Endoscopic endonasal management of non-functioning pituitary adenomas with cavernous sinus invasion: a 10- year experience

Advances in Pituitary Surgery

Pituitary surgery has advanced considerably in recent years with the exploration and development of various endoscopic approaches and techniques. Different endoscopic skull base approaches are being applied to access sellar tumors in different locations. Moreover, extracapsular dissection and cavernous sinus exploration have enabled gross total resection of sellar tumors where it could not have been achieved in the past. Techniques for skull base reconstruction have also progressed, allowing surgeons to remove larger and more complicated tumors than before. This review article discusses different endoscopic skull base approaches, surgical techniques for removing pituitary adenomas, and reconstruction methods for repairing postoperative low-flow and high-flow cerebrospinal fluid leakage.

Outcomes and Complications of Aggressive Resection Strategy for Pituitary Adenomas in Knosp Grade 4 With Transsphenoidal Endoscopy

Surgery for pituitary adenomas (PAs) with cavernous sinus (CS) invasion in Knosp grade 4 is a great challenge and whether to adopt a conservative or aggressive surgical strategy is controversial. The aim of this study is to provide the outcomes and complications of an aggressive resection strategy for Knosp grade 4 PAs with transsphenoidal endoscopic surgery. Outcomes and complications were retrospectively analyzed in 102 patients with Knosp grade 4 PAs. Among them, primary PAs were seen in 60 patients and recurrent PAs were seen in 42 cases. Gross total resection (GTR) of the entire tumor was achieved in 72 cases (70.6%), subtotal tumor resection (STR) in 18 cases (17.6%), and partial tumor resection (PTR) in 12 cases (11.8%). Additionally, GTR of the tumor within the CS was achieved in 82 patients (80.4%), STR in 17 patients (16.7%), and PTR in 3 patients (2.9%). Statistical analyses showed that both recurrent tumors and firm consistency tumors were adverse factors for complete resection (P<0.05). Patients with GTR of the entire tumor were more likely to have favorable endocrine and visual outcomes than those with incomplete resection (P<0.05). Overall, the most common surgical complication was new cranial nerve palsy (n=7, 6.8%). The incidence of internal carotid artery (ICA) injury and postoperative cerebrospinal fluid (CSF) leakage was 2.0% (n=2) and 5.9% (n=6), respectively. Six patients (5.9%) experienced tumor recurrence postoperatively. For experienced neuroendoscopists, an aggressive tumor resection strategy via transsphenoidal endoscopic surgery may be an effective and safe option for Knosp grade 4 PAs.

Thin-Slice Pituitary MRI with Deep Learning-based Reconstruction: Diagnostic Performance in a Postoperative Setting

Background Achieving high-spatial-resolution pituitary MRI is challenging because of the trade-off between image noise and spatial resolution. Deep learning-based MRI reconstruction enables image denoising with sharp edges and reduced artifacts, which improves the image quality of thin-slice MRI. Purpose To assess the diagnostic performance of 1-mm slice thickness MRI with deep learning-based reconstruction (DLR) (hereafter, 1-mm MRI+DLR) compared with 3-mm slice thickness MRI (hereafter, 3-mm MRI) for identifying residual tumor and cavernous sinus invasion in the evaluation of postoperative pituitary adenoma. Materials and Methods This single-institution retrospective study included 65 patients (mean age ± standard deviation, 54 years ± 10; 26 women) who underwent a combined imaging protocol including 3-mm MRI and 1-mm MRI+DLR for postoperative evaluation of pituitary adenoma between August and October 2019. Reference standards for correct diagnosis were established by using all available imaging resources, clinical histories, laboratory findings, surgical records, and pathology reports. The diagnostic performances of 3-mm MRI, 1-mm slice thickness MRI without DLR (hereafter, 1-mm MRI), and 1-mm MRI+DLR for identifying residual tumor and cavernous sinus invasion were evaluated by two readers and compared between the protocols. Results The performance of 1-mm MRI+DLR in the identification of residual tumor was comparable to that of 3-mm MRI (area under the receiver operating characteristic curve [AUC], 0.89-0.92 vs 0.85-0.89, respectively; P ≥ .09). In the identification of cavernous sinus invasion, the diagnostic performance of 1-mm MRI+DLR was higher than that of 3-mm MRI (AUC, 0.95-0.98 vs 0.83-0.87, respectively; P ≤ .02). Conventional 1-mm MRI (AUC, 0.82-0.83) showed comparable diagnostic performance to 3-mm MRI (AUC, 0.83-0.87) (P ≥ .38). With 1-mm MRI+DLR, residual tumor was diagnosed in 20 patients and cavernous sinus invasion was diagnosed in 14 patients, in whom these diagnoses were not made with 3-mm MRI. Conclusion In the postoperative evaluation of pituitary adenoma, 1-mm slice thickness MRI with deep learning-based reconstruction showed higher diagnostic performance than 3-mm slice thickness MRI in the identification of cavernous sinus invasion and comparable diagnostic performance to 3-mm slice thickness MRI in the identification of residual tumor. © RSNA, 2020 Online supplemental material is available for this article.

Gamma Knife Radiosurgery as a Primary Treatment for Nonfunctioning Pituitary Adenoma Invading the Cavernous Sinus

OBJECTIVES

Surgical resection of nonfunctioning pituitary adenoma (NFPA) invading the cavernous sinus (CS) remains a challenging and significant factor associated with incomplete resection. The residual tumor in CS is usually treated with adjuvant stereotactic radiosurgery (SRS), but there is little information concerning SRS as an initial treatment for CS-invading NFPA. In this study, we investigated the tumor control rate and clinical outcomes of the patients who received primary gamma knife radiosurgery (GKRS) for CS-invading NFPA.

METHODS

This was a single-institute retrospective analysis of 11 patients. CS invasion of tumor was categorized using the modified Knosp grading system. The median tumor volume and maximal diameter were 1.6 cm3 (range 0.4-6.5) and 17.2 mm (range 11.6-23.3), respectively. The median clinical follow-up period was 48.5 months (range 16.4-177.8). The median prescription dose at tumor margin was 15 Gy (range 11-25) and median prescription isodose was 50% (range 45-50). The maximum radiation dose to optic chiasm and optic nerve were 7.2 Gy (range 3.4-9.2) and 7.5 Gy (range 4.5-11.5), respectively.

RESULTS

Tumor control was achieved in all patients. The median tumor volume and maximal diameter at last follow-up were 0.4 cm3 (range 0.1-2.3) and 11.4 mm (range 4.7-19.5), respectively. The median volume reduction rate was 52% (range 33-88). Six patients showed downgrading of modified Knosp grade after GKRS. No patients developed GKRS-related complications such as hypopituitarism or visual disturbance.

CONCLUSIONS

SRS may be an alternative primary treatment option for CS-invading NFPA if there is no urgent and absolute indication for surgery such as optic apparatus compression.

Quality of care evaluation in non-functioning pituitary adenoma with chiasm compression: visual outcomes and timing of intervention clinical recommendations based on a systematic literature review and cohort study

PURPOSE

Surgery in patients with non-functioning pituitary macroadenomas (NFMA) is effective in ameliorating visual function. The urgency for decompression, and preferred timing of surgery related to the preoperative severity of dysfunction is unknown.

METHODS

Systematic review for evidence to provide clinical guidance for timing of surgical decompression of the optic chiasm, and a cohort study of 30 NFMA patients, in whom mean deviation (MD), and severity of visual dysfunction was assessed.

RESULTS

Systematic review 44 studies were included with a total of 4789 patients. Postoperatively, visual field defects improved in 87.0% of patients, stabilized in 12.8% and worsened in 1.0%. Specific protocols regarding timing of surgery were not reported. Only seven studies (16.7%) reported on either the duration of visual symptoms, or diagnostic, or treatment delay. Cohort study 30 NFMA patients (50% female, 60 eyes, mean age 58.5 ± 14.8 years), had a median MD of - 5.3 decibel (IQR - 3.1 to - 10.1). MD was strongly correlated with clinical severity (r =  - 0.94, P < 0.0001), and were used for severity of defects cut-off values: (1) normal >  - 2 dB, (2) mild - 2 dB to - 4 dB, (3) moderate - 4 to - 8 dB, (4) severe - 8 to - 17 dB, (5) very severe <  - 17 dB.

CONCLUSION

Surgical decompression is highly effective in improving visual function. Uniform, quantitative grading of visual dysfunction was lacking. MD is a promising quantitative outcome measure. We provide recommendations for the evaluation of timing of surgery, considering severity of visual impairment, which will need further validation based on expert clinical practice.

Quantitative Analysis of Proteome in Non-functional Pituitary Adenomas: Clinical Relevance and Potential Benefits for the Patients

Background: Non-functional pituitary adenoma (NFPA) is a common tumor that occurs in the pituitary gland, and generally without any symptoms at its early stage and without clinical elevation of hormones, which is commonly diagnosed when it grows up to compress its surrounding tissues and organs. Currently, the pathogenesis of NFPA has not been clarified yet. It is necessary to investigate molecular alterations in NFPA, and identify reliable biomarkers and drug therapeutic targets for effective treatments. Methods: Tandem mass tags (TMT)-based quantitative proteomics was used to identify and quantify proteins in NFPAs. GO and KEGG enrichment analyses were used to analyze the identified proteins. Differentially expressed genes (DEGs) between NFPA and control tissues were obtained from GEO datasets. These two sets of protein and gene data were analyzed to obtain overlapped molecules (genes; proteins), followed by further GO and KEGG pathway analyses of these overlapped molecules, and molecular network analysis to obtain the hub molecules with Cytoscape. Two hub molecules (SRC and AKT1) were verified with Western blotting. Results: Totally 6076 proteins in NFPA tissues were identified, and 3598 DEGs between NFPA and control tissues were identified from GEO database. Overlapping analysis of 6076 proteins and 3598 DEGs obtained 1088 overlapped molecules (DEGs; proteins). KEGG pathway analysis of 6076 proteins obtained 114 statistically significant pathways, including endocytosis, and spliceosome signaling pathways. KEGG pathway analysis of 1088 overlapped molecules obtained 52 statistically significant pathways, including focal adhesion, cGMP-PKG pathway, and platelet activation signaling pathways. These pathways play important roles in cell energy supply, adhesion, and maintenance of the tumor microenvironment. According to the association degree in Cytoscape, ten hub molecules (DEGs; proteins) were identified, including GAPDH, ALB, ACACA, SRC, ENO2, CALM1, POTEE, HSPA8, DECR1, and AKT1. Western-blotting analysis confirmed the upregulated expressions of SRC and PTMScan experiment confirmed the increased levels of pAKT1, in NFPAs compared to controls. Conclusions: This study established the large-scale quantitative protein profiling of NFPA tissue proteome. It offers a basis for subsequent in-depth proteomics analysis of NFPAs, and insight into the molecular mechanism of NFPAs. It also provided the basic data to discover reliable biomarkers and therapeutic targets for NFPA patients.

Direct Transcavernous Sinus Approach for Endoscopic Endonasal Resection of Intracavernous Sinus Tumors

OBJECTIVE

Because of its vascular supply and neurovascular contents, the cavernous sinus (CS) is a challenging area to dissect in the setting of skull base tumors with intracavernous extension or invasion. In the present study, we report the clinical outcomes of 14 patients with tumors with CS invasion that were surgically treated using a direct transcavernous sinus approach for endoscopic endonasal resection of their intracavernous sinus tumors.

METHODS

Fourteen patients had undergone surgery using a direct endoscopic endonasal transcavernous sinus approach. The pathologic entities included Knosp grade 3-4 pituitary adenomas (n = 8), meningioma (n = 3), squamous cell carcinoma (n = 2), and chondrosarcoma (n = 1). The indications, surgical technique, and outcomes are discussed.

RESULTS

Gross total resection was achieved in 11 patients (78.6%). All patients experienced resolution or improvement of symptoms. One patient experienced a transient oculomotor nerve palsy, which had resolved within 2 months postoperatively. No other complications occurred. For those tumors that had been grossly resected, no recurrence developed in any patient (mean follow-up, 40.4 ± 24.8 months; range 10-84).

CONCLUSIONS

Depending on the space created by intracavernous sinus tumors, use of the transanterior wall for the CS approach in endoscopic endonasal surgery could adequately treat most patients in our case series. This approach provided good visualization of the CS and can be used to treat tumors with favorable outcomes and a low incidence of complications in appropriately evaluated patients.

Endoscopic endonasal transoculomotor triangle approach for adenomas invading the parapeduncular space: surgical anatomy, technical nuances, and case series

OBJECTIVEPituitary adenomas may extend into the parapeduncular space by invading through the roof of the cavernous sinus. Currently, a transcranial approach is the preferred choice, with or without the combination of an endonasal approach. In this paper the authors present a novel surgical approach that takes advantage of the natural corridor provided by the tumor to further open the oculomotor triangle and resect tumor extension into the parapeduncular space.METHODSSix injected specimens were used to demonstrate in detail the surgical anatomy related to the approach. Four cases in which the proposed approach was used were retrospectively reviewed.RESULTSFrom a technical perspective, the first step involves accessing the superior compartment of the cavernous sinus. The interclinoid ligament should be identified and the dura forming the oculomotor triangle exposed. The oculomotor dural opening may be then extended posteriorly toward the posterior petroclinoidal ligament and inferolaterally toward the anterior petroclinoidal ligament. The oculomotor nerve should then be identified; in this series it was displaced superomedially in all 4 cases. The posterior communicating artery should also be identified to avoid its injury. In all 4 cases, the tumor invading the parapeduncular space was completely removed. There were no vascular injuries and only 1 patient had a partial oculomotor nerve palsy that completely resolved in 2 weeks.CONCLUSIONSThe endoscopic endonasal transoculomotor approach is an original alternative for removal of tumor extension into the parapeduncular space in a single procedure. The surgical corridor is increased by opening the dura of the oculomotor triangle and by working below and lateral to the cisternal segment of the oculomotor nerve.

Investigating the application of diving endoscopic technique in determining the extent of pituitary adenoma resection via the trans-nasal-sphenoidal approach

The aim of the present study was to investigate the advantages and disadvantages of the diving endoscopic technique in pituitary adenoma surgery, and the application value in determining the extent of tumor resection. A total of 37 patients with pituitary adenoma initially underwent tumor resection under an endoscope-assisted microscope via standard trans-nasal-sphenoidal approach, and tumor cavity structure was observed by applying the diving endoscopic technique. Surgery was subsequently performed again under a microscope or endoscope. The diving endoscopic technique allowed surgeons to directly observe the structure inside a tumor cavity in high-definition. In the present study, 24 patients had pituitary macroadenomas or microadenomas that did not invade the cavernous sinus, and were considered to have undergone successful total resection. Among these patients, no tumor residues were observed through the diving endoscopic technique. Some white lichenoid or fibrous cord-like tissues in the tumor cavity were considered to be remnants of tumors. However, pathology confirmed that these were not tumor tissues. For tumors that invaded the cavernous sinus in 13 patients, observation could only be conducted under the angulation endoscope of the diving endoscope; i.e., the operation could not be conducted under an endoscope. The present study suggests that the diving endoscopic technique may be used to directly observe the resection extent of tumors within the tumor cavity, especially the structure of the tumor cavity inside the sella turcica. The present study also directly validates the reliability of pituitary adenoma resection under endoscope-assisted microscope. In addition, the diving endoscopic technique also allows the surgeon to observe the underwater environment within the sella turcica.

Visual outcomes after endoscopic endonasal pituitary adenoma resection: a systematic review and meta-analysis

PURPOSE

Patients with pituitary adenomas often present with visual deficits. While the aim of endoscopic endonasal transsphenoidal surgery (EETS) is to improve these deficits, permanent worsening is a possible outcome. The aim of this meta-analysis was to evaluate the effect of EETS for pituitary adenomas on visual outcomes.

METHODS

A meta-analysis was conducted according to the PRISMA guidelines. Pooled prevalence was calculated for complete recovery, improvement, and deterioration of visual field deficits, visual acuity and unspecified visual function in fixed- and random-effect models, including assessment of heterogeneity (I²) and publication bias (Begg's test).

RESULTS

Out of 2636 articles, 35 case series were included in the meta-analysis. Results are described for fixed-effect models. For patients with impaired visual acuity, only one study reported complete recovery (27.2%). Pooled prevalence for improvement was 67.5% (95% CI = 59.1-75.0%), but with considerable heterogeneity (I²: 86.0%), and 4.50% (95% CI = 1.80-10.8%) for patients experiencing deterioration. For patients with visual field deficits, the prevalence was 40.4% (95% CI = 34.8-46.3%) for complete recovery, 80.8% (95% CI = 77.7-83.6%) for improvement, and 2.3% (95% CI = 1.1-4.7%) for deterioration. For the unspecified visual outcomes, pooled prevalence of complete recovery was 32.9% (95% CI: 28.5-37.7%), but with considerable heterogeneity (I² = 84.2%). The prevalence was 80.9% (95% CI = 77.9-83.6) for improvement and 2.00% (95% CI = 1.10-3.40%) for deterioration. Random-effect models yielded similar results. Publication bias was non-significant for all the outcomes.

CONCLUSION

While visual deficits improved after EETS in the majority of patients, complete recovery was only achieved in less than half of the patients and some patients even suffered from visual deterioration.

Reoperative endoscopic endonasal surgery for residual or recurrent pituitary adenomas

OBJECTIVE

Regrowth of the lesion after surgical removal of pituitary adenomas is uncommon unless subtotal resection was originally achieved in the first surgery. Treatment for recurrent tumor can involve surgery or radiotherapy. Locations of residual tumor may vary based on the original approach. The authors evaluated the specific sites of residual or recurrent tumor after different transsphenoidal approaches and describe the surgical outcome of endoscopic endonasal transsphenoidal reoperation.

METHODS

The authors analyzed a prospectively collected database of a consecutive series of patients who had undergone endoscopic endonasal surgeries for residual or recurrent pituitary adenomas after an original transsphenoidal microscopic or endoscopic surgery. The site of the recurrent tumor and outcome after reoperation were noted and correlated with the primary surgical approach. The chi-square or Fisher exact test was used to compare categorical variables, and the Mann-Whitney U-test was used to compare continuous variables between surgical groups.

RESULTS

Forty-one patients underwent surgery for residual/recurrent pituitary adenoma from 2004 to 2015 at Weill Cornell Medical College. The previous treatment was a transsphenoidal microscopic (n = 22) and endoscopic endonasal (n = 19) surgery. In 83.3% patients (n = 30/36) there was postoperative residual tumor after the initial surgery. A residual tumor following endonasal endoscopic surgery was less common in the sphenoid sinus (10.5%; 2/19) than it was after microscopic transsphenoidal surgery (72.7%; n =16/22; p = 0.004). Gross-total resection (GTR) was achieved in 58.5%, and either GTR or near-total resection was achieved in 92.7%. Across all cases, the average extent of resection was 93.7%. The rate of GTR was lower in patients with Knosp-Steiner Grade 3–4 invasion (p < 0.0005). Postoperative CSF leak was seen in only one case (2.4%), which stopped with lumbar drainage. Visual fields improved in 52.9% (n = 9/17) of patients and were stable in 47% (n = 8/17). Endocrine remission was achieved in 77.8% (n = 14/18) of cases, 12 by surgery alone and 2 by adjuvant medical (n = 1) and radiation (n = 1) therapy. New diabetes insipidus occurred in 4.9% (n = 2/41) of patients—in one of whom an additional single anterior hormonal axis was compromised—and 9.7% (n = 4/41) of patients had a new anterior pituitary hormonal insufficiency.

CONCLUSIONS

Endonasal endoscopic reoperation is extremely effective at removing recurrent or residual pituitary adenomas that remain after a prior surgery, and it may be preferable to radiation therapy particularly in symptomatic patients. Achievement of GTR is less common when lateral cavernous sinus invasion is present. The locations of residual/recurrent tumor were more likely sphenoidal and parasellar following a prior microscopic transsphenoidal surgery and sellar following a prior endonasal endoscopic surgery.

Endoscopic Endonasal Surgery for Tumors of the Cavernous Sinus: A Series of 234 Patients

BACKGROUND

Cavernous sinus (CS) tumors often are considered inoperable. We present our experience with endoscopic endonasal surgery (EES) and compare the outcomes for different tumor.

METHODS

EES (medial or lateral approach) was used in 234 patients with CS tumors. The cohort included 175 (75%) pituitary adenomas and 59 (25%) nonadenomatous lesions.

RESULTS

Presenting symptoms were significantly different between the 2 groups, with cranial neuropathies occurring mainly in nonadenomas (P < 0.0001). The overall gross total tumor resection rate from the CS was 37.3% (37.1% in adenomas, 38.1% in non-adenomas). In total, preexisting cranial nerve (CN) dysfunction improved in 56.4% of the patients. After treatment completion (including radiation of residual tumor), 83.3% of acromegalic patients, 50% of prolactinomas and 33.3% of Cushing's disease, were in remission. Visual loss improved in 86.8% of adenomas and in 70.8% of nonadenomas. Intracavernous CN palsies improved in 77.3% of adenomas and 42.4% of nonadenomas. New permanent CN palsies occurred in 7 nonadenomas, which is significantly greater than in adenomas (P = 0.007). The leak rate of cerebrospinal fluid was 6.3% for adenomas and 11.9% for nonadenomas. Four patients suffered an internal carotid artery injury with no neurologic sequelae in 3 cases and 1 death (0.4%).

CONCLUSIONS

EES provides an easily accessible midline corridor to the CS with equivalent or superior results to transcranial approaches in the management of select tumors. Symptomatology due to CS invasion is more likely to improve in pituitary adenomas and the rate of surgical complications is greater in nonadenomas. Using a team approach, the overall mortality due to vascular injury is low.

Expanded Endonasal Endoscopic Approaches to the Skull Base for the Radiologist

The cranial base is a complex 3-D region that contains critical neurovascular structures. Pathologies affecting this region represent some of the most challenging lesions to manage due to difficulty with access and risk of significant postoperative morbidity. With the development of expanded endonasal endoscopic approaches, skull base surgeons use the nose and paranasal sinuses as a corridor to access selected ventral skull base lesions. This review discusses high-resolution imaging in the evaluation of patients with skull base lesions considered for endonasal endoscopic surgery, summarizes various expanded endonasal endoscopic approaches, and provides examples of commonly used expanded endonasal endoscopic procedures.

Different Volumetric Measurement Methods for Pituitary Adenomas and Their Crucial Clinical Significance

Confirming the status of residual tumors is crucial. In stationary or spontaneous regression cases, early treatments are inappropriate. The long-used geometric calculation formula is 1/2 (length × width × height). However, it yields only rough estimates and is particularly unreliable for irregularly shaped masses. In our study, we attempted to propose a more accurate method. Between 2004 and 2014, 94 patients with pituitary tumors were enrolled in this retrospective study. All patients underwent transsphenoidal surgery and received magnetic resonance imaging (MRI). The pre- and postoperative volumes calculated using the traditional formula were termed A1 and A2, and those calculated using the proposed method were termed O1 and O2, respectively. Wilcoxon signed rank test revealed no significant difference between the A1 and O1 groups (P = 0.1810) but a significant difference between the A2 and O2 groups (P < 0.0001). Significant differences were present in the extent of resection (P < 0.0001), high-grade cavernous sinus invasion (P = 0.0312), and irregular shape (P = 0.0116). Volume is crucial in evaluating tumor status and determining treatment. Therefore, a more scientific method is especially useful when lesions are irregularly shaped or when treatment is determined exclusively based on the tumor volume.

Endoscopic transorbital route to the cavernous sinus through the meningo-orbital band: a descriptive anatomical study

OBJECTIVE Exposure of the cavernous sinus is technically challenging. The most common surgical approaches use well-known variations of the standard frontotemporal craniotomy. In this paper the authors describe a novel ventral route that enters the lateral wall of the cavernous sinus through an interdural corridor that includes the removal of the greater sphenoid wing via a purely endoscopic transorbital pathway. METHODS Five human cadaveric heads (10 sides) were dissected at the Laboratory of Surgical NeuroAnatomy of the University of Barcelona. To expose the lateral wall of the cavernous sinus, a superior eyelid endoscopic transorbital approach was performed and the anterior portion of the greater sphenoid wing was removed. The meningo-orbital band was exposed as the key starting point for revealing the cavernous sinus and its contents in a minimally invasive interdural fashion. RESULTS This endoscopic transorbital approach, with partial removal of the greater sphenoid wing followed by a "natural" ventral interdural dissection of the meningo-orbital band, allowed exposure of the entire lateral wall of the cavernous sinus up to the plexiform portion of the trigeminal root and the petrous bone posteriorly and the foramen spinosum, with the middle meningeal artery, laterally. CONCLUSIONS The purely endoscopic transorbital approach through the meningo-orbital band provides a direct view of the cavernous sinus through a simple and rapid means of access. Indeed, this interdural pathway lies in the same sagittal plane as the lateral wall of the cavernous sinus. Advantages include a favorable angle of attack, minimal brain retraction, and the possibility for dissection through the interdural space without entering the neurovascular compartment of the cavernous sinus. Surgical series are needed to demonstrate any clinical advantages and disadvantages of this novel route.

Parasellar Extension Grades and Surgical Extent in Endoscopic Endonasal Transsphenoidal Surgery for Pituitary Adenomas : A Single Surgeon's Consecutive Series with the Aspects of Reliability and Clinical Validity

Objective

The inter-rater reliability of the modified Knosp's classification was measured before the analysis. The clinical validity of the parasellar extension grading system was evaluated by investigating the extents of resection and complication rates among the grades in the endoscopic endonasal transsphenoidal surgery (EETS) for pituitary adenomas.

Methods

From November 2008 to August 2015, of the 286 patients who underwent EETS by the senior author, 208 were pituitary adenoma cases (146 non-functioning pituitary adenomas, 10 adrenocorticotropic hormone-secreting adenomas, 31 growth hormone-secreting adenomas, 17 prolactin-secreting adenomas, and 4 thyroid-stimulating hormone-secreting adenomas; 23 microadenomas, 174 macroadenomas, and 11 giant adenomas). Two neurosurgeons and a neuroradiologist independently measured the degree of parasellar extension on the preoperative sellar MRI according to the modified Knosp's classification. Inter-rater reliability was statistically assessed by measuring the intraclass correlation coefficient. The extents of resection were evaluated by comparison of the pre- and post-operative MR images; the neurovascular complications were assessed by reviewing the patients' medical records. The extent of resection was measured in each parasellar extension grade; thereafter, their statistical differences were calculated.

Results

The intraclass correlation coefficient value of reliability across the three raters amounted to 0.862. The gross total removal (GTR) rates achieved in each grade were 70.0, 69.8, 62.9, 21.4, 37.5, and 4.3% in Grades 0, 1, 2, 3A, 3B, and 4, respectively. A significant difference in the extent of resection was observed only between Grades 2 and 3A. In addition, significantly higher complication rates were observed in the groups above Grade 3A.

Conclusion

Although the modified Knosp's classification system appears to be complex, its inter-rater reliability proves to be excellent. Regarding the clinical validity of the parasellar extension grading system, Grades 3A, 3B, and 4 have a negative predictive value for the GTR rate, with higher complication rates.