Endoscopic Endonasal Approach to Multilobular Giant Pituitary Adenoma with Cavernous Sinus Invasion and Petroclival Extension

Abstract

Giant pituitary adenomas are considered a surgical challenge. Their invasiveness, irregular growth, and extensions make this surgery critical. Because of this reason, the radical resection rate is low in such pathology. The endoscopic endonasal approach pushes its limits to get successful results in skull base lesions. Irregular shape, cavernous sinus invasion, and extensions are being successfully resected during the last decades. Lateral extension, especially posterolateral extension, of this tumor makes them impossible to radical resection. In this video case, we try to present an expanded endonasal approach to the irregular giant pituitary adenoma with a 360° cavernous sinus invasion and petroclival extension of the tumor. We are presenting a patient with an irregular-shaped giant pituitary adenoma who underwent an expanded endonasal approach for this reason. This is a 27-year-old male patient admitted with right-sided ophthalmoplegia and visual deterioration mainly in the left eye. Multilobular giant pituitary adenoma with right cavernous sinus involvement presented on magnetic resonance imaging. Right internal carotid artery (ICA) encased 360° with the tumor. The tumor extends to the petroclival region on the right side and compresses the brainstem. Anteriorly, tumor extends to the gyrus rectus and compresses the left optic nerve. 0:45: As usual we are preparing a wide nasoseptal flap for the reconstruction at the end of the surgery. We do it routinely in cases of giant pituitary adenoma surgery to avoid cerebrospinal fluid leak after the surgery. 1:00: The next step is drilling the anterior wall of the sphenoid sinus and opening the corridor to achieve enough space that lets us maneuver at the skull base. It is important to make a wide exposure to gain a high control of important anatomic structures at the skull base. 1:15: After the opening of the sellar floor, we made a "U-shaped" incision on the dura, taking a biopsy for the histopathological investigation and started debulking the tumor. The tumor tissue is soft and it is possible to remove it with suction. 2:08: Although the sellar part is removed, we are trying to remove the tumor from the posterior and superior part of the cavernous sinus. 2:28: To achieve access to the anterior part of the cavernous sinus we are drilling the bone overlying the anterior wall of the cavernous sinus on the right side. Then we are using micro-Doppler to identify the location of ICA. We made an incision lateral to the ICA, to widen the dural opening. To avoid possible carotid injury we are placing a cottonoid under the dura. Then we enter the space and remove the tumor inside the cavernous sinus as much as possible. 3:54: Removing the periosteum covering the sellar floor makes us reach the posterior clinoidal process. In order to gain an access to petroclival regoin inferior wall of sellar floor drilled out and middle and posterior clinoidal processes were removed by drilling. Removal of anterior petrous process has been done so manipulation of tumor would become easy. Now we can see the paraclival petrosal dura lying posterior to the ICA, at the foramen lacerum. 4:48: We are cutting the dura and widening the defect to enter the petroclival region. After entering the space we are trying to dissect out surrounding neurovascular tissue. Although the tumor is located inferior to the entering point and because mobilization of the tumor inferiorly is unachievable, we are pulling the tumor capsule to remove the soft component of the tumor with suction. As you can see, the tumor removed totally, and the tumor capsule is resected for achieving radical resection. 6:17: After complete resection of the extended part of the tumor to the posterior fossa we are inspecting the surgical area. 6:34: After the removal of the tumor as the last step, we are packing the cavity with fat graft and covering with vascularized nasoseptal flap. Postoperative first day magnetic resonance imaging shows near-total removal of the tumor. The patient did well after surgery. He had no hypopituitarism and diabetes insipidus after the surgery. Cerebrospinal fluid leak was not observed. Unfortunately, oculomotor palsy did not improve after surgery (Video 1).