Transcranial approach to pituitary adenomas invading the cavernous sinus: A modification of the classical technique to be used in a low-technology environment

Abstract

Objective: Pituitary adenomas invading the cavernous sinus represent a therapeutic challenge. Those tumors have been traditionally treated with incomplete surgical removal, observation and/ or adjunctive medical therapy, and radiotherapy. In relatively recent years, some authors have suggested a main direct surgical approach to cavernous sinus (CS) with the aim of complete removal of the adenoma, either by a modified trans-sphenoidal route, using or not an endoscopy-assisted approach, or by a transcranial direct approach. The latter has the advantage of allowing direct exposure of the lesion with a view of the surgical field unhindered by important neurovascular structures.

Materials and methods: We report a technical modification of the classical epidural approach for CS adenoma removal. This was used in 14 patients. Surgical technique included a fronto-orbito-zygomatic craniotomy with extradural anterior clinoidectomy, and intradural approach to the Hakuba's triangle for intracavernous dissection. The tumors were removed under direct vision.

Results: Total macroscopical removal was achieved in all but one case. This patient required postoperative radiation therapy as well as adjuvant dopaminergic regime for achieving control of preoperatively increased hormonal values. No other case required radiotherapy. Hormonal and/ or clinical control was also achieved in all the remaining cases. Out of the remaining 13 cases, all appeared to be tumor free at an average postoperative observation at 78 months (34 to 90 months). Significant surgical sequels were detected in only 1 case (persistent 3(rd) nerve palsy and moderate hemiparesis).

Conclusions: This experience, though limited, would suggest that the transcranial limited CS exposure through the Hakuba's triangle may allow adequate removal of intracavernous pituitary adenomas with very good long-term results and acceptable complication rate.

Keywords: Cavernous sinus surgery; Hakuba’s triangle; fronto-orbito-zygomatic craniotomy (FOZ); invasive adenoma; transcranial approach.

Figure 1

a) MRI scan, axial T2 image. A pituitary tumor invading the left CS and encasing the ICA is demonstrated. b) The T1 post-contrast coronal scan gives clear evidence of the extra-sellar lateral and superior extensions of the lesion

Figure 2

Drawing of the surgical anatomy. The intracavernous portion of the adenoma is fully exposed following lateral displacement of the released III cranial nerve using a nerve self-retaining retractor

Figure 3

Same case as Figure 1. Immediate postoperative CT scan, before Figure 3a and after Figure 3b, contrast enhancement shows apparent total tumor removal

Figure 4

a) Axial T1 scan shows a pituitary tumor with significant left lateral extra-sellar extension. b) Immediate postoperative CT scan shows a huge hematoma. c) CT scan following re-operation demonstrates partial removal of the mass

Figure 5

a) MRI, T1 post-contrast coronal scan shows a Knosp 3-4 intracavernous adenoma. b) Postoperative MRI, T1 axial scan. This demonstrates apparent total removal of the tumor

Figure 6

Same patient as in Figures 1 and 3. Two-year postoperative MRI. T2 axial. a) Post-contrast T1 coronal; b) Scans show no recurrence of the tumor

Figure 7

Same patient as in Figures 1, 3, 6. Five-year postoperative axial; a) coronal; Figure b) MRI shows no changes as compared to the earlier postoperative MRI controls