Microsurgical anatomy of the diaphragma sellae and its role in directing the pattern of growth of pituitary adenomas

Identifying prognostic predictors for postoperative pituitary neuroendocrine tumour recurrence: an integrated clinical, radiological, and immunohistochemistry assessment

OBJECTIVE

Pituitary neuroendocrine tumours (PitNETs) are the second most common type of intracranial tumour. Several studies have explored the prognostic factors for PitNETs. However, prognostic factors for postoperative PitNET recurrence remain not fully understood. This study aimed to explore potential prognostic factors for PitNET recurrence, such as surrounding tissue invasion and the extent of surgical resection in patients with postoperative PitNETs.

METHODS

We included 106 patients who underwent PitNET surgery between 2013 and 2018, dividing them into two groups: those with recurrence and those without recurrence. Tumours were classified based on demographics, neuroradiological, and immunohistological characteristics. Univariate and multivariate analyses were used to determine factors predicting recurrence. Kaplan-Meier plots and log-rank tests were used to analyse each independent factor based on the cumulative 5-year recurrence rate.

RESULTS

During the 5-year follow-up period, 29.2% of the patients (n = 31) had disease recurrence. Univariate analysis showed that predictors of recurrence included cavernous and sphenoid sinus invasions, optic chiasm compression, larger tumour volume, giant adenoma >4 cm, and gross total resection (GTR). Multivariate analysis showed that lactotroph tumour type, sphenoid sinus invasion, and GTR were independent predictors. Kaplan-Meier analysis revealed significant differences in the 5-year recurrence rate among the three independent predictors, with significantly lower recurrence rate in patients with lactotroph tumours and GTR, and a significantly higher recurrence risk in patients with sphenoid sinus invasion.

CONCLUSIONS

Lactotroph tumour type, sphenoid sinus invasion, and GTR are independent predictors of postoperative PitNET recurrence. This study provides insights into the factors affecting postoperative PitNET recurrence.

Intrasellar Arachnoid Diverticulae as a Risk Factor for Intraoperative Cerebrospinal Fluid Leakage in Patients Undergoing Endoscopic Transsphenoidal Surgery

BACKGROUND AND OBJECTIVES

Intrasellar arachnoid diverticulae can often be identified on preoperative imaging in patients undergoing endoscopic transsphenoidal surgery. The objective of this study was to characterize arachnoid diverticulae both qualitatively and quantitatively in a large institutional cohort of patients with pituitary tumors and to evaluate its association with intraoperative cerebrospinal fluid (CSF) leak.

METHODS

Preoperative imaging studies of 530 patients who underwent primary endoscopic transsphenoidal resection of pituitary tumors were examined both quantitatively and qualitatively for the presence of an intrasellar arachnoid diverticulum. A matched cohort analysis was performed to compare patients with a "significant" (>50% sellar depth) diverticulum with those with nonsignificant/no diverticulum. Morphologically, diverticulae were separately classified as Type 1 (ventral CSF cleft with no tumor/gland tissue between sellar face and infundibulum) or Type 2 (central CSF cleft with tumor/gland tissue between sellar face and infundibulum).

RESULTS

Arachnoid diverticulae were noted in 40.2% of cases, and diverticulum depth was linearly correlated with tumor size and body mass index. A significant diverticulum was identified in 66 cases (12.5%) and was significantly associated with the functional tumor subtype ( P = .005) and intraoperative CSF leak ( P < .001). Type 1 clefts were associated with nonfunctional pathology ( P = .034) and the presence of suprasellar extension ( P = .035) and tended to be deeper than Type 2 clefts ( P < .001), with a higher incidence of intraoperative CSF leak ( P = .093). On logistic regression analysis, only the presence of a significant diverticulum was independently associated with intraoperative CSF leak (odds ratio 4.545; 95% CI 2.418-8.544; P < .001).

CONCLUSION

The presence of an intrasellar arachnoid diverticulum should alert the surgeon to an elevated risk of intraoperative CSF leak during transsphenoidal surgery for pituitary tumors. A relatively limited surgical exposure tailored to the craniocaudal extent of the sellar pathology should be considered in these patients.

Rarely Used Endoscopic Transnasal Transdiaphragmatic Technique in Patients with Suprasellar Extension: A Tertiary Center's Experience with Eleven Patient Cases

OBJECTIVE

As surgical techniques become less invasive, the use of endoscopy in brain surgery supports this trend. Numerous endoscopic surgical approaches have been defined, especially for skull base diseases. The current study summarizes our experience of using the rarely reported endoscopic transnasal transdiaphragmatic approach through the existing hole in the diaphragma sella to access lesions extending into the suprasellar region.

METHODS

Our surgical team performed 4876 endoscopic endonasal surgeries between August 1997 and December 2022 at the Department of Neurosurgery, Pituitary Research Center, Faculty of Medicine, Kocaeli University. The study retrospectively analyzed data from 11 patients who had undergone endoscopic transnasal transdiaphragmatic surgery since January 2020. Preoperative and postoperative magnetic resonance imaging, pituitary function examination, and clinical observation were carried out.

RESULTS

The mean age of the patients was 31.1 ± 10.7 years and the female/male ratio was 6:5. Pathologic subtypes observed included breast cancer metastasis (n = 1), adrenocorticotropic hormone-secreting adenoma (n = 4), growth hormone-secreting adenoma (n = 3), craniopharyngioma (n = 2), and Rathke cleft cyst (n = 1). The mean postoperative hospital stay was 4.7 ± 1.1 days and none of the patients showed cerebrospinal fluid leakage during this period.

CONCLUSIONS

The endoscopic transnasal transdiaphragmatic approach may be considered an alternative to the conventional extended endoscopic transnasal approach in patients with lesions extending into the suprasellar region. The main strength of this method is that it facilitates suprasellar region access through a small dural incision and bone defect in the base of the skull. As a result, it also reduces the risk of postoperative cerebrospinal fluid leakage and associated complications.

Endonasal endoscopic surgery for pituitary adenomas

Pituitary adenomas are slow-growing, benign intracranial tumors that can be characterized as functional (hormone-producing) or non-functional (non-hormone producing). Symptoms therefore arise from either endocrinologic abnormalities or mass effect on surrounding structures resulting in symptoms such as visual impairment and headache. In the last two decades, technical innovations have shifted surgical resection of such adenomas to endoscopic endonasal approaches. In this review, we describe the evolving approach to pituitary adenomas in the modern endoscopic era, including preoperative multidisciplinary review, relevant surgical anatomy, and a description of the technical nuances of standard and expanded approaches to the anterior skull base.

Anatomical variations of foramen of the diaphragma sellae and neighboring structures: a cadaveric study

The aim of our study was to examine the variations and types of foramen of diaphragma sellae (FDS) and their relationship with nearby surgical landmarks on cadavers.Twenty adult (9 male, 11 female) formalin-fixed cadaveric heads were bilaterally used to analyze the anatomical relationships around the supradiaphragmatic region of sella turcica. Lengths and distances of nearby surgical landmarks were measured by a digital microcaliper. SPSS version 25 was used to analyze the comparison between genders and body sides. Dorsum sellae distances to tuberculum sellae and the optic chiasm(OC) were higher in males than females (p < 0.05). Type 8 infundibulum passage was the most common variation with 50%. There was no finding related to types 1-4 of infundibulum passage. Thus, the present study has indicated that the infundibulum passes mostly from the posterior half of the foramen. The shape of the foramen was irregular in 45%, circular in 20%, sagittally oval in 20%, and horizontally oval in 15% of the cases. The OC was noted normal in 60%, prefixed in 35%, and postfixed in 5% of the cases. Comprehensive anatomical knowledge about the types of the FDS and their neighboring structures is crucial for preoperative planning of sellar region diseases in terms of navigating the region when accessing the foramen. Discrimination of variations of FDS, OC, and pituitary stalk, their relationships, and differences between genders is useful to minimize potential surgical complications.

Morphological Classification of Pituitary Tumors With Suprasellar Extension

BACKGROUND AND OBJECTIVES

The objective of this study was to study the association among various morphological parameters and surgical outcomes in pituitary macroadenomas with suprasellar extension.

METHODS

MRI studies of 160 patients undergoing endoscopic transsphenoidal resection of pituitary macroadenomas with suprasellar extension were reviewed. In the coronal plane, tumors were classified into Type 1 (dome-shaped, no constriction at the level of diaphragma sellae) and Type 2 (dumbbell-shaped, with constriction at the level of diaphragma sellae). Based on the dome-to-neck ratio (D/Nr), Type 2 tumors were further classified as Type 2A (wide neck; D/Nr >1 and <1.3) and Type 2B (narrow neck; D/Nr ≥1.3). Surgical outcomes and complications were analyzed using a logistic regression model. Overall extent of resection (EOR) and presence of residual sellar-suprasellar tumor was separately assessed in all patients with available postoperative MRI (n = 149).

RESULTS

There were 108 Type 1 tumors and 26 patients each in the Type 2A and Type 2B subgroups. Tumor subtype was significantly associated with tumor size (P < .001), intraoperative cerebrospinal fluid leak (P < .001), EOR (P < .001), postoperative suprasellar residual tumor (P < .001), and postoperative complications, including diabetes insipidus (P = .005) and visual worsening (P = .003). On multivariate analysis, after adjusting for confounders, Type 2B tumors were negatively associated with EOR (odds ratio [OR] 0.22; 95% CI 0.07-0.68; P = .008) and associated with the presence of postoperative suprasellar residual tumor (OR 18.08; 95% CI 5.20-62.89; P < .001), intraoperative cerebrospinal fluid leak (OR 5.33; 95% CI 1.89-14.99; P = .002), and postoperative diabetes insipidus (OR 4.89; 95% CI 1.67-14.35; P < .001).

CONCLUSION

Preoperative tumor classification based on D/Nr is clinically and surgically relevant, and Type 2B macroadenomas are significantly associated with lower rates of gross total resection and higher rates of postoperative complications after endoscopic transsphenoidal resection.

Pituitary adenoma with oculomotor cistern extension: membranous anatomy and clinical application

BACKGROUND

The anatomical basis of pituitary adenomas (PAs) with oculomotor cistern (OC) extension as a growth corridor is overlooked in the literature. In this paper, the authors use the technique of epoxy sheet plastination to study the membranous structure of the OC and validate the results by retrospective analysis of patients with OC extension.

METHODS

Eighteen specimens were used to study the membranous anatomy surrounding the OC using the epoxy sheet plastination technique. Thirty-four patients with OC extension were retrospectively reviewed.

RESULTS

The OC consisted of two thin membranous layers. The inner layer was extended by the arachnoid layer from the posterior fossa, and the lateral layer consisted of the dura mater sinking from the roof of the cavernous sinus. The oculomotor nerve is more likely to displace with a superolateral trajectory due to the weakness of the posterior dura and the relatively large space in the medial and posterior trajectories, which is consistent with the intraoperative observations. Among the anatomical factors that affect the PA by OC extension, we found that the relative position of the internal carotid artery (ICA) and posterior clinoid process may lead to the narrowing of the OC. Of 34 cases, 28 patients achieved total resection. Among 24 preoperative patients with oculomotor nerve palsy, 16 cases were relieved to varying degrees postoperatively. There was no ICA injury or severe intracranial infection found in any of the patients.

CONCLUSIONS

Extension into the OC is influenced by two anatomical factors: a weak point in the dura in the posterior OC and a potential space beyond this region of the dura. Meticulous knowledge of the membranous anatomy in endoscopic endonasal surgery is required to safely and effectively resect PA with OC extension.

The Party Wall: Redefining the Indications of Transcranial Approaches for Giant Pituitary Adenomas in Endoscopic Era

The evolution of endoscopic trans-sphenoidal surgery raises the question of the role of transcranial surgery for pituitary tumors, particularly with the effectiveness of adjunct irradiation. This narrative review aims to redefine the current indications for the transcranial approaches for giant pituitary adenomas in the endoscopic era. A critical appraisal of the personal series of the senior author (O.A.-M.) was performed to characterize the patient factors and the tumor's pathological anatomy features that endorse a cranial approach. Traditional indications for transcranial approaches include the absent pneumatization of the sphenoid sinus; kissing/ectatic internal carotid arteries; reduced dimensions of the sella; lateral invasion of the cavernous sinus lateral to the carotid artery; dumbbell-shaped tumors caused by severe diaphragm constriction; fibrous/calcified tumor consistency; wide supra-, para-, and retrosellar extension; arterial encasement; brain invasion; coexisting cerebral aneurysms; and separate coexisting pathologies of the sphenoid sinus, especially infections. Residual/recurrent tumors and postoperative pituitary apoplexy after trans-sphenoidal surgery require individualized considerations. Transcranial approaches still have a critical role in giant and complex pituitary adenomas with wide intracranial extension, brain parenchymal involvement, and the encasement of neurovascular structures.

Predictive model of resection in endoscopic endonasal approach for pituitary adenomas based on anatomical limits

INTRODUCTION

The aim of this project is to study several anatomical-radiological features of pituitary adenomas obtained from preoperative radiological images and to analyze their relationship with the extent of resection achieved through the endoscopic endonasal approach. The second objective was to create a prediction model of the extent of resection.

MATERIAL AND METHODS

We retrospectively evaluated 105 patients. Tumor volume, Knosp grade, suprasellar-diaphragm coefficient and invasion of the posterior compartment have been analyzed. The extent of resection was assessed by analyzing the postoperative magnetic resonance. We created the predictive scale using statistically independent variables.

RESULTS

When each of the variables has been studied individually, a statistically significant value of all of them is appreciated to obtain a complete resection. However, only the Knosp grade and the suprasellar-diaphragm coefficient had a statistically significant value as independent variables. The sum of the Odds Ratio obtained from the Knosp scale, and the suprasellar-diaphragm coefficient gives the probability of complete resection. A new set of cases was employed to validate the scale.

CONCLUSIONS

The cavernous sinus invasion and the newly designed suprasellar diaphragm coefficient are directly related to the extent of resection in pituitary adenoma surgery performed by a transellar endoscopic approach. Moreover, based on both radiologic factors, a predictive scale may predict the probability of complete resection in a series of patients.

Clinical Applicability of the Sellar Barrier Concept in Patients with Pituitary Apoplexy: Is It Possible?

There is evidence of association between sellar barrier thickness and intraoperative cerebrospinal fluid (CSF) leakage, impacting the postoperative prognosis of the patients. The aim of this study is to analyze the clinical applicability of the sellar barrier concept in a series of operated patients with pituitary apoplexy (PA). A retrospective study was conducted including 47 patients diagnosed with PA who underwent surgical treatment through a transsphenoidal approach. Brain magnetic resonance imaging (MRI) of the patients were evaluated and classified utilizing the following criteria: strong barrier (greater than 1 mm), weak barrier (less than 1 mm), and mixed barrier (less than 1 mm in one area and greater than 1 mm in another). The association between sellar barrier types and CSF leakage was analyzed, both pre- and intraoperatively. The preoperative MRI classification identified 10 (21.28%) patients presenting a weak sellar barrier, 20 patients (42.55%) with a mixed sellar barrier, and 17 patients (36.17%) exhibiting a strong sellar barrier. Preoperative weak and strong sellar barrier subtypes were associated with weak (p ≤ 0.001) and strong (p = 0.009) intraoperative sellar barriers, respectively. Strong intraoperative sellar barrier subtypes reduced the odds of CSF leakage by 86% (p = 0.01). A correlation between preoperative imaging and intraoperative findings in the setting of pituitary apoplexy has been observed.

A retrospective cohort study assessing geometrical parameters related to visual deterioration in pituitary macroadenoma

PURPOSE

We aim to identify specific parameters that will allow identification of those patients at greater risk of vision loss, specifically variables such as geometry, volume and size of the pituitary tumour.

METHODOLOGY

Volume measurements were made with both manual (using the formula width × height × length × 0.5) and video size, sub-voxel interpolation using Brainlab software. The shape of the tumour was divided into four categories, ovoid, dumbbell, pyramidal and other. Chiasmal compression was divided into central and lateral compression and the chiasm location was classified based on pre/post and normal fixed chiasm in relation to the tuberculum sella. We used a visual impairment score ranging from (0-100), which was then further subdivided in to four grades: Grade I - 0-25 (mild); Grade II - 26-50 (moderate); Grade III - 51-75 (severe); Grade IV - 76-100 (subtotal or complete).

RESULTS

Univariate analysis of variables related to vision loss found tumour volume, suprasellar growth and lateral chiasmal compression related to pre-operative vision loss. On multivariate regression analysis tumour volume and lateral chiasmal compression remained significant (p < 0.008). In relation to post-operative vision, univariate analysis indicated that variables such as giant macroadenoma, pre-operative visual impairment score and suprasellar growth were significant. Multivariate analysis showed pre-operative visual impairment and suprasellar growth as the only statistically significant variables.

CONCLUSION

Our ROC analysis suggests tumours with suprasellar extension 16 mm (sensitivity 85 %, specificity 67 %) in sagittal plane are more likely to result in moderate to severe grade vision loss (VIS grade ≥ 2).

Change in the pituitary stalk deviation angle after transsphenoidal surgery can predict the development of diabetes insipidus for pituitary adenomas

Purpose

We aimed to assess the factors influencing the development of diabetes insipidus after transsphenoidal surgery for pituitary adenomas.

Methods

A retrospective analysis was conducted on the clinical data of patients with pituitary adenomas who underwent transsphenoidal surgery. The predictors of postoperative diabetes insipidus were determined using statistical analysis.

Results

Of the 415 patients who underwent microscopic transsphenoidal surgery for pituitary adenomas, 196 experienced postoperative diabetes insipidus. The sinking depth of the diaphragma sellae and the difference between the preoperative and postoperative pituitary stalk deviation angles in the diabetes insipidus group were greater than those in the non-diabetes insipidus group. Logistic regression analysis showed that the risk of diabetes insipidus after transsphenoidal surgery was higher in patients with a larger difference in their pituitary stalk deviation angles (odds ratio = 2.407, 95% CI = 1.335-4.342; P = 0.004).

Conclusion

The difference in the pituitary stalk deviation angle could predict the onset of diabetes insipidus after transsphenoidal surgery for pituitary adenomas.

Radio-Morphometric Analysis of Sella Turcica in Relation to Age and Gender in Sri Ganganagar Population: A Prospective Cephalometric Study

Background Sella turcica (ST) is a crucial structure that is morphologically situated in the median position and is well-utilised in cephalometrics. This saddle-shaped sella constitutes a significant radiographic landmark for various related analyses. Therefore, studying its varying dimensions in different populations is of utmost importance. This paper evaluates and compares the linear dimensions and morphological variations of ST in different facial skeletal classes in relation to age and gender using lateral cephalograms in the Sri Ganganagar population. Methodology The study population was selected through simple random sampling from the accessible population of the Sri Ganganagar district. A total of 180 participants of both genders were selected from patients who visited the outpatient clinic of the Department of Oral Medicine and Radiology of Surendra Dental College and Research Institute in Sri Ganganagar. These samples were equally divided into three age groups. Apart from typical morphology, five possible variations of ST were determined. The area of ST on the lateral cephalogram was also evaluated. The extent of ST was calculated from the tubercle portion to the top of the dorsal side. The relative deepness of the sella was assessed by making a tangent across the innermost point of the sella. SPSS software was utilised for statistical analysis and related inferences. Results In the study sample (n = 180), 50% were men and 50% were women. The sample was divided into three equal groups based on age: Group I (n = 60; 33.33%) consisted of participants aged 15-20; Group II (n = 60; 33.33%) consisted of participants aged 21-25; and Group III (n = 60; 33.33%) consisted of participants aged 26-30. Conclusions The anteroposterior diameter of the sella structure is strongly related to age progression with no significant gender correlation. The most common shape of ST other than the normal one was oblique. Additionally, skeletal relationships showed a significant relationship with the shape of ST in the study population.

Relationship with the diaphragm to predict the surgical outcome in large and giant pituitary adenomas

Objective

Large and giant pituitary adenomas (L- and G-PAs) continue to remain a surgical challenge. The diaphragm may have a role in determining the shape of the tumor and therefore influencing the extent of resection. Our study aims to analyze our surgical series of L- and G-PAs according to their relationship with the diaphragm and invasion of cavernous sinus (CS).

Material and methods

We performed a retrospective analysis of our surgical series of patients operated for L- and G-PAs. We categorized the tumors into four grades according to their relationship with the diaphragm: grade 1 (supradiaphragmatic component with a wide incompetent diaphragm), grade 2 (purely infra-diaphragmatic tumor with a competent diaphragm), grade 3 (dumbbell-shape tumors), and grade 4 (multilobulated tumor with invasion of the subarachnoid space).

Results

A total of 37 patients were included in our analysis. According to our classification, 43.3% of patients had grade 1 tumors, 27% had grade 2, 5.4% had grade 3, and 24.3% had grade 4 tumors. CS invasion was confirmed intraoperatively in 17 out of 37 patients (46%). The gross total resection (GTR) was obtained in 19% of the cases, near-total resection in 46%, and subtotal resection in 35%. All the patients who achieved GTR had grade 1 tumors and the lowest rate of CS invasion (p < 0.01).

Conclusion

Radiological evaluation of the tumor relationship with the diaphragm, invasion of CS, and invasion of the subarachnoid space are crucial to plan the surgical strategy and maximize the possibilities of achieving GTR in L- and G-PAs.

Dumbbell-shaped pituitary adenomas: prognostic factors for prediction of tumor nondescent of the supradiaphragmal component from a multicenter series

OBJECTIVE

Dumbbell-shaped pituitary adenomas (DSPAs) are a subgroup of macroadenomas with suprasellar extension that are characterized by a smaller diameter at the level of the diaphragma sellae opening compared with the supradiaphragmal tumor component (SDTC). Hence, DSPAs may be particularly prone to a nondescending suprasellar tumor component and risk for residual tumor or postoperative bleeding.

METHODS

A multicenter retrospective cohort analysis of 99 patients with DSPA operated on via direct endoscopic endonasal transsphenoidal approach between 2011 and 2020 was conducted. Patient recruitment was performed at two tertiary care centers (Medical University of Vienna and University of Southern California) with expertise in endoscopic skull base surgery. DSPA was defined as having a smaller diameter at the level of the diaphragma sellae compared with the SDTC.

RESULTS

On preoperative MRI, all DSPAs were macroadenomas (maximum diameter range 17-71 mm, volume range 2-88 cm3). Tumor descent was found in 73 (74%) of 99 patients (group A), and nondescent in 26 (26%) of 99 patients (group B) intraoperatively. DSPAs in group A had a significantly smaller diameter (30 vs 42 mm, p < 0.001) and significantly smaller volume (10 vs 22 cm3, p < 0.001) than those in group B. The ratio of the minimum area at the level of the diaphragmal opening in comparison with the maximum area of the suprasellar tumor component ("neck-to-dome area") was significantly lower in group A than in group B (1.7 vs 2.7, p < 0.001). Receiver operating characteristic curve analysis revealed an area under the curve of 0.75 (95% CI 0.63-0.87). At a cutoff ratio of 1.9, the sensitivity and specificity for a nondescending suprasellar tumor component were 77% and 34%, respectively.

CONCLUSIONS

In the present study, the neck-to-dome area ratio was of prognostic value for prediction of intraoperative tumor nondescent in DSPAs operated on via a direct endonasal endoscopic approach. Pituitary adenoma SDTC nondescent carried the inherent risk of hemorrhagic transformation in all cases.

How I do it: endoscopic endonasal chiasmopexy for optic chiasm prolapse

BACKGROUND

Prolapse of the optic system into an empty sella is an unusual complication of the management of pituitary tumors.

METHOD

We described the technical nuances for an endoscopic endonasal chiasmopexy, the indications for the procedure, and the caveats on the diagnosis of optic chiasm prolapse.

CONCLUSION

The endoscopic endonasal chiasmopexy provides a direct route to lift the optic system. In most cases, the procedure may be achieved extradurally, protecting the chiasm from manipulation and postoperative fibrosis.

Microwaves as Diagnostic Tool for Pituitary Tumors: Preliminary Investigations

To date, tumors, the second cause of death worldwide, are a modern medicine plight. The development of rapid, cost-effective and reliable prevention and diagnostics tools is mandatory to support clinicians and ensure patients’ adequate intervention. Pituitary tumors are a class of neoplasm, which calls for suitable and ad hoc diagnostic tools. Recently, microwaves have gained interest as a non-ionizing, non-invasive valuable diagnostic approach for identifying pathologic tissues according to their dielectric properties. This work deals with the preliminary investigation of the feasibility of using microwaves to diagnose pituitary tumors. In particular, it focuses on benign tumors of the adenohypophysis, e.g., the pituitary adenomas. It is assumed to access the region of interest of the pituitary region by following a trans-sphenoidal approach. The problem was modeled by developing an equivalent transmission line model of the multi-layered, lossy tissues (front bone of sphenoid sinuses, air in the sinuses, posterior bone of sphenoid sinuses, the pituitary gland and the tumor). The forward problem was developed to investigate the transmission coefficient for identifying the most favorable propagation conditions. Then, it was analyzed if, by the solution of an inverse problem, it is possible to reconstruct the permittivity and electrical conductivity profiles and identify the tumor presence. The results are promising since a maximum reconstruction error of 8% is found, in the worst case, thus paving the way for the use of microwaves for the diagnosis of pituitary tumors.

Classifying Pituitary Adenoma Invasiveness Based on Radiological, Surgical and Histological Features: A Retrospective Assessment of 903 Cases

Invasiveness is a major predictor of surgical outcome and long-term prognosis in patients with pituitary adenomas (PAs). We assessed PA invasiveness via radiological, surgical and histological perspectives to establish a classification scheme for predicting invasive behavior and poor prognosis. We retrospectively analyzed 903 patients who underwent transnasal-transsphenoidal surgery between January 2013 and December 2019. Radiological (hazard ratio (HR) 5.11, 95% confidence interval (CI): 3.98−6.57, p < 0.001) and surgical (HR 6.40, 95% CI: 5.09−8.06, p < 0.001) invasiveness better predicted gross-total resection (GTR) and recurrence/progression-free survival (RPFS) rates than did histological invasiveness (HR 1.44, 95% CI: 1.14−1.81, p = 0.003). Knosp grades 2 (HR 4.63, 95% CI: 2.13−10.06, p < 0.001) and 3 (HR 2.23, 95% CI: 1.39−3.59, p = 0.011) with surgical invasiveness were better predictors of prognosis than corresponding Knosp grades without surgical invasiveness. Classifications 1 and 2 were established based on radiological, surgical and histological invasiveness, and Knosp classification and surgical invasiveness, respectively. Classification 2 predicted RPFS better than Knosp classification and Classification 1. Overall, radiological and surgical invasiveness were clinically valuable as prognostic predictors. The convenience and good accuracy of Invasiveness in Classification 2 is useful for identifying invasive PAs and facilitating the development of treatment plans.

Pseudocapsule-Based Resection for Pituitary Adenomas via the Endoscopic Endonasal Approach

Introduction

The endoscopic endonasal approach (EEA) is a safe and effective treatment for pituitary adenomas (PAs). Since extracapsular resection (ER) of PAs improves tumor resection and endocrine remission rates, the interface between the pseudocapsule and gland draws increasing attention. However, it is difficult to precisely dissect the tumor along the exact boundary, and complete removal of the tumor increases the risks of normal tissue damage and cerebrospinal fluid (CSF) leakage. In this study, we investigated the extracapsular resection as well as the pseudocapsule histology to evaluate the effectiveness and safety of pseudocapsule-related surgical interventions.

Methods

From December 2017 to December 2019, 189 patients of PAs via EEA in our single center were analyzed retrospectively. The images, operative details, and clinical follow-up of patients were collected. Sixty-four patients underwent pseudocapsule-based ER, and 125 patients also underwent traditional intracapsular resection (IR) with or without intensive excision for FPAs. The clinical characteristics, tumor resection, endocrinological outcomes, and postoperative morbidities of the two groups were compared. Informed consent for publication of our article was obtained from each patient. Histological examination of pseudocapsule was performed using hematoxylin and eosin and reticulin staining.

Results

The gross total recession was 62 (96.9%) in the ER group and 107 (85.6%) cases in the IR group, whereas the endocrine remission rate was 29/31 (93.5%) and 40/53 (75.5%) cases, respectively. Anterior pituitary functions were not aggravated postoperatively in any patient, but transient diabetes insipidus (DI) occurred more in the IR group (64.0%) than in ER (48.4%). Pseudocapsule specimens were obtained in 93 patients, and clusters of small cell aggregation were detected in 11 pseudocapsule specimens (11.8%) whereas other patients showed no remarkable developed pseudocapsule. Intraoperative CSF leak occurred more in the ER group (28.1%) than in the IR group (13.6%), but no difference was seen between two groups postoperatively. No case of intracranial hematoma or pituitary crisis occurred in both groups. After a mean follow-up of 22.8 months, tumor recurrence was observed in 4 (2.1%) cases.

Conclusion

Pseudocapsule-based extracapsular resection of PAs via EEA is an effective and safe procedure to achieve complete resection with high and sustained endocrine remission and without deteriorating pituitary function.

Utilizing a Novel Pituitary Retractor for Early Descent of the Diaphragma Sellae during Endoscopic Transsphenoidal Pituitary Surgery

Objective

Early descent of the diaphragm sellae (DS) during endoscopic endonasal transsphenoidal surgery (EETS) for pituitary macroadenoma surgery is occasionally a troublesome event by blocking the surgical field. Here we introduce an alternative technique with the new pituitary retractor and present our clinical experiences.

Methods

We designed a simple and rigid pituitary retractor with the least space occupation in the nasal cavity to be compatible in EETS. The pituitary retractor was held by external holder system to support the herniated DS stably. We retrospectively reviewed a clinical 22 cases of pituitary macroadenomas underwent EETS using the pituitary retractor.

Results

The pituitary retractor stably pushed up the herniated DS in all cases, and the surgeon proceeded the procedure with bimanual maneuver. The pituitary retractor was helpful to remove tumors around the medial cavernous sinus and behind the DS in 16 and seven cases, respectively. In four cases, the meticulous hemostasis was completed with the direct visualization by the DS elevation with this retractor. Gross total tumor resection was performed in 20/22 patients (91%). The impaired visual function and hypopituitarism were improved in 18/20 (90%) and 7/14 (50%) patients after surgery, respectively. There was no complication related with the pituitary retractor.

Conclusion

During EETS for pituitary macroadenomas, the novel pituitary retractor reported in this study is a very useful technique when the herniated DS block the surgical field and bimanual maneuver. This pituitary retractor can help to result in the excellent surgical outcomes with minimal morbidity.

Diaphragma sellae sinking can predict the onset of hyponatremia after transsphenoidal surgery for pituitary adenomas

PURPOSE

Sinking of the diaphragma sellae (DS) may stretch the pituitary stalk, which in turn impairs neurohypophyseal function; thus, it may play a role in the development of postoperative hyponatremia. We aimed to assess the factors influencing the development of hyponatremia after transsphenoidal surgery (TSS) for pituitary adenomas and analyze the effect of DS sinking on hyponatremia.

METHODS

After applying the inclusion and exclusion criteria, we retrospectively analyzed the clinical data of patients with pituitary adenoma who underwent TSS. The pituitary gland was scanned using a 3.0-T magnetic resonance imaging, and sagittal and coronal images were acquired. We evaluated the following: preoperative and postoperative hypothalamus‒pituitary‒thyroid axis function, hypothalamus‒pituitary‒adrenal axis function, intra-operative cerebrospinal fluid leaks, diabetes insipidus, hyponatremia, time from the day of surgery to the day of discharge, and time of hyponatremia onset.

RESULTS

Of the 460 patients who had microscopic TSS for pituitary adenoma, 83 experienced postoperative hyponatremia. Hyponatremia occurred approximately 5.25 days postoperatively and persisted for 5.54 days. The lowest average blood sodium level was 123.9 mEq/L, which occurred at 7.49 days after surgery. Logistic regression analysis showed that the risk of hyponatremia was greater for patients with a significant DS sinking depth, a large pituitary stalk deviation angle difference, and a longer postoperative "measurable pituitary stalk". The difference in blood sodium levels between pre-TSS and 2 days post-TSS was also an independent predictor of postoperative hyponatremia onset.

CONCLUSION

DS sinking plays an important role in predicting hyponatremia onset after TSS for pituitary adenomas.

Anatomic Variation for the Endoscopic Endonasal Transsphenoidal Approach

Knowledge of anatomy and its variations is the key to safe and efficient surgery. The endoscopic endonasal route to the sella has evolved to become the preferred route to access a wide variety of diseases. We describe the skeletal, vascular, and neural anatomic variations that could be encountered from the nasal phase, through the sphenoid phase, to the sellar phase of the operative exposure. A preoperative checklist is also provided.

The Difference Between Preoperative and Postoperative Pituitary Stalk Deviation Angles Can Predict Delayed Hyponatremia After Transsphenoidal Surgery

OBJECTIVE

Our aim was to assess the factors influencing the development of delayed hyponatremia after transsphenoidal surgery (TSS) for pituitary adenomas and analyze the effect of the difference between preoperative and postoperative pituitary stalk deviation angles on delayed hyponatremia.

METHODS

A retrospective study was performed on the clinical data of patients with pituitary adenomas who were treated with TSS at a single institution. On the basis of the observation of indicators such as pituitary stalk deviation angle and length of "measurable pituitary stalk" on magnetic resonance imaging, we determined the predictors of postoperative delayed hyponatremia through univariate and multivariate analyses.

RESULTS

Microscopic TSS was performed in 422 patients with pituitary adenoma, of whom 66 experienced postoperative delayed hyponatremia. Logistic regression analysis showed that the risk of delayed hyponatremia was greater for patients with a large difference between preoperative and postoperative pituitary stalk deviation angle (odds ratio = 1.040, 95% confidence interval: 1.018-1.051; P < 0.001) and a large difference in the "measurable pituitary stalk" (odds ratio = 1.128, 95% confidence interval: 1.011-1.258; P = 0.032), and patients with high blood sodium on the second day after surgery have a lower probability of developing delayed hyponatremia.

CONCLUSIONS

This study is the first to suggest the important role of the difference between preoperative and postoperative pituitary stalk deviation angles in predicting the development of delayed hyponatremia after TSS for pituitary adenomas.

Identification of the Extradural and Intradural Extension of Pituitary Adenomas to the Suprasellar Region: Classification, Surgical Strategies, and Outcomes

Objective

Suprasellar pituitary adenomas (PAs) can be located in either extradural or intradural spaces, which impacts surgical strategies and outcomes. This study determined how to distinguish these two different types of PAs and analyzed their corresponding surgical strategies and outcomes.

Methods

We retrospectively analyzed 389 patients who underwent surgery for PAs with suprasellar extension between 2016 to 2020 at our center. PAs were classified into two main grades according to tumor topography and their relationships to the diaphragm sellae (DS) and DS-attached residual pituitary gland (PG). Grade 1 tumors were located extradurally and further divided into grades 1a and 1b, while grade 2 tumors were located intradurally.

Results

Of 389 PAs, 292 (75.1%) were surrounded by a bilayer structure formed by the DS and the residual PG and classified as grade 1a, 63 (16.2%) had lobulated or daughter tumors resulting from the thinning or absence of the residual PG and subsequently rendering the bilayer weaker were classified as Grade 1b, and the remaining 34 (8.7%) PAs that broke through the DS or traversed the diaphragmic opening and encased suprasellar neurovascular structures were classified as Grade 2. We found that the gross total removal of the suprasellar part of grade 1a, 1b, and 2 PAs decreased with grading (88.4%, 71.4%, and 61.8%, respectively). The rate of major operative complications, including cerebrospinal fluid leakage, hemorrhage, and death, increased with grading.

Conclusions

It is essential to identify whether PAs with suprasellar extension are located extradurally or intradurally, which depends on whether the bilayer structure is intact. PAs with an intact bilayer structure were classified as grade 1. These were extradural and usually had good surgical outcomes and lower complications. PAs with no bilayer structure surrounding them were classified as grade 2. These were intradural, connected to the cranial cavity, and had increased surgical complications and a lower rate of gross total removal. Different surgical strategies should be adopted for extradural and intradural PAs.

Arachnoid and dural reflections

The dura mater is the major gateway for accessing most extra-axial lesions and all intra-axial lesions of the central nervous system. It provides a protective barrier against external trauma, infections, and the spread of malignant cells. Knowledge of the anatomical details of dural reflections around various corners of the skull bases provides the neurosurgeon with confidence during transdural approaches. Such knowledge is indispensable for protection of neurovascular structures in the vicinity of these dural reflections. The same concept is applicable to arachnoid folds and reflections during intradural excursions to expose intra- and extra-axial lesions of the brain. Without a detailed understanding of arachnoid membranes and cisterns, the neurosurgeon cannot confidently navigate the deep corridors of the skull base while safely protecting neurovascular structures. This chapter covers the surgical anatomy of dural and arachnoid reflections applicable to microneurosurgical approaches to various regions of the skull base.

Surgery for diaphragma sellae meningioma: how I do it

Background

Surgery for diaphragma sellae meningiomas (DSM) remains challenging due to the intimate neurovascular relationships of the tumor. Excision of DSM along with a decompression of the optic apparatus requires a good knowledge of the skull base anatomy and a precise preoperative evaluation of the tumor extensions.

Method

We describe the key steps of transcranial approach for DSM with a video illustration. The surgical anatomy is described along with the advantages and limitations of this approach.

Conclusions

The transcranial approach allows a safe tumor excision with an early and adequate control of the neurovascular structures, while minimizing postoperative CSF rhinorrhea.

Electronic supplementary material

The online version of this article (10.1007/s00701-020-04581-6) contains supplementary material, which is available to authorized users.

Sellar Remodeling after Surgery for Nonfunctioning Pituitary Adenoma: Intercarotid Distance as a Predictor of Recurrence

Introduction  As they grow, pituitary adenoma can remodel the sella turcica and alter anatomical relationships with adjacent structures. The intercarotid distance (ICD) at the level of the sella is a measure of sella width. The purpose of this study was to (1) assess how ICD changes after transsphenoidal surgery and (2) explore whether the extent of ICD change is associated with tumor recurrence. Methods  A retrospective analysis of preoperative and postoperative coronal magnetic resonance imaging (MRI) scans was carried out by two independent assessors on patients who underwent transsphenoidal surgery for nonfunctioning pituitary macroadenomas. Preoperative tumor volume and any change in ICD following surgery were recorded and compared between groups. Logistic regression models of recurrence were generated. Results  In 36 of 42 patients, ICD fell after surgery (mean = 1.8 mm) and six cases were static. At time of follow-up (mean = 77 months), 25 had not required further intervention and 17 had undergone second surgery or radiosurgery. In patients in whom no further intervention has yet been necessary, the postoperative reduction in ICD was significantly smaller than in those who required repeat intervention (1.1 vs. 2.7 mm respectively, p  < 0.01). ICD decrease was weakly correlated with tumor volume ( r  = 0.35). ICD decrease was a significant predictor of recurrence (odds ratio [OR] = 3.15; 95% confidence interval [CI]: 1.44-6.87), largely independent of tumor volume. Conclusion  For most patients, ICD falls following surgical excision of a nonfunctioning pituitary macroadenoma. A greater reduction in ICD postsurgery appears to predict recurrence. Change in ICD shows promise as a radiographic tool for prognosticating clinical course after surgery.

Predicting Arachnoid Membrane Descent in the Chiasmatic Cistern in the Treatment of Pituitary Macroadenoma

Objective

Preoperative prediction of the arachnoid membrane descent in pituitary surgery is useful for achieving gross total removal and avoiding cerebrospinal fluid leakage resulting from tearing of the arachnoid membrane in the chiasmatic cistern. In this study, we analyzed the patterns of arachnoid membrane descent during or after pituitary tumor surgery and identified the factors related to this descent.

Methods

Analysis was restricted to pituitary macroadenomas not extending into the third ventricle or over the internal carotid artery. To minimize confounding factors, patients who underwent revision surgery, those who had a torn arachnoid during operation or small medial diaphragma sellae (DS) opening, and subtotal resections were excluded. We enrolled 41 consecutive patients in this retrospective analysis. The degree of arachnoid descent was categorized using intraoperative videos. Preoperative magnetic resonance findings, including tumor height, suprasellar extension, and variables including DS area and medial opening size, tumor composition, and displacement of the pituitary stalk and gland were evaluated to determine their correlations with arachnoid membrane descent.

Results

Arachnoid membrane descent was significantly correlated with DS area and medial opening size. Based on T2-weighted images (T2WI) magnetic resonance (MR) images, tumor composition was significantly associated with arachnoid membrane descent. Other factors were not significantly correlated with arachnoid membrane descent.

Conclusion

T2WI of tumor composition and preoperative MR imaging of DS area and medial opening provided valuable information regarding arachnoid membrane descent. These parameters may serve as fundamental measures to facilitate complete resection of pituitary macroadenomas.

Diagnosis and Surgical Management of Exophytic Suprasellar Pituitary Adenoma Extending Over the Diaphragma Sellae and Mimicking Craniopharyngioma: A Case Report

Pituitary adenomas developing from the lateral surface of the pituitary gland are referred to as exophytic pituitary adenomas. When an exophytic pituitary adenoma extends into the suprasellar region, the tumor exhibits an atypical growth pattern that makes it difficult to distinguish it from craniopharyngiomas or other parasellar lesions on MRI. A 53-year-old woman who presented with general malaise and visual disturbances was diagnosed with a brain tumor. MRI showed a suprasellar tumor presenting as superior lobulation with reticular enhancement and partial calcification. Subsequently, endoscopic transsphenoidal surgery was performed on the patient. The suprasellar tumor was found to originate from the superior surface of the normal pituitary gland and it extended into the supra-diaphragm region. Subtotal tumor resection was achieved, and her clinical symptoms subsequently improved. Exophytic suprasellar pituitary adenomas (SPAs) are extremely rare and may be mistaken for ectopic SPAs in some cases. Contrast-enhanced fast imaging employing steady-state acquisition (CE-FIESTA) can clearly depict the connection between an exophytic SPA and the normal pituitary gland via a diaphragma sellae defect. During surgery, it was seen that the exophytic SPA and anterior lobe of the pituitary gland connected with each other directly. The tumor originated from the superior surface of the pituitary gland and extended into the supra-diaphragm region. These findings clearly confirmed the difference between exophytic SPAs and ectopic SPAs. In surgical management, an exophytic SPA needs careful consideration for resecting the tumor from encased surrounding structures without vascular and nerve injury. Ultrasonic aspiration devices may be useful for safely resecting the tumor from important structures due to tissue selection. Exophytic SPAs are distinguished from ectopic SPAs with respect to the direct connection between the tumor and the normal pituitary gland. These findings can be clearly depicted using CE-FIESTA and should be confirmed during surgery. Clinicians should be aware of the risk that exophytic SPA may extend into the supra-diaphragm region and of the difficulties of resecting the tumor encasing surrounding structures in the suprasellar region.

Endoscopic anatomy of the sellar barrier: From the anatomical model to the operating room

BACKGROUND

The sellar barrier concept reflects the association between the components of the roof of the pituitary fossa and the risk of intraoperative cerebrospinal fluid (CSF) leak in the surgery of pituitary adenomas. We based our concept in previous reports on the microsurgical anatomy of the pituitary fossa's superior wall. However, proof of the usefulness of this concept in endoscopic approaches is yet missing. The aim of this study was to describe the endoscopic anatomy of the sellar barrier and its subtypes in a laboratory setting and to provide evidence of its clinical usefulness.

METHODS

We provided anatomical models in six fresh-frozen head and neck specimens. We performed an endoscopic endonasal approach and recreated a pathological model of each possible subtype of sellar barrier. To demonstrate the usefulness of this model in clinical practice, we conducted a prospective study including all patients with pituitary adenoma operated by an endoscopic approach between June and July 2019.

RESULTS

We successfully recreated the models for each subtype of sellar barrier. When analyzing the clinical cases, we found that intraoperatively, 73.69% (14) had a strong sellar barrier; 21.05% (4) had mixed sellar barrier, and 5.26% (1) had weak sellar barrier. We recorded one case of intraoperative CSF leak in a patient with a weak sellar barrier by magnetic resonance imaging.

CONCLUSION

We described the endoscopic anatomy of the sellar barrier and we recreated the three subtypes in anatomical models. We also identified these subtypes in a series of clinical cases, proving its clinical usefulness.

Anatomic and histologic features of diaphragma sellae that effects the suprasellar extension

This study aimed to determine the anatomical and histological features of diaphragma sellae that affect the suprasellar extension of intrasellar tumours. Twenty-four fresh adult cadavers were dissected for the study. Diaphragma sellae and pituitary capsules with sellar structures were resected. The diaphragma sellae was anatomically reviewed in detail. Immunohistochemical staining was performed for collagen types I, II, III, and IV. We examined the suprasellar growth of 13 sellar tumours extending superiorly through the diaphragma sellae by performing a series of 2704 endoscopic transnasal operations to analyse the anatomic and histologic results of the study. The diameter of the foramen of diaphragma sellae varied between specimens. Of 24 specimens, the diaphragma sellae in five (21%) had a tight-type foramen and those in 19 (79%) were more spacious. An increased expression of collagen types I and IV was observed in the pituitary capsule and the diaphragma sellae. In this clinical series, we observed that all types of sellar tumours could expand through the foramen. We observed radiologically and intraoperatively that the diaphragma sellae was displaced laterally and formed a dome in two cases with an adenoma extending to the suprasellar area. Two types of suprasellar extension through the diaphragma sellae are possible: 1) The collagen structure of diaphragma sellae can be destroyed by invasive tumours; 2) The morphology of the foramen of the diaphragma sellae facilitates suprasellar tumoural extension. All sellar tumours, including non-invasive cystic tumours, may invade the suprasellar area by expanding through the foramen of the diaphragma sellae.

Pituitary Adenomas and Invasiveness from Anatomo-Surgical, Radiological, and Histological Perspectives: A Systematic Literature Review

Invasiveness in pituitary adenomas has been defined and investigated from multiple perspectives, with varying results when its predictive value is considered. A systematic literature review, following PRISMA guidelines, was performed, searching PubMed and Scopus databases with terms that included molecular markers, histological, radiological, anatomical and surgical data on invasiveness of pituitary adenomas. The results showed that differing views are still present for anatomical aspects of the sellar region that are relevant to the concept of invasiveness; radiological and histological diagnoses are still limited, but might improve in the future, especially if they are related to surgical findings, which have become more accurate thanks to the introduction of the endoscope. The aim is to achieve a correct distinction between truly invasive pituitary adenomas from those that, in contrast, present with extension in the parasellar area through natural pathways. At present, diagnosis of invasiveness should be based on a comprehensive analysis of radiological, intra-operative and histological findings.

The Mixed Sellar Barrier: A New Subtype of this Novel Concept

BACKGROUND

The use of the recent concept of sellar barrier revealed that a specific group of patients were difficult to categorize. For this reason, we propose to add a new subtype: the mixed sellar barrier. The aim of this work was to define the new mixed barrier subtype and analyze this in a series of operated patients.

METHODS

A retrospective study was carried out. From January to December 2018, 72 patients with pituitary adenomas underwent surgery by transsphenoidal approach. Patients with more than 1 surgery were excluded. Each patient's magnetic resonance imaging (MRI) was analyzed and classified using the following criteria: strong barrier (>1 mm), weak barrier (<1 mm), and mixed barrier (<1 mm in one region and >1 mm in another part).

RESULTS

Mixed sellar barrier is the coexistence of 2 types of sellar barrier (strong and weak). The presence of a mixed sellar barrier on MRI was associated with the presence of a mixed sellar barrier intraoperatively (P < 0.0001). By using the new MRI classification that includes the mixed sellar barrier, we found a stronger statistically significant association regarding the risk of cerebrospinal fluid leak (for the extreme categories; i.e., strong and weak) compared to the original work.

CONCLUSIONS

The new mixed sellar barrier subtype was precisely defined and illustrated. The correlation between MRI and intraoperative findings for this new subtype has been demonstrated in this study. A prospective study with a larger series of patients is required for validation.

Anatomical Risk Factors for Intraoperative Cerebrospinal Fluid Leaks During Transsphenoidal Surgery for Pituitary Adenomas

BACKGROUND

Cerebrospinal fluid (CSF) fistulas are among the most clinically important and frequent complications of transsphenoidal surgery for pituitary adenomas. Between the adenoma and the CSF, a "barrier" exists that consists of ≤3 elements. These, from cephalad to caudad, are the arachnoid, dura mater (sellar diaphragm), and pituitary glandular tissue. The objective of the present study was to determine whether the presence or absence of any of these 3 anatomical elements would be associated with the development of an intraoperative CSF fistula.

METHODS

From November 2016 to June 2018, 40 patients with pituitary adenomas underwent surgery, by transsphenoidal endonasal access, under a microscope. All procedures were filmed in 3 dimensions. The intraoperative findings and preoperative magnetic resonance images were analyzed and compared. The patients who had developed a fistula were compared against those who had not.

RESULTS

In 20 patients, glandular tissue was identified between the tumor and subarachnoid space. In 13, dura mater was evident, and in 7, only the arachnoid was noted. An intraoperative CSF fistula occurred in 6 patients, all of whom had the arachnoid as the only barrier. The presence of a fistula was significantly more likely statistically for patients with an arachnoid-only barrier than for those with any other barrier composition (P < 0.001).

CONCLUSIONS

The anatomical architecture forming the roof of the pituitary fossa is an important determinant of intraoperative CSF fistula risk. When the barrier consists of only the arachnoid, the risk will be significantly greater than when the barrier contains additional elements. Preoperative magnetic resonance imaging would be useful to determine the type of the existing barrier.

Degrees of Diaphragma Sellae Descent during Transsphenoidal Pituitary Adenoma Resection: Predictive Factors and Effect on Outcome

This study is aimed to classify degrees of diaphragma sellae (DS) descent into sella turcica according to the surgical field block caused by the descent and to construct predictive imaging criteria for the degree of descent, and in addition, to determine whether there is any correlation between the degree of DS descent and the operative outcome (in the form of cerebrospinal fluid leak and/or presence of residual tumor). Totally, 72 patients were enrolled in our study. Their clinical and radiological data as well as the high definition videos of operations were retrospectively reviewed. The degree of DS descent during the operation was classified into five degrees according to surgical field block caused by the descent. We investigated the correlation between these five degrees and the clinical findings, radiological findings as well as the surgical outcomes. We found that the most important determining factors of DS descent degree were the volume and the height of the tumor portion above diaphragma opening. On the other hand, the total tumor volume, the maximum tumor height and the morphological pattern according to Wilson's system (modified from Hardy) had no statistically significant correlation with DS degree of descent. Presence of residual tumor on postoperative magnetic resonance images was significantly correlated with Wilson's classification and with supradiaphragmatic tumor height. On the other hand, cerebrospinal fluid leak showed no statistically significant difference between variable degrees of DS descent. Volumetric data of the tumor portion above the diaphragma opening are more important than morphological data for prediction of surgical field block caused by descended DS. While DS prolapse significantly increases the difficulty of the operative procedure, residual tumor presence is mainly dependent on morphological classification, especially cavernous sinus invasion.

Macroprolactinoma appearing after resolution of hydrocephalus

The role of mechanical forces influencing the growth of a pituitary adenoma is poorly understood. In this paper we report the case of a young man with hyperprolactinaemia and an empty sella secondary to hydrocephalia, who developed a macroprolactinoma following the relief of high intraventricular pressure.

Learning points:

The volume of a pituitary tumour may be influenced not only by molecular but also by local mechanical factors.

Intratumoural pressure, resistance of the sellar diaphragm and intracranial liquid pressure may play a role in the final size of a pituitary adenoma.

The presence of hydrocephalus may hide a pituitary macroadenoma.

The utility of high-resolution intraoperative MRI in endoscopic transsphenoidal surgery for pituitary macroadenomas: early experience in the Advanced Multimodality Image Guided Operating suite

OBJECTIVE

Endoscopic skull base surgery has become increasingly popular among the skull base surgery community, with improved illumination and angled visualization potentially improving tumor resection rates. Intraoperative MRI (iMRI) is used to detect residual disease during the course of the resection. This study is an investigation of the utility of 3-T iMRI in combination with transnasal endoscopy with regard to gross-total resection (GTR) of pituitary macroadenomas.

METHODS

The authors retrospectively reviewed all endoscopic transsphenoidal operations performed in the Advanced Multimodality Image Guided Operating (AMIGO) suite from November 2011 to December 2014. Inclusion criteria were patients harboring presumed pituitary macroadenomas with optic nerve or chiasmal compression and visual loss, operated on by a single surgeon.

RESULTS

Of the 27 patients who underwent transsphenoidal resection in the AMIGO suite, 20 patients met the inclusion criteria. The endoscope alone, without the use of iMRI, would have correctly predicted extent of resection in 13 (65%) of 20 cases. Gross-total resection was achieved in 12 patients (60%) prior to MRI. Intraoperative MRI helped convert 1 STR and 4 NTRs to GTRs, increasing the number of GTRs from 12 (60%) to 16 (80%).

CONCLUSIONS

Despite advances in visualization provided by the endoscope, the incidence of residual disease can potentially place the patient at risk for additional surgery. The authors found that iMRI can be useful in detecting unexpected residual tumor. The cost-effectiveness of this tool is yet to be determined.

Current biomarkers of invasive sporadic pituitary adenomas

Though pituitary adenomas (PA) are considered benign, some of them exhibit invasive behaviors such as recurrence and low rate of total surgical resection. Reliable prognostic biomarkers for invasive PA are highly desired; however they remain to be identified. In this review, we summarize the current controversial findings of biomarkers for invasive sporadic PA, and we discuss the possible reasons for the controversies.

Skull Base Anatomy

The anatomy of the skull base is complex with multiple neurovascular structures in a small space. Understanding all of the intricate relationships begins with understanding the anatomy of the sphenoid bone. The cavernous sinus contains the carotid artery and some of its branches; cranial nerves III, IV, VI, and V1; and transmits venous blood from multiple sources. The anterior skull base extends to the frontal sinus and is important to understand for sinus surgery and sinonasal malignancies. The clivus protects the brainstem and posterior cranial fossa. A thorough appreciation of the anatomy of these various areas allows for endoscopic endonasal approaches to the skull base.

Emerging Histopathological and Genetic Parameters of Pituitary Adenomas: Clinical Impact and Recommendation for Future WHO Classification

The review assesses immunohistochemical findings of somatostatin receptors and of metalloproteinases in different pituitary adenoma types and the significance of molecular genetic data. Current evidence does not support routine immunohistochemical assessment of somatostatin or dopamine receptor subtype expression on hormone-secreting or nonfunctioning pituitary adenomas. Further prospective studies are needed to define its role for clinical decision making. Until then we suggest to restrict membrane receptor profiling to individual cases or for study purposes. The problems of adenoma expansion and invasion are discussed. Despite partially contradictory publications, proteases clearly play a major role in permission of infiltrative growth of pituitary adenomas. Therefore, detection of at least MMP-2, MMP-9, TIMP-2, and uPA seems to be justified. Molecular characterization is important for familial adenomas, adenomas in MEN, Carney complex, and McCune-Albright syndrome and can gain insight into pathogenesis of sporadic adenomas.