An advanced navigation protocol for endoscopic transsphenoidal surgery

Three-Dimensional Multimodality Image Reconstruction as Teaching Tool for Case-based learning among medical postgraduates: a focus on primary pelvic bone Tumour Education

BACKGROUND

Postgraduate medical education in oncology orthopedics confronts obstacles when instructing on pelvic tumors, primarily due to their intricate anatomy and the limitations of conventional teaching techniques. The employment of Three-dimensional multimodality imaging (3DMMI) can be considered a valuable teaching tool, as it gracefully elucidates the intricacies of pelvic anatomical structures and the interactions between tumors and surrounding tissues through three-dimensional imaging, thereby providing a comprehensive and nuanced perspective. This study aimed to assess the feasibility and effectiveness of incorporating 3DMMI in combination with a Case-Based Learning (CBL) approach for postgraduate education.

METHODS

The study encompassed a 10-week course involving 90 surgical postgraduates, focusing on common pelvic tumor diseases. Students were assigned representative clinical cases, and each group created a PowerPoint presentation based on these cases. The core educational content included fundamental knowledge of pelvic anatomy, as well as clinical presentations, radiological features, and treatment principles of common pelvic tumor diseases. The research compared two groups: a traditional CBL group (n = 45) and a 3DMMI-CBL group (n = 45). The 3DMMI-CBL group had access to advanced imaging technology for better visualization. Various evaluations, including image interpretation, theoretical knowledge, and questionnaires, were used to assess the learning outcomes.

RESULTS

The 3DMMI-CBL group outperformed the CBL group not only in the imaging diagnosis of common pelvic diseases but also in their mastery of the related theoretical knowledge. Student questionnaires indicated higher scores for the 3DMMI-CBL group in basic pelvic anatomy knowledge (8.08 vs. 6.62, p < 0.01), image interpretation (8.15 vs. 6.69, p < 0.01), learning efficiency (8.07 vs. 7.00, p < 0.01), clinical reasoning (7.57 vs. 6.77, p < 0.01), and learning interest (8.46 vs. 7.00, p < 0.01). Teacher questionnaires revealed that 3DMMI technology enhanced teachers' clinical knowledge, facilitated instruction, and increased overall satisfaction and interest in teaching.

CONCLUSION

Our study introduced an enhancement to the conventional Case-Based Learning (CBL) model by incorporating 3DMMI technology for visualizing pelvic anatomy. In contrast to pure CBL, this adaptation improved teacher instruction, substantially heightened student engagement, ignited greater interest in learning, and boosted overall efficiency, ultimately leading to positive learning outcomes. Consequently, our study demonstrated the potential feasibility and acceptability of the 3DMMI-CBL teaching method for postgraduates in pelvic bone tumor education.

Use of Neuronavigation and Augmented Reality in Transsphenoidal Pituitary Adenoma Surgery

The aim of this study was to report on the clinical experience with microscope-based augmented reality (AR) in transsphenoidal surgery compared to the classical microscope-based approach. AR support was established using the head-up displays of the operating microscope, with navigation based on fiducial-/surface- or automatic intraoperative computed tomography (iCT)-based registration. In a consecutive single surgeon series of 165 transsphenoidal procedures, 81 patients underwent surgery without AR support and 84 patients underwent surgery with AR support. AR was integrated straightforwardly within the workflow. ICT-based registration increased AR accuracy significantly (target registration error, TRE, 0.76 ± 0.33 mm) compared to the landmark-based approach (TRE 1.85 ± 1.02 mm). The application of low-dose iCT protocols led to a significant reduction in applied effective dosage being comparable to a single chest radiograph. No major vascular or neurological complications occurred. No difference in surgical time was seen, time to set-up patient registration prolonged intraoperative preparation time on average by twelve minutes (32.33 ± 13.35 vs. 44.13 ± 13.67 min), but seems justifiable by the fact that AR greatly and reliably facilitated surgical orientation and increased surgeon comfort and patient safety, not only in patients who had previous transsphenoidal surgery but also in cases with anatomical variants. Automatic intraoperative imaging-based registration is recommended.

The Role of Endonasal Endoscopic Skull Base Repair in Posttraumatic Tension Pneumocephalus

OBJECTIVES

Information about the endonasal endoscopic approach (EEA) for the management of posttraumatic tension pneumocephalus (PTTP) remains scarce. Concomitant rhinoliquorrhea and posttraumatic hydrocephalus (PTH) can complicate the clinical course.

METHODS

The authors systematically reviewed pertinent articles published between 1961 and December 2020 and identified 6 patients with PTTP treated by EEA in 5 reports. Additionally, the authors share their institutional experience including a seventh patient, where an EEA resolved a recurrent PTTP without rhinoliquorrhea.

RESULTS

Seven PTTP cases in which EEA was used as part of the treatment regime were included in this review. All cases presented with a defect in the anterior skull base, and 3 of them had concomitant rhinoliquorrhea. A transcranial approach was performed in 6/7 cases before EEA was considered to treat PTTP. In 4/7 cases, the PTTP resolved after the first intent; in 2/7 cases a second repair was necessary because of recurrent PTTP, 1 with and 1 without rhinoliquorrhea, and 1/7 case because of recurrent rhinoliquorrhea only. Overall, PTTP treated by EEA resolved with a mean radiological resolution time of 69 days (range 23-150 days), with no late recurrences. Only 1 patient developed a cerebrospinal fluid diversion infection probably related to a first incomplete EEA skull base defects repair. A permanent cerebrospinal fluid diversion was necessary in 3/7 cases.

CONCLUSIONS

Endonasal endoscopic approach repair of air conduits is a safe and efficacious second-line approach after failed transcranial approaches for symptomatic PTTP. However, the strength of recommendation for EEA remains low until further evidence is presented.

Classification of Pituitary Adenomas Invading the Cavernous Sinus Assisted by Three-Dimensional Multimodal Imaging and Its Clinical Application

Introduction  To help diagnose and evaluate the prognosis of pituitary adenoma with cavernous sinus (CS) invasion and guide endonasal endoscopic surgery (EES) assisted by intraoperative navigation (ION) with three-dimensional multimodal imaging (3D-MMI). We propose a classification of CS invasion based on 3D-MMI. Methods  We picked some appropriate cases and reconstructed the 3D-MMI and then classified them into 3 grades according to the stereo relationship among ICA, tumor and CS in 3D-MMI. Then, we applied different strategies according to their grade to remove pituitary adenomas that invaded the CS. Results  All 38 patients were divided into 3 grades. Tumors compressing the ICA and CS without CS invasion were divided into grade 1. Tumors encasing the ICA and invading the superior-posterior compartment and/or anterior-inferior compartment but without distinct separation of the ICA and CS lateral wall were deemed as grade 2. Tumors encasing the ICA and filling the lateral compartment of the CS that dissociated the lateral wall from the ICA were deemed as grade 3. The 3D-MMI enabled adequate spatial visualization of the ICA, CS and tumors. All patients were operated on under the guidance of ION with 3D-MMI. Conclusion  Classification based on 3D-MMI can better demonstrate the relationships among tumor, ICA and CS in a stereo and multi-angle view, which will have significance in guiding the surgical strategy.

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

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

Optimizing MR imaging for intraoperative image guidance in sellar pathologies

PURPOSE

With the advancement of extended endonasal approaches, the ability to surgically reach parasellar tumor extensions increase. The aim of the study was to propose an optimized imaging protocol for surgical guidance in the cavernous sinus (CS) for proper visualization structures at risk.

METHODS

Prospective case control analysis of 20 consecutive pituitary adenoma patients scheduled for endoscopic transnasal surgery. Assessment of the capability of three different MRI sequences (MPRAGE, VIBE, CISS) by 4 investigators to correctly visualize sellar and parasellar structures. Invasiveness and position of the normal pituitary gland were compared with the intraoperative findings.

RESULTS

The consensus between the 4 examiners to achieve the same results for all modalities was 40% for MPRAGE, 70% for VIBE and 60% for CISS sequences (p = 0.155). A consensus of Knosp Grade per patient was 80% for MPRAGE, 100% for VIBE and 90% for CISS (overall kappa 0.60). A higher Knosp Grade was found in MPRAGE sequences compared to the other sequences. Intraoperative status of invasiveness was correctly identified in 12/20 (60%) with MPRAGE, 19/20 (95%) with VIBE and 11/20 (55%) with CISS sequences. The position of the normal pituitary gland was most frequent evaluable in 15/20 (75%) and correctly identified in 12/15 (80%) cases.

CONCLUSION

Our data showed that VIBE sequences obtain the highest degree of consensus with intraoperative findings of invasiveness and position of the normal pituitary gland. VIBE sequences, due to their high spatial resolution and at the same time fast image acquisition could provide improved imaging for neuronavigation.

Endoscopic Transsphenoidal Surgery of Microprolactinomas: A Reappraisal of Cure Rate Based on Radiological Criteria

BACKGROUND

Current standard treatment of microprolactinomas is dopamine agonist therapy. As this drug treatment is lifelong in up to 80% of cases, many patients consult pituitary surgeons regarding a surgical alternative.

OBJECTIVE

To identify prognostic criteria for surgical remission, we reviewed outcomes of our series of microprolactinomas treated with endoscopic transsphenoidal surgery, with a special emphasis on magnetic resonance adenoma delineation and position.

METHODS

Our study cohort comprises a single center series of 60 patients operated for histopathologically verified magnetic resonance imaging unequivocally identifiable endosellar microprolactinoma between 2003 and 2017. In 31 patients the adenoma was enclosed by pituitary gland (group ENC), in 29 patients the adenoma was located lateral to the gland adherent to the medial cavernous sinus wall (group LAT).

RESULTS

After a mean follow-up of 37 mo (range 4-143 mo), remission rate was significantly higher in adenomas enclosed by pituitary gland (group ENC) than adenomas located lateral to the gland (group LAT), with 87% vs 45%, P = .01. Intraoperatively, 4 patients showed signs of invasiveness. Preoperative prolactin levels did not differ between the groups (mean 155 and 187 ng/ml in group ENC and LAT, respectively).A binary logistic regression model revealed that only the radiological criteria applied showed a significant correlation (P = .003) with endocrine remission.

CONCLUSION

According to our results, remission rate is significantly higher in microprolactinomas enclosed by the pituitary gland. However, the decision for surgery should take into account surgeons experience and possibility of complications.

An advanced protocol for intraoperative visualization of sinunasal structures: experiences from pituitary surgery

OBJECTIVE

The transsphenoidal route to pituitary adenomas challenges surgeons because of the highly variable sinunasal anatomy. Orientation may be improved if the appropriate information is provided intraoperatively by image guidance. The authors developed an advanced image guidance protocol dedicated to sinunasal surgery that extracts information from multiple modalities and forms it into a single image that includes fine sinunasal structures and arteries.The aim of this study was to compare the advantages of this novel image guidance protocol with the authors' previous series, with emphasis on anatomical structures visualized and complication rate.

METHODS

This retrospective analysis comprised 200 patients who underwent surgery for pituitary adenoma via a transnasal transsphenoidal endoscopic approach. The authors' standard image guidance protocol consisting of CT for solid bone, T1CEMRI for soft tissues, and MRA for the carotid artery was applied in 100 consecutive cases. The advanced image guidance protocol added a first-hit ray casting of the CT scan for visualization of fine sinunasal structures, and adjustments to the MRA to visualize the sphenopalatine artery (SPA) were applied in a subsequent 100 consecutive cases.

RESULTS

A patent sphenoid ostium-i.e., an ostium not covered by a mucosal layer-was visualized significantly more often by the advanced protocol than the standard protocol (89% vs 40%, p < 0.001) in primary surgeries. The SPA and its branches were only visualized by the advanced protocol (87% and 91% of cases in primary surgeries and reoperations, respectively) and not once by the standard protocol. The number of visualized complete and incomplete sphenoid septations matched significantly more commonly with the surgical view when using the advanced protocol than the standard protocol at primary operation (mean 1.9 vs 1.6, p < 0.001). However, in 25% of all cases a complex and not a simple sinus anatomy was present. In comparison with the intraoperative results, a complex sphenoid sinus anatomy was always detected by the advanced but not by the standard protocol (25% vs 8.5%, p = 0.001).Furthermore, application of the advanced protocol reduced the cumulative rate of complications (25% vs 18% [standard vs advanced group]). Although an overall significant difference could not be determined (p = 0.228), a subgroup analysis of reoperations (35/200) revealed a significantly lower rate of complications in the advanced group (5% vs 30%, p = 0.028).

CONCLUSIONS

The data show that the advanced image guidance protocol could intraoperatively visualize the fine sinunasal sinus structures and small arteries with a high degree of detail. By improving intraoperative orientation, this may help to reduce the rate of complications in endoscopic transsphenoidal surgery, especially in reoperations.

Radiological "Teddy Bear" Sign on CT Imaging to Aid Internal Carotid Artery Localization in Transsphenoidal Pituitary and Anterior Skull Base Surgery

Objectives  Internal carotid artery (ICA) injury remains a rare but potentially fatal complication of transsphenoidal pituitary or anterior skull base surgery. Preoperative imaging must be scrutinized to minimize risk. On axial computed tomography (CT), the protrusions of the ICAs into the sphenoid resemble a "teddy bear." This article aims to describe the sign, its grading system (0-2) and quantify its presence. Design  Retrospective review of preoperative CT imaging. Setting  Tertiary referral center in the United Kingdom. Participants  One hundred patients who underwent endoscopic transsphenoidal surgery for pituitary disease were enrolled. Main Outcome Measure  The presence and grading of the "teddy bear" sign were assessed on preoperative CT imaging. Results  A grade 2 (strongly positive) "teddy bear" sign was identified in 40% at the level of the superior pituitary fossa, 78% at the inferior pituitary fossa, and 59% at the clivus. A grade 1 (intermediate) sign was seen in 23.5, 7.5, and 10% of cases, respectively. In 5% of cases, the sign was grade 0 at all levels-indicating poor intraoperative localization of the ICA. Conclusion  The "teddy bear" sign is a useful preoperative tool for identification of anatomy predisposing patients to a higher risk of ICA injury. Those patients who have an absent or grade 0 "teddy bear" sign require extra care to ensure intraoperative localization of the ICAs which may include the use of neuronavigation or a Doppler probe. A grade 2 sign predicts good intraoperative localization of the ICA intraoperatively to inform the safe lateral limit of sellar bone resection.

Clinical Application of Multimodal Neuronavigation System in Neuroendoscope-Assisted Skull Base Chordoma Resection

Skull base chordoma is a rare tumor arising from embryonic remnants of the notochord with invasive potential. Due to the destruction of osseous landmarks and invasion of surrounding structures, surgical resection is challenging. The authors explored the clinical value of a multimodal neuronavigation system in skull base chordoma resection using a neuroendoscope. Between January 2012 and January 2016, the authors utilized neuroendoscopy to excise skull base chordoma in 93 patients. The authors performed 45 operations assisted by multimodal neuronavigation (neuronavigation group) and 48 without intraoperative imaging guidance (control group). In the control group, 35 patients (73%) underwent gross total resection. In the neuronavigation group, all patients underwent gross total resection without radiographically identified bleeding. Only 1 patient (2%) in the neuronavigation group showed a temporary reduction in vision, which improved after symptomatic treatment. In contrast, there were 4 patients (8%) with postoperative complication, including 2 patients with intracranial hematoma and 2 with neurological deficits. Complication rates were higher than the neuronavigation group. In the follow-up period, 2 patients in the control group with subtotal resection had recurrence within 24 months, but without extracranial metastases. The multimodal neuronavigation system could contribute intraoperative real-time guidance for spatial relationships between lesions and adjacent neurovascular structures, as well as eroded and distorted anatomical landmarks through multiple image fusion and 3-dimensional reconstruction. It significantly improves surgical outcome and provides a new insight into the management of skull base chordomas.

Three-Dimensional Endoscopic Endonasal Approach and Outcomes in Sellar Lesions: A Single-Center Experience of 104 Cases

BACKGROUND

Pituitary tumors account for approximately 15% of primary intracranial neoplasms and often are diagnosed incidentally. Common sellar lesions are pituitary adenomas, craniopharyngiomas, and Rathke cleft cysts. Currently endoscopic transsphenoidal approaches are largely used, and many centers also use 3-dimensional (3D) technology, although additional results of long-term follow-up are still being accumulated.

METHODS

We present a retrospective analysis of 104 patients with sellar lesions (57 male and 47 female, mean age 52 years) who underwent 3D endoscopic transsphenoidal surgery in our center from December 2011 to March 2015 and were followed up for a mean time of 18 months.

RESULTS

A total of 16 patients were diagnosed with growth hormone-secreting adenomas, 9 with adrenocorticotropic hormone-secreting, 5 with prolactin-secreting, and 2 with thyroid-stimulating hormone-secreting tumors and 58 with nonsecreting pituitary adenomas. Five patients had Rathke cleft cysts, 5 craniopharyngiomas, 2 fibrous solitary tumors, 1 a metastasis, and 1 a chordoma. At baseline, 47 patients (45.2%) had hormonal changes and 52 (50%) had visual field changes. Complete resection was achieved in 73 patients (70.1%). Follow-up evaluation detected hormonal remission in 7 patients with Cushing disease (77.7%) and in 11 patients with acromegaly (68.7%). Complications were cerebrospinal fluid leak in 5 cases (4.8%) and transient diabetes insipidus in 6 cases (5.7%). A total of 55 patients (52.9%) were discharged less than 72 hours after surgery.

CONCLUSIONS

The use of an endoscopic endonasal approach with 3D technology provides several advantages relating to patient length of stay, rate of complications, postoperative recovery, and novice surgeons' training. Advantages of 3D endoscopy and long-term follow-up still need further elucidation.