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Posterior Frontal Glioma: White Matter Dissection

October 28, 2019


This video describes resection of an Inferior Posterior Frontal Glioma on the non-dominant hemisphere. This is rather a rare location for a glioma, very close to the somatosensory and modal cortices, but inferior to it. And therefore, I would like to review strategies for resection of this tumor type while doing sleep mapping. This is a 50 year-old female who presented with a generalized seizure. MRI evaluation revealed the location of the tumor as I described. You can see evidence of nodular enhancement within the center of the tumor. Also, the tumor is essentially hugging the posterior aspect of the Sylvian fissure and atomically located inferior to the motor and somatosensory cortices. Before we proceed with resection, let's go ahead and get a functional MRI. You can see again, the modal cortex resides just above the tumor as expected, and here's this somatosensory sensory cortex just behind the tumor border. Here's the positioning for the patient. You can see the use of a horseshoe incision just above the ear and a single pin placed ipsilaterally. This configuration of skull clamp placement provides ample amount of space without necessarily interfering with the operative space. Again, sleep mapping was conducted for motor and somatosensory functions. Here, you can see the tumor has been delineated using a piece of suture. Before I start resection, I used supra threshold parameters to stimulate the cortex of the tumor, I did not elicit any functions. This means that I increased the parameter of stimulation just enough to cause, after discharged and then went ahead and decreased it slightly so I can stimulate the cortex just below the after discharge threshold. This is called Negative Mapping Technique. Since no function was detected, I proceeded with the resection. Initially tried to protect as envisaged arteries as I can and created peeling incisions between the vessels. Here, you can see the technique of white matter dissection using the bipolar forceps as scissors, while transecting the edges of the tumor from the surrounding white matter tracks. Obviously neuronavigation was used. Initially, I attempted to preserve as many of the vessels as I can. Then using the bipolar forceps and the spring action like scissors while the bipolar is on to emulsify the tumor white matter interface. Here, you can see the white matter, here we can see the rubbery feel of the tumor and its discoloration. And some of the envisaged vessels were protected as I wasn't sure if some of these are not leading to the functional cortices. And some of the deep vessels were protected as well. Here, you can see further dissection of the tumor at its base, creating incisions as necessary to remove the white matter and affected regions of the brain and cortices by the tumor while preserving this avascular structures. Some of the vessels didn't appear to be patent. At some point during the operations and those vessels were sacrificed. I can see this deep vessel was protected. Again, inspecting the edges of the resection cavity, make sure everything appears clean. I can see this vessel was preserved. This was leading to the motor and somatosensory cortices. Some of the rubbery material at the depth of the resection cavity was also removed. Propylene soak gel form may be used to bathe the vessels intermittently to relieve their vasospasm. I can see the very, brilliant, clear margins that assure me that the tumor has been removed in cholesterol fashion Here's the final product. The envisaged vessels are protected. Propylene is used. And the postoperative MRI revealed gross total resection of the tumor and this patient made their recovery without any complicating features. Thank you.

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