The primary goal of surgical treatment of giant pituitary adenoma is improvement of the visual, endocrinological, and neurological symptoms, whilst ensuring the lowest risk for morbidity and mortality rates. However, radical removal of giant pituitary adenomas remains a challenge for neurosurgeons despite the development of microsurgical techniques. Surgical management of giant adenoma has a higher complication rate than that of non-giant adenoma. The reported mortality and morbidity rates in surgical series of giant pituitary adenomas are 0–3.2 and 4.2–15.5%, respectively [1, 2, 7, 8]. Clival invasion is also associated with a higher rate of operative complications .
The most likely explanation for the worse surgical outcome is that resection of giant tumors is frequently incomplete, thus putting patients at increased risk of postoperative pituitary apoplexy occurring within the immediate postoperative period [4, 5]. Postoperative pituitary apoplexy is usually associated with very poor outcomes due to significant postoperative tumor swelling, hemorrhage, infarction, necrosis precipitating further mass effect, cerebral edema, and herniation syndrome [1, 4, 5]. Giant pituitary adenomas have much more vascularity than non-giant pituitary adenomas , so that postoperative pituitary apoplexy may correlate with such hypervascularity. In the present case, preoperative neuroimaging, including contrast-enhanced magnetic resonance imaging and angiography, suggested that the tumor was hypervascular. Therefore, we performed preoperative embolization followed by two-stage transsphenoidal surgery. Although we could not completely remove the tumor extending into the cavernous sinus and clivus, the postoperative course was uneventful without hemorrhagic complication after both stages of transsphenoidal surgery. We suggest that preoperative embolization of giant pituitary adenoma has the potential to prevent postoperative pituitary apoplexy.
Embolization facilitates tumor resection by limiting blood loss and softening the tumor, which result in a clear operation field and reduced forces transmitted to adjacent neural structures, making surgical resection safer [6, 11, 12]. The usefulness of preoperative embolization through the internal carotid artery branches is much less understood due to the technical difficulties and higher risks compared with embolization through the external carotid artery branches [11, 13]. The risks include thromboembolic events, post-embolization cranial nerve deficits, intratumoral hemorrhage, post-embolization swelling, and general complications related to angiography . The recent development of the high-resolution road mapping system and concurrent development of softer and smaller microcatheters and microwires have enabled super-selective embolization through the internal carotid artery branches . Major blood supply of giant pituitary adenomas originates from branches of the infraclinoidal portion of the internal carotid artery . The MHT is generally very small and arises at an acute angle from the internal carotid artery, and these anatomical relationships create challenges to direct catheterization, but few clinical trials have investigated preoperative embolization of the MHT in meningiomas [13, 14, 16]. Consequently, the surgical indications must carefully balance the risks against the potential benefit.
The present case describes the technique of preoperative embolization of giant pituitary adenoma. No complications were observed and marked devascularization was achieved. The tumor was hypervascular, and was supplied by feeders such as thick branches of the MHT. We used n-butyl cyanoacrylate at a relatively low concentration, because we could insert the microcatheter into a distal portion of the MHT and could deliver embolic material deep inside the tumor. Use of n-butyl cyanoacrylate is very safe for the embolization of head and neck tumors . Moreover, we planned to perform the embolization and the immediate transsphenoidal surgery in a single session before reconstitution of the collaterals to the occluded tumor area. Early surgical tumor removal can also reduce the risk of repeated general anesthesia and reduce other delayed reactions to tumor embolization such as mass effect of the tumor due to swelling with herniation or obstructive hydrocephalus . Ischemic pituitary adenoma apoplexy often leads to the progression of cranial nerve palsy and decreased level of consciousness . Control of intraoperative bleeding was effective, and intraoperative blood loss was low, resulting in successful staged transsphenoidal surgery without complications. The present case demonstrates that preoperative embolization of giant pituitary adenoma should be regarded as a feasible option to decrease surgical blood loss.
In conclusion the present case illustrates the usefulness and feasibility of preoperative embolization of giant pituitary adenomas. Recent advances in microcatheter, microguidewire, and imaging technology may allow the introduction of new therapeutic strategies and indications for these complex lesions.