Endoscopic Endonasal Approach to Giant Pituitary Adenomas: Surgical Outcomes and Review of the Literature.

OBJECTIVE: To present the outcomes of endoscopic endonasal surgery for giant pituitary adenomas and discuss the extent of resection to minimize morbidity and mortality. METHODS: We retrospectively reviewed medical records of 44 patients with giant pituitary adenomas who underwent endoscopic endonasal surgery. Clinical presentation, laboratory results, imaging studies, clinical outcomes, extent of resection, and complications were collected and analyzed. Factors affecting long-term outcome according to surgical technique were identified and analyzed. RESULTS: Radical resection (RR) was defined as either gross total resection or near-total resection (90%-100% of the tumor). There were 28 patients (63.6%) who underwent RR, 10 patients (22.7%) who underwent subtotal resection, and 6 patients (13.6%) who underwent partial resection. Visual improvement was achieved in 27 patients (81.8%). Thirteen patients (72.2%) with pituitary dysfunction had improvement in at least 1 preoperative endocrinological dysfunction. RR rates for dumbbell and multilobular tumors were 44.4% and 28.6%, respectively. Surgical complications were observed in 14 (31.8%) patients. Major vascular injury occurred in 3 patients (6.8%). Mean follow-up period was 38.5 months (range, 1-70 months). No patients with RR had recurrence or residual tumor progression. Ten patients (22.7%) received adjuvant radiation therapy after resection. Two patients were reoperated on for tumor regrowth, and 3 patients (including the 2 patients with tumor regrowth) were lost to follow-up. CONCLUSIONS: Long-term follow-up results and low recurrence rate of tumors indicate that RR is effective to decrease morbidity and mortality.

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

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).

Aquaporin-4 expression is not elevated in mild hydrocephalus.

BACKGROUND: Aquaporin-4 (aqp-4) is a member of water channel family proteins primarily expressed in the central nervous system. Physiologically it is the main channel providing water transport into the nervous system water compartments and across the blood-brain barrier. Several studies demonstrated its compensatory role in severe hydrocephalus. However, its role is not clear during the initial stages of hydrocephalus. OBJECTIVE: This study was designed to investigate aqp-4 expression in less severe forms of hydrocephalus and to determine its role in disease progression. METHODS: Twenty-five male Wistar-Hannover rats, were distributed into experimental (n = 20) and control (n = 5) groups. Hydrocephalus was induced in the experimental group by injection of 5 µl 25% kaolin suspension into the cisterna magna. Control animals received an injection of 5 µl normal saline. Eight weeks later, the animals were killed by the perfusion-fixation method. Immunohistochemical and Western blot analysis were performed. RESULTS: Ventricular dilatations were noted in all experimental animals. Both groups demonstrated positive immunoreactive signals to aqp-4. Immunohistochemically there were no changes in aqp-4 pattern and expression intensity between experimental and control animals. Similarly, Western blot analysis revealed mean aqp-4 values in experimental and control groups as 0.3436 and 0.3917, respectively, and the difference did not reach statistical significance (p > 0.05). CONCLUSION: Our results indicate that aqp-4 is not up-regulated during the initial stages of hydrocephalus. This implies that aqp-4 may not play a significant role in hydrocephalus compensation until severe ventricular dilatation occurs.

Expression of water channel aquaporin-4 during experimental syringomyelia: laboratory investigation.

OBJECT: Aquaporins (aqp) are protein channels providing water transport across cell membranes. The main member of this family expressed in the CNS is aqp-4. The pattern and amount of expression of this channel suggest a dominant role in bulk water movement into the nervous tissue. It has also been shown to play a role in several water balance disorders in the CNS. In this study, the authors investigated the possible role of aqp-4 in syringomyelia. METHODS: Twenty-five male Wistar-Hannover rats were divided into experimental (20 rats) and control (5 rats) groups. Syringomyelia was induced in the experimental group by kaolin injection into the cisterna magna. Eight weeks later, the animals were killed, and their spinal cords were removed. Central canal dilations were noted in all experimental animals. Immunohistochemistry and Western blot analysis were performed to evaluate aqp-4 expression. RESULTS: Both groups demonstrated positive immunoreactive signals to aqp-4. Western blot analysis revealed a slight decrease in the mean aqp-4 value in the experimental group; however, the difference did not reach statistical significance (p > 0.05). Immunohistochemical analysis showed a similar pattern and intensity of aqp-4 staining in both groups. CONCLUSIONS: The results of this study indicate that aqp-4 most likely does not play a major role in chronic syringomyelia. Its slight downregulation during the initial stage of syrinx formation is possibly a compensatory mechanism. This effect is not present during the late stage of syringomyelia, and aqp-4 is most likely not involved in the pathophysiology of syrinx cavity formation.