Can Postoperative Apoplexy in Giant Pituitary Adenomas be prevented using Combined Trans-Sphenoidal and Cranial Surgery?

Endoscopic trans-sphenoidal surgery (ETSS) is presently the preferred technique for excision of all pituitary tumors. One of the main concerns following trans-sphenoidal surgery for giant pituitary adenomas (GPAs) is the occurrence of apoplexy in the residual tumor, which is often lethal. The only strategy to avoid such a devastating outcome is to perform radical excision of the tumor. However, when there is an extension of the tumor subfrontally or laterally into the temporal lobes or there is an invasion of the brain parenchyma, trans-sphenoidal approach alone might not enable a surgeon to radically excise the tumor and transcranial (TC) surgery is generally required to excise the residual tumor, after partial excision is achieved through the trans-sphenoidal route.

The authors in this study reported the magnetic resonance (MR) characteristics of the tumor and the outcomes in patients with GPAs who underwent ETSS only and combined surgery. Total tumor volume (TTV), tumor extension volume (TEV), and suprasellar extension of tumor (SET) were calculated based on the lines drawn on MR images and were compared between those who underwent ETSS only and those who underwent combined surgery.

“Our objective was to identify features of the GPAs on MR imaging which would rationalize the choice between combined surgery and ETSS in patients with GPAs”, said the authors

In their series, of the 72 patients with GPAs who underwent ETSS only, 12 (16.7%) had dumbbell shape and 21 (29.1%) had a multilobulated tumor. The resection in these 33 patients was GTR (gross total resection) in six, NTR (near total resection) in 16, STR( sub total resection ) in seven, and partial excision in four patients. They did not consider dumbbell or multilobulated shape alone to be a contraindication for ETSS only.

The authors feel that suprasellar extension even up to 5 cm can be safely managed with ETSS only. A combined approach is justified only if there are lateral intradural or anterior extensions of the tumor. In 13 of 16 of their patients with GPAs, in whom the suprasellar extension measured >3 cm, ETSS only was done. EOR in these 13 patients was GTR in three, NTR in nine, and STR in one patient.

They also suggest the encasement of vessels in the circle of Willis an indication for combined surgery, but not in isolation. Therefore, we had 12 of 72 patients with GPAs who underwent ETSS only even when there was encasement of vessels. But all eight patients who underwent combined surgery had encasement of the vessels.

Intradural versus extradural tumor extension for decision-making

The authors further studied the pros and cons of doing the combined surgeries in sequence vs doing them in the same sitting. The advantage of performing the two approaches simultaneously is that the suprasellar tumor and its extensions can be separated from the neurovascular structures and can be pushed into the sella for easy excision by the team performing the TS surgery. The other advantage is reduction of anesthesia time. The major disadvantage is that it requires two surgical teams with expert surgeons, and this can pose logistical challenges as two surgeons experienced in pituitary tumor surgery might not be readily available in all centers.

Sequential combined surgery offers the advantage of having a single surgical team. The main disadvantage is the additional anesthesia time. The major disadvantage of staging the combined surgery is that it does not protect the patient from the risks of the consequences of a postoperative apoplexy in a large residue following ETSS.

The complication rate following combined surgery can be as high as 30%. Surgical complications include diabetes insipidus (33%), third nerve palsy (30%), sixth nerve palsy (7%), hemiparesis (30%), hydrocephalus (20%), and CSF leak (18.2%).

The authors conclude that while most GPAs can be safely excised using ETSS, some with the MR characteristics such as multilobulated, subfrontal or intradural temporal extension, or encasement of the circle of Willis might require combined surgical approaches. Combined surgery should not be staged but should be done in a single sitting.

Reference

Preventing Postoperative Apoplexy in Giant Pituitary Adenomas using Combined Trans-Sphenoidal and Cranial Surgery

Manish Baldia, Vedantam Rajshekhar

Neurology India, Vol. 71, No. 3, May-June 2023, pp. 439-446

DOI: 10.4103/0028-3886.378658