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Transcranial Approach to Pituitary Adenoma

April 21, 2016

Transcript

Transcranial approaches for pituitary adenomas are exceedingly rarely necessary in the area of transnasal endoscopic surgery. This is a patient of mine who previously underwent endoscopic resection of his multi-compartmental pituitary adenoma. However, residual tumor was noted on post-operative MRI, and therefore he subsequently underwent a transcranial or pterional operation. He's a 26-year-old male. Again, underwent previous surgery. Here's the initial tumor before the transnasal operation. The tumor is relatively heterogeneous and multi-compartmental and relatively asymmetric toward the left side. This was the result of the endoscopic approach by either transellar-transcavernous approach to remove as much of the tumor as possible. You can see I was able to reach either the medial temporal lobe and the lateral part of thalamus to aggressively remove the tumor. However, there was portion of the tumor that did not descend and therefore a transcranial operation was deemed necessary. Here's the result three months after the transnasal operation revealing residual tumor. Here's the left side of pterional craniotomy. I do not believe an orbitozygomatic approach is necessary. The Sylvian fissure was widely dissected and the subfrontal trajectory was used to reach the proceleusmatic area. Here's disconnection of the arachnoid bands from the optic nerves, away from the subfrontal area. Here's the contralateral optic nerve used to chiasm. Here's the tumor affecting the ipsilateral optic nerve. The capsule of the tumor was incised and the tumor was evacuated. The capsule of the pituitary tumors can be quite adherent and typically engulfs the perforating vessels in this area and aggressive resection or manipulation of the capsule may not be warranted. So here I'm working between the carotid artery and the optic nerve within the opticocarotid triangle to remove as much of the tumor as possible. However the tumor was quite fibrous and did not lend itself to effective evacuation. Here's the A1 branch just beyond the borders of our operative view. Here you can see the capsule of the tumor that was very adherent to underneath surface of the optic nerve. I did not wanna compromise any of the perforating vessels to the nerve and aggressive manipulation of the capsule was deemed unsafe. Then I continue to work lateral and medial to the carotid artery to maximize the extent of resection. More of the tumor was evacuated through these different working channels. Next the superior carotid triangle was attempted. However, the perforating vessels were obstructive and therefore this triangle was not used. Next, I worked again medial to the carotid artery using ring curettes of various sizes to evacuate as much of the central portion of the tumor as possible. Portion of the tumor caps were coagulated when deemed safe. Here is the A1 M1 carotid bifurcation. Here's some of the perforating vessels that are engulfed within the tumor capsule. Here you can see one of them. Therefore entry into this operative corridor is unsafe. I was able to remove a central portion of the tumor, in this case, working around the carotid artery. The post-operative MRI revealed some decompression of the tumor. The optic nerve was definitely well decompressed, which was the initial goal of this operation. Portion of the tumor that was inaccessible was that portion adherent to the thalamus where my operative corridor was obstructed by the perforating vessels at the level of the IC bifurcation and proximal M1. I left this portion of the tumor alone, as this portion of the tumor was not symptomatic. This patient subsequently underwent radiosurgery. His vision has remained excellent, and he has not had any untoward effect from his radiosurgical treatment or further growth of his tumor during his five-year follow up. Thank you.

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