Elsevier

World Neurosurgery

Volume 107, November 2017, Pages 137-141
World Neurosurgery

Original Article
The Likelihood of Remnant Nonfunctioning Pituitary Adenomas Shrinking Is Associated with the Lesion's Blood Supply Pattern

https://doi.org/10.1016/j.wneu.2017.07.141Get rights and content

Objective

Nonfunctioning pituitary adenomas (NFPA) often shrink after transsphenoidal surgery. However, little is known about the predictors of spontaneous NFPA regression. The aim of this study was to determine whether the blood supply pattern of remnant NFPA lesions was associated with the likelihood of such lesions shrinking.

Methods

A total of 37 remnant tumors in 31 patients who were treated at the Department of Neurosurgery, Yamagata University Hospital, were included in this study. All patients underwent preoperative dynamic 3.0T magnetic resonance imaging (MRI) to evaluate their tumors' arterial blood supplies, followed by endoscopic transsphenoidal surgery and intraoperative 1.5T MRI. Follow-up MRI scans were obtained at 1–2 weeks and 3–6 postoperative months.

Results

We detected tumor shrinkage in 15 of 37 (40.5%) remnant tumors on follow-up MRI scans obtained at 3–6 postoperative months. Remnant tumors were found in rostral and caudal locations in 21 and 16 cases, respectively. Rostral remnant tumors were significantly more likely to shrink (P < 0.0001). The tumors were classified into 3 groups according to their blood supply patterns (23 ascending, 6 descending, and 2 monophasic). The ascending blood supply pattern was found to be a positive predictor of tumor shrinkage (P = 0.002). Furthermore, no remnant tumors with rich blood supplies underwent spontaneous regression (P < 0.0001).

Conclusions

Evaluations of the blood supplies of remnant NFPA via preoperative dynamic MRI and the locations of the remnant tumors could be useful for predicting postoperative tumor shrinkage.

Introduction

Nonfunctioning pituitary adenoma (NFPA) usually is treated with endoscopic transsphenoidal surgery (eTSS), which rapidly relieves the patient's symptoms. A recent meta-analysis reported that the initial rate of remission after transsphenoidal surgery (TSS) was approximately 44% among patients with NFPA.1 Age, sex, tumor size, and tumor invasion were found to be correlated with prognosis in some studies but not in others.2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 In contrast, tumor shrinkage after TSS for NFPA has been observed in some studies.8, 13

The incidence of tumor shrinkage has been reported to be approximately 50% among patients with NFPA, and cystic tumors, the additional resection of remnant tumors that are detected by intraoperative magnetic resonance imaging (MRI), a smaller tumor volume, and a smaller craniocaudal remnant tumor diameter were found to be associated positively with tumor shrinkage.13 In this study, we focused on the blood supplies of pituitary tumors. We attempted to determine whether the tumor blood supply pattern is correlated with tumor shrinkage in NFPA.

Section snippets

Patient Population

From January 2007 to June 2016, a total of 73 patients with NFPA underwent eTSS at Yamagata University Hospital. Of these, the 31 patients included in this retrospective study fulfilled the following criteria: undergoing a preoperative dynamic study involving high-field MRI conducted with a 3.0-T Discovery MR750w MRI scanner (GE Medical Systems, Milwaukee, Wisconsin, USA), found to have a remnant tumor after eTSS, and undergoing follow-up MRI without receiving additional treatment. Patients

Results

Among 37 residual lesions in 31 patients, tumor shrinkage was observed on follow-up MRI in 15 (40.5) lesions, as shown in Table 1. The mean ages of the patients in the shrinkage and no-shrinkage groups were 63 and 58.8, respectively, and the difference was not significant. Twenty-one (56.8%) and 16 (43.2%) of the remnant tumors were located at rostral and caudal sites, respectively. Remnant tumors in the rostral region were significantly more likely to shrink (P = 0.0002, Table 2). However, 7

Discussion

In this study, tumor shrinkage after TSS was seen in approximately 40% of remnant NFPA, which confirmed the findings of previous studies.7, 13 Early postoperative MRI can be used to discriminate between residual tumors, hematomas, and packing materials.14, 15 Berkmann et al.13 previously reported that there were 3 mechanisms that can explain the spontaneous regression of NFPA after eTSS: 1) the resorption of hemorrhagic changes within the remnant tumor; 2) intratumoral ischemia followed by

Conclusions

Evaluations of the blood supplies of NFPA with preoperative dynamic MRI and the locations of remnant NFPA could be useful for predicting postoperative tumor shrinkage.

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Conflict of interest statement: The authors declare that the article content was composed in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

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