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Premotor Glioma: Resection Strategies

January 11, 2016


I prefer the use of awake cortical stimulation mapping for removal of gliomas in close proximity of the sensory motor cortex. Although the similar technique under anesthesia can be quite effective, I believe the reliability of cortical and subcortical mapping in an awake patient is superior than those under anesthesia. Therefore, if the tumor is very intimately associated with the sensory motor cortex, I prefer the use of awake cortical mapping. This is a 42-year-old female with a seizure who underwent stereotactic biopsy of her tumor elsewhere. The final pathology was consistent with a Grade 3 astrocytoma. You can see the location of the tumor. Partially cystic, intimately associated with the motor cortex. The central sulcus is anatomically located here. Similarly, on the sagittal images, you can see the marginal sulcus and sensory motor cortex, just anterior to that sulcus and the location of the tumor immediately anterior to the central labial. Patient was placed in a supine position. Awake techniques were used. You can see the incision. The previous stereotactic biopsy was performed in an outside institution via a linear incision here and a small craniotomy. The location of the superior sagittal sinus is also marked. The incision crosses the midline slightly. Here is the midline. The sinus has been gently immobilized. This is the location of the previous biopsy, and here is the margins of the tumor marked using neuronavigation. I guess, estimate, that this should be the motor cortex, and I'll go ahead and confirm the identity of this cortex using cortical stimulation mapping. The threshold of a mapping is used later for subcortical mapping. I usually increase the cortical mapping threshold by one to two milliamps and use that parameter for subcortical mapping. Standard techniques are used to remove the tumor. You can see the interhemispheric corridor. Sub-pial resection is conducted, further, deeper, within the interhemispheric space, to avoid any injury to pericallosal arteries. The bipolar forceps emulsify the tumor while the suction device removes it. An attempt is made to remove the tumor en bloc. You can see I use bipolar forceps to emulsify the tumor. That often has a different texture than normal brain. You can see the color of the tumor along the posterior aspect of the resection cavity. Here is the sub-pial resection to protect the pericallosal arteries. Here's the ventricular space that was entered at the end of our resection cavity where the portion of the callosum affected by the tumor was removed. The ventricle was covered to achieve hemostasis and avoid bleeding into the ventricle. Here's the final resection cavity. Subcortical mapping was used along the posterior aspect of the resection cavity to avoid any injury to any descending motor fiber tracts. Post-operative MRI demonstrates reasonable resection of the tumor. This patient did suffer from supplementary motor association cortex syndrome immediately after surgery. However, her deficits resolved within two weeks after the surgery and she remains neurologically intact. Thank you.

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