Indocyanine Green Fluorescence to Evaluate Nasoseptal Flap Viability in Endoscopic Endonasal Cranial Base Surgery

Indocyanine Green Angiography for Real-time Evaluation of Nasoseptal Flap Vascularity and Perfusion

OBJECTIVES

To investigate the characteristics of the vascular pedicle of the nasoseptal flap (NSF) and its perfusion patterns using intraoperative indocyanine green (ICG) angiography during endoscopic skull base surgery (ESBS), and examine the correlation between ICG perfusion patterns and clinical outcomes, including postoperative cerebrospinal fluid (CSF) leak and flap necrosis.

METHODS

This study enrolled patients undergoing ESBS between January 2017 and December 2021. Intraoperative ICG angiography was performed to visualize the arterial supply of the nasal septum and evaluate NSF perfusion. Postoperative CT scans and clinical follow-ups were conducted to assess flap outcomes.

RESULTS

A total of 126 patients were included in the study. The posterior septal artery (PSA) was most commonly identified in the middle third of the sphenoidal rostrum (63.5% right, 60.3% left). Three branching patterns were observed: single-branch (58.7% right, 64.3% left), double-branch (12.7% right, 11.1% left), and reticular-branch (26.6% right, 24.6% left). Among 72 patients who underwent NSF placement, ICG angiography showed full enhancement in 37 patients (51.4%), partial enhancement in 27 patients (37.5%), and no enhancement in eight patients (11.1%). Postoperative CSF leak occurred in eight patients (11.1%), with no significant correlation to ICG enhancement patterns (p = 0.07). Flap necrosis occurred in five patients (6.9%), all of whom had shown no ICG enhancement beyond the pedicle (p < 0.01).

CONCLUSIONS

ICG angiography is a valuable tool for visualizing the vascular supply of NSF during ESBS. While it does not correlate with postoperative CSF leak, ICG enhancement pattern showed a significant association with flap necrosis. This technique may contribute to improved surgical outcomes and reduced complications in NSF reconstructions.

LEVEL OF EVIDENCE

3 Laryngoscope, 135:1060-1065, 2025.

Ipsilateral Nasoseptal Flaps in a Transpterygoid Approach: Technical Pearls and Reconstruction Outcomes

Background  Transpterygoid approaches to the skull base require dissection of the sphenopalatine artery, potentially compromising the option to harvest an ipsilateral nasoseptal flap (NSF) for reconstruction. In cases where other reconstructive options are limited, it may be necessary to utilize a NSF ipsilateral to the transpterygoid approach. Here, we describe the technique of NSF pedicle preservation with reconstruction outcomes. Methods  This was a retrospective single-institution review of all expanded endonasal skull base cases utilizing a NSF ipsilateral to a transpterygoid approach. Reconstruction outcomes collected include intraoperative fluorescence with indocyanine green (ICG), postoperative magnetic resonance imaging (MRI) gadolinium enhancement, endoscopic assessment, and reconstruction-related complications. Results  Twenty-one cases were included in this study (mean age 51.0 ± 20.6 years, 61.9% female). Indications for NSF ipsilateral to the transpterygoid approach included: bilateral transpterygoid approach (52.4%), revision reconstruction (23.8%), or significant septal deviation (19.0%). Twelve of 14 (85.7%) flaps demonstrated intraoperative perfusion with ICG, 15 of 15 (100%) enhanced on postoperative MRI, and 21 of 21 (100%) flaps had a healthy, viable appearance on postoperative endoscopy. There were no instances of flap necrosis or postoperative cerebrospinal fluid leaks. Technical keys to optimize mobilization of the pedicle include wide decompression of the sphenopalatine foramen and release of neurovascular tethering points of the pterygopalatine fossa. These steps allow for wide skull base exposure with preservation of the sphenopalatine artery. Conclusion  With this technique, the transpterygoid approach can be performed in a manner that preserves the pedicle for an ipsilateral NSF and achieve an excellent reconstructive outcome.

Indocyanine Green as a Marker for Tissue Ischemia in Spinal Tumor Resections and Extended Revisions: A Technical Note

Background/Objectives: The increasing complexity of spinal oncology procedures, particularly in en-bloc tumor resections, creates challenges in tissue perfusion assessment due to extended operative times and extensive surgical dissection. Real-time visualization of tissue perfusion can be achieved with ICG using commercially available handheld imaging systems, offering potential advantages in spinal oncology cases. This study assessed the utility of ICG in analyzing soft-tissue viability during complex spine procedures extending beyond 7.5 h, with a particular focus on oncologic resections. Methods: Three cases that required over 7.5 h of operative time were chosen for ICG utilization. These cases included an en-bloc malignant peripheral nerve sheath tumor resection, an en-bloc resection of a malignant epithelioid neoplasm, and a long-segment fusion revision for pseudoarthrosis. At the conclusion of the critical portion of the procedure, a handheld intraoperative fluorescence camera was utilized to visualize the tissue penetration of intravenous ICG. Results: Prior to injecting ICG, devascularized tissue was not clearly visible. Injecting ICG allowed clear separation of vascularized (fluorescing) and devascularized (non-fluorescing) tissues. One region of non-florescent tissue was later confirmed to be devascularized with MRI and experienced postoperative infection. Conclusions: As the complexity of spinal oncology procedures increases, ICG fluorescence imaging offers a novel method for real-time assessment of tissue perfusion. This technique may be particularly valuable in extensive tumor resections, post-radiation cases, and revision surgeries where tissue viability is at risk. Further investigation in the spinal oncology population could help establish whether early identification of poorly perfused tissues impacts wound healing outcomes.

Assessing chiasm perfusion and postoperative visual function with superior hypophyseal artery indocyanine green angiograms during endoscopic endonasal surgery

BACKGROUND

To date, there are no validated intraoperative tools to predict postoperative visual function following endoscopic endonasal surgery (EES). Assessment of post-surgical vision during surgery can help in postoperative planning and disposition and inform surgical decisions in real-time. The objective of this study was to evaluate the capability of intraoperative endoscopic indocyanine green (ICG) angiography to measure optic chiasm perfusion and determine its relationship with postoperative visual function.

METHODS

A retrospective review was performed on patients undergoing EES for sellar and suprasellar lesions. ICG was injected prior to surgical closure at a time when the optic chiasm and anterior circulation were visible. Luminescence of the superior hypophyseal artery (SHA) branches enveloping the optic chiasm was registered 10 seconds after ICG penetration into the anterior cerebral arteries (ACAs). Pre and post-operative visual acuity and field exams were used to assess visual function. Patients with and without new deficits were compared to examine statistical association with intraoperative ICG findings.

RESULTS

Twenty patients were included (mean age 49 years, 55% female). Eighteen patients displayed stable or improved vision after resection and demonstrated luminescence of all chiasmatic branches within 10 s of ACA fluorescence. Two patients experienced new postoperative visual deficits. Upon review, their ICG administrations showed no fluorescence of the SHA branches enveloping the chiasm. A lack of chiasm fluorescence within ten seconds of ACA fluorescence was associated with new postoperative vision deficits (p = 0.005).

CONCLUSIONS

This study shows that the lack of ICG fluorescence of SHA branches at the chiasm correlates with ischemic changes and new post-operative bitemporal hemianopsia. Lack of chiasm fluorescence after 10 seconds of observation reflects compromised chiasm perfusion and likely new post-surgical visual deficits.

Fluorescence guidance in skull base surgery: Applications and limitations - A systematic review

Introduction

Intraoperative fluorescence guidance is a well-established surgical adjunct in high-grade glioma surgery. In contrast, the clinical use of such dyes and technology has been scarcely reported in skull base surgery.

Research question

We aimed to systematically review the clinical applications of different fluorophores in both open and endonasal skull base surgery.

Material and methods

We performed a systematic review and discussed the current literature on fluorescence guidance in skull base surgery.

Results

After a comprehensive literature search, 77 articles on skull base fluorescence guidance were evaluated. A qualitative analysis of the articles is presented, discussing clinical indications and current controversies. The use of intrathecal fluorescein was the most frequently reported in the literature. Beyond that, 5-ALA and ICG were two other fluorescent dyes most extensively discussed, with some experimental fluorophore applications in skull base surgery.

Discussion and conclusion

Intraoperative fluorescence imaging can serve as an adjunct technology in skull base surgery. The scope of initial indications of these fluorophores has expanded beyond malignant glioma resection alone. We discuss current use and controversies and present an extensive overview of additional indications for fluorescence imaging in skull base pathologies. Further quantitative studies will be needed in the future, focusing on tissue selectivity and time-dependency of the different fluorophores currently commercially available, as well as the development of new compounds to expand applications and facilitate skull base surgeries.

Superior Hypophyseal Artery Intraoperative Indocyanine Green Angiogram as a Predictor of Postoperative Visual Function After Endoscopic Endonasal Surgery

BACKGROUND AND OBJECTIVES

To date, there are no tools to intraoperatively predict postoperative visual function after endoscopic endonasal surgery (EES) for suprasellar lesions. The objective of this study was to retrospectively evaluate the utility of indocyanine green (ICG) angiography as an intraoperative tool to measure optic chiasm perfusion and determine its relationship with postoperative visual function.

METHODS

Videos of patients undergoing EES for resection of suprasellar lesions were reviewed, where 5 mg of ICG was diluted in 10 mL of saline and administered. Time between luminescence of the anterior cerebral artery and the superior hypophyseal artery branches supplying the optic chiasm was noted, and the percentage of optic chiasm vessels that luminesced was recorded. Postoperative examinations and imaging studies were used to assess visual function. Patients with and without new deficits were compared with examination of trends in ICG findings.

RESULTS

A total of 7 trials were reviewed on 6 patients, with no complications occurring from ICG administration. Mean time to chiasm peak luminescence was 3.8 seconds, and 81.8% of chiasm vessels luminesced. Patients with stable or improved vision after resection demonstrated over 90% chiasm luminescence in every case, and mean chiasm time in these postresection ICG administrations was 4.0 seconds. One patient experienced new postoperative visual deficits; on review of their ICG administration, 11.5% of chiasm vessels luminesced, and the chiasm itself failed to display robust luminescence after 30 seconds of direct observation.

CONCLUSION

This pilot study showed the capability of intraoperative ICG angiography to demonstrate perfusion of the optic chiasm during EES for resection of suprasellar lesions. While larger studies are required, preliminary results suggest chiasm times under 5 seconds and over 90% chiasm vessel illumination may reflect adequate chiasm perfusion, while those with delayed or absent chiasm luminescence may have compromised chiasm perfusion.

Delayed nasoseptal flap reuse in patients with revision endoscopic endonasal anterior skull base surgery

The reuse of the nasoseptal flap represents a favorable option for skull base reconstruction in revision endoscopic anterior skull base surgery. This study demonstrated that a detached nasoseptal flap can remain viable for several days even if not immediately reattached.

The role of indocyanine green fluorescence in endoscopic endonasal skull base surgery and its imaging correlations

OBJECTIVE

The use of endoscope-integrated indocyanine green (E-ICG) has recently been introduced in skull base surgery. The quantitative correlation between E-ICG and T1-weighted gadolinium-enhanced (T1WGd) images for skull base tumors has not been previously assessed, to the authors' knowledge. In this study, the authors investigated the indications for use and the limitations of E-ICG and sought to correlate the endoscopic fluorescence pattern with MRI contrast enhancement.

METHODS

Following IRB approval, 20 patients undergoing endoscopic endonasal skull base surgery between June 2017 and August 2018 were enrolled in the study. Tumor fluorescence was measured using a blue color value and blood fluorescence as a control. Signal intensities (SIs) of tumor T1WGd images were measured and the internal carotid artery (ICA) SI was used as a control. For pituitary adenoma, the pituitary gland fluorescence was also measured. The relationships between ICG fluorescence and MRI enhancement measurements were analyzed.

RESULTS

Data showed that in pituitary adenoma there was a strong correlation between the ratios of gland/blood fluorescence to gland/ICA SI (n = 8; r = 0.92; p = 0.001) and tumor/blood fluorescence to tumor/ICA SI (n = 9; r = 0.82; p = 0.006). In other pathologies there was a strong correlation between the ratios of tumor/blood fluorescence and tumor/ICA SI (n = 9; r = 0.74; p = 0.022). The ICG fluorescence allowed perfusion assessment of the pituitary gland as well as of the nasoseptal flaps. Visualization of the surrounding vasculature was also feasible.

CONCLUSIONS

Defining the indications and understanding the limitations are critical for the effective use of E-ICG. Tumor fluorescence seems to correlate with preoperative MRI contrast enhancement.

Complications after 1002 endoscopic endonasal approach procedures at a single center: lessons learned, 2010-2018

OBJECTIVE

The endoscopic endonasal approach (EEA) has evolved into a mainstay of skull base surgery over the last two decades, but publications examining the intraoperative and perioperative complications of this technique remain scarce. A prior landmark series of 800 patients reported complications during the first era of EEA (1998-2007), parallel to the development of many now-routine techniques and technologies. The authors examined a single-institution series of more than 1000 consecutive EEA neurosurgical procedures performed since 2010, to elucidate the safety and risk factors associated with surgical and postoperative complications in this modern era.

METHODS

After obtaining institutional review board approval, the authors retrospectively reviewed intraoperative and postoperative complications and their outcomes in patients who underwent EEA between July 2010 and June 2018 at a single institution.

RESULTS

The authors identified 1002 EEA operations that met the inclusion criteria. Pituitary adenoma was the most common pathology (n = 392 [39%]), followed by meningioma (n = 109 [11%]). No patients died intraoperatively. Two (0.2%) patients had an intraoperative carotid artery injury: 1 had no neurological sequelae, and 1 had permanent hemiplegia. Sixty-one (6.1%) cases of postoperative cerebrospinal fluid leak occurred, of which 45 occurred during the original surgical hospitalization. Transient postoperative sodium dysregulation was noted after 87 (8.7%) operations. Six (0.6%) patients were treated for meningitis, and 1 (0.1%) patient died of a fungal skull base infection. Three (0.3%) patients died of medical complications, thereby yielding a perioperative 90-day mortality rate of 0.4% (4 deaths). High-grade (Clavien-Dindo grade III-V) complications were identified after 103 (10%) EEA procedures, and multivariate analysis was performed to determine the associations between factors and these more serious complications. Extradural EEA was significantly associated with decreased rates of these high-grade complications (OR [95% CI] 0.323 [0.153-0.698], p = 0.0039), whereas meningioma pathology (OR [95% CI] 2.39 [1.30-4.40], p = 0.0053), expanded-approach intradural surgery (OR [95% CI] 2.54 [1.46-4.42], p = 0.0009), and chordoma pathology (OR [95% CI] 9.31 [3.87-22.4], p < 0.0001) were independently associated with significantly increased rates of high-grade complications.

CONCLUSIONS

The authors have reported a large 1002-operation cohort of EEA procedures and associated complications. Modern EEA surgery for skull base pathologies has an acceptable safety profile with low morbidity and mortality rates. Nevertheless, significant intraoperative and postoperative complications were correlated with complex intradural procedures and meningioma and chordoma pathologies.

Intraoperative Indocyanine Green Angiography for Assessing Flap Perfusion in Skull Base Reconstruction: A Systematic Review

Objective This study was aimed to study the current use of intraoperative indocyanine green (ICG) angiography during skull base reconstruction and understand its efficacy in predicting postoperative magnetic resonance imaging (MRI) enhancement and flap.

Study Design The Embase, the Cochrane Central Register of Controlled Trials (CENTRAL), Web of Science, and Google Scholar databases were searched from the date of inception until August 2020 for studies of ICG flap perfusion assessment during skull base reconstruction. The primary outcome of interest was the development of cerebrospinal fluid (CSF) leak after skull base reconstruction. Secondary outcomes of interest included postoperative meningitis, flap MRI enhancement, flap necrosis, flap perfusion measurements, and total complications.

Results Search results yielded 189 studies, from which seven studies with a total of 104 patients were included in the final analysis. There were 44 nasoseptal flaps (NSF), two lateral nasal wall flaps (LNWF), 14 pericranial flaps (PCF), and 44 microvascular free flaps. The rates of CSF leak and postoperative MRI enhancement were 11 and 94%, respectively. There was one case of postoperative meningitis. Pooled analysis of the available data showed that intraoperative ICG flap perfusion was associated with flap enhancement on postoperative MRI (p = 0.008) and CSF leak (p = 0.315) by Fisher's exact test.

Conclusion The available literature suggests intraoperative ICG enhancement is associated with postoperative MRI enhancement. Given the small sample sizes in the literature and the rarity of complications associated with skull base reconstruction, intraoperative ICG enhancement has not been predictive of flap necrosis or postoperative complications such as CSF leak or meningitis.

Level of Evidence This study presents level 3 evidence as a systematic review of case studies, case reports, and retrospective and prospective trials with no blinding, controls, and inconsistently applied reference standards.

Creative and Innovative Methods and Techniques for the Challenges in the Management of Adult Craniopharyngioma

Craniopharyngioma remains a major challenge in daily clinical practice. The pathobiology of the tumor is still elusive, and there are no consensus or treatment guidelines on the optimal management strategy for this relatively rare tumor. However, recent technical and scientific advances, including genomic and radiomic profiling, innovation in surgical approaches, more precise radiotherapy protocols, targeted therapy, and restoration of lost functions all have the potential to significantly improve the outcome of patients with craniopharyngioma in the near future. Although many of these innovative tools in the new armamentarium of the clinician are still in their infancy, they could reduce craniopharyngioma-related morbidity and mortality and improve the patients' quality of life. In this article, we discuss these creative and innovative approaches that may offer solutions to the obstacles faced in treating craniopharyngioma and future possibilities in improving the care of these patients.

Relationship between the posterior septal artery and the upper edge of the choana

BACKGROUND

The pedicled nasoseptal flap has been a key element in advancing the endoscopic transnasal approach (ETA) for the treatment of skull base lesions from the anterior cranial fossa to the occipitocervical junction. To preserve vascular supply, an anatomical knowledge of the location of the posterior septal artery (PSA) is essential. The objective of this work is to establish the relationship between PSA and the superior edge of the choana to define a safety margin during the opening of the sphenoidal rostrum preserving PSA.

METHODS

One hundred and eighty angiotomographies of the brain were assessed. The sphenopalatine artery (SPA) was evaluated in the pterygopalatine fossa and PSA at its entrance into the nasal cavity and on the sphenoidal rostrum.

RESULTS

PSA was found in all 3 tomographic planes (axial, coronal and sagittal) in 100 patients (200 PSAs). Thirty-five were male and 65 were females. Average age was 62 years with a range of 19-90 years. Total average distance between PSA and the superior edge of the choana was 8.5 mm with a range of 2.5-18 (12.45 90th percentile).

CONCLUSION

Although the distance between the choanal edge and PSA is 8.5 mm on average, due to its variability, a distance of at least 12.45 mm for the opening of the sphenoidal sinus in the ETA approach should be considered as a safety margin.

The Use of Indocyanine Green Angiography for Cosmetic and Reconstructive Assessment in the Head and Neck

Reconstructive procedures in the head and neck can be a surgical challenge owing to the complex anatomical and physiological structure. Different locoregional and microvascular flaps are used for various defects to improve both function and cosmesis. Subjective clinical findings have been the mainstay for perfusion monitoring; however, areas of borderline perfusion are much more difficult to assess clinically. Multiple technologies that offer objective perfusion assessment have been developed to improve surgical outcomes. Indocyanine green (ICG) angiography has gained popularity owing to its minimal invasiveness and increased sensitivity and specificity in assessing flap perfusion particularly in the head and neck. It has been extensively used in free flaps, pedicled flaps (including nasal reconstruction), facelift procedures, random flaps, skull base reconstruction, and pharyngocutaneous fistula prediction. Its perioperative use has provided valuable qualitative and quantitative data that aid our understanding of flap hemodynamics. Clinically, this impacted decision-making in flap design, harvest, inset, and precocious salvage interventions. Though increased cost and intraoperative time could be limitations, cost-effectiveness studies have supported its use, particularly in high-risk individuals. Limitations include the lack of standardized dosing and consistent methodology agreement for data analysis. Future studies should involve larger cohorts and multi-institute studies to overcome such limitations.

Reconstruction of pediatric skull base defects: A retrospective analysis emphasizing the very young

INTRODUCTION

Pathology of the pediatric skull base is rare and ranges from congenital defects to malignancy and traumatic defects. Pediatric patients, particularly those ≤6 years of age, present a unique set of anatomic challenges for the skull base surgeon. The goal of this study was to retrospectively review our experience with reconstruction of pediatric skull base defects with particular emphasis on those ≤6 years of age.

METHODS

A retrospective chart review was conducted of patients ≤20 years of age who underwent endoscopic endonasal and combined endoscopic and open approaches to address cranial base pathology from 2007 to 2018. Patients were divided into two groups; those ≤6 years of age (group A) and those >6 years of age and ≤20 years of age (group B) and reconstructive techniques and outcomes were analyzed.

RESULTS

Intraoperative communication with the subarachnoid space (CSF leak) was created in 50% (3/6) of patients ≤ 6 years of age compared to 32.7% (16/49) in patients > 6 years and ≤20 years of age (P < 0.40) in management of their skull base disease. A vascularized flap was utilized for reconstruction in 66.7% (4/6) of patients ≤ 6 years of age and included a nasoseptal flap in 33.3% (2/6). A vascularized flap was utilized for reconstruction in 38.8% (19/49) of patients > 6 years and ≤20 years of age and most commonly included a nasoseptal flap (22.4%, 11/49). A lumbar drain was utilized in 50% (3/6) of patients ≤ 6 years of age compared to 18.4% (9/49) in patients > 6 and ≤20 years of age (P < 0.08). Post-operative CSF leaks were encountered in 16.7% (1/6) of patients ≤ 6 years of age compared to 10.2% (5/49) in patients > 6 and ≤20 years of age (P < 0.63). Behavioral issues were noted to potentially contribute to failed skull base reconstruction in patients <6 years of age.

CONCLUSIONS

Pediatric patients, particularly those ≤6 years of age, present a unique set of anatomic and behavioral challenges for the skull base surgeon as highlighted in this study.

Technological and Ideological Innovations in Endoscopic Skull Base Surgery

BACKGROUND

Endoscopic skull base surgery has evolved over the last several decades due to technological advances and operative techniques. Several innovations that are not yet mainstream may have significant impact on the future of endoscopic skull base surgery.

METHODS

Current literature pertaining to innovations in endoscopic skull base surgery was retrieved using PubMed, Embase, Web of Science, and Google Scholar.

RESULTS

Several recent innovations may play an influential role in the advancement of endoscopic skull base surgery, including fluorescent dyes such as indocyanine green fluorescence, fluorescein, and 5-aminolevulinic acid, 3-dimensional endoscopes, robotic surgery, and intraoperative magnetic resonance imaging.

CONCLUSIONS

Several technologies are under current investigation with the hope to improve future outcomes in endoscopic skull base surgery. Additional research and evolution are necessary and will require intense scrutiny before becoming standard of care.

Complications of Nasoseptal Flap Reconstruction: A Systematic Review

Objective  The nasoseptal flap (NSF) is considered the primary vascularized flap for reconstruction of dural defects with endoscopic endonasal surgery (EES) of the skull base. However, the complications and morbidities associated with this reconstructive flap are poorly understood. This article presents a systematic review of the complications and morbidities related to the use of the NSF in skull base surgery. Method  A systematic review of the literature based on published guidelines was performed to identify potential complications and morbidities related to the NSF. The MEDLINE and Embase databases were searched from January 1, 1950 to February 5, 2018. Results  Twenty-seven articles were identified. Reported complications were as follows: NSF necrosis (4 studies; [0-1.3%]), mucocele formation (5 studies; [0-3.6%]), septal perforation (6 studies, [0-14.4%]), nasal dorsum collapse (2 studies, [0.7-5.8%]), effects on quality of life (QoL) (8 studies), and olfactory loss (11 studies). Conclusion  Although complications associated with the NSF may be underreported in the literature, the NSF appears to be a safe and reliable reconstructive flap in EES of the skull base.