The Hypothalamic-Pituitary-Adrenal Axis in Health and Disease by Eliza B. Geer

Author:Eliza B. Geer
Language: eng
Format: epub
Publisher: Springer International Publishing, Cham

After dural incision, the surface of the anterior gland is carefully inspected for areas of irregularity or discoloration. Some authors have reported the use of a micro-Doppler for visualization with varying degrees of success [36]. In our opinion, visualization of the pseudocapsule is the most consistent finding to locate the tumor. Once the possible location of the adenoma is identified, the pituitary capsule is incised sharply and then the pseudocapsule is dissected. We try to avoid piecemeal resection, when possible. Special care is taken not to lose any of the specimens in the suction.

Sectioning of the gland is performed if no adenoma can be detected after gross inspection of the anterior and lateral surfaces. Incisions are made horizontally or vertically at 2 mm intervals until a tumor is uncovered or the posterior gland is identified. If the adenoma is uncovered, then dissection of the pseudocapsule is performed with attempted gross total resection . If the pseudocapsule or surrounding dura is breached, careful inspection is performed to ensure that no areas of dural invasion are missed.

Parasellar ectopic ACTH-producing tumors have been reported [20]. They may be suspected if no adenoma is found after all abovementioned steps have been performed. In this case, careful inspection of the gland back to the neurohypophysis is recommended. If no tumor can be identified, a partial or total hypophysectomy can be considered. Because panhypopituitarism develops after total resection, a partial resection is preferred and can be directed based on the results of the preoperative IPSS . With this method, a high rate of remission (92 %, 24 of 26 patients) can be achieved through partial hypophysectomy [26].

Jagannathan et al. [37] determined the success of using the pseudocapsule as a surgical capsule through a retrospective review of 261 patients. Tumor was identified radiographically in only 135 patients (52 %). However, through meticulous exploration of the sella and identification of the pseudocapsule, the group was able to attain remission in 252 cases (97 %). In the remaining 9 patients, remission was achieved for 4 with repeated surgery. Further evidence for the efficacy of this method of dissection was found in the rate at which patients became hypocortisolemic after surgery. Using the pseudocapsule as a guide in dissection, patients became hypocortisolemic 19.4 h after surgery, which was more rapid than other methods of dissection and suggested a more complete resection [38]. This further suggests that identification of the pseudocapsule is critical for achieving a gross total resection .

Depending on the clinical situation, more aggressive or more conservative resection may be indicated. For the seriously debilitated or elderly patient, transsphenoidal surgery may be attempted first but if no adenoma is found, it may be appropriate to perform complete hypophysectomy to minimize the need for repeated surgery.

After completing the resection of the adenoma, we routinely inspect for possible CSF leak with a Valsalva maneuver . Any evidence of communication of cerebrospinal fluid with the sella mandates intrasellar packing in addition to obliteration of the sphenoid by fat taken from the abdomen.

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