Seizure detection using intracranial electroencephalography (iEEG) contributes to improved treatment of patients with refractory epilepsy. For that purpose, a feature of iEEG to characterize the ...ictal state with high specificity and sensitivity is necessary. We evaluated the use of phase-amplitude coupling (PAC) of iEEG signals over a period of 24 h to detect the ictal and interictal states. PAC was estimated by using a synchronisation index (SI) for iEEG signals from seven patients with refractory temporal lobe epilepsy. iEEG signals of the ictal state was characterised by a strong PAC between the phase of β and the amplitude of high γ. Furthermore, using SI values, the ictal state was successfully detected with significantly higher accuracy than by using the amplitude of high γ alone. In conclusion, PAC accurately distinguished the ictal state from the interictal state.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Maximum safe resection of infiltrative brain tumors in eloquent area is the primary objective in surgical neuro-oncology. This goal can be achieved with direct electrical stimulation (DES) to perform ...a functional mapping of the brain in patients awake intraoperatively. When awake surgery is not possible, we propose a pipeline procedure that combines advanced techniques aiming at performing a dissection that respects the anatomo-functional connectivity of the peritumoral region. This procedure can benefit from intraoperative monitoring with computerized tomography scan (iCT-scan) and brain shift correction. Associated with this intraoperative monitoring, the additional value of preoperative investigation combining brain mapping by navigated transcranial magnetic stimulation (nTMS) with various neuroimaging modalities (tractography and resting state functional MRI) has not yet been reported.
A 42-year-old left-handed man had increased intracranial pressure (IICP), left hand muscle deficit, and dysarthria, related to an infiltrative tumor of the right frontal lobe with large mass effect and circumscribed contrast enhancement in motor and premotor cortical areas. Spectroscopy profile and intratumoral calcifications on CT-scan suggested an WHO grade III glioma, later confirmed by histology. The aforementioned surgical procedure was considered, since standard awake surgery was not appropriate for this patient. In preoperative time, nTMS mapping of motor function (deltoid, first interosseous, and tibialis anterior muscles) was performed, combined with magnetic resonance imaging (MRI)-based tractography reconstruction of 6 neural tracts (arcuate, corticospinal, inferior fronto-occipital, uncinate and superior and inferior longitudinal fasciculi) and resting-state functional MRI connectivity (rs-fMRI) of sensorimotor and language networks. In intraoperative time, DES mapping was performed with motor evoked response recording and tumor resection was optimized using non-rigid image transformation of the preoperative data (nTMS, tractography, and rs-fMRI) to iCT data. Image guidance was updated with correction for brain shift and tissue deformation using biomechanical modeling taking into account brain elastic properties. This correction was done at crucial surgical steps, i.e., when tumor bulged through the craniotomy after dura mater opening and when approaching the presumed eloquent brain regions. This procedure allowed a total resection of the tumor region with contrast enhancement as well as a complete regression of IICP and dysarthria. Hand paresis remained stable with no additional deficit. Postoperative nTMS mapping confirmed the good functional outcome.
This case report and technical note highlights the value of preoperative functional evaluation by nTMS updated intraoperatively with correction of brain deformation by iCT. This multimodal approach may become the optimized technique of reference for patients with brain tumors in eloquent areas that are unsuitable for awake brain surgery.
Electrical stimulation of the primary somatosensory cortex using intracranial electrodes is crucial for the evocation of artificial somatosensations, typically tactile sensations associated with ...specific regions of the body, in brain-machine interface applications. The qualitative characteristics of these artificially evoked somatosensations has been well documented. As of yet, however, the quantitative aspects of these evoked somatosensations, that is to say the quantitative relationship between intensity of electrical stimulation and perceived intensity of the resultant somatosensation remains obscure. This study aimed to explore this quantitative relationship by surface electrical stimulation of the primary somatosensory cortex in two human participants undergoing electrocorticographic monitoring prior to surgical treatment of intractable epilepsy. Electrocorticogram electrodes on the primary somatosensory cortical surface were stimulated with varying current intensities, and a visual analogue scale was employed to provide a quantitative measure of intensity of the evoked sensations. Evoked sensations included those of the thumb, tongue, and hand. A clear linear relationship between current intensity and perceived intensity of sensation was observed. These findings provide novel insight into the quantitative nature of primary somatosensory cortex electrical stimulation-evoked sensation for development of somatosensory neuroprosthetics for clinical use.
Brain function analysis from a physiological point of view, especially brain network analysis, is progressing rapidly and this progress is expected to result in the elucidation of the brain network ...and in overcoming neurological diseases. Furthermore, analysis of the brain information processing mechanism itself is also applicable to machine learning and artificial intelligence. A large amount of funding is invested in this field with new research projects springing up all over the world. In this paper, we outline the brain network and introduce our recent research concerning idiopathic normal pressure hydrocephalus and temporal lobe epilepsy.
Objective: Debranching thoracic endovascular aortic repair (TEVAR), in which endovascular stent-grafting with cervical vascular reconstruction for aortic aneurysm arch lesion is increasing, and these ...cases have difficulties in access during neuroendovascular treatment. In this study, we investigated the selection of appropriate access route according to the methods of debranching TEVAR during neuroendovascular treatment.Methods: We examined a zone classification of aortic lesion, the number of debranch, and vascular reconstruction techniques of debranching TEVAR and assessed an optimal access route for each debranching TEVAR reconstruction method.Results: Four patients underwent neuroendovascular treatment after debranching TEVAR. Aortic lesion of each patient located in zone 0 in 1 patient, zone 1 in 2 patients, and was unclassifiable in 1 patient. Total debranching was performed in 1 case, 2 cases of 2-debranching, and 1 case of 1-debranching with chimney reconstruction. The pathologies treated included 1 unruptured basilar artery aneurysm, 1 direct carotid cavernous fistula, 1 subclavian artery aneurysm, and 1 acute basilar artery occlusion.The access routes selected were the brachial artery approach in 3 cases and direct puncture of right common carotid artery in 1 case. Optimal access route selection for each method of debranching TEVAR resulted in no complications associated with the access route and technical success in all cases.Conclusion: With the expansion of indications for debranching TEVAR, opportunities for neuroendovascular treatment of these patients will increase. Physicians need to be aware of the problems of access routes for neuroendovascular treatment in patients with debranching TEVAR.
Objective: Debranching thoracic endovascular aortic repair (TEVAR), in which endovascular stent-grafting with cervical vascular reconstruction for aortic aneurysm arch lesion is increasing, and these ...cases have difficulties in access during neuroendovascular treatment. In this study, we investigated the selection of appropriate access route according to the methods of debranching TEVAR during neuroendovascular treatment.Methods: We examined a zone classification of aortic lesion, the number of debranch, and vascular reconstruction techniques of debranching TEVAR and assessed an optimal access route for each debranching TEVAR reconstruction method.Results: Four patients underwent neuroendovascular treatment after debranching TEVAR. Aortic lesion of each patient located in zone 0 in 1 patient, zone 1 in 2 patients, and was unclassifiable in 1 patient. Total debranching was performed in 1 case, 2 cases of 2-debranching, and 1 case of 1-debranching with chimney reconstruction. The pathologies treated included 1 unruptured basilar artery aneurysm, 1 direct carotid cavernous fistula, 1 subclavian artery aneurysm, and 1 acute basilar artery occlusion.The access routes selected were the brachial artery approach in 3 cases and direct puncture of right common carotid artery in 1 case. Optimal access route selection for each method of debranching TEVAR resulted in no complications associated with the access route and technical success in all cases.Conclusion: With the expansion of indications for debranching TEVAR, opportunities for neuroendovascular treatment of these patients will increase. Physicians need to be aware of the problems of access routes for neuroendovascular treatment in patients with debranching TEVAR.
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