Effect of pituitary adenoma consistency on surgical outcomes in patients undergoing endonasal endoscopic transsphenoidal surgery

Background Most pituitary adenomas (PAs) are considered to have a soft tumor consistency. However, there is a non-negligible percentage (5–13%) of tumors presenting or exhibiting a fibrous consistency that would entail a more difficult and complicated surgical excision with higher surgical morbidity and mortality rates. Purpose To analyze the clinical consequences of PA tumor consistency on the surgical outcomes in patients undergoing endonasal endoscopic transsphenoidal (EET) pituitary surgery. Methods An ambispective study of patients with PAs operated on through an EET approach in two Spanish tertiary hospitals over the last 12 years. A total of 226 consecutive interventions were carried out in the Neurosurgery Departments of the Hospital Universitario Ramón y Cajal (HURC) and the Hospital Universitario Puerta del Sur by the same neurosurgeon. PAs were grouped into soft ( n = 150) and fibrous ( n = 76). All patients underwent hormonal and magnetic resonance imaging (MRI) studies before and after surgery. In addition, neurosurgical complications were recorded in each patient. Results Fibrous adenomas were independently associated with lower resection rates compared to soft adenomas (fibrous gross total resection [GTR] rate 48.7% vs. 76.3%, p < 0.001), even in those adenomas without invasion of the cavernous sinus (Knosp grades 0, I, and II). There were more intraoperative cerebrospinal fluid (CSF) leaks in patients with fibrous PAs. Moreover, fibrous PAs showed higher rates of postoperative hypopituitarism, permanent diabetes insipidus (DI) and postoperative treatments (hormonal treatment and radiotherapy). The excision of a fibrous PA required a longer surgical time (22.5 min more than soft PAs, p = 0.014), regardless of other factors. Conclusion The consistency of the PAs significantly conditions both the results of surgery (lower resections rates), complications (higher incidence of postoperative hypopituitarism, permanent DI), and the prognosis (higher incidence of postoperative treatments) of the patient undergoing EET.