Relationship between pneumatization of lateral recess in the sphenoid sinus and removal of cavernous sinus invasion in pituitary adenomas by endoscopic endonasal surgery

Volumetric measurement of paranasal sinuses and its clinical significance in pituitary neuroendocrine tumors operated using an endoscopic endonasal approach

Objective

Endoscopic endonasal surgery (EES) for deep intracranial lesions has gained popularity following recent developments in endoscopic technology. The operability of invasive pituitary neuroendocrine tumors (PitNETs) depends on the anatomy of the nasal cavity and paranasal sinus. This study aimed to establish a simple volume reconstruction algorithm of the nasal cavity and paranasal sinus. Additionally, this is the first study to demonstrate the relationship between the segmentation method and the clinical significance in patients with PitNET.

Methods

Pre-and postoperative tumor volumes were analyzed in 106 patients with primary (new-onset) PitNETs (80 nonfunctioning and 26 functioning) who underwent EES. The efficiency and accuracy of the semiautomatic segmentation with manual adjustments (SSMA) method was compared with other established segmentation methods for volumetric analysis in the nasal cavity and paranasal sinuses. Correlations between the measured nasal cavity and paranasal sinus volumes and the extent of tumor removal were evaluated.

Results

The SSMA method yielded accurate and time-saving results following the volumetric analyses of nasal cavity and paranasal sinuses with complex structures. Alternatively, the manual and semiautomatic segmentation methods proved time-consuming and inaccurate, respectively. The sphenoid sinus volume measured by SSMA was significantly correlated with the extent of tumor removal in patients with nonfunctioning Knosp grade 3 and 4 PitNET (r = 0.318; p = 0.015).

Conclusion

The volume of sphenoid sinus potentially could predict the extent of resection due to better visualization of the tumor for PitNETs with CS invasion.

Neurovascular structures in the lateral recess of the sphenoid sinus. A computed tomography evaluation

INTRODUCTION AND OBJECTIVES

Anatomical variations of the lateral recess of the sphenoid sinus and its relations with the adjacent neurovascular structures should be preoperatively evaluated to plan an adequate surgical approach and avoid iatrogenic injuries. This study aims to analyze the patterns of pneumatization of the lateral recess of the sphenoid sinus and their association with the presence of protrusion and dehiscence of the optic canal, carotid canal, vidian canal, and maxillary nerve.

MATERIALS AND METHODS

A retrospective evaluation of 320 sphenoid sinuses by computed tomography was performed. Studied variables included type of lateral recess, and protrusion, and dehiscence of the optic and carotid canal, and vidian and maxillary nerve.

RESULTS

The mean age was 45.67±17.43. A total of 55.6% (n=178) of the evaluated sphenoid sinuses corresponded to male subjects. Protrusion of the carotid canal, maxillary nerve, and vidian canal was associated with a type 3 lateral recess pneumatization, while dehiscence of these structures was most commonly observed in a type 2 lateral recess (p=<0.001).

CONCLUSIONS

Protrusion or dehiscence of neurovascular structures surrounding the sphenoid sinus has been associated with the extent of pneumatization of the lateral recess, increasing the risk of intraoperative injury. Preoperative identification of anatomical variations is mandatory to select the best approach for skull base lesions and avoid iatrogenic injuries.

Subclassification of Knosp Grade 4 Pituitary Adenoma: Bringing Insights Into the Significance of Tumor Growth Pathways

BACKGROUND

Understanding the growth pathway of Knosp grade 4 pituitary adenoma (KG4PA) has a direct impact on surgical planning and safety for tumor eviction.

OBJECTIVE

To analyze the different characteristics between KG4PAs with a focus on the tumor growth pathway and its relationship to the cavernous segment of internal carotid artery.

METHODS

Clinical data from 129 patients with KG4PAs who underwent endoscopic endonasal surgery were retrospectively reviewed. A subclassification scheme was proposed based on the tumor growth pathway and its relevant features. The clinical connotation of the subclassification on surgical outcomes was also analyzed.

RESULTS

The KG4PAs were classified into 3 types based on the tumor growth pathway and its relevant features: groups A, B, and AB. The gross total resection rate in group A (51.2%) was much lower than that in group B (87.5%) and AB (87%) with a significant difference between the 3 groups ( P = .0004). The overall rate of visual function improvement, preoperative cranial nerve (CN) palsy improvement, and postoperative hormonal remission was 85.1%, 83.3%, and 85.7%, respectively. The rate of transient CN palsy, permanent CN palsy, permanent diabetes insipidus, panhypopituitarism, CSF leakage, and internal carotid artery injury was 7.8%, 3.9%, 4.7%, 2.3%, 1.5%, and 0.7%, respectively.

CONCLUSION

The subclassification strengthens our understanding of KG4PAs on tumor growth corridors and topographic relations of tumor and cavernous segment of internal carotid artery. Furthermore, the distinction into groups 4A, 4B, and 4AB is of benefits for selecting approaches, predicting risk and avoiding complications, and generating more tailored individualized surgical strategies for KG4PAs with better outcomes.

Surgical Planning and Simulation of Endonasal Endoscopic Surgery for Pituitary Adenoma With Cavernous Sinus Invasion

BACKGROUND

Transsphenoidal endoscopic endonasal surgery (EES) provides effective treatment for patients with lesions of the sella turcica. The endoscopic technique requires different instrumentation, which depends on the gross anatomy of the nasal cavity. The treatment of lateral lesions is more challenging in EES.

OBJECTIVE

To evaluate the effect of preoperative simulation using multiple anatomic landmarks.

METHODS

Pre- and postoperative tumor volumes were analyzed in 33 patients with nonfunctioning pituitary adenomas who underwent EES (Knosp grades 3 and 4). The surgical working angle and space were three-dimensionally simulated at the plane of the anterior/posterior surgical field (tuberculum sellae/posterior clinoid process) using multiple anatomic landmarks of high-resolution computed tomography scans, such as nasal piriform aperture (proximal surgical corridor), and the width of bilateral vidian canals or lamina perpendicularis of palatine bone (distal surgical corridor). Receiver operating characteristic curves for the removed tumor volume were used to determine the cutoff value for the simulated working angle and space.

RESULTS

Simulated working space at the plane of tuberculum sellae using piriform aperture and lamina perpendicularis of palatine bone was associated with the removed tumor volume in the cavernous sinus. Patients with a larger working space (≥42.7 mm) significantly showed a higher removed tumor volume ( P = .023). There was no relationship between other parameters and the removed tumor volume.

CONCLUSION

A new method to predict the surgical field for cavernous sinus lesions around sella turcica was successfully established. Further studies are needed to define and expand applications of this simulation method.

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.

Diagnostic value of Knosp grade and modified Knosp grade for cavernous sinus invasion in pituitary adenomas: a systematic review and meta-analysis

OBJECTIVE

This study aimed to examine the reliability of existing Knosp grade (KG) and modified KG for cavernous sinus invasion (CSI).

METHODS

A thorough search of literature from 1993 to 2020 in six databases was performed. Studies that reported the intraoperative confirmation of CSI using KG and/or modified KG were included. The pooled estimates were calculated by meta-analysis with a bivariate mixed-effect model and the assessment of heterogeneity with I² statistic.

RESULTS

The final search yielded 12 eligible studies, which enrolled 3006 patients assessed with KG and 1315 patients assessed with modified KG. The results of the area under the receiver operating characteristic curve showed the good discriminative abilities of grades 2-4 (0.90), 3-4 (0.86) and 3B-4 (0.91) in predicting CSI. Grade 3A showed a remarkably lower CSI rate (44% versus 81%) and incomplete resection rate (26% versus 52%) than grade 3B. Grades 0 and 1 showed a low CSI rate. CSI and incomplete resection rates in grade 2 (30% and 21%, respectively) were close to those in grade 3A.

CONCLUSIONS

Modifying the KG improved its prognostic role in CSI and gross total resection. However, these grading systems cannot be used as the group standard for invasive and non-invasive pituitary adenomas (PAs) because of the weak reliability of the scale's middle grades (grades 2 and 3A). Authors of future PA studies should consider reporting KG as high (grades 3B and 4), medium (grades 2 and 3A) and low (grades 0 and 1) to optimise the application of the scale.

Magnetic resonance fingerprinting for preoperative differentiation between gonadotroph and non-gonadotroph pituitary macroadenomas

OBJECTIVES

To use magnetic resonance fingerprinting (MRF)-derived T1 and T2 values to differentiate gonadotroph from non-gonadotroph pituitary macroadenomas based on the 2017 World Health Organization classification of pituitary adenomas.

METHODS

A total of 57 patients with suspected pituitary macroadenomas were enrolled for analyses in this study between May 2018 and January 2020. Conventional magnetic resonance imaging (MRI) and MRF were performed in all patients before surgery using a 3-T MRI scanner. MRF-derived T1 and T2 values were compared between the gonadotroph and non-gonadotroph pituitary macroadenomas using a Mann-Whitney U test. The Knosp classification was used to evaluate cavernous sinus invasion by the adenomas. Receiver operating characteristic analyses were used to determine the diagnostic performance of T1 and T2 values.

RESULTS

Quantitative T1 and T2 values yielded from MRF of gonadotroph pituitary macroadenomas were significantly higher than those of the non-gonadotroph pituitary macroadenomas (p < 0.001 and = 0.002, respectively). The AUC for the T2 value (0.888) was significantly greater than that for the T1 value (0.742) (p = 0.034). The AUC for combined T1 and T2 values was 0.885. Non-gonadotroph pituitary macroadenomas were more likely to invade the cavernous sinus than gonadotroph pituitary macroadenomas (55% vs 26%, p = 0.026).

CONCLUSIONS

MRF may help to preoperatively differentiate between gonadotroph and non-gonadotroph pituitary macroadenomas and may be useful in guiding the treatment of these adenomas.

KEY POINTS

• Somatostatin receptor type 3 is the most abundant receptor subtype in gonadotroph pituitary adenomas. • Magnetic resonance fingerprinting may help to preoperatively differentiate between gonadotroph and non-gonadotroph pituitary macroadenomas. • Magnetic resonance fingerprinting shows potential for guiding the treatment of pituitary macroadenomas.