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Temporal Lobectomy and Amygdalohippocampectomy

January 13, 2016


This video reviews the nuance of technique for performance of an Anteromedial Temporal Lobectomy and Selective Amygdalohippocampectomy. This is a 42 year old male who presented with intractable seizures and was diagnosed with a relatively heterogeneous mass within the anterior aspect of the mesial temporal lobe, consistent with a PNET or a ganglioglioma. The final pathology was consistent with a ganglioglioma. The patient is placed in a supine position. The head of the patient's turned approximately 30 degrees contralaterally. The head is turned or extended more than a usual pterional craniotomy. The extension of the head brings the axis of the hippocampus more parallel to the axis of the operative trajectory and facilitates removal of the tail of the hippocampus. You can see the exposure is primarily temporal and there is minimal exposure of the frontal lobe. The incision extended up to the root of the side gomal. So the middle fossa can be relatively reachable. As you can see, here is the initial exposure to salient fissure exposure is primarily again, temporal three and a half to four centimeter of the anterior temporal lobe is resected. The superior temporal gyrus is preserved, if possible. Here you can see the horizontal corticotomy extended entirely to the dura along the tip of the temporal lobe. After completion of the new cortical resection, you can appreciate the location and the anatomy of the dura over the middle fossa here is protuberance. That is an important anatomical landmark, essentially the two planes of transection, including the posterior plane and a superior plane. You meet each other at this protuberance so that the ventricle and the hippocampus are not touched early on during neocortical resection. Importantly, the middle temporal gyrus is used as a landmark to unroof the temporal horn. The temporal horn is the most important anatomical landmark during anteromedial temporal lobectomy and amygdalohippocampectomy. As it's early identification exposure protects the medial structures, including the brainstem. Here's some of the tumor along the medial temporal lobe identified. Here's the unroofing of the temporal horn. The entry aspect of the hippocampus is exposed. The occipital temporal fasciculusis transected along the axis of the hippocampus. The hippocampus is left untouched, so it can be removed and blocked if necessary for research purposes. Here you can see the turn of the hippocampus. Here's the pes hippocampus or its anterior portion. Here's the intra or limbic gyrus. It's the roof of the temporal horn. Here's the inferior choroidal point, just along the anterior aspect of the choroidal fissure. Now that the initial anatomical landmarks are identified, let's go ahead and isolate the amygdala and conduct an amygdalectomie. Again, this is an important anatomical landmark, the inferior choroidal point just at the level of the choroidal fissure. Now you can appreciate, again, the location of the hippocampus. Here's the extent of the amygdala, here is a magnified view of our exposure through a very minimal anteromedial, choroidal temporal resection. Next step involves identification of the M1. The medial portion of the middle of temporal gyrus is removed. So that the M1 within the peel bands of the psyllium fissures identified, as you can see here. Now that the artery is identified, a line connecting this artery to the inferior choroidal point here, marks the superior extent of resection of the amygdala. Here you can see the anterior aspect of the chorodial fissure. Just in front of the choroid plexus, a line joining the artery. Again, marks the superior board of our resection. This linear anatomical landmark protects the striatum from any injury during selective amygdalohippocampectomy. These atomical landmarks actually allow selective amygdalohippocampectomy that can be performed and the tissue can be preserved for research purposes. Here you can see the amygdala being removed. Here is the location of M1 in choroidal point and the line joining the two. Here you can see the peel membranes over the basal cisterns. The edge of the tentorium can be identified on the other side of the peel membrane. Here's the entry aspect of the hippocampus. The amygdala has been aggressively resected. Additional portion of the amygdala along the roof of the anterior temporal horn is being removed. Here is final steps in remove all the amygdala. Here's portion of the uncus over the peel of the basal cisterns. Here's another piece of the tumor that is being removed for histological analysis. Now the thin layer of the uncus over the peel of the basal cistern is being peeled off. A third nerve is coming in view, as you can see here. The arachnoid and peel surfaces over the nerve are left intact. The fourth nerve is hiding just underneath the incisure here and should also be carefully protected. You can see that part of the medial temporal lobe can herniate around the incisure, making its removal challenging. A flat dissector is quite effective to mobilize the medial part of the uncus over the brain stem and the third nerve. Coagulation is prohibited around the nerve. Now the entry aspect of the hippocampus is being dissected. You can see the pes hippocampus is disconnected from the tail of the hippocampus. This is dissection along the parahippocampus. Here is parahippocampus disconnected inferiorly from the pia over the basal cisterns. So the hippocampus can be disconnected circumferentially along its anterior aspect. Next the intralimbic gyrus is disconnected, just lateral to the choroid plexus. So the last connections of the hippocampus are disconnected. A piece of carotenoid patties used on the choroid plexus so that the suction device will not lead to bleeding, while touching the vascular choroid plexus. Obviously coagulation of the choroid plexus should be minimized to avoid injury to the anterior choroidal artery. Here's the peel membranes, just medial to the hippocampus along the choroidal fissure. You can see these white matter tracks are disconnected in very thin layers and very gently to avoid inadvertent intrusion into the peel surfaces of the brain stem. Here's the poster part of the pes hippocampus that's being disconnected from its tail, and the anterior part of the hippocampus is removed and blocked. Here's the final attachment of the hippocampus from its tail that is being cut. Some of the perforating vessels from the PCA, at this juncture should be selectively coagulated and cut to minimize injury to the PCA. Here's removal of part of the tail of the hippocampus. You can see these perforating vessels within the arachnoid bands coming from the PCA into the hippocampus. They're carefully isolated, coagulated and cut. Here you can see other small perforating vessels from the PCA, encased by the arachnoid bands of the peel surfaces entering in the hippocampus. Now the hippocampus is removed and blocked. The tail of the hippocampus is identified. You can see the choroid plexus. Gentle fixed retraction may be necessary for its removal. Here is the peel membranes over the brain stem. Obviously all these perforating vessels should be protected. Here's branches of the PCA. They used to feed the hippocampus. Here's additional pieces of FEN tissue, of the medial temporal lobe that is being removed. The PCA is located just underneath these peel membranes. Here is the surface of the brain stem and lateral thalamus. Third nerve is located there. Here's the edge of the tentorium. It can, this portion of video is illustrating the final anatomy along the incisure. Here is the fourth nerve. Aggressive resection of the parahippocampus is confirmed Importantly, the resection of the tail continues as it turns to enter the air of the calcar avis. Here's the third nerve. Coagulation of the pia over the basal cisterns is avoided. Here's the final view of the resection cavity, very small anterior neocortical resection aggressive remove the medial temporal lobe structures. This procedure is very similar to the one used for a medial temporal lobe sclerosis Post-operative MRI demonstrates postural removal of the entry hippocampus, and it's tail as it enters the area of the calcar avis, without any complicating feature. Thank you.

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