January 11, 2016
Insular tumors can have predominantly temporal or frontal extensions. In this case, I'm reviewing the case of a young lady who presented with seizures and was diagnosed with primarily a temporal tumor extending into the insular. As you can see on these MRI sequences, the tumor's relatively large, affects most of the temporal lobe and the medial structures with a portion of the brain herniating across the tentorium and the incisura. The tumor does not have any significant amount of enhancement. And again, extents into the insular and displaces the thalamus in the medial striatum. There is section was conducted via a right frontotemporal craniotomy. Before we proceed with the review of the events, in the operation I would like to review the principles for removal of the tumors, adjacent to the medial structures in patients who suffer from epilepsy. The principle decision-making process depends on the location of a dominant hippocampus. Most of the patients are right-handed and therefore the left hippocampus is dominant. For tumors that are contained or confined within the lateral temporal lobe neocortex and come in close proximity of the non-dominant hippocampus and also lead to seizures, I remove both the tumor and the non-affected hippocampus. In this patient, both the hippocampus and the lateral temporal lobe is affected. And therefore, both structures will removed, however, in the patient whose tumor ends just about here, and the hippocampus is unaffected the tumor, and the non-affected hippocampus will be removed. This decision-making process is different if the dominant hippocampus involved in verbal memory is involved, or the tumor comes in close proximity of the dominant hippocampus. If the tumor is non-contiguous with a dominant hippocampus, but comes in a very close proximity of the hippocampus, I only remove the tumor, but preserve the dominant hippocampus. For those tumors that affect and infiltrate the dominant hippocampus, preoperative neuropsychological evaluation determines if resection of the dominant hippocampus is indicated. If the patient does not suffer from any dysfunction in his/her verbal memory, removal of the dominant hippocampus is cautioned, as this procedure can lead to disabling, dysfunction in memory. Let's go ahead and discuss the newest of technique for removal of this large tumor, obviously the effect in your cortex will be removed up to the poster end of the latter aspect of the tumor and an anterior to posterior trajectory will be utilized to be able to remove the tumor and obviously enter the ventricle. Entering the ventricle, defines the margins, and the board is of resection and orients the surgeon regarding achieving adequate resection posteriorly. So the extent of resection more medially is guided by obviously the peel membranes over the Sylvian fissure and potentially some of the medial and lateral lenticular straight arteries. The extent of resection in fairly is guided by the peel membranes over the basal cisterns and the PCA, as well as the third nerve. Neuro navigation obviously assists with all the steps of the operation. Here's patient positioning and incision. The exposure is primarily temporal and not frontal. You can see the Sylvian fissure, the anterior temporal lobe. expanded. Anter temporal vein is compromised, but the vein of Libya is obviously protected. This is about four centimeter from the temporal tip and lateral temporal neocortical resection is conducted in standard fashion. They made a fossa flores identified early. Part of the tumor is removed in the process of lateral new quarter quarter section. The next step involves remove the tumor or the peel membranes covering the basal cisterns. Obviously the thick bands of the peel surfaces are used to protect the contents of the basal cisterns. I like this maneuver of using this flat dissector and peeling of the onciss from its peel membranes. You can see the third nerve and the neurovascular structures early. The tempo horn is uncovered. The hippocampus is identified. I continue removal of the medial temporal lobe over the peel membranes of the basal cisterns. The third nerve is identified. Violation of this membrane is avoided. As you remember, based on preoperative evaluation and imaging, portion of the medial temporal lobe was herniating around the tentorium. And as you can see, the brain had to be really pulled out centrally over the peel of the basal cisterns. Next, as you can see the tumor and mobile extended until they peel membranes over the cell and fisher are exposed. Tumor removal extended more medially until some of lintiqluose straight arteries are encountered. Neuro navigation guides to extend of tumor removal within the insula. Postoperative MRI demonstrates desirable resection of the tumor with only minimal residual T2 signal change. The final pathology in this patient was consistent with a great to all ago dental cleoma. Thank you.
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