Intraoperative Magnetic Resonance Imaging During Endoscopic Transsphenoidal Surgery of Growth Hormone-Secreting Pituitary Adenomas

Impact of Intraoperative Magnetic Resonance Imaging on Short-Term and Long-Term Outcomes After Transsphenoidal Resection of Pituitary Adenoma: A Systematic Review and Meta-Analysis

BACKGROUND

Intraoperative magnetic resonance imaging (iMRI) allows for greater tumor visualization and extent of resection. It is increasingly used in transsphenoidal surgeries but its role is not yet established.

OBJECTIVE

We aimed to clarify the usefulness of iMRI in transsphenoidal surgery using direct statistical comparisons, with additional subgroup and regression analyses to investigate which patients benefit the most from iMRI use.

METHODS

Systematic searches of PubMed, Embase, and Cochrane Central were undertaken from database inception to May 2020 for published studies reporting the outcomes of iMRI use in transsphenoidal resection of pituitary adenoma.

RESULTS

Thirty-three studies reporting 2106 transsphenoidal surgeries in 2099 patients were included. Of these surgeries, 1487 (70.6%) were for nonfunctioning pituitary adenomas, whereas 619 (29.4%) were for functioning adenomas. Pooled gross total resection (GTR) was 47.6% without iMRI and 66.8% with iMRI (risk ratio [RR], 1.32; P < 0.001). Subgroup and meta-regression analyses demonstrated comparable increases in GTR between microscopic (RR, 1.35; P < 0.001) and endoscopic (RR, 1.31; P < 0.001) approaches as well as functioning and nonfunctioning adenomas (P = 0.584). The pooled rate of hypersecretion normalization was 73.0% within 3 months and 51.7% beyond 3 months postoperatively. The pooled rate of short-term and long-term improvement in visual symptoms was 96.5% and 84.9%, respectively. The incidence of postoperative surgical complications was low. The pooled reoperation rate was 3.8% across 1106 patients.

CONCLUSIONS

The use of iMRI as an adjunct significantly increases GTR for both microscopic and endoscopic resection of pituitary adenomas, with comparable benefits for both functioning and nonfunctioning adenomas. Satisfactory endocrinologic and visual outcomes were achieved.

The value of intraoperative MRI for resection of functional pituitary adenomas-a critical assessment of a consecutive single-center series of 114 cases

This series sought to evaluate the role of intraoperative MRI (iMRI) for resection of functional pituitary adenomas (FPAs). We retrospectively reviewed clinical data of 114 consecutive FPAs with excessive hormone secretion treated with transsphenoidal surgery and iMRI during 01/2010–12/2017. We focused on iMRI findings, extend of resection and postoperative hormonal remission. Variables of incomplete resections and persistent hormone excess were evaluated by binary regression. Patients with FPAs presented with hypercortisolism (n = 23, 20%), acromegaly (n = 56, 49%), and as prolactinomas (n = 35, 31%) resistant to medical treatment. Preoperative MRI showed 81 macroadenomas (71%) and optic system involvement in 41 cases (36%). IMRI was suggestive for residual tumor in 51 cases (45%). Re-inspection of the cavity cleared equivocal findings in 16 cases (14%). Additional tumor was removed in 22 cases (19%). Complete resection was achieved in 95 cases (83%). Postoperative morbidity was low (1.7% revision surgeries, 0.8% permanent diabetes insipidus). Overall hormonal remission-rate was 59% (hypercortisolism 78%, acromegaly 52%, prolactinoma 57%). Supra- and parasellar invasion and preoperative visual impairment were significant predictors for incomplete resections despite use of iMRI. Risk for persistent hormone excess was increased sevenfold after incomplete resections. IMRI enabled reliable identification of tumor remnants during surgery and triggered further resection in a considerable proportion of cases. Nevertheless, tumor size and invasiveness set persistent boundaries to the completeness of resections. The low rate of surgical complications could point at a less invasive iMRI-guided surgical approach while achieving a complete tumor resection was a crucial determinant for hormonal outcome.

Effectiveness of the intraoperative magnetic resonance imaging during endoscopic endonasal approach for acromegaly

PURPOSE

Acromegaly is an acquired disorder usually caused by growth hormone-secreting pituitary adenoma, resolution of which requires correction of the excess hormone production. Recently, intraoperative magnetic resonance imaging (iMRI) was reported to be useful during the endoscopic endonasal approach (EEA) for pituitary adenoma. The present study was performed to quantitatively assess the role of iMRI in improving surgical outcomes in EEA for acromegaly.

METHODS

Twenty surgeries for acromegaly in EEA performed at Shinshu University Hospital between April 2016 and March 2020 were reviewed retrospectively. The inclusion criteria were cases without severe cavernous sinus tumor invasion (Knosp grade 0 - 3) or history of prior pituitary surgery. Fifteen consecutive patients were enrolled in this study. Clinical characteristics and postoperative clinical outcomes were compared between patients with and without use of iMRI during EEA for acromegaly.

RESULTS

Conventional navigation-guided surgery was performed in nine patients, and six underwent iMRI-guided EEA for acromegaly. Gross total resection (GTR) was obtained in the six (100%) patients in the iMRI group, and in four (44.4%) patients in the conventional group without iMRI. Postoperative clinical outcomes, including hormonal remission rate and surgical complications, were comparable between the two groups.

CONCLUSION

Although iMRI significantly increased the GTR rate, we found no direct evidence of increased hormonal remission rate by use of iMRI. It is important to confirm complete tumor resection carefully with not only iMRI findings, but also with intraoperative high-definition endoscopic direct visualization to increase the hormonal remission rate of acromegaly.

What is the current clinical practice in pituitary adenoma surgery in Europe? European Pituitary Adenoma Surgery Survey (EU-PASS) results-technical part

Pituitary adenoma surgery has evolved rapidly in recent decades, changing clinical practice markedly and raising new challenges. There is no current consensus or guidelines for perioperative care that includes possible complication management. This study aims to determine current practice across European neurosurgical centres. We created a list of eligible departments performing pituitary adenoma surgery based on cooperation with EANS, national neurosurgical societies, and personal communication with local neurosurgeons. We contacted the chairpersons from each department and asked them (or another responsible neurosurgeon) to fill out the survey. The survey consisted of 58 questions. For further analysis, departments were divided into subgroups: "academic"/ "non-academic centre", "high-volume"/"low-volume", "mainly endoscopic"/ "mainly microscopic"/ "mixed practise", and by geographical regions. Data from 254 departments from 34 countries were obtained. The average time to complete the survey was 18 min. Notably, the endoscopic approach is the predominant surgical approach in Europe, used in 56.8% of the centres. In routine cases without intraoperative cerebrospinal fluid leak, high-volume centres are less pedantic with sellar closure when compared with low-volume centres (p < 0.001). On the other hand, when a postoperative cerebrospinal fluid leak occurs, high-volume centres are more active and indicate early reoperation (p = 0.013). Less than 15% of the participating centres perform early postoperative MRI scans. Marked variation was noted among different groups of respondents and some contentious issues are discussed. Such information can encourage useful debate about the reasons for the variations seen and perhaps help develop standardised protocols to improve patient outcomes. A future research focus is to compare European results with other regions.

Radiographic and clinical outcomes using intraoperative magnetic resonance imaging for transsphenoidal resection of pituitary adenomas

OBJECTIVE

The utility and safety of intraoperative MRI (iMRI) for resection of pituitary adenomas is not clearly established in the context of advances in endoscopic approaches. The goal in this study was to evaluate the safety and efficacy of iMRI for pituitary adenoma resection, with endoscopic transsphenoidal (ETS) versus microscopic transsphenoidal (MTS) approaches.

METHODS

Radiographic and clinical outcomes of all pituitary adenomas resected using iMRI between 2008 and 2017 at a single institution were retrospectively evaluated.

RESULTS

Of 212 tumors treated, 131 (62%) underwent further resection based on iMRI findings, resulting in a significant increase in gross-total resection on postoperative MRI compared with iMRI (p = 0.0001) in both ETS and MTS groups. iMRI increased rates of gross-total resection for cavernous sinus invasion Knosp grades 1 and 2, but not in Knosp ≥ 3 across treatment groups (p < 0.0001). The extent of resection on postoperative MRI was significantly correlated with increased progression-free survival (p < 0.0001). Initial hormone remission off medical therapy was achieved in 64%, with a significantly higher rate of remission in tumors resected via the ETS approach (81%) compared with the MTS approach (55%) (p = 0.02). The rate of persistent new hormone deficit was low at 8%, including a 2.8% rate of permanent diabetes insipidus, and 45% of patients had improvement in preoperative hormone deficit following surgery. Serious postoperative complications including CSF leaks requiring reoperation were rare at 1%, with no postoperative infections.

CONCLUSIONS

These results suggest that iMRI is a safe and effective method of increasing the extent of resection for pituitary adenomas while preserving hormone function. When paired with the endoscope, iMRI may offer the ability to tailor more aggressive removal of tumors while optimizing pituitary function, resulting in high rates of secretory hormone remission. Secretory tumors and adenomas with Knosp grade < 3 cavernous sinus invasion may benefit most from the use of iMRI.

ICAR: endoscopic skull-base surgery

BACKGROUND

Endoscopic skull-base surgery (ESBS) is employed in the management of diverse skull-base pathologies. Paralleling the increased utilization of ESBS, the literature in this field has expanded rapidly. However, the rarity of these diseases, the inherent challenges of surgical studies, and the continued learning curve in ESBS have resulted in significant variability in the quality of the literature. To consolidate and critically appraise the available literature, experts in skull-base surgery have produced the International Consensus Statement on Endoscopic Skull-Base Surgery (ICAR:ESBS).

METHODS

Using previously described methodology, topics spanning the breadth of ESBS were identified and assigned a literature review, evidence-based review or evidence-based review with recommendations format. Subsequently, each topic was written and then reviewed by skull-base surgeons in both neurosurgery and otolaryngology. Following this iterative review process, the ICAR:ESBS document was synthesized and reviewed by all authors for consensus.

RESULTS

The ICAR:ESBS document addresses the role of ESBS in primary cerebrospinal fluid (CSF) rhinorrhea, intradural tumors, benign skull-base and orbital pathology, sinonasal malignancies, and clival lesions. Additionally, specific challenges in ESBS including endoscopic reconstruction and complication management were evaluated.

CONCLUSION

A critical review of the literature in ESBS demonstrates at least the equivalency of ESBS with alternative approaches in pathologies such as CSF rhinorrhea and pituitary adenoma as well as improved reconstructive techniques in reducing CSF leaks. Evidence-based recommendations are limited in other pathologies and these significant knowledge gaps call upon the skull-base community to embrace these opportunities and collaboratively address these shortcomings.

Outcomes of the Endoscopic Transsphenoidal Surgery for Resection of Pituitary Adenomas Utilizing Extracapsular Dissection Technique with a Cotton Swab

Purpose

The purpose of this study was to determine the effectiveness and safety of a cotton swab for extracapsular dissection in endoscopic transsphenoidal surgery (ETSS) for pituitary adenoma (PA).

Materials and Methods

A retrospective review of patients undergoing ETSS for PA from 2014 to 2017 was undertaken. Only patients with extracapsular dissection by cotton swab with the intent to completely remove the tumor were included. Assessment of the prospectively recorded clinical, laboratory, and radiographic presentation as well as the intra- and postoperative data was carried out. Factors influencing the extent of resection were analyzed.

Results

Of the 222 patients, one hundred cases met the inclusion criteria. The cohort consisted of 81 nonfunctioning and 19 functioning PAs. Fifty patients presented with visual disturbance and 34 patients had prior surgical treatment. The majority of PAs was macroadenoma (97%) with 73% modified Hardy Stage C and 38% Knosp Grade 4. Intraoperative cerebrospinal fluid (CSF) leakage was the most frequently noted complication (78%). Meningitis occurred in three cases and repeat ETSS for CSF leakage repair was necessary in three patients. No death or vascular injury was observed. At 12 months after ETSS, magnetic resonance imaging scan confirmed 43% complete tumor resection. Previous surgery and Knosp Grade 4 were the strong factors for incomplete PA removal by multivariate logistic regression analysis. For functioning PAs, thirteen patients (68.42%) achieved biochemical remission.

Conclusion

Cotton swab for extracapsular dissection proved its clinical effectiveness and safety. In spite of the technique, negative predictors for complete PA resection were parasellar extension and previous surgery.

Economics of Acromegaly Treatment in Brazil: A Budget Impact Analysis of Pituitary Surgery Compared with Long-Term Octreotide LAR

BACKGROUND

Acromegaly is a rare, chronic and debilitating disease whose treatment places a high burden on health systems. In the reality of the Brazilian public health network, many patients are kept on drug treatment because of barriers to access to surgery.

OBJECTIVE

The aim of this study was to estimate the costs and budget impact of routine transsphenoidal endoscopic surgery in relation to those of long-term drug treatment with octreotide long-acting release (LAR) from a cohort of patients followed at the referral medical centre for acromegaly treatment in the Federal District, Brazil.

METHODS

Based on micro-costing data collected using mixed methods from a local perspective of the public health system, we performed a budget impact analysis (BIA) on a 3-year time horizon. Uncertainty was handled with deterministic (tornado and scenario) and probabilistic (Monte Carlo simulations) sensitivity analyses.

RESULTS

Compared with the continued use of octreotide LAR at a dose of 30 mg every 28 days, the incremental budget impact of conducting two surgeries per month, considering a cure rate of 55%, could bring savings of approximately US$879,362.18 (95% CI 860,176.29-898,548.08) over 3 years. Depending on the key variable values, the savings amplitude ranged from US$431,836.39 to US$1,519,132.04.

CONCLUSIONS

Improving access to surgery could result in significant cost reductions in acromegaly treatment. The present study stands out for being the first to estimate the costs of transsphenoidal surgery in the context of the public health system in Brazil.

The optimal surgical techniques for pituitary tumors

In this paper, the currently used and well evaluated techniques for the surgery of pituitary tumors will be reviewed. Since the first surgical approaches to pituitary tumors more than 100 years have elapsed. Various surgical techniques have been developed, refined and standardized. Most of these tumors are to date treated via transsphenoidal approaches. Many pituitary adenomas, particularly, smaller, enclosed ones, can be completely excised and a selective adenomectomy is usually attempted. It leads to remission of hormonal oversecretion and also to recovery of pituitary function in many patients. The resection of pseudocapsule around the adenoma seems to improve the operative results further. Transcranial approaches, employing craniotomies, are still needed in some patients with pituitary adenomas and in many of those harbouring craniopharyngiomas. The operative techniques will be described and briefly commented. Moreover, the application and usefulness of several technical developments will be reviewed, such as the use of the endoscope, magnetic resonance imaging, fluorenscent dyes and neuronavigation. The use of the intraoperative Doppler probe, ultrasound and the value of intraoperative hormonal measurements will be briefly discussed. There is sufficient evidence that the best and optimal outcome in terms of tumor resection and correction of hormonal oversecretion as well as the lowest rate of complications are obtained in centers of excellence with sufficiently experienced, specialized surgeons and a high patient load.

Role and mechanisms of a three-dimensional bioprinted microtissue model in promoting proliferation and invasion of growth-hormone-secreting pituitary adenoma cells

Growth-hormone-secreting pituitary adenoma (GHSPA) is a benign tumour with a high incidence and large economic burden, which greatly affects quality of life. The aetiological factors are yet to be clarified for GHSPA. Conventional two-dimensional (2D) monolayer culture of tumour cells cannot ideally reflect the growth status of tumours in the physiological environment, and insufficiencies of in vitro models have severely restricted the progress of cancer research. Three-dimensional (3D) bioprinting technology is being increasingly used in various fields of biology and medicine, which allows recapitulation of the in vivo growth environment of tumour cells. In this study, a GHSPA microtissue model was established using 3D bioprinting. Tumour cells in the 3D environment exhibited more active cell cycle progression, secretion, proliferation, invasion, and tumourigenesis compared with those in the 2D environment. Furthermore, the molecular mechanisms of the 3D-printed microtissue model were explored. We demonstrated that the 3D-printed microtissue provides an excellent in vitro model at the tissue level for oncological research and may facilitate in-depth studies on the aetiology, treatment, drug resistance, and long-term prognosis of GHSPA .

Surgical Results and Predictors of Initial and Delayed Remission for Growth Hormone-Secreting Pituitary Adenomas Using the 2010 Consensus Criteria in 162 Patients from a Single Center

BACKGROUND

The factors associated with initial and delayed remission after growth hormone (GH)-secreting pituitary adenoma excision have not been completely elucidated.

METHODS

We recruited 185 consecutive patients who had undergone resection of GH-secreting pituitary adenomas from January 2013 to December 2014 and assessed their tumor characteristics and surgical outcomes. The criteria for initial or delayed remission (using the 2010 consensus criteria) were normalized insulin-like growth factor 1 (IGF-1) levels, GH levels <0.4 μg/L with an oral glucose tolerance test, and/or random GH levels <1.0 μg/L at or after the postoperative 3-month (PO3M) follow-up, without adjuvant therapy.

RESULTS

Remission was achieved in 92 of 162 patients (56.8%) after surgery alone and was associated with a lower Knosp grade of 0-2 and lower postoperative day 1 GH level on multivariate regression analysis. A baseline IGF-1 index (IGF-1 level/upper limit of normal) of <2.835 predicted for initial remission at the PO3M follow-up (positive predictive value, 95.3%; negative predictive value, 36.6%; P < 0.001). The PO3M IGF-1 index was significantly lower in the delayed remission group than in the nonremission group. Furthermore, the former had had fewer invasive tumors (1.23 ± 0.21 vs. 1.77 ± 0.37 [9.52% vs. 76.47%]; P < 0.001). A PO3M IGF-1 index of <1.485 predicted for delayed remission during subsequent follow-up (positive predictive value, 84.6%; negative predictive value, 92.3%; P < 0.001).

CONCLUSIONS

A lower Knosp grade of 0-2 and lower postoperative day 1 GH level were independent predictors of surgical remission. The baseline IGF-1 and PO3M IGF-1 indexes might predict for initial and delayed remission, respectively.

Intraoperative low field MRI in transsphenoidal pituitary surgery

BACKGROUND

Intraoperative low field MRI (iMRI, 0.15 T) during transsphenoidal surgery on pituitary adenomas (PAs) may significantly improve tumor removal. However, extensive surgery can lead to pituitary hormone deficiency. Furthermore, introduction of iMRI will prolong duration of surgery, which may elevate risk of postoperative infections.

METHODS

Overall, 180 transsphenoidal surgeries for PAs from 2007 to 2015 were included. IMRI was available from 2011 to 2015, during this period 67/78 (86%) surgeries were with iMRI (iMRI, n = 67). A total of 113 surgeries were performed without iMRI (controls). All surgical procedures were performed by microscopic technique. Tumor size, hormonal status and vision were assessed before surgery and 3-5 months postoperatively.

RESULTS

Gross total resection (GTR), mean tumor remnant volume and ∆-volumes were comparable between iMRI and controls: 15% (10/66) vs 23% (26/109) (P = 0.17), 2.97 cm³ (0.9-5) vs 2.1 cm³ (1.6-2.6) (P = 0.3) and 4.5 cm³ (3.6-5.5) vs 5.1 cm³ (4.2-6) (P = 0.4), respectively. Duration of surgery was significantly longer during iMRI vs controls: 126 min (117-135) vs 98 min (92-103) (P < 0.001). New pituitary-adrenal deficiency in iMRI vs controls was seen in 35% (17/48) and 35% (23/66) of surgeries, respectively (P = 0.95). New thyroid deficiency was found in 33% (13/29) and 41% (28/69) and visual field deficiencies improved in 44% (19/43) and 38% (23/60) in iMRI vs controls, respectively (P > 0.1).

CONCLUSION

Tumor remnant after pituitary surgery was not significantly reduced using intraoperative low field MRI. Duration of surgery was increased in iMRI, but was not associated with increased infection rate. Pituitary hormonal function and vision were comparable between iMRI and controls.

Microsurgical versus endoscopic transsphenoidal resection for acromegaly: a systematic review of outcomes and complications

PURPOSE

The aim of this systematic review is to evaluate the long-term endocrine outcomes and postoperative complications following endoscopic vs. microscopic transsphenoidal resection (TSR) for the treatment of acromegaly.

METHODS

A literature review was performed, and studies with at least five patients who underwent TSR for acromegaly, reporting biochemical remission criteria and long-term remission outcomes were included. Data extracted from each study included surgical technique, perioperative complications, biochemical remission criteria, and long-term remission outcomes.

RESULTS

Fifty-two case series from 1976 to 2016 met the inclusion criteria, comprising 4375 patients. Thirty-six reports were microsurgical (n = 3144) and 13 were endoscopic (n = 940). Three studies compared microsurgical (n = 111) to endoscopic TSR outcomes (n = 180). The overall initial and long-term remission rates were 58.2 vs. 57.4% and 69.2 vs. 70.2% for the microsurgical and endoscopic groups, respectively. For microadenomas, the initial and long-term remission rates were 77.6 vs. 82.2% and 76.9 vs. 73.5% for microsurgical and endoscopic approaches, respectively. For macroadenomas, the initial and long-term remission rates were 46.9 vs. 60.0% and 40.2 vs. 61.5% for microsurgical and endoscopic approaches, respectively. The rates of postoperative CSF leak were 3.0 vs. 2.3% for the microscopic and endoscopic groups, respectively. The rates of hypopituitarism and transient diabetes insipidus were 6.7 vs. 6.4% and 9.0 vs. 7.8% for the microscopic and endoscopic groups, respectively.

CONCLUSIONS

Both endoscopic and microsurgical approaches for TSR of growth hormone-secreting adenomas are viable treatment options for patients with acromegaly, and yield similarly high rates of remission under the most current consensus criteria.

The surgical treatment of acromegaly

PURPOSE

Surgical extraction of as much tumour mass as possible is considered the first step of treatment in acromegaly in many centers. In this article the potential benefits, disadvantages and limitations of operative acromegaly treatment are reviewed.

METHODS

Pertinent literature was selected to provide a review covering current indications, techniques and results of operations for acromegaly.

RESULTS

The rapid reduction of tumour volume is an asset of surgery. To date, in almost all patients, minimally invasive, transsphenoidal microscopic or endoscopic approaches are employed. Whether a curative approach is feasible or a debulking procedure is planned, can be anticipated on the basis of preoperative magnetic resonance imaging. The radicality of adenoma resection essentially depends on localization, size and invasive character of the tumour. The normalization rates of growth hormone and IGF-1 secretion, respectively, depend on tumour-related factors such as size, extension, the presence or absence of invasion and the magnitude of IGF-1 and growth hormone oversecretion. However, also surgeon-related factors such as experience and patient load of the centers have been shown to strongly affect surgical results and the rate of complications. As compared to most medical treatments, surgery is relatively cheap since the costs occur only once and not repeatedly. There are several new technical gadgets which aid in the surgical procedure: navigation and variants of intraoperative imaging.

CONCLUSIONS

For the mentioned reasons, current algorithms of acromegaly management suggest an initial operation, unless the patients are unfit for surgery, refuse an operation or only an unsatisfactory resection is anticipated. A few suggestions are made when a re-operation could be considered.