Ayataka Fujimoto

Neurosurgical management of intractable rolandic epilepsy in children: role of resection in eloquent cortex. Clinical article.

OBJECT The authors undertook this study to review their experience with cortical resections in the rolandic region in children with intractable epilepsy. METHODS The authors retrospectively reviewed the medical records obtained in 22 children with intractable epilepsy arising from the rolandic region. All patients underwent preoperative electroencephalography (EEG), MR imaging, prolonged video-EEG recordings, functional MR imaging, magnetoencephalography, and in some instances PET/SPECT studies. In 21 patients invasive subdural grid and depth electrode monitoring was performed. Resection of the epileptogenic zones in the rolandic region was undertaken in all cases. Seizure outcome was graded according to the Engel classification. Functional outcome was determined using validated outcome scores. RESULTS There were 10 girls and 12 boys, whose mean age at seizure onset was 3.2 years. The mean age at surgery was 10 years. Seizure duration prior to surgery was a mean of 7.4 years. Nine patients had preoperative hemiparesis. Neuropsychological testing revealed impairment in some domains in 19 patients in whom evaluation was possible. Magnetic resonance imaging abnormalities were identified in 19 patients. Magnetoencephalography was performed in all patients and showed perirolandic spike clusters on the affected side in 20 patients. The mean duration of invasive monitoring was 4.2 days. The mean number of seizures during the period of invasive monitoring was 17. All patients underwent resection that involved primary motor and/or sensory cortex. The most common pathological entity encountered was cortical dysplasia, in 13 children. Immediately postoperatively, 20 patients had differing degrees of hemiparesis, from mild to severe. The hemiparesis improved in all affected patients by 3-6 months postoperatively. With a mean follow-up of 4.1 years (minimum 2 years), seizure outcome in 14 children (64%) was Engel Class I and seizure outcome in 4 (18%) was Engel Class II. In this series, seizure outcome following perirolandic resection was intimately related to the childs age at the time of surgery. By univariate logistic regression analysis, age at surgery was a statistically significant factor predicting seizure outcome (p < 0.024). CONCLUSIONS Resection of rolandic cortex for intractable epilepsy is possible with expected morbidity. Accurate mapping of regions of functional cortex and epileptogenic zones may lead to improved seizure outcome in children with intractable rolandic epilepsy. It is important to counsel patients and families preoperatively to prepare them for possible worsened functional outcome involving motor, sensory and/or language pathways.

High-frequency oscillations of ictal muscle activity and epileptogenic discharges on intracranial EEG in a temporal lobe epilepsy patient

OBJECTIVE During seizures, intracranial EEG electrodes can record ictal muscle movements. Our purpose was to differentiate the high-frequency oscillations (HFOs) of extracranial muscle contractions from those of intracranial epileptogenic discharges. METHODS Using intracranial video-EEG (IVEEG), we recorded seizures in a 17-year-old boy with left mesial-temporal lobe epilepsy. We used multiple band frequency analysis (MBFA) to differentiate extracranial HFOs of craniofacial muscle activities from intracranial HFOs recorded ictally and interictally. RESULTS During 11 seizures, IVEEG showed low-amplitude fast waves ( approximately 60Hz) starting at the left mesial-temporal electrodes. Ictal facial grimacing projected low-amplitude ( approximately 20muV) fast waves ( approximately 160Hz) on inferior lateral-temporal electrodes. Interictal chewing projected medium-amplitude ( approximately 100muV) fast waves ( approximately 140Hz) correlating to mouth movements. MBFA topographic power spectrograms revealed a sustained, consistent ictal fast-frequency band from electrodes in the seizure-onset zone and randomly scattered HFOs without a specific frequency band from ictal and interictal extracranial muscle contractions. CONCLUSIONS MBFA power spectrograms differentiated randomly scattered muscle HFOs without a specific frequency band at electrodes close to temporal muscles from ictal epileptic HFOs with a sustained, fast-frequency band in the seizure-onset zone. SIGNIFICANCE The pattern and distribution of frequency power spectrograms of extracranial HFOs differ from those of intracranial HFOs.

Stereotactic radiofrequency thermocoagulation for hypothalamic hamartoma with intractable gelastic seizures

Management of hypothalamic hamartoma with intractable gelastic epilepsy remains controversial. We have used stereotactic thermocoagulation for treatment of hypothalamic hamartoma with intractable gelastic epilepsy since 1997. Herein, we review our experience in five cases to clarify the usefulness of this treatment. A total of five patients with hypothalamic hamartoma were treated by stereotactic thermocoagulation at our hospital during the period October 1997 through February 2004. In all patients, the hamartoma was less than 10mm in diameter and was located on the floor of the third ventricle with sessile attachment to the wall. To identify ictal onset, chronic intracranial electroencephalography was performed in three patients with the use of a depth electrode implanted in the hamartoma. Attempts were made to induce gelastic seizure by electrical stimulation of the hamartoma in three patients. After magnetic resonance imaging-guided targeting, radiofrequency thermocoagulation of the boundary between the hamartoma and normal hypothalamus was performed to achieve disconnection effects. Marked reductions in seizure frequency were obtained in all cases, with three patients becoming seizure-free after the procedure. No intraoperative complications occurred except in one patient who experienced acute and transient panidrosis with hot flushes during coagulation. Our results suggest that stereotactic thermocoagulation of hypothalamic hamartoma is an acceptable treatment option for patients with intractable gelastic seizures.

Comparison of dense array EEG with simultaneous intracranial EEG for Interictal spike detection and localization

PURPOSE To evaluate the clinical utility of dense array electroencephalography (dEEG) for the detection yield and localization of interictal spikes in mesial temporal lobe epilepsy. METHODS We simultaneously recorded 256-channel dEEG and intracranial electroencephalography (icEEG) implanted over the lateral and mesial temporal lobe in patients with intractable epilepsy. We calculated the dEEG spike detection rate for mesial temporal spikes which were confirmed by icEEG and applied source estimation to dEEG to compare noninvasive localization to the invasive recordings. RESULTS 339 of 760 interictal spikes (45%) were detected by dEEG examining the 256-channel head surface array. The average icEEG amplitude of dEEG detectable spikes was 1083 μV, and that of dEEG undetectable spikes was 780 μV (P<0.05). All spikes detected in dEEG were localized to the temporal lobe. 295 of 339 spikes (87%) were well localized in mesial temporal lobe, close to the position confirmed by subdural electrodes. SIGNIFICANCE 256-channel dEEG may provide more precise information for the localization of interictal epileptiform discharges than conventional EEG or MEG in patients with deep spike foci. 256-channel dEEG may be clinically useful in the presurgical work-up for epilepsy, providing accurate noninvasive guidance for the placement of intracranial electrodes.

Dense array EEG source estimation in neocortical epilepsy.

Rationale: Dense array EEG (dEEG) evenly covers the whole head surface with over 100 channels contributing to more accurate electrical source imaging due to the higher spatial and temporal resolution. Several studies have shown the clinical utility of dEEG in presurgical clinical evaluation of epilepsy. However validation studies measuring the accuracy of dEEG source imaging are still needed. This can be achieved through simultaneously recording both scalp dEEG with intracranial electrodes (icEEG), which is considered as the true measure of cortical activity at the source. The purpose of this study is to evaluate the accuracy of 256-channel dEEG electrical source estimation for interictal spikes. Methods: Four patients with medically refractory neocortical epilepsy, all surgical candidates, underwent subdural electrode implantation to determine ictal onset and define functional areas. One patient showed a lesion on the magnetic resonance imaging in the right parietal lobe. The patient underwent simultaneous recording of interictal spikes by both scalp 256-channelsvdEEG and icEEG. The dEEG was used to non-invasively estimate the source of the interictal spikes detected by the 256-channel dEEG array, which was then compared to the activity measured directly at the source by the icEEG. Results: From the four patients, a total of 287 interictal spikes were measured with the icEEG. One hundred fifty-five of the 287 spikes (54%) were visually detected by the dEEG upon examination of the 256 channel head surface array. The spike amplitudes detected by the 256-channel dEEG correlated with icEEG spike amplitudes (p < 0.01). All spikes detected in dEEG were localized to the same lobe correctly. Conclusion: Our study demonstrates that 256-channel dEEG can reliably detect interictal spikes and localize them with reasonable accuracy. Two hundred fifty-six-channel dEEG may be clinically useful in the presurgical workup for epilepsy and also reduce the need for invasive EEG evaluation.

Integrating Dense Array EEG in the Presurgical Evaluation of Temporal Lobe Epilepsy

Purpose. To evaluate the clinical utility of dense array electroencephalography (dEEG) for detecting and localizing interictal spikes in temporal lobe epilepsy. Methods. Simultaneous invasive and noninvasive recordings were performed across two different groups. (1) The first group underwent both noninvasive recording with 128 channels of (scalp) dEEG and invasive sphenoidal electrode recording. (2) The second group underwent both noninvasive recording with 256 channels of (scalp) dEEG and invasive intracranial EEG (icEEG) involving coverage with grids and strips over the lateral and mesial temporal lobe. A noninvasive to noninvasive comparison was made comparing the overall spike detection rate of the dEEG to that of conventional 10/20 EEG. A noninvasive to invasive comparison was made comparing the spike detection rate of dEEG to that of conventional 10/20 EEG plus sphenoidal electrodes. And finally, a noninvasive to invasive evaluation measuring the source localization ability of the dEEG using the icEEG as validation. Results. In the 128-channel dEEG study (1), 90.4% of the interictal spikes detected by the dEEG were not detected in the 10/20 montage. 91% of the dEEG-detected spikes were accurately localized to the medial temporal lobe. In the 256-channel dEEG study (2), 218 of 519 interictal spikes (42%) were detected by dEEG. 85% of these spikes were accurately localized to the medial temporal lobe, close to the position confirmed by subdural electrodes. Conclusion. Dense array EEG may provide more precise information than conventional EEG and has a potential for providing an alternative to sphenoidal electrode monitoring in patients with temporal lobe epilepsy.

Somatosensory-evoked fields on magnetoencephalography for epilepsy infants younger than 4 years with total intravenous anesthesia

OBJECTIVE Patients must remain immobile for magnetoencephalography (MEG) and MRI recordings to allow precise localization of brain function for pre-surgical functional mapping. In young children with epilepsy, this is accomplished with recordings during sleep or with anesthesia. This paper demonstrates that MEG can detect, characterize and localize somatosensory-evoked fields (SEF) in infants younger than 4 years of age with or without total intravenous anesthesia (TIVA). METHODS We investigated the latency, amplitude, residual error (RE) and location of the N20m of the SEF in 26 infants (mean age=2.6 years). Seventeen patients underwent TIVA and 9 patients were tested while asleep, without TIVA. RESULTS MEG detected 44 reliable SEFs (77%) in 52 median nerve stimulations. We found 27 reliable SEFs (79%) with TIVA and 13 reliable SEFs (72%) without TIVA. TIVA effects included longer latencies (p<0.001) and lower RE (p<0.05) compared to those without TIVA. Older patients and larger head circumferences also showed significantly shorter latencies (p<0.01). CONCLUSIONS TIVA resulted in reliable SEFs with lower RE and longer latencies. SIGNIFICANCE MEG can detect reliable SEFs in infants younger than 4 years old. When infants require TIVA for MEG and MRI acquisition, SEFs can still be reliably observed.

Changing ictal-onset EEG patterns in children with cortical dysplasia

PURPOSE Cortical dysplasia (CD) is intrinsically epileptogenic. We hypothesize that CDs clinically emerging in the early developing brain tend to extend into multifocal or larger epileptic networks to pronounce intractability in contrast to CDs which clinically emerge at a later age. METHODS We evaluated the spatial and temporal profiles of ictal-onset EEG patterns in children with histopathologically confirmed CD. We designated Group A as children with changing ictal-onset EEG patterns over time, and Group B without change. We compared seizure profiles, consecutive scalp video-EEGs (VEEGs), MRI, MEG, and surgical outcomes. RESULTS We found 14 children consisting of 10 Group A patients (7 girls) and 4 Group B patients (all boys). Eight (80%) Group A patients had their seizure onset <5 years while all Group B patients had seizure onset >or=5 years (p<.05). Changes of ictal onset EEG pattern in Group A consisted of bilateral (4 patients), extending (2); extending and bilateral (2); and generalized (2). We saw MRI lesions (6) and single clustered MEG spike sources (MEGSSs) in (5). Six patients underwent surgery before 15 years of age, and 4 of them attained seizure freedom. All 4 Group B patients had MRI lesions and single clustered MEGSSs. Three patients underwent surgery after 15 years of age. All 4 patients attained seizure freedom. CONCLUSION Ictal-onset EEG patterns change over time in children with early seizure onset and intractable epilepsy caused by CD. Younger epileptic children with CD more frequently have multifocal epileptogenic foci or larger epileptogenic foci. Early resection of CD, guided by MRI, MEG, and intracranial video EEG, resulted in seizure freedom despite changes in ictal-onset EEG patterns.

Clinical utility of vagus nerve stimulation for progressive myoclonic epilepsy.

Progressive myoclonic epilepsy (PME) is a group of disorders in which myoclonus is a major component. Patients with PME typically have generalized tonic–clonic or clonic seizures, mental retardation culminating in dementia, and a neurologic syndrome that almost always includes cerebellar dysfunction. It comprises a heterogeneous group of inherited disorders. Conditions inwhich PME is seen include Unverricht–Lundborg disease, sialidosis, Gaucher’s disease, mitochondrial encephalomyelopathy with ragged-red fibers (MERRF), Lafora’s disease, neuronal ceroid lipofuscinosis, and Dentato-Rubro-Pallido Luysian Atrophy (DRPLA). The intensity of the various clinical features varies depending on the etiology. Although valproate, benzodiazepines, piracetam, zonisamide, topiramate, and levetiracetam have had a positive impact on the control of the epilepsy, the prognosis of this syndrome is poor. PME is also not responsive to open surgical resection. Among complimentary treatment options for epilepsy resistant tomedical and open surgical treatments, most patients so far have been treated by vagus nerve stimulation (VNS). VNS is a widely used neurostimulation for treatment-resistant epilepsy. Its components are a pulse generator and a bipolar vagus nerve lead. The generator is designed to be implanted in the patient’s chest on the upper left side. This pulse generator produces charge-balanced waveforms at a constant current. The effectiveness of VNS for PME has rarely been reported. The purpose of this study was to evaluate the efficacy of VNS for PME.

Ictal SPECT in supplementary motor area seizures

Abstract Objectives: We used ictal single photon emission computed tomography (SPECT) to clarify the propagation pathways of epileptic discharges in patients with supplementary motor area (SMA) seizure. Methods: In four patients (four males, age range, 18–27 years) with SMA seizures, SPECT studies by radioisotope 99mTc-ECD were performed as a preoperative evaluation. Two of the patients remained seizure-free after complete resection of the focal cortical dysplasia on magnetic resonance (MR) images including epileptic foci. In the other two patients, MR images were normal, but subdural electrode monitoring allowed for verifying the ictal onset in the left SMA. After partial resection of the SMA including epileptic foci, these patients experienced a significant (>90%) reduction of seizure frequency. Regional cerebral blood flow (rCBF) measurements obtained under ictal and interictal conditions were compared on a voxel-by-voxel basis by means of the SPM99 paired t-test option (uncorrected p<0.001). Results: Significant increases in rCBF under ictal conditions were identified in the bilateral anterior cingulate cortex (ACC), the globus pallidus ipsilateral to epileptic foci and the contralateral cerebellar hemisphere. The right ACC included a cluster with a submaximum in the right primary sensorimotor area. Discussion: In patients with SMA seizures, the hyperperfusion areas of ictal SPECT did not localize within the SMA but spread to the adjacent cortex such as the ACC and sensorimotor cortex ipsilateral to epileptic foci. Additionally, the epileptic discharges propagated to the remote areas such as the globus pallidus and cerebellum. We caution that ictal SPECT localization in patients with SMA seizures is not always concordant to epileptic focus but reveals already spread seizure activities.