Awake Mapping for Peri-Central Lobule Gliomas
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Let's talk about awake cortical stimulation mapping for resection of a peri-central lobule glioma. This is a young patient who presented with a motor seizure on the right side and on MRI evaluation was found to have a low grade glioma just behind their central lobule. Based on anatomical localization as you can see on the MRI, this is the central sulcus and on the affected side the tumor essentially is right behind the sensory cortex. The location of the tumor or satchel images is better demonstrate on the right side. I prefer to perform resection of tumors that are very intimate with a central lobule under awake conditions. The awake conditions provide an excellent opportunity for reliable intraoperative mapping and immediate feedback of the patient regarding his neurological status. Functional MRI demonstrated the central lobule located just anterior to the most interior margin of the tumor and motor fibers as expected were located just medial to the apex of the lesion. And awake mapping was performed. You can see the incision that is very generous so that the normal central lobule can be adequately mapped. Location of the head and the use of navigation is standard. I use navigation initially before any mapping is performed and also use a piece of suture or cottontail to outline the location of tumor over the cortex. Next cortical mapping of the sensory model cortices was performed. Here's the ORM area. You can see on the right lower quadrant. The movement of the arm, finger and the face area were adequately mapped. Super stimulation over the area of the tumor did not reveal any function. Additional detailed mapping just along the anterior aspect of the tumor was conducted. The ear is over on this side for orientation of our viewers. This is the temporalis muscle that's reflected inferiorly. Portion of the finger area overlaps with the tumor. I'm going to leave a strip of normal cortex between my corticotomy and the functional areas. Therefore, the initial corticotomy has performed slightly more posteriorly and undermining of the normal cortex is conducted to protect as much of the normal cortex in the periphery of the functional areas for the thumb and the finger regions. The initial sapial disseption is extended more deeply and grayish soft tumor was encountered. The corticotomy was extended more posteriorly. Essentially a directomy was conducted so that additional working space and tumor exposure are available for gross total resection of the mass. The tumorous quite rubbery ring can be used for resection of a tumor piecemeal. Here's more of a normal whitish color of the white matter. You can appreciate the different color between the grayish tumor and glistening white, normal white matter. Navigation continues to guide the extent of resection in this area. Here's the tumor that is quite evident. I emulsify the tumor between the tips of their bipolar forceps and use the suction to evacuate the motorized tumor. Some of the bands between the GRI are dissected. Continuous intra-operative neurological examination are performed to examine the status of the patient. Now the undermining of the normal cortex is performed while preserving the embersite vessels to evacuate additional portion of the tumor. As we get close to the functional cortices, subcortical mapping is employed. I increased the threshold of mapping onto cortex that led to motor movements by 1 to 2 milliamps and use this new threshold to conduct subcortical mapping. Here is more of the normal white matter areas that are evident. I work between the vessels to remove as much of the abnormal tissue as possible. Some of it discolored tissue along the larger of the resection cavity is also evacuated. Now subcortical stimulation mapping is used to guide the rest of resection. In this patient 5 milliamps led to cortical mapping and I used 7 milliamps for subcortical mapping. No model movement was noted upon subcortical mapping and therefore additional resection in layers was continued until as you can see subcortical mapping led to movements of the right upper extremity in the anterior inferior aspect of the resection cavity. Further into removal was only director to the most superior areas of their resection field. Here's the final product. Post operative MRI demonstrates a radical subtotal resection of the mass. There is questionable man of very faint T2 signal changes within the model cortex. It obviously should be left behind to avoid any neurological morbidity. This patient recovered from surgery without any new deficits and has since remained seizure-free. Thank you.
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