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  • The Circular Grid: 360o Electrocorticography Monitoring During Awake Brain Surgery

    Final Number:

    Karim ReFaey; Tito G.M. Vivas-Buitrago MD; Kaisorn L. Chaichana; Anteneh M. Feyissa M.D.; William Tatum DO; Alfredo Quinones-Hinoja MD

    Study Design:

    Subject Category:

    Meeting: Congress of Neurological Surgeons 2018 Annual Meeting

    Introduction: The present study describes a novel device and techniques for intracranial monitoring of cortical electrical activity during awake brain surgery. This novel device is a ring-shaped cortical electrode (the circular grid) that allows for 360 degrees cortical monitoring.

    Methods: We prospectively collected the intraoperative electrocorticography (ECoG) data in seven patients who presented with seizures and who underwent an awake craniotomy with intraoperative ECoG recording using the circular grid and validating its efficacy with the conventionally-used high-density grid (HD-Grid).

    Results: High-frequency oscillations (HFOs) and periodic-focal-epileptiform-discharges (PFEDs) were observed using the circular grid in two and five patients, respectively. These findings were validated with the HD-Grid with the exception of one patient in which HFOs were initially identified with the circular. Gross total resection was achieved in all of the patients except in one patient due to tumor infiltration to the motor strip. There were no cases with intraoperative seizures. No worsening of neurological deficits was identified. All patients were seizure-free by the time of last follow up (mean 2.6 months).

    Conclusions: The circular grid was effective in monitoring cortical electrical activity during awake brain mapping and allowed early detection of cortical electrical signals, e.g., afterdischarges (ADs), HFOs, and PFEDs

    Patient Care: During the cortical mapping craniotomies, the existing electrocorticography (ECoG) electrodes is used for continuous monitoring during cortical stimulations and identification of after-discharge (AD) activity, which can occur after direct cortical electrical stimulation and serve as a surrogate for an impending seizure. Intraoperative seizures can limit the use of further stimulation and interfere with perioperative brain mapping and neurological assessment. The existing ECoG devices only allow monitoring in one direction (i.e. superior) unless multiple are placed, and the grid ECoG makes it challenging to operate in the desired area since it covers the entire surgical field. Hence, we devised an ECoG device that allows surgical resection to take place simultaneously while recording the cortical electrical activity. In this study, our proposed describe will allow intracranial monitoring of electrical activity of the brain using a ring-shaped cortical electrode that allows a continuous 360-degree recording during surgical resection. This will allow early detection of intraoperative seizure activities and improve postoperative outcomes.

    Learning Objectives: 1. The circular grid’s unique spatial design allows intracranial electrical activity monitoring in a 360o degrees fashion with direct visual and surgical access to the desired brain areas. 2. The circular grid is reliable for monitoring intraoperative ECoG and recording of electrical signals during awake craniotomies, e.g., ADs, HFOs, and PFEDs. 3. The Circular grid permits safe surgical resection while recording of the brain electrical signals which allows early detection seizure detection during awake craniotomies.

    References: 1. M. S. Berger, J. Kincaid, G. A. Ojemann, E. Lettich, Brain mapping techniques to maximize resection, safety, and seizure control in children with brain tumors. Neurosurgery 25, 786-792 (1989). 2. M. S. Berger, G. A. Ojemann, Intraoperative brain mapping techniques in neuro-oncology. Stereotact Funct Neurosurg 58, 153-161 (1992). 3. C. I. Eseonu et al., Awake Craniotomy vs Craniotomy Under General Anesthesia for Perirolandic Gliomas: Evaluating Perioperative Complications and Extent of Resection. Neurosurgery, (2017). 4. W. J. Marks, in In Aminoff's Electrodiagnosis in Clinical Neurology (Sixth Edition), L. Saunders, Ed. (2012), chap. Chapter 7 - Invasive Clinical Neurophysiology in Epilepsy and Movement Disorders. 5. K. R. Norma Arechiga, Jordina Rincon-Torroella, Kaisorn L. Chaichana, Alfredo Quiñones-Hinojosa, Video Atlas of Neurosurgery: Contemporary Tumor and Skull Base Surgery. Cortical/Subcortical Motor Mapping for Gliomas. (Elsevier Philadelphia, 2016), vol. 1. 6. A. N. Almeida, V. Martinez, W. Feindel, The first case of invasive EEG monitoring for the surgical treatment of epilepsy: historical significance and context. Epilepsia 46, 1082-1085 (2005). 7. C. I. Eseonu, K. ReFaey, O. Garcia, G. Raghuraman, A. Quinones-Hinojosa, Volumetric Analysis of Extent of Resection, Survival, and Surgical Outcomes for Insular Gliomas. World Neurosurg 103, 265-274 (2017). 8. M. S. Berger, G. A. Ojemann, E. Lettich, Neurophysiological monitoring during astrocytoma surgery. Neurosurg Clin N Am 1, 65-80 (1990). 9. M. S. Berger, Functional mapping-guided resection of low-grade gliomas. Clin Neurosurg 42, 437-452 (1995). 10. E. Formaggio et al., Frequency and time-frequency analysis of intraoperative ECoG during awake brain stimulation. Front Neuroeng 6, 1 (2013). 11. C. I. Eseonu et al., Intraoperative Seizures in Awake Craniotomy for Perirolandic Glioma Resections That Undergo Cortical Mapping. J Neurol Surg A Cent Eur Neurosurg, (2018).

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