Cerebral motor control in patients with gliomas around the central sulcus studied with spatially filtered magnetoencephalography

Abstract

Objective: Application of spatially filtered magnetoencephalography (MEG) to investigate changes in the mechanism of cerebral motor control in patients with tumours around the central sulcus. Methods: MEG records were made during a repetitive hand grasping task in six patients with gliomas around the central sulcus and in four control subjects. Power decreases in the a (8-13 Hz), b (13-30 Hz), and low c bands (30-50 Hz) during the motor tasks (event related desynchronisation, ERD) were analysed statistically with synthetic aperture magnetometry. The tomography of ERD was superimposed on the individual's magnetic resonance image. Results: b ERD was consistently localised to the contralateral primary sensorimotor cortex (MI/SI) in control subjects, whereas the a and low c ERD showed considerable intersubject variability. b ERD in patients during non-affected side hand movement was also localised to the contralateral MI/SI, but exclusively to the ipsilateral hemisphere during affected side hand movement. Conclusions: The altered pattern of ERD in the patient group during affected side hand movement suggests recruitment of diverse motor areas, especially the ipsilateral MI/SI, which may be required for the effective movement of the affected hand.

Ipsilateral Motor-Related Hyperactivity in Patients With Cerebral Occlusive Vascular Disease

“…12,17 It has been proposed recently that this activity has a hyperactive component attributable, in some cases, to interhemispheric disinhibition. 18,19 Our results that show characteristic ipsilateral distribution of ␤ERD during grasping with the contralesional hand, a significantly increased activity in the ipsilateral hemisphere without a decrease on the side of the vascular lesion, and a "normal" behavior in the tapping task indicate that hyperactivity on the ipsilateral hemisphere seen in patients with vascular lesions but without motor impairment is not compensatory.…”

“…11,12 The working hand was supinated while the resting hand was pronated and placed on an arm rest. The data for each trial were collected relative to the trigger (sound cue or time "0") for 20 seconds and consisted of 2 periods: the "control" state in the time window Ϫ10 to 0 seconds, in which the patient remained still, and the "active" state in the time window 0 to ϩ10 seconds, which involved grasp and release movements ( Figure 1A).…”

“…For all measurements, fiducial skin markers were placed on the patient's nasion and at bilateral preauricular points to establish common coordinate systems for MR images and MEG. 9,[11][12][13] This MEG protocol was approved by the ethics committee of the Osaka University Hospital. Informed consent for MEG recording was obtained from all patients and control subjects.…”

Motor field sensitivity for preoperative localization of motor cortex

“…18,23 Recently, spatially filtered MEG was performed to explore functional activation of areas important in motor control around the central sulcus. 27 In that study, MEG data were analyzed using synthetic aperture magnetometry to determine power changes in various frequency bands (event-related desynchronization). Beta event-related desynchronization was shown to localize to the contralateral sensorimotor cortex in control volunteers, whereas activation localized to the ipsilateral hemisphere of the affected hand in patients with tumors, suggesting that this paradigm may be useful in identifying not only regions of residually active cortex in the contralateral hemisphere, but also compensatory regions recruited in the ipsilateral hemisphere.…”

“…In previous MEG-based studies of preoperative localization, investigators have used similar magnetometers with sensor arrays containing from 37 to 204 channels. 1,[3][4][5][6]19,22,24,25,27 Newer models such as whole-head MEG systems combined with advanced analysis methods provide a higher spatial sampling density, which may improve the accuracy of source localization beyond dipole fitting. Nonetheless, the motor cortex in the present study was adequately covered with a high density of sensors.…”