Indocyanine green videoangiography (ICGV)-guided surgery of parasagittal meningiomas occluding the superior sagittal sinus (SSS)

How I do it: the surgical resection of a middle third parasagittal meningioma with venous preservation strategy

BACKGROUND

The surgical resection of the middle third parasagittal meningioma (PSM) is difficult, where the challenge is to systematically protect the eloquent parenchyma and collateral venous drainage.

METHOD

We report a case of PSM that eroded the skull, wholly occluded the superior sagittal sinus at the middle third segment, underwent radical resection with evaluation and preservation of the collateral venous drainage by preoperative venography, and intraoperative indocyanine green videoangiography (ICGVA) that aimed to avoid postoperative complications.

CONCLUSION

This case demonstrates the importance of venous preservation strategy and the value of ICGVA in the intraoperative assessment of collateral venous drainage function.

Fluorescence-Guided Surgery: A Review on Timing and Use in Brain Tumor Surgery

Fluorescence-guided surgery (FGS) allows surgeons to have improved visualization of tumor tissue in the operating room, enabling maximal safe resection of malignant brain tumors. Over the past two decades, multiple fluorescent agents have been studied for FGS, including 5-aminolevulinic acid (5-ALA), fluorescein sodium, and indocyanine green (ICG). Both non-targeted and targeted fluorescent agents are currently being used in clinical practice, as well as under investigation, for glioma visualization and resection. While the efficacy of intraoperative fluorescence in studied fluorophores has been well established in the literature, the effect of timing on fluorophore administration in glioma surgery has not been as well depicted. In the past year, recent studies of 5-ALA use have shown that intraoperative fluorescence may persist beyond the previously studied window used in prior multicenter trials. Additionally, the use of fluorophores for different brain tumor types is discussed in detail, including a discussion of choosing the right fluorophore based on tumor etiology. In the following review, the authors will describe the temporal nature of the various fluorophores used in glioma surgery, what remains uncertain in FGS, and provide a guide for using fluorescence as a surgical adjunct in brain tumor surgery.

Meningioma: not always a benign tumor. A review of advances in the treatment of meningiomas

Meningiomas are the most common primary intracranial tumors. The majority of meningiomas are benign, but they can present different grades of dedifferentiation from grade I to grade III (anaplastic/malignant) that are associated with different outcomes. Radiological surveillance is a valid option for low-grade asymptomatic meningiomas. In other cases, the treatment is usually surgical, aimed at achieving a complete resection. The use of adjuvant radiotherapy is the gold standard for grade III, is debated for grade II and is not generally indicated for radically resected grade I meningiomas. The use of systemic treatments is not standardized. Here we report a review of the literature on the clinical, radiological and molecular characteristics of meningiomas, available treatment strategies and ongoing clinical trials.

Characteristics of Fluorescent Intraoperative Dyes Helpful in Gross Total Resection of High-Grade Gliomas-A Systematic Review

Background: A very important aspect in the treatment of high-grade glioma is gross total resection to reduce the risk of tumor recurrence. One of the methods to facilitate this task is intraoperative fluorescence navigation. The aim of the study was to compare the dyes used in this technique fluorescent intraoperative navigation in terms of the mechanism of action and influence on the treatment of patients. Methods: The review was carried out on the basis of articles found in PubMed, Google Scholar, and BMC search engines, as well as those identified by searched bibliographies and suggested by experts during the preparation of the article. The database analysis was performed for the following phrases: "glioma", "glioblastoma", "ALA", "5ALA", "5-ALA", "aminolevulinic acid", "levulinic acid", "fluorescein", "ICG", "indocyanine green", and "fluorescence navigation". Results: After analyzing 913 citations identified on the basis of the search criteria, we included 36 studies in the review. On the basis of the analyzed articles, we found that 5-aminolevulinic acid and fluorescein are highly effective in improving the percentage of gross total resection achieved in high-grade glioma surgery. At the same time, the limitations resulting from the use of these methods are marked-higher costs of the procedure and the need to have neurosurgical microscope in combination with a special light filter in the case of 5-aminolevulinic acid (5-ALA), and low specificity for neoplastic cells and the dependence on the degree of damage to the blood-brain barrier in the intensity of fluorescence in the case of fluorescein. The use of indocyanine green in the visualization of glioma cells is relatively unknown, but some researchers have suggested its utility and the benefits of using it simultaneously with other dyes. Conclusion: The use of intraoperative fluorescence navigation with the use of 5-aminolevulinic acid and fluorescein allows the range of high-grade glioma resection to be increased.

Can safe and radical resection of all types of parasagittal meningiomas be achievable? -the introduction of a simplified surgical strategy

Background: Surgery of parasagittal meningiomas (PSMs) is still technically challenging, for the balance between radical resection and preservation of venous circulation. In this article, we'd systemically introduce the technical nuances of a simplified strategy for radical resection of all types of PSMs. All the cases were operated by one single neurosurgeon from a single institution.Methods: Clinical charts of patients with PSMs between 2014 and 2020were retrospectively reviewed. A simplified classification method was adopted, which was based on the relationship between the tumor and superior sagittal sinus (SSS). Surgery aiming at radical resection and venous flow preservation was performed. Only in case of total occlusion of SSS, we performed tumor resection without reconstruction of the venous sinus.Results: Clinical data obtained in 55 consecutive patients (47 primary and 8 recurrent cases) were analyzed, among which 20 were with patent sinus, 27 were with partially occluded sinus and 8 were with completely occluded sinus. Forty-two (76.4%) and 13 patients (23.6%) had the same and improved functional status as compared to that of pre-operation, respectively. Four patients (7.3%) experienced transient neurological deterioration but improved to the normal level in the long-term follow-up. All patients achieved Simpson I/II radical resection. No patients suffered from post-operative recurrence in the follow-up duration of 27.05 ± 19.55 (2-91) months.Conclusion: Radical and safe resection of all types of PSMs is achievable and not difficult if the simplified surgical strategy mentioned in the article is adopted, no matter to which extent the sinus is invaded.

Combined microsurgical fluorescence for optimizing resection in refractory empyema and cerebritis

PURPOSE

Due to the generalization of new microsurgical equipment, intraoperative fluorescence techniques have extended in neurosurgical practice, mainly in neurovascular and neuro-oncology patients. The aim of identifying pathological tissue and also differentiating from the normal brain helps neurosurgeons to approach other kinds of intracranial entities such as infections.

METHODS

It is described in the case of an 11-year-old patient who underwent a subdural empyema by performing a craniotomy and evacuation of the purulent collection. After a non-optimal evolution, a frontobasal meningoencephalitis was assessed with cerebral involvement and associated intracranial hypertension. Indocyanine green (ICG) was used in reintervention for demonstrating a great damage of cortical vascularization around the infected area as well as fluorescein (FL), which identified a large area of avascularized tissue.

RESULTS

Both techniques allowed a selective excision of the affected brain parenchyma while preserving viable parenchymal areas. Radiological evolution and clinical outcome were good.

CONCLUSIONS

The identification of vascular patterns in brain lesions and the recognition of viable or necrotized tissues are suitable for a selective resection of the parenchyma, minimizing morbidity. Clinical outcome is related to a safe and effective management of inflammatory and infectious processes.

Importance of collateral venous circulation on indocyanine green videoangiography in intracranial meningioma resection: direct evidence for venous compression theory in peritumoral edema formation

OBJECTIVE

Indocyanine green videoangiography (ICGVA) has been used in many neurosurgical operations, including vascular and brain tumor fields. In this study, the authors applied ICGVA to intracranial meningioma surgery and evaluated it usefulness with attention to collateral venous flow.

METHODS

Forty-two patients with intracranial meningioma who underwent ICGVA during microsurgical resection were retrospectively analyzed. For ICGVA, the ICG was injected intravenously at the standard dose of 12.5 mg before and/or after tumor resection. Intravascular fluorescence from blood vessels was imaged through a microscope with a special filter and infrared excitation light to illuminate the operating field. The authors assessed the benefits of ICGVA and analyzed its findings with preoperative radiological findings on MRI.

RESULTS

ICGVA allowed real-time assessment of the patency and flow direction in very small peritumoral vessels in all cases. A safe dural incision could also be done based on information from ICGVA. The collateral venous channel due to venous obstruction of tumoral compression was found in 10 cases, and venous flow restoration after tumor resection was observed promptly after tumor resection in 4 cases. Peritumoral brain edema (PTBE) was observed on preoperative T2-weighted MRI in 19 patients. The presence of collateral venous circulation or flow restoration was significantly related to PTBE formation in multivariate analysis (p = 0.001; HR 0.027, 95% CI 0.003-0.242).

CONCLUSIONS

ICGVA, an excellent method for monitoring blood flow during meningioma resection, provides valuable information as to the presence of venous collaterals and flow restoration. Furthermore, the fact that the presence of venous collaterals was found to be associated with PTBE may directly support the venous theory as the pathogenesis of PTBE formation.

The application of fluorescence techniques in meningioma surgery-a review

Surgical resections of meningiomas, the most common intracranial tumor in adults, can only be curative if radical resection is achieved. Potentially, the extent of resection could be improved, especially in complex and/or high-grade meningiomas by fluorescence-guided surgery using 5-aminolevulinic acid (5-ALA), indocyanine green (ICG), or fluorescein. This review aims to summarize and evaluate these fluorescence-guided meningioma surgery techniques. PubMed and Embase were searched for relevant articles. Additionally, we checked reference lists for further studies. Forty-eight articles were included in the final analysis. 5-ALA fluoresced with varying sensitivity and selectivity in meningiomas and in invaded bone and dura mater. Although ICG was mainly applied for video angiography, one report shows tumor fluorescence 18-28 h post-ICG injection. Lastly, the use of fluorescein could aid in the identification of tumor remnants; however, detection of dural tail is highly questionable. Fluorescence-guided meningioma surgery should be a reliable, highly specific, and sensitive technique. Despite numerous studies reporting the use of fluorescent dyes, currently, there is no evidence that these tools improve the radical resection rate and long-term recurrence-free outcome in meningioma surgery without neurological deficits. Evidence regarding the effectiveness and increased safety of resection after the application of these fluorophores is currently lacking. Future research should focus on the development of a meningioma-targeted, highly sensitive, and specific fluorophore.

Use of ICG videoangiography and FLOW 800 analysis to identify the patient-specific venous circulation and predict the effect of venous sacrifice: a retrospective study of 172 patients

OBJECTIVE The best management of veins encountered during the neurosurgical approach is still a matter of debate. Even if venous sacrifice were to lead to devastating consequences, under certain circumstances, it might prove to be desirable, enlarging the surgical field or increasing the extent of resection in tumor surgery. In this study, the authors present a large series of patients with vascular or oncological entities, in which they used indocyanine green videoangiography (ICG-VA) with FLOW 800 analysis to study the patient-specific venous flow characteristics and the management workflow in cases in which a venous sacrifice was necessary. METHODS Between May 2011 and December 2017, 1972 patients were admitted to the authors' division for tumor and/or neurovascular surgery. They retrospectively reviewed all cases in which ICG-VA and FLOW 800 were used intraoperatively with a specific target in the venous angiographic phase or for the management of venous sacrifice, and whose surgical videos and FLOW 800 analysis were available. RESULTS A total of 296 ICG-VA and FLOW 800 studies were performed intraoperatively. In all cases, the venous structures were clearly identifiable and were described according to the flow direction and speed. The authors therefore defined different patterns of presentation: arterialized veins, thrombosed veins, fast-draining veins with anterograde flow, slow-draining veins with anterograde flow, and slow-draining veins with retrograde flow. In 16 cases we also performed a temporary clipping test to predict the effect of the venous sacrifice by the identification of potential collateral circulation. CONCLUSIONS ICG-VA and FLOW 800 analysis can provide complete and real-time intraoperative information regarding patient-specific venous drainage pattern and can guide the decision-making process regarding venous sacrifice, with a possible impact on reduction of surgical complications.

Application of indocyanine green fluorescence endoscopic system in transsphenoidal surgery for pituitary tumors

BACKGROUND

For the precise removal of pituitary tumors, preserving the surrounding normal structures, we need real-time intraoperative information on tumor location, margins, and surrounding structures. The aim of this study was to evaluate the benefits of a new intraoperative real-time imaging modality using indocyanine green (ICG) fluorescence through an endoscopic system during transsphenoidal surgery (TSS) for pituitary tumors.

METHODS

Between August 2013 and October 2014, 20 patients with pituitary and parasellar region tumors underwent TSS using the ICG fluorescence endoscopic system. We used a peripheral vein bolus dose of 6.25 mg/injection of ICG, started with a time counter, and examined how each tissue type increased and decreased in fluorescence through time.

RESULTS

A total of 33 investigations were performed for 20 patients: 9 had growth hormone secreting adenomas, 6 non-functioning pituitary adenomas, 3 Rathke's cleft cysts, 1 meningioma, and 1 pituicytoma. After the injection of ICG, the intensity of fluorescence of tumor and normal tissues under near-infrared light showed clear differences. We could differentiate tumor margins from adjacent normal tissues and define clearly the surrounding normal structures using the different fluorescent intensities time changes and tissue-specific fluorescence patterns.

CONCLUSIONS

The ICG endoscopic system is simple, user-friendly, quick, cost-effective, and reliable. The method offered real-time information during TSS to delimit pituitary and parasellar region tumor tissue from surrounding normal structures. This method can contribute to the improvement of total removal rates of tumors, reduction of complications after TSS, saving surgical time, and preserving endocrinological functions.

Optimal surgical strategy for meningiomas involving the superior sagittal sinus: a systematic review

Involvement of the superior sagittal sinus (SSS) by meningiomas poses specific challenges, without an agreement about the degree of surgical aggressiveness when dealing with these lesions. In this systematic review and meta-analysis, we compare outcomes and complication rates, after different surgical strategies. Studies focused on meningiomas involving the SSS were collected from numerous online databases. Surgical outcome and complication data were abstracted. Comparisons were made considering complication and recurrence rates between an "aggressive" and a "non-aggressive" surgical attitude. A total of 26 studies, encompassing 1614 patients, were identified. Most of the tumors (53%) arose from the middle third of SSS and 75% of patients had a patent sinus at the time of surgery. A favorable outcome was achieved in 73% of patients treated with an "aggressive" surgical attitude compared to 78% of patients treated with a "non-aggressive" surgical attitude. Complication rates were similar between "aggressive" and "non-aggressive" attitudes, except for a higher rate of venous infarct (4% versus 2%, respectively) and worsening of preexisting motor deficits (34% versus 13%, respectively) in aggressively treated patients. Recurrence rates were not substantially different in the two groups after accounting for length of follow-up. Patients with incomplete resection (Simpson grades II-V) or with high histological grade (WHO grade III) had significantly higher recurrence rates. A complete resection achieves higher rates of tumor control, however, without nullifying the risk of recurrence. Moreover, "aggressive" tumor removal is associated with higher rates of venous complications and worsening of preexisting motor deficits.

The role of indocyanine green videoangiography with FLOW 800 analysis for the surgical management of central nervous system tumors: an update

OBJECTIVE

Indocyanine green videoangiography (ICG-VA) is an intraoperative technique used to highlight vessels in neurovascular surgery. Its application in the study of the vascular pathophysiology in CNS tumors and its role in their surgical management are still rather limited. A recent innovation of ICG-VA (i.e., the FLOW 800 algorithm integrated in the surgical microscope) allows a semiquantitative evaluation of cerebral blood flow. The aim of this study was to evaluate for the first time the systematic application of ICG-VA and FLOW 800 analysis during surgical removal of CNS tumors.

METHODS

Between May 2011 and December 2017, all cases in which ICG-VA and FLOW 800 analysis were used at least one time before, during, or after the tumor resection, and in which surgical videos were available, were retrospectively reviewed. Results of the histological analysis were analyzed together with the intraoperative ICG-VA with FLOW 800 in order to investigate the tumor-related videoangiographic features.

RESULTS

Seventy-one patients who underwent surgery for cerebral and spinal tumors were intraoperatively analyzed using ICG-VA with FLOW 800, either before or after tumor resection, for a total of 93 videoangiographic studies. The histological diagnosis was meningioma in 25 cases, glioma in 14, metastasis in 7, pineal region tumor in 5, hemangioblastoma in 4, chordoma in 3, and other histological types in 13 cases. The authors identified 4 possible applications of ICG-VA and FLOW 800 in CNS tumor surgery: extradural surveys allowed exploration of sinus patency and the course of veins before dural opening; preresection surveys helped in identifying pathological vascularization (arteriovenous fistulas and neo-angiogenesis) and regional venous outflow, and in performing temporary venous clipping tests, when necessary; postresection surveys were conducted to evaluate arterial and venous patency and parenchymal perfusion after tumor removal; and a premyelotomy survey was conducted in intramedullary tumors to highlight the posterior median sulcus.

CONCLUSIONS

The authors found ICG-VA with FLOW 800 to be a useful method to monitor blood flow in the exposed vessels and parenchyma during microsurgical removal of CNS tumors in selected cases. In particular, a preresection survey provides useful information about pathophysiological changes of brain vasculature related to the tumor and aids in the individuation of helpful landmarks for the surgical approach, and the postresection survey helps to prevent potential complications associated with the resection (such as local hypoperfusion or venous infarction).

Utility of Indocyanine Green Video Angiography for Sylvian Fissure Dissection in Subarachnoid Hemorrhage Patients - Sylvian ICG Technique

Indocyanine green (ICG) emits fluorescence in the far-red domain under light excitation. ICG video angiography (ICG-VA) has been established as a useful method to evaluate blood flow in the operative field. We report the usefulness of ICG-VA for Sylvian fissure dissection in patients with subarachnoid hemorrhage (SAH). Subjects comprised 7 patients who underwent ICG-VA before opening the Sylvian fissure during neck clipping for ruptured cerebral aneurysm. We observed contrasted Sylvian veins before opening the Sylvian fissure using surgical microscopes. This procedure was termed “Sylvian ICG”. We observed ICG fluorescence quickly in all cases. Sylvian veins that appeared unclear in the standard microscopic operative field covered with subarachnoid hemorrhage were extremely clearly depicted. These Sylvian ICG findings were helpful in identifying entry points and the dissecting course of the Sylvian fissure. At the time of clipping, no residual fluorescence from Sylvian ICG was present, and aneurysm clipping was not impeded. Sylvian ICG for SAH patients is a novel technique to facilitate dissection of the Sylvian fissure. We believe that this technique will contribute to improved safety of clipping surgery for ruptured aneurysms.

Transdural Indocyanine Green Videography for Superficial Temporal Artery-to-Middle Cerebral Artery Bypass-Technical Note

BACKGROUND

Neurosurgical application of indocyanine green (ICG) videography before performing a dural opening, known as transdural ICG videography, has been used during surgery of meningiomas associated with venous sinuses as well as cranial and spinal arteriovenous malformations. However, its use for a superficial temporal artery (STA)-to-middle cerebral artery (MCA) bypass has not been reported.

METHODS

We performed a retrospective analysis of medical records of patients who underwent transdural ICG videography during STA-MCA bypass performed between January 2012 and March 2015. The primary outcome was visualization of recipient cortical arteries; secondary outcomes were surgical modifications and complications as well as any adverse events associated with transdural ICG videography.

RESULTS

We analyzed 29 STA-MCA bypass procedures performed in 30 hemispheres with atherosclerotic steno-occlusive disease and found that the proper recipient was identified in 28 hemispheres. Subsequently modified procedures for those were a tailored dural incision and craniotomy correction. No complications associated with ICG administration were encountered; during the postoperative course, transient aphasia was noted in 1 case, chronic subdural hematoma was noted in 1 case, and subdural effusion was noted in 2 cases.

CONCLUSIONS

Transdural ICG videography for atherosclerotic steno-occlusive disease facilitates modifications during STA-MCA bypass procedures. Recognition of the proper recipient cortical arteries before a dural incision allows the neurosurgeon to perform a tailored dural incision and extension of the bone window, although the contribution to surgical outcome has yet to be determined.

3D digital subtracted CT angiography to evaluate the venous anatomy in extra-axial tumors invading the major dural venous sinuses

Background Investigation of the venous system surrounding a tumor that is invading a dural sinus is of great use for guiding the surgical excision. Non-invasive imaging is often inadequate since enhancement of the tumor causes it to blend with the contrast of the venous vascular structures. Conventional two-dimensional angiography is also often insufficient. Objective The objective of this study was to report regarding the potential of three-dimensional digital subtracted computed tomography angiography (3D DS-CTA) as a technique to preoperatively explore these tumors. Methods We retrospectively studied the radiological and surgical features of patients explored with 3D DS-CTA for a tumor invading a major dural sinus. Results Three patients were included in this study, one hemangiopericytoma and two meningiomas. 3D DS-CTA allows for accurate assessment of the patency of the sinus, the location of the secondary intra- and trans-osseous venous outlets, and surgical guidance by neuronavigation. Conclusion 3D DS-CTA could be a promising guiding and diagnostic tool for the pre- and intraoperative treatment of vascular tumors invading the dural sinuses, for which the venous morbidity and mortality is substantial.

Multimodal optical analysis of meningioma and comparison with histopathology

Meningioma is the most frequent primary central nervous system tumor. The risk of recurrence and the prognosis are correlated with the extent of the resection that ideally encompasses the infiltrated dura mater and, if required, the infiltrated bone. No device can deliver real-time intraoperative histopathological information on the tumor environment to help the neurosurgeon to achieve a gross total removal. This study assessed the abilities of nonlinear microscopy to provide relevant and real-time data to help resection of meningiomas. Nine human meningioma samples (four World Health Organization Grade I, five Grade II) were analyzed using different optical modalities: spectral analysis and imaging, lifetime measurements, fluorescence lifetime imaging microscopy, fluorescence emitted under one- and two-photon excitation and the second-harmonic generation signal imaging using a multimodal setup. Nonlinear microscopy produced images close to histopathology as a gold standard. The second-harmonic generation signal delineated the collagen background and two-photon fluorescence underlined cell cytoplasm. The matching between fluorescence images and Hematoxylin and Eosin staining was possible in all cases. Grade I meningioma emitted less autofluorescence than Grade II meningioma and Grade II meningioma exhibited a distinct lifetime value. Autofluorescence was correlated with the proliferation rates and seemed to explain the observed differences between Grade I and II meningiomas. This preliminary multimodal study focused on human meningioma samples confirms the potential of tissue autofluorescence analysis and nonlinear microscopy in helping intraoperatively neurosurgeons to reach the actual boundaries of the tumor infiltration. Correspondence between H&E staining (top pictures) and the two-photon fluorescence imaging (bottom pictures).

Parasagittal meningiomas: Our surgical experience and the reconstruction technique of the superior sagittal sinus

Background:

The radical resection of parasagittal meningiomas without complications and recurrences is the goal of the neurosurgeon. Nowadays, different managements are proposed. This study describes our surgical technique during the lesional excision and the reconstruction of the superior sagittal sinus (SSS).

Methods:

The total removal (Simpson I and II) of parasagittal meningiomas (WHO grade I and II) was obtained in 75 patients from September 2000 to January 2010. The indocyanine green videoangiography was used before the dural opening and, when necessary, to identify and preserve the cortical veins. The surgery of the SSS was performed in accordance with Sindou's classification, and its reconstruction was achieved through the use of a patch of galea capitis.

Results:

We had no cases of recurrence and thrombotic occlusion of the SSS in 5 years after the reconstruction. No complications were observed in 65 patients, and no cases of mortality were reported. Neurological focal deficits were observed in 5 patients. A brain swelling and a venous infarction were observed in 1 patient. Only one case of thrombotic occlusion was observed. A cerebrospinal fluid leak was observed in 2 patients, and a systemic complication was found in 1 patient.

Conclusion:

Several factors contribute to the success of the parasagittal meningioma surgery. We consider the preservation of the cortical veins to be important, and, when possible, we recommend the reconstruction of the anterior third of the SSS. Our experience has led us to believe that until now surgery is a winning choice if practiced by expert hands.

Intraoperative Fluorescence Imaging for Personalized Brain Tumor Resection: Current State and Future Directions

INTRODUCTION

Fluorescence-guided surgery is one of the rapidly emerging methods of surgical "theranostics." In this review, we summarize current fluorescence techniques used in neurosurgical practice for brain tumor patients as well as future applications of recent laboratory and translational studies.

METHODS

Review of the literature.

RESULTS

A wide spectrum of fluorophores that have been tested for brain surgery is reviewed. Beginning with a fluorescein sodium application in 1948 by Moore, fluorescence-guided brain tumor surgery is either routinely applied in some centers or is under active study in clinical trials. Besides the trinity of commonly used drugs (fluorescein sodium, 5-aminolevulinic acid, and indocyanine green), less studied fluorescent stains, such as tetracyclines, cancer-selective alkylphosphocholine analogs, cresyl violet, acridine orange, and acriflavine, can be used for rapid tumor detection and pathological tissue examination. Other emerging agents, such as activity-based probes and targeted molecular probes that can provide biomolecular specificity for surgical visualization and treatment, are reviewed. Furthermore, we review available engineering and optical solutions for fluorescent surgical visualization. Instruments for fluorescent-guided surgery are divided into wide-field imaging systems and hand-held probes. Recent advancements in quantitative fluorescence-guided surgery are discussed.

CONCLUSION

We are standing on the threshold of the era of marker-assisted tumor management. Innovations in the fields of surgical optics, computer image analysis, and molecular bioengineering are advancing fluorescence-guided tumor resection paradigms, leading to cell-level approaches to visualization and resection of brain tumors.

Development of and Clinical Experience with a Simple Device for Performing Intraoperative Fluorescein Fluorescence Cerebral Angiography: Technical Notes

To perform intraoperative fluorescence angiography (FAG) under a microscope without an integrated FAG function with reasonable cost and sufficient quality for evaluation, we made a small and easy to use device for fluorescein FAG (FAG filter). We investigated the practical use of this FAG filter during aneurysm surgery, revascularization surgery, and brain tumor surgery. The FAG filter consists of two types of filters: an excitatory filter and a barrier filter. The excitatory filter excludes all wavelengths except for blue light and the barrier filter passes long waves except for blue light. By adding this FAG filter to a microscope without an integrated FAG function, light from the microscope illuminating the surgical field becomes blue, which is blocked by the barrier filter. We put the FAG filter on the objective lens of the operating microscope correctly and fluorescein sodium was injected intravenously or intra-arterially. Fluorescence (green light) from vessels in the surgical field and the dyed tumor were clearly observed through the microscope and recorded by a memory device. This method was easy and could be performed in a short time (about 10 seconds). Blood flow of small vessels deep in the surgical field could be observed. Blood flow stagnation could be evaluated. However, images from this method were inferior to those obtained by currently commercially available microscopes with an integrated FAG function. In brain tumor surgery, a stained tumor on the brain surface could be observed using this method. FAG could be performed with a microscope without an integrated FAG function easily with only this FAG filter.

Transdural indocyanine green video-angiography of vascular malformations

BACKGROUND

The role of indocyanine green video-angiography (ICG-VA) in the surgical resection of vascular malformations has been largely described; conversely, the utility of ICG-VA before dural opening (transdural ICG-VA) in this situation remains unclear. The aim of this study is to present the application of transdural ICG-VA in a consecutive series of patients in order to explore the potential provided by a transdural visualisation of vascular malformations.

METHOD

We retrospectively analysed the application of intra-operative ICG-VA before dural opening in 15 consecutive patients who underwent surgical resection of vascular malformations. The cases included 12 cerebral arterio-venous malformations (AVMs), 2 cerebral dural arterio-venous fistulas (dAVFs) and 1 spinal arterio-venous fistula (AVF).

RESULTS

ICG-VA before dural opening allowed the visualisation of the site and extension of the malformation in 13 out of 15 cases, whilst arterial feeders and venous drainages were identified in 9 out of 15 cases. In two patients with dAVF, the point of fistula could be transdurally identified through ICG-VA. In 14% of cases, the size of bone flap designed on neuronavigation data was then modified according to transdural ICG-VA findings.

CONCLUSIONS

Transdural ICG-VA proved an efficient tool that allows optimising the exposure of the malformation, performing a safe dural opening and identifying dural vascular connections of the lesion.

Indocyanine green videoangiography methodological variations: review

Indocyanine green videoangiography (ICGVA) procedures have become widespread within the spectrum of microsurgical techniques for neurovascular pathologies. We have conducted a review to identify and assess the impact of all of the methodological variations of conventional ICGVA applied in the field of neurovascular pathology that have been published to date in the English literature. A total of 18 studies were included in this review, identifying four primary methodological variants compared to conventional ICGVA: techniques based on the transient occlusion, intra-arterial ICG administration via catheters, use of endoscope system with a filter to collect florescence of ICG, and quantitative fluorescence analysis. These variants offer some possibilities for resolving the limitations of the conventional technique (first, the vascular structure to be analyzed must be exposed and second, vascular filling with ICG follows an additive pattern) and allow qualitatively superior information to be obtained during surgery. Advantages and disadvantages of each procedure are discussed. More case studies with a greater number of patients are needed to compare the different procedures with their gold standard, in order to establish these results consistently.

Application of indocyanine green video angiography in parasagittal meningioma surgery

Object

There are no doubts about the role that indocyanine green video angiography (ICGVA) can play in current vascular neurosurgery. Conversely, in brain tumor surgery, and particularly in meningioma surgery, this role is still unclear. Vein management is pivotal for approaching parasagittal meningiomas, because venous preservation is strictly connected to both extent of resection and clinical outcome. The authors present the technical traits and the postoperative outcome of the application of ICGVA in patients undergoing parasagittal meningioma surgery.

Methods

The authors retrospectively collected demographic, radiological, intraoperative, and follow-up data in 43 patients with parasagittal meningiomas who underwent surgery with the assistance of ICGVA at Padua Neurosurgical Department between October 2010 and July 2013. Intraoperative ICGVA findings at different stages (before dural opening, after dural opening, during resection, after resection) were reviewed. Additional data on functional monitoring, temporary venous clipping, and flow measurements were also recorded. The overall postoperative outcome was evaluated by assessing both the extent of resection and the clinical outcome data.

Results

The ICGVA studies were performed 125 times in 43 patients, providing helpful data for vein management and tumor resection in all stages of surgery. In 16% of meningiomas completely occluding the superior sagittal sinus, the ICGVA data differed from radiological findings and changed the surgical approach. In 20% of cases the intraoperative ICGVA findings directly guided the surgical strategy: venous sacrifice was necessary in 7 cases, without postoperative consequences; temporary clipping with neurophysiological monitoring proved to be predictive of safe venous sacrifice. In 7% of cases the ICGVA data needed to be supplemented with flow measurements. Simpson Grade I–II and Grade III resections were achieved in 86% and 14% of cases, respectively, with a 4.6% rate of overall morbidity.

Conclusions

This study shows that ICGVA can assist the different stages of parasagittal meningiomas surgery, guiding the vein management and tumor resection strategies with a favorable final clinical outcome. However, in the authors' experience the use of other complementary tools was mandatory in selected cases to preserve functional areas. Further studies are needed to confirm that the application of ICGVA in parasagittal meningioma surgery may improve the morbidity rate, as reported in this study.