Parasellar Extension Grades and Surgical Extent in Endoscopic Endonasal Transsphenoidal Surgery for Pituitary Adenomas : A Single Surgeon's Consecutive Series with the Aspects of Reliability and Clinical Validity

Abstract

ObjectiveThe inter-rater reliability of the modified Knosp's classification was measured before the analysis. The clinical validity of the parasellar extension grading system was evaluated by investigating the extents of resection and complication rates among the grades in the endoscopic endonasal transsphenoidal surgery (EETS) for pituitary adenomas.MethodsFrom November 2008 to August 2015, of the 286 patients who underwent EETS by the senior author, 208 were pituitary adenoma cases (146 non-functioning pituitary adenomas, 10 adrenocorticotropic hormone-secreting adenomas, 31 growth hormone-secreting adenomas, 17 prolactin-secreting adenomas, and 4 thyroid-stimulating hormone-secreting adenomas; 23 microadenomas, 174 macroadenomas, and 11 giant adenomas). Two neurosurgeons and a neuroradiologist independently measured the degree of parasellar extension on the preoperative sellar MRI according to the modified Knosp's classification. Inter-rater reliability was statistically assessed by measuring the intraclass correlation coefficient. The extents of resection were evaluated by comparison of the pre- and post-operative MR images; the neurovascular complications were assessed by reviewing the patients' medical records. The extent of resection was measured in each parasellar extension grade; thereafter, their statistical differences were calculated.ResultsThe intraclass correlation coefficient value of reliability across the three raters amounted to 0.862. The gross total removal (GTR) rates achieved in each grade were 70.0, 69.8, 62.9, 21.4, 37.5, and 4.3% in Grades 0, 1, 2, 3A, 3B, and 4, respectively. A significant difference in the extent of resection was observed only between Grades 2 and 3A. In addition, significantly higher complication rates were observed in the groups above Grade 3A.ConclusionAlthough the modified Knosp's classification system appears to be complex, its inter-rater reliability proves to be excellent. Regarding the clinical validity of the parasellar extension grading system, Grades 3A, 3B, and 4 have a negative predictive value for the GTR rate, with higher complication rates.

Endocrine Function after Transsphenoidal Surgery in Patients with Non-Functioning Pituitary Adenomas: A Systematic Review and Meta-Analysis

“…Previous studies have found that parasellar extension [14, 15], surgical experience [16, 17] and prior irradiation of the pituitary gland [36, 37] could be associated with postoperative pituitary function, which could contribute to the observed heterogeneity. Contrarily, Kim et al [12] did not find any of these variables to be predictors of postoperative pituitary recovery or insufficiency.…”

“…The tool was modified for the current review, by leaving out the comparative elements, and assessing bias through four domains, i.e., bias due to confounding, selection of participants into the study, missing data, and selection of the reported result. A priori, the main confounders for the primary outcomes were defined as: Parasellar extension [14, 15], experience of the surgeon [16, 17], prior irradiation of the pituitary gland [36, 37] and the time of pituitary function evaluation before and after surgery. Two authors (M.B.P.…”

“…In these studies, preoperative loss of adrenocorticotropic hormone (ACTH) function was the most likely deficiency to recover. Some of the differences in the reported effect of surgery on pituitary function may be due to confounding factors like parasellar extension [14, 15] and surgical experience [16, 17].…”

The influence of radiological tumor growth pattern on sino‑nasal health in pituitary adenomas

“…It was introduced 1993 and is based on coronal magnetic resonance images of the Sella region describing the invasion of the cavernous sinus space using the intra- and supracavernous internal carotid arteries as a landmark ( 6 ). Due to its simplicity and acceptable interrater reliability, it has a good clinical validity and predictive value for gross total reduction ( 7 ).…”