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Large Dominant Frontal Glioma: Awake Mapping Techniques

March 10, 2016

Transcript

This video reviews resection of a posterior frontal glioma in the dominant hemisphere. And, at the same time, reviews the methods for motor and speech mapping. This is a young patient with a single seizure. MR evaluation revealed a non-enhancing mass within the left posterior frontal lobe. You can see this mass is relatively large. Most likely associated with the Broca's area and, nearby, the motor cortex. Mapping of the central lobule, Wernicke's, and Broca's areas seemed appropriate. Let's go ahead and review the basics of an awake craniotomy. Local scalp anesthesia, to the supraorbital and supratrochlear nerves. The skull clamp is placed with a single pin behind the left ear ipsilaterally, so that this single pin does not interfere with the large scalp incision. Obviously, these pin sites are well injected. The head is fixated in a relatively comfortable position for the patient, so she can swallow. And her neck is not in a non-physiological position. Navigation is used. A generous curvilinear incision is mapped and well injected with a local anesthetic. Draping is conducted. This form of draping allows communication between the surgeon and the patient. While maintaining the sterility of the operative field, the dura is also injected and bathed in the local anesthetic for patient comfort. Generous craniotomy is completed. A strip electrode is passed for electrocorticography. Let's go in and start with mapping the face.

- Go ahead, go ahead.

- Ready? On. Off.

- Yep.

- You saw the twitching on the right side of the face. Here's marking for the face area. Let's go ahead and map the hand. You can see the twitching in the hand. Here's the hand area.

- 11, 12, 13, 14, 15, 16, 17, 18, n, n, n...

- That's face.

- 21, 22, 23, 24, 25, 26, 27, 28, 29...

- It just looks like we need a higher discharge.

- 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16...

So you can see that during the first series of stimulations, the face was also affected. So, not only the Broca's area, but also the face area may have been stimulated. However, in the subsequent stimulations, only the motor speech was affected, better defining the boundaries of the Broca's area. Let's go ahead and map the Wernicke's cortex.

- Say it again for me.

- The monkey swung in the tree.

- That's all right.

- The family brought a new house.

- Okay, go ahead.

- The girls took a vacation on a boat.

- See that? She can read. So she can read.

- The woman talked on,n,n, on the phone. The fireman climbed the ladder.

- That was more space, see, she just got a pic. Go ahead.

- The boy played the game for...

- I--

So, as you can see, during some of the stimulation episodes, the patient had trouble reading as well as naming. That is not an accurate stimulation map. In other words, the patient should continue to be able to read but unable to name, for the surgeon to be able to map the Wernicke's area accurately. Here is the final map of the brain, in relation to the boundaries of the tumor that are marked with a black suture. I started disconnection of the tumor from the surrounding normal brain by coagulating the pia at the perimeter of the tumor. Following the bulking of the central portion of the tumor, the surrounding affected brain was also removed. Tumor was relatively grayish, discolored, and different from the normal white or yellow glistening pre-tumoral areas. Here, you can see a relatively normal-appearing white matter. Additional pieces of the tumor at the depth of the cavity were removed. Continuous intraoperative neurological monitoring was performed during tumor resection. Post-operative MRI evaluation revealed relatively gross, total removal of the mass, and this patient did not suffer from any neurological deficits postoperatively. Thank you.

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