January 29, 2016
The orbitozygomatic craniotomy and the translaminar approach provide an opportunity for resection of third ventricular craniopharyngiomas. Recently, I've essentially approached almost all craniopharyngiomas through the transnasal approach except occasional, large multicompartmental ones. This video reviews removal of a predominantly large third ventricular craniopharyngioma via the translaminar terminalis approach. This is a 40-year-old male with a large third ventricular craniopharyngioma with a large third ventricular craniopharyngioma who presented with visual dysfunction. You can see the lesion is, again, predominantly within the third ventricle without any significant suprasellar extension. This tumor is amenable through the inter-nasal approach via the translaminal terminalis approach. However, in this case, the patient underwent a transcranial route, since this procedure was performed a few years ago before the endoscopic route was more frequently used by me. The details of the orbitozygomatic craniotomy are discussed elsewhere. Following removal of the bone, you can see the roof of the orbit was also drilled away for an unobstructed operative trajectory toward the suprachiasmatic area. You can see the dural reflection, use of the retention sutures to gently depress the orbit. The optic nerves and the chiasm were untethered from the sub-frontal area using sharp dissection. This approach requires aggressive retraction of the frontal lobe. You can see the A1 just under the suction and the axon complex. This procedure, as mentioned a moment ago, requires significant mobilization of the frontal lobe and, therefore, dynamic retraction is quite important. The use of fixed retractor blades can lead to significant injury during mobilization of the sub-frontal area. Next, the area of the laminar terminalis, where the tumor is protruding through is found. The thin roof of the laminar terminalis is further dissected as far posterior as possible from the chiasm. This operative route is quite limited and removal of larger tumors, especially the ones filling the posterior third ventricle, can be quite challenging. In this case, the sub-frontal operative trajectories used for removal of the tumor, the anterior is also dissected. The tumor is removed piecemeal. You can see the limited exposure within the laminar terminalis. Debulking of the tumor allows mobilization of the mass into the resection cavity. You can see some of the contents along the inferior capsule of the tumor, including the floor of the third ventricle, obviously all the walls, and the floors of the third ventricle are very carefully protected. The blind spot is again within the posterior aspect of the third ventricle. This is a postoperative MRI, which demonstrates small residual tumor within the blind spot of the surgeon. However, chiasm was adequately decompressed. The endonasal approach provides a more expanded trajectory along the long axis of the tumor, and can frequently prevent any residual tumor within the blind spots, which are relatively very small for the endoscopic approach. Thank you.
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