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Parietal Glioma: Subcortical Mapping

January 21, 2016


Let's review an interesting case of a parietal glioma infiltrating their central labial and the use of mapping strategies to allow a subtotal but aggressive safe removal of the tumor. This procedure also demonstrates the use of subcortical mapping. This is a 42 year old male who underwent an open biopsy in an outside institution and was noted to suffer from an anaplastic oligoastrocytoma. You can see the location of the tumor most likely infiltrating the sensory cortex. There is having some nodular enhancement. The tumor extends all the way to the area of the atrium. Functional imaging confirmed my suspicion. The tumor does invade this sensory cortex and even part of the motor cortex. I felt that more than 70 or 80% of the tumor can be safely resected and this procedure can potentially benefit the patient. In a week, craniotomy was performed since I felt that we'll be essentially resecting up to the level of the sensory cortex and therefore frequent intra-operative examinations of the motor and sensory cortices are critical for guiding our resection. The initial incision was performed via a linear incision. I therefore extended the linear incision in a form of an S incision to be able to widely expose the functional cortices and the regions well beyond the tumor. This is the previous small craniotomy for the biopsy that was performed elsewhere. You can see that lateral position can be used for an awake craniotomy with a patient relatively comfortable. Suture defines the borders of the tumor. Here's the previous area of the biopsy. I suspect this part to be the motor cortex. Let's go ahead and map the motor cortex, starting with the face area, and then subsequently the hand area. Here's the hand area. Let's go ahead and mark the face and hand areas. Therefore, this is the sensory cortex. Again, the foot of the patient is in this direction. This is the top of the patient here. So I continued the process of resection while preserving the sensory cortex, but extended my resection exactly up to the level of the sensory cortex. Frequent intraoperative neurological examinations gave me enough confidence to continue my aggressive resection just up to the level of the functional cortex rather leaving a margin of safety. Here you can see coming all the way to the level of the sensory cortex. Subcortical mapping was used as you see in a moment with motor activity in the lower extremity, obviously guiding the extent of resection. Here is the subcortical mapping. You can see that interior part of the resection cavity was stimulated and the leg area demonstrated motor activity. Post operative MRI demonstrates reasonable resection of the tumor. There is definitely some tumor infiltration within the central labial. This patient did have some sensory dysfunction that developed about a day after the procedure. However, this dysfunction resolved within a month after the surgery. Also, there was some evidence of proprioceptive deficits that also improved within six weeks after the surgery and the patient returned to his previous activities. Thank you.

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