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Insular Low-Grade Glioma: Principles of Resection

December 01, 2015

Transcript

This video is an excellent demonstration of techniques for resection of non-dominant insular gliomas. I use the awake craniotomy technique for removal of dominant or non-dominant select tumors. The reason I use the awake craniotomy for non-dominant tumors is the fact that subcortical mapping can be performed more reliably and secondly, frequent interoperative, neurological examinations provide immediate feedback regarding the neurological status of the patient and provide certain level of confidence to the surgeon to be aggressive regarding the resection of the tumor. This is a 32 year-old male who presented with a single seizure on MRI evaluation, was diagnosed with a large insular, low grade glioma, primarily centered, or the insula and extending into the temporal lobe. The frontal extension of this tumor is relatively small. So this is primarily a temporal insular glioma. Let's review the basic principles for an awake craniotomy. I use local anesthetic for both the pin sites and incision. In addition, regional scalp, anesthesia is quite effective. In other words, this supra trochlear, super orbital nerves, temporal nerves and the occipital nerves are also anesthetized. The location of the pin sites on the scalp are next marked and generously injected as well. Here's the marking, based on the distance between the pin sites, here's the configuration for the skull clamp, so that a generous area is available for it, large craniotomy. Head positioning should be comfortable for the patient allowing easy swallowing, avoiding any neck discomfort. Neuro navigation is used and a generous curvilinear scalp incision is in order. Here's the techniques for draping, this method of draping allows immediate interaction between the surgeon and the patient while providing sterility. Next, I create the burr hole after the scalp flap is reflected along with a temporal Rasmussen in one layer, the burr hole is injected with local anesthetic so that the epidural space is irrigated with a local anesthetic and some level of anesthesia and pain control is provided during elevation of the bone frap and stripping of the dura. The stripping of the dura can be specially uncomfortable to the patient. Cautious edition is used doing performance of the craniotomy and initial stages of the operation, including in this case, temporal lobectomy. The speed of the operation has slightly increased just for this part of the procedure, a standard anteromedial temporal lobectomy is performed. Removal of this portion of the temporal lobe provides a nice operative trajectory into the insula and removal of the insular portion of the tumor next. Here's the completion of the anteromedial temporal resection. The medial structures are also removed, since this tumor is on the non-dominant side. The edge of the tentorium is apparent. Third nerve would be located about here. Now I use the working channels between the M two and M three branches to remove the tumor within the insula, the anterior temporal artery was sacrificed since an intermediate temporal lobectomy was completed. You can see the M two trunks, Small court economy along the anterior aspect of inferior frontal gyrus provides additional operative trajectory toward the insula. Now you can see these working channels that I'm developing between the M two branches in order to remove the tumor within the insula. These working channels are further expanded. The gelatinous tumor is aggressively removed, and the bipolar forceps provide a nice instrument to emulsify the mass and remove the tumor. Next, you can see that some of the M two branches are tethering the frontal lobe preventing further resection along the superior pole of the tumor. The working channels between the M two branches are expanded. Additional tumor is removed, towards the superior and posterior aspect of the insula further tumor removal is not easily possible due to the tethering effect of the M two branches. Dynamic retraction provides some additional space to remove the superior insular part of the tumor. The trans insular trajectory provides a relatively limited access to superior pole of the tumor. Therefore, the face area and the motor cortex is mapped as you can see here, sub-cortical mapping may also be used After the face area is identified, I proceed with further expansion of the inferior frontal gyrus cortical resection, so that more of the tumor in this superior insula can be removed. Subsequently the lateral lenticular stride arteries will be apparent along the depth of the resection cavity. These arteries, they find the most medial plaintiff resection, here you can see these lateral lenticular steroid arteries. They should be carefully protected in order to avoid the risk of hemiparesis after the procedure. Sub-cortical mapping is also used at this juncture, especially for resection of the posterior insular part of the mass around the ear of the internal capsule. Any bleeding is managed via irrigation and gentle temporal node, not aggressive, quiet delusion prohibited. Postoperative MRI in this patient demonstrates excellent removal of the tumor and this patient recovered from his surgery uneventfully and has remained seizure-free, thank you.

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