Critical analysis of anatomical landmarks within the sphenoid sinus for transsphenoidal surgery

Relationship of anatomical variations of sphenoid sinus and the outcomes of endoscopic endonasal transsphenoidal surgeries: a systematic review

BACKGROUND

The sphenoid sinus features many anatomical variations between individuals from different populations in the world. The understanding of these variations is important for the surgeons to plan for surgeries which involve intervention through the nasal approach. The aim of the present systematic review was to perform a qualitative synthesis of available studies which assess the effect of sphenoid sinus (SS) anatomical variations on the outcomes of endoscopic endonasal transsphenoidal surgeries (ETSS).

METHODS

The current review followed PRISMA 2020 guidelines. A systematic advanced electronic search was performed in four databases Medline (via PubMed), Scopus, Web of Science (WoS) and Lilacs in December 2023. Studies that assessed the anatomical variations of the SS that affect the outcomes of ETSS were eligible for inclusion. A qualitative synthesis of the methodology and results of the included studies was carried out. Quality assessment was performed using the National Institute of Health (NIH) quality assessment tool (last accessed on December 24, 2023).

RESULTS

A total of 14 studies were included in the qualitative synthesis. Most of the studies included in the review found that the sellar pneumatization was the commonest followed by the postsellar type. Single intersphenoid sinus septum (ISS) was found to be the most common variation, which is more frequently found in males compared to females. There was sex difference seen in the attachment of the ISS to the carotid canal. It is more commonly attached to the posterolateral wall of the sinus in males compared to the females. Though complicated cases were less compared to uncomplicated ones, cerebrospinal fluid (CSF) leak was the leading post operative complication amongst the complicated cases and paranasal sinus (PNS) computed tomography (CT) scan showed ISS findings differed from intraoperative findings.

CONCLUSION

It is concluded that the ISS poses the commonest anatomical variations encountered during the ETSS. During planning for transsphenoidal endoscopic procedure, the ISS should thoroughly be assessed to minimize potential surgical complications.

Anatomical Differences in Sphenoid Sinus During Endoscopic Transsphenoidal Surgery: Comparison Between Nonfunctioning Pituitary Neuroendocrine Tumor (PiTNET) and Growth Hormone-Secreting PiTNET

BACKGROUND

In surgical practice during endoscopic endonasal approach, growth hormone-secreting pituitary neuroendocrine tumor (GH-secreting PitNET) patients show morphologic differences in the nasal cavities and sinuses, leading to a narrower surgical field and a carotid prominence and potentially increasing the complexity of the surgical and the risk of complications. The aim of the study is to evaluate the anatomical differences of the sphenoid sinus between patients with GH-secreting PitNETs and patients with nonfunctioning pituitary neuroendocrine tumor (NF-PitNET) who underwent endoscopic endonasal approach.

METHODS

This is a monocentric retrospective study conducted at the author's institution. The minimum intercarotid distance, the largest diameter of the sphenoid sinus (DSS), and the distance between vomer and clivus (VCD) were collected and compared. Presence, localization, and course of intersphenoid sinus septum were also evaluated.

RESULTS

One hundred consecutive patients were identified: 57 males (57%) and 43 females (43%), with a mean age of 55 years. Sixty patients had NF-PitNET (60%) and 40 had GH-secreting PitNET (40%). GH-secreting PitNET group presented inferior values of intercarotid distance (16.8 ± 3.94 mm vs. 20.4 ± 3.94 mm, P < 0.001), DSS (32.5 ± 9.81 mm vs. 38.6 ± 11.03 mm, P = 0.006), and VCD (25.5 ± 6.96 mm vs. 29.6 ± 8.47 mm, P = 0.012) compared to NF-PitNET group. Intersphenoid sinus septum showed no differences between the 2 groups.

CONCLUSIONS

Intercarotid distance, DSS, and VCD resulted smaller in acromegalic patients, confirming that patients with GH-secreting PitNETs have a narrower surgical field. A meticulous anatomical preoperative planning and neuronavigation are important to recognize the sphenoid anatomical landmarks in order to reduce the risk of complications, especially in acromegalic patients.

Augmented Reality in Extratemporal Lobe Epilepsy Surgery

Background: Epilepsy surgery for extratemporal lobe epilepsy (ETLE) is challenging, particularly when MRI findings are non-lesional and seizure patterns are complex. Invasive diagnostic techniques are crucial for accurately identifying the epileptogenic zone and its relationship with surrounding functional tissue. Microscope-based augmented reality (AR) support, combined with navigation, may enhance intraoperative orientation, particularly in cases involving subtle or indistinct lesions, thereby improving patient outcomes and safety (e.g., seizure freedom and preservation of neuronal integrity). Therefore, this study was conducted to prove the clinical advantages of microscope-based AR support in ETLE surgery. Methods: We retrospectively analyzed data from ten patients with pharmacoresistant ETLE who underwent invasive diagnostics with depth and/or subdural grid electrodes, followed by resective surgery. AR support was provided via the head-up displays of the operative microscope, with navigation based on automatic intraoperative computed tomography (iCT)-based registration. The surgical plan included the suspected epileptogenic lesion, electrode positions, and relevant surrounding functional structures, all of which were visualized intraoperatively. Results: Six patients reported complete seizure freedom following surgery (ILAE 1), one patient was seizure-free at the 2-year follow-up, and one patient experienced only auras (ILAE 2). Two patients developed transient neurological deficits that resolved shortly after surgery. Conclusions: Microscope-based AR support enhanced intraoperative orientation in all cases, contributing to improved patient outcomes and safety. It was highly valued by experienced surgeons and as a training tool for less experienced practitioners.

Interracial anatomical differences in the transsphenoidal approach to the sellar region

OBJECTIVE

Injury to vascular structures such as the internal carotid artery (ICA) is a rare but catastrophic complication of minimally invasive transsphenoidal surgery. Thorough preoperative planning, and knowledge of anatomical landmarks, such as the intercarotid distance (ICD) reduce this risk. Numerous anatomical studies have been conducted regarding the transsphenoidal approach, but none have taken racial disparities into account.

METHODS

Since differences of the cranium, especially of the skull base exist, we sought to analyze anatomical differences of the sellar region in thin sliced T2-weighted MRI scans of 187 (87 male and 100 female) Asian, African American and Caucasian patients provided by the 'Human Connectome Project' (HCP).

RESULTS

We found significant differences in the ICD between males and females across all races. Furthermore, we found that the ICD was up to 2.4 mm smaller in the Caucasian cohort compared to the African American/Asian cohort.

CONCLUSION

These findings indicate that racial disparities regarding the sellar anatomy should be considered in patients undergoing pituitary surgery.

Application of expanding bilateral sphenoid sinus plasty in the treatment of sphenoid sinus diseases

Expanding bilateral sphenoid sinus plasty is an essential technique for the treatment of sphenoid sinus diseases, such as refractory sphenoid sinusitis, sphenoid sinus cyst, fungal sphenoid sinusitis, sphenoid sinus carcinoma and sphenoid sinus chordoma. The present study evaluated the potential application of expanding bilateral sphenoid sinus plasty in the treatment of sphenoid sinus diseases. A retrospective medical record review of 42 patients treated with the expanding bilateral sphenoid sinus plasty from December 2012 to December 2018 was performed in a tertiary-care university hospital. A follow-up of the surgical effects and complications was performed. Of the 42 patients, the symptoms were relieved after operation in all except preoperative hyposmia in 2 and impaired vision in one with no obvious improvement. No complications such as nasal bleeding, olfactory hypofunction and perforation of nasal septum occurred. Follow-up data revealed good mucosal epithelization in all patients within a mean time of 8.6 weeks. Endoscopic sinus reexamination demonstrated that the sphenoid sinus orifice was well opened, and no cases of sphenoid sinus orifice closure were observed. Expanding bilateral sphenoid sinus plasty, with advantages of clearly exposed surgical field, full opening of the sinus cavity, high surgical safety, short epithelialization time and intuitionistic postoperative follow-up, demonstrated great promise for greater use in the treatment of sphenoid sinus diseases in the future.

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.

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.

Carotid canal and optic canal at sphenoid sinus

In the present study, we investigated the relationship between sphenoid sinus, carotid canal, and optic canal on paranasal sinus computed tomography (PNSCT). This study was performed retrospectively. PNSCT images of 300 adult subjects (159 male, 141 female). Sphenoid sinus (pneumatisation, dominancy, septation, inter-sinus septa deviation), anterior clinoid process pneumatisation, Onodi cell, carotid and optic canals (width, dehiscence, classification) were measured. In males, type 3 pneumatised sphenoid sinus (in both sides) and in females type 2 pneumatised sphenoid sinus (right side) and type 3 pneumatised sphenoid sinus (left side) were detected more. Anterior clinoid pneumatisation was present 47.2% in males and 39.7% in females. In male group, more septation (i.e. 22.6%, ≥ 3 septa) in sphenoid sinus were detected. Onodi cell was present 26.6 and 19.1% in males and females, respectively. Carotid canal protrudation to the sphenoid sinus wall was present 23.9-32.1% in males and 35.5-36.2% in females. Dehiscence in carotid canal was detected more in females (34%) compared to males (22%). Optic canal protrudation was 33.3 and 30.5% in males and females. Type 4 optic canal was detected more in both gender. Optic canal dehiscence was detected 11.3 and 9.9% in males and females. Carotid and optic canal diameters were higher in males. In pneumatised sphenoid sinuses and in females, type 3 carotid canal (Protrudation to SS wall) (bilaterally) and type 1 optic canal type (No indentation) (ipsilateral side) were detected more. In elderly patients, carotid and optic canal width increased. When carotid canal protrudation was detected, there was no indentation in optic canals In pneumatised SS, carotid canal protrudation was observed with a greater risk in surgery. However, type 1 (non indentation) optic canal was present in highly pneumatised SS with lower risk for the surgery. In women, the risk of carotid canal protruding (about 1/3) is greater than that of males, and carotid canal dehiscence rates are also higher in females. Therefore, physicians should be very careful during the preparatory stages of the sphenoid sinus surgery. Otherwise, it may not be possible to prevent lethal carotid artery bleeds.