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SummaryPurpose: Ictal magenetoencephalographic (MEG) discharges convey significant information about ictal onset and propagation, but there is no established method for analyzing ictal MEG. This study sought to clarify the usefulness of time-frequency analyses using short-time Fourier transform (STFT) for ictal onset and propagation of ictal MEG activity in patients with neocortical epilepsy.Methods: Four ictal MEG discharges in two patients with perirolandic epilepsy and one with frontal lobe epilepsy (FLE) were evaluated by time-frequency analyses using STFT.Prominent oscillation bands were collected manually and the magnitudes of those specific bands were superimposed on individual 3D-magnetic resonance images.Results: STFT showed specific rhythmic activities from alpha to beta bands at the magnetological onset in all four ictal MEG records. Those activities were located at the vicinity of interictal spike sources, as estimated by the single dipole method (SDM), and two of the four ictal rhythmic activities promptly propagated to ipsilateral or bilateral cerebral cortices. The patients with FLE and perirolandic epilepsy underwent frontal lobectomy and resection of primary motor area respectively including the origin of high-magnitude areas of a specific band indicated by STFT, and have been seizure free after the surgery.Conclusions: STFT for ictal MEG discharges readily demonstrated the ictal onset and propagation. These data were important for decisions on surgical procedure and extent of resection. Ictal MEG analyses using STFT could provide a powerful tool for noninvasive evaluation of ictal onset zone.

The shear relaxation spectra and the alternating-current (AC) conductivity of 1-alkyl-3-methylimidazolium hexafluorophosphate were measured in the MHz region, with the chain lengths varied from butyl to octyl. The relaxation times of both the conductivity and shear viscosity increased with increasing chain length approximately in proportion to the variation of the reciprocal molar conductivity. On the other hand, the increase in the shear viscosity was smaller than that of the relaxation time, which indicates that the high-frequency shear modulus decreases with the chain length. The decrease in the the Walden product with the chain length is thus ascribed to that of the high-frequency shear modulus.

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SUMMARYA dysplastic neuronal lesion of the floor of the fourth ventricle (DNFFV) causes hemifacial seizures (HFS) from early infancy. However, it is still controversial whether HFS is generated by the facial nerve nucleus or cerebellar cortex. In this study, we confirm a direct correlation between the rhythmic activities in the DNFFV and HFS using intraoperative electroencephalography (EEG) and electromyography (EMG) monitoring. Our results support the theory that a DNFFV provokes ipsilateral HFS via the facial nerve nucleus. KEY WORDS: Facial nerve nucleus, Hemifacial seizure, Dysplastic neuronal lesion, Floor of the fourth ventricle.There are several reports of hemifacial seizures (HFS) caused by dysplastic neuronal lesions of the floor of the fourth ventricle (DNFFV). Delalande et al. (2001) described theta or beta rhythmic activity in the DNFFV using a depth electrode inserted during surgery. However, there have been no reports elucidating a direct correlation between DNFFV and HFS or explaining the possible pathophysiology of a relationship between DNFFV and HFS. In this study, we sought to assess the pathophysiology of DNFFV and HFS by real-time monitoring of HFS during surgery. Case ReportThe patient was a 20-month-old boy who was born without perinatal problems. However, he had seizures with motion arrest and right eyelid contraction soon after birth. At 3 months of age, brain magnetic resonance imaging (MRI) demonstrated a mass lesion on the right side of the floor of the fourth ventricle, which showed isointensity to gray matter in both the T 1 -and T 2 -weighted images and was not enhanced by gadolinium injection. From 4 months of age, his seizures changed to intermittent closure of the right eye and right perioral contraction. Although the patient's psychomotor development was normal in infancy, he could not walk alone at 20 months. His seizures increased gradually and by 20 months of age were occurring every day at almost 20-s intervals while he was both awake and asleep.He underwent tumor resection at 20 months of age. An MRI study obtained for preoperative evaluation revealed a mass lesion the same as at 3 months of age (Fig. 1A). Written informed consent was obtained for intraoperative monitoring before the operation. Needle electrodes were inserted into the right upper and lower eyelids and the right orbicular muscle of the mouth to detect the hemifacial seizures during surgery. A muscle relaxant was not used. Sheet electrodes with 20 contacts were used for evaluating cerebellar cortices, and a strip electrode with four contacts was used within the fourth ventricle.During the surgery, although the sheet electrodes on the bilateral cerebellar cortices did not show any ictal findings related with eyelid twitching, the strip electrode on the tumor demonstrated rhythmic theta waves during eyelid twitching corresponding to electromyography (EMG) (Fig. 1B,C). At the moment of biopsy resection, aberrant EMG occurred with wild eyelid twitching, and then the patient's seizure disappeared soon after appro...