Background: The amount of parasellar extension is a known limitation for gross total resection (GTR) of pituitary adenomas. Endoscopic technique seems to improve resection of adenomas extending laterally. Knosp classification is used to evaluate the extent of parasellar invasion: increasing Knosp grades correspond with lower rates of GTR. The 4-quadrant method could help to estimate the risk of partial resection in adenomas with parasellar extension. The objective of this study was to compare the rate of GTR between microsurgical and endoscopic techniques in pituitary adenomas with parasellar extension. The secondary aim was to compare the predictive value of Knosp classification and of the 4-quadrant classification regarding GTR.
Methods: This was a retrospective comparison of GTR in different Knosp grades and per quadrant in 55 consecutive patients who underwent microsurgical (n = 28, 2001-2008) or endoscopic (n = 27, 2008-2016) resection of a pituitary adenoma with parasellar extension.
Results: The endoscopic group (19/27 patients) had a significant higher rate of GTR than the microsurgical group (8/28 patients) (P = 0.005). This was evident in all patients but those with Knosp grade 4. Using the quadrant classification, the endoscopic group had a significantly higher rate of GTR than the microsurgical group in all but the inferolateral quadrant. The 2 classifications showed similar sensitivity in predicting subtotal resection (78% quadrant vs. 82% Knosp), with limited specificity (both 25%).
Conclusions: GTR of macroadenomas with parasellar extension is significantly enhanced by the endoscopic approach. The 4-quadrant classification appears as sensitive as the Knosp classification and could be a simple adjunct to predict surgical radicality, in particular in cases of inferolateral quadrant invasion.
Keywords: Cavernous sinus; Endoscopy; Gross total resection; Knosp classification; Microsurgery; Pituitary adenoma; Quadrants.
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