identified 71 possible cases of OFE, 32 with confident focus localization. Extracted data from these cumulated cases supported observations made from our case series.ConclusionsOrbitofrontal epilepsy should be suspected with sleep-related, hyperkinetic seizures with no specific aura, and frontotemporal interictal discharges. Several patients have nonmotor seizures with or without auras which may resemble temporal lobe seizures. Postoperative seizure outcome was favorable, but there is inherent bias as we only included patients with a seizure-free outcome if the MRI was negative. A larger study is required to address identified gaps in knowledge such as identifying discriminative features between medial and lateral OFE, evaluating the value of more recent diagnostic tools, and assessing the neuropsychological outcome of orbital epilepsy surgery.     

Feasibility and limitations of magnetoencephalographic detection of epileptic discharges: Simultaneous recording of magnetic fields and electrocorticography

Abstract

Magnetoencephalography (MEG) is considered clinically useful in localizing the epileptogenic focus in partial epilepsy. However, the relationship between the extent of the brain involved in paroxysmal activities and the magnetic field changes at the scalp has not been fully clarified. Furthermore, whether paroxysmal activities generated in deep brain structures such as the hippocampus can be detected magnetically is uncertain. Eight patients with temporal lobe epilepsy and two with extratemporal lobe epilepsy underwent chronic recording from subdural electrodes. Magnetic and electrocorticographic discharges representing epileptic activity were recorded simultaneously. MEG recorded magnetic field changes originating from paroxysmal activity in the superiolateral cerebral cortex when the amplitudes of the electrical paroxysmal activities exceeded 100 µ V and extended over more than 3 cm² of cortical surface. MEG failed to record paroxysmal activity localized to the medial temporal lobe. MEG is often useful in identifying a spike focus in the superiolateral aspects of the cerebral hemisphere, but not discharges arising from the medial temporal lobe. Rapid decay of the magnetic field is likely to be the reason for this limited sensitivity to medial discharges. [Neurol Res 2002; 24: 531-536]     

Focal epilepsy with paroxysmal pain due to somatic injury

We present two cases with paroxysmal pain that developed after a somatic injury to the trunk. The main characteristic of the episodes was paroxysmal severe pain, mainly located in the original region of somatic injury, with ipsilateral tonic or dystonic behaviour. The clinical characteristics supported a diagnosis of focal epilepsy. Both scalp EEG and MEG findings suggested epileptic activities on the contralateral central cortex. The focal seizures had a good response to antiepileptic drugs. It is hypothesized that peripheral somatic injuries can modify cortical excitability and lead to plastic changes in the sensory/motor cortex, ultimately resulting in focal seizures. We provide additional evidence for the phenomenon that a peripheral somatic injury could induce focal epilepsy. [Published with video sequence on www.epilepticdisorders.com ]     

Neuromagnetic cerebellar activation during seizures arising from the motor cortex

We utilized the high temporal resolution, whole head coverage and novel analysis methodology of magnetoencephalography (MEG) to record the dynamics of cerebellar activation during focal motor seizures. We analyzed ictal MEG data from a four-year old using an event-related beamformer to localize and display ictal changes over the motor cortex and cerebellum. Contralateral activation of the cerebellum was seen 14 s after MEG ictal onset over the motor cortex. These findings represent the first indication of ictal activity within the cerebellum in humans, measured non-invasively with MEG.     

Factors that modify the risk of intraoperative seizures triggered by electrical stimulation during supratentorial functional mapping

ObjectiveIntraoperative mapping via electrical stimulation is the gold standard technique for surgeries close to the eloquent cortex. However, it can trigger seizures which immediately impact patient’s safety. We studied whether administration of antiepileptic drugs (AED) prior to and/or at the beginning of the surgery decreases the probability of triggering seizures, while adjusting for other risk factors.Methods544 consecutive intraoperative mapping cases performed at a tertiary care center for epilepsy and brain tumor surgery were included in the study. Using a multivariate logistic regression analysis, we analyzed the independent impacts of AED loading at time of surgery, preoperative AED maintenance, history of seizures, type of stimulation paradigm, lobar location of stimulation, age, opioid administration and pathology on the probability of triggering seizures.ResultsSeizures were identified in 135 patients. Intravenous loading with AED decreased the odds of triggering seizures by 45% (OR = 0.55, p = 0.01), Penfield (versus multipulse train) stimulation and diffuse (versus well circumscribed) pathology increased it twice (OR = 1.97, p = 0.01) and 2.4 times (OR = 2.42, p = 0.003) respectively. No other factors had a significant impact.ConclusionsSeizures triggered during mapping occur frequently and are multifactorial.SignificanceLoading with AED independently reduces the risk of their occurrence.     

Regional Cerebral Blood Flow Changes Associated With Focal Electrically Administered Seizure Therapy (FEAST)

IntroductionUse of electroconvulsive therapy (ECT) is limited by cognitive disturbance. Focal electrically-administered seizure therapy (FEAST) is designed to initiate focal seizures in the prefrontal cortex. To date, no studies have documented the effects of FEAST on regional cerebral blood flow (rCBF).MethodsA 72 year old depressed man underwent three single photon emission computed tomography (SPECT) scans to capture the onset and resolution of seizures triggered with right unilateral FEAST. We used Bioimage Suite for within-subject statistical analyses of perfusion differences ictally and post-ictally compared with the baseline scan.ResultsEarly ictal increases in regional cerebral blood flow (rCBF) were limited to the right prefrontal cortex. Post-ictally, perfusion was reduced in bilateral frontal and occipital cortices and increased in left motor and precuneus cortex.ConclusionFEAST appears to triggers focal onsets of seizure activity in the right prefrontal cortex with subsequent generalization. Future studies are needed on a larger sample.     

Magnetoencephalographic signatures of insular epileptic spikes based on functional connectivity

Failure to recognize insular cortex seizures has recently been identified as a cause of epilepsy surgeries targeting the temporal, parietal, or frontal lobe. Such failures are partly due to the fact that current noninvasive localization techniques fare poorly in recognizing insular epileptic foci. Our group recently demonstrated that magnetoencephalography (MEG) is sensitive to epileptiform spikes generated by the insula. In this study, we assessed the potential of distributed source imaging and functional connectivity analyses to distinguish insular networks underlying the generation of spikes. Nineteen patients with operculo‐insular epilepsy were investigated. Each patient underwent MEG as well as T1‐weighted magnetic resonance imaging (MRI) as part of their standard presurgical evaluation. Cortical sources of MEG spikes were reconstructed with the maximum entropy on the mean algorithm, and their time courses served to analyze source functional connectivity. The results indicate that the anterior and posterior subregions of the insula have specific patterns of functional connectivity mainly involving frontal and parietal regions, respectively. In addition, while their connectivity patterns are qualitatively similar during rest and during spikes, couplings within these networks are much stronger during spikes. These results show that MEG can establish functional connectivity‐based signatures that could help in the diagnosis of different subtypes of insular cortex epilepsy. Hum Brain Mapp 37:3250–3261, 2016. © 2016 Wiley Periodicals, Inc .     

Magnetoencephalographic Evaluation of Children and Adolescents with Intractable Epilepsy

Summary: Magnetoencephalographic (MEG) discharges were recorded with multichannel superconducting quantum interference device (SQUID) gradiometers in 13 young candidates for epilepsy surgery. The sources of epileptic activity were related to generators of somatosensory and auditory evoked cortical responses and projected on magnetic resonance imaging (MRI) scans. Seven subjects had restricted or regional MEG foci, located in the frontoopercular (1), sensorimotor (3), perisylvian (1), mesiotemporal (1), or temporooccipital cortex (1). The MEG foci in the 3 patients who underwent operation agreed with the intracranial findings. Findings in the other patients emphasize the need to collect further data to define the ultimate role of MEG in preoperative evaluation of epilepsy.     

Fast epileptic discharges associated with ictal negative motor phenomena

ObjectiveFocal motor negative phenomena have been described in seizures primarily involving “negative” motor areas (opercular pre-motor and medial pre-motor regions) and the rolandic region (post-central or pre-central). The localizing value of such signs and the mechanisms by which an epileptic discharge may generate negative phenomena remain debated.MethodsIctal positive and negative motor phenomena occurring during seizures affecting the rolandic area were studied in a patient having intracerebral recordings (stereo-electro-encephalography, SEEG) for drug resistant epilepsy.ResultsDuring the video-SEEG and EMG recording, nine positive and 27 negative motor seizures were recorded. All were generated within the same area (right opercular central area, Brodmann Area 4). The 2 different types of clinical seizure were differentiable by their power/frequency spectrum: positive motor seizures were associated with a prominent alpha–beta band discharge while negative motor seizures were associated with a gamma band discharge (>45 Hz).ConclusionsWe propose that within the primary motor cortex, high frequency sustained discharges may disrupt the ongoing excitatory drive to the peripheral motoneurons and produce negative motor signs, while sustained lower frequency discharges (alpha and beta bands) may activate the cortico-nuclear or cortico-spinal pathway and produce positive motor signs.SignificanceBoth positive and negative ictal motor phenomena can be observed in the primary motor cortex depending on the properties of the epileptic discharge.