Invasion of the cavernous sinus space in pituitary adenomas: endoscopic verification and its correlation with an MRI-based classification

Abstract

abbreviatioNs CS = cavernous sinus; ER = endocrinological remission; GTR = gross-total resection; ICA = internal carotid artery. submitted May 22, 2014. accepted December 2, 2014. iNclude wheN citiNg Published online February 6, 2015; DOI: 10.3171/2014.12.JNS141083. disclosure The authors report no conflict of interest concerning the materials or methods used in this study or the findings specified in this paper. obJect An important prognostic factor for the surgical outcome and recurrence of a pituitary adenoma is its invasiveness into parasellar tissue, particularly into the space of the cavernous sinus (CS). The aims of this study were to reevaluate the existing parasellar classifications using an endoscopic technique and to evaluate the clinical and radiological outcomes associated with each grade. methods The authors investigated 137 pituitary macroadenomas classified radiologically at least on one side as Grade 1 or higher (parasellar extension) and correlated the surgical findings using an endoscopic technique, with special reference to the invasiveness of the tumor into the CS. In each case, postoperative MRI was performed to evaluate the gross-total resection (GTR) rate and the rate of endocrinological remission (ER) in functioning adenomas. results The authors found a 16% rate of CS invasion during surgery for these macroadenomas. Adenomas radiologically classified as Grade 1 were found to be invasive in 1.5%, and the GTR/ER rate was 83%/88%. For Grade 2 adenomas, the rate of invasion was 9.9%, and the GTR/ER rate was 71%/60%. For Grade 3 adenomas, the rate of invasion was 37.9%, and the GTR/ER rate was 75%/33%. When the superior compartment of the CS (Grade 3A) was involved, the authors found a rate of invasion that was lower (p < 0.001) than that when the inferior compartment was involved (Grade 3B). The rate of invasion in Grade 3A adenomas was 26.5% with a GTR/ER rate of 85%/67%, whereas for Grade 3B adenomas, the rate of surgically observed invasion was 70.6% with a GTR/ER rate of 64%/0%. All of the Grade 4 adenomas were invasive, and the GTR/ER rate was 0%. A comparison of microscopic and endoscopic techniques revealed no difference in adenomas with Grade 1 or 4 parasellar extension. In Grade 2 adenomas, however, the CS was found by the endoscopic technique to be invaded in 9.9% and by microscopic evaluation to be invaded in 88% (p < 0.001); in Grade 3 adenomas, the difference was 37.9% versus 86%, respectively (p = 0.002). Grade 4 adenomas had a statistically significant lower rate of GTR than those of all the other grades. In case of ER only, Grade 1 adenomas had a statistically significant higher rate of remission than did Grade 3B and Grade 4 adenomas. coNclusioNs The proposed classification proved that with increasing grades, the likelihood of surgically observed invasion rises and the chance of GTR and ER decreases. The direct endoscopic view confirmed the low rate of invasion of Grade 1 adenomas but showed significantly lower rates of invasion in Grade 2 and 3 adenomas than those previousl...

Apparent diffusion coefficient and pituitary macroadenomas: pre-operative assessment of tumor atypia

“…Invasion was defined as tumor visualized in the medial margin of the cavernous sinus and or within the adjacent structures to the sella, confirmed by MR imaging and intraoperative visualization. Invasion was further classified as per the Knosp grading scale and Table 2 summarizes the Knosp scores, ADC ratio, and MIB-1 index for all 17 patients [19]. Overall, the adenomas with local invasion demonstrated statistically significant lower normalized ADC values as compared to the non-invasive counterparts, with a mean of 0.68 as compared to 1.05 in non-invasive adenomas (p = 0.0057).…”

Factors predicting pasireotide responsiveness in somatotroph pituitary adenomas resistant to first-generation somatostatin analogues: an immunohistochemical study

“…Cavernous sinus extension was assessed using the Knosp's classification; grade 3 and 4 defined cavernous sinus extension (31,32).…”

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

“…The grading was performed by two neurosurgeons and one neuroradiologist using the coronal section of preoperative T2 and gadolinium-enhanced T1 images by the modified Knosp's grading system21). The grading results of the raters were blinded to each other during the procedure.…”

“…1), Micko et al21) divided Grade 3 of the previous classification into Grades 3A and 3B based on the involvement of the CS compartment. Grade 3A adenomas extend into the superior CS compartment, while Grade 3B adenomas extend into the inferior CS compartment.…”