Indocyanine green videoangiography for the identification of superficial temporal artery branches in EC-IC bypass surgery

BOLD Cerebrovascular Reactivity and NOVA Quantitative MR Angiography in Adult Patients with Moyamoya Vasculopathy Undergoing Cerebral Bypass Surgery

Revascularization surgery for the symptomatic hemisphere with hemodynamic impairment is effective for Moyamoya vasculopathy patients. However, careful patient selection is crucial and ideally supported by advanced quantitative hemodynamic imaging. Recently, blood oxygenation level-dependent cerebrovascular reactivity (BOLD-CVR) and quantitative magnetic resonance angiography with non-invasive optimal vessel analysis (qMRA-NOVA) have gained prominence in assessing these patients. This study aims to present the results of BOLD-CVR and qMRA-NOVA imaging along with the changes in cerebral hemodynamics and flow status following flow augmentation with superficial temporal artery-middle cerebral artery (STA-MCA) bypass in our Moyamoya vasculopathy patient cohort. Symptomatic patients with Moyamoya vasculopathy treated at the Clinical Neuroscience Center of the University Hospital Zurich who underwent hemodynamic and flow imaging (BOLD-CVR and qMRA-NOVA) before and after bypass were included in the analysis. Reduced hemispheric volume flow rates, as well as impaired BOLD-CVR, were measured in all 12 patients with Moyamoya vasculopathy before STA-MCA bypass surgery. Following the surgical procedure, post-operative BOLD-CVR demonstrated a non-significant increase in BOLD-CVR values within the revascularized, symptomatic middle cerebral artery territory and cerebral hemisphere. The results of the statistical tests should be viewed as indicative due to the small sample size. Additionally, post-operative qMRA-NOVA revealed a significant improvement in the hemispheric volume flow rate of the affected hemisphere due to the additional bypass flow rate. Our findings affirm the presence of hemodynamic and flow impairments in the symptomatic hemisphere of the Moyamoya vasculopathy patients. Bypass surgery proves effective in improving both BOLD-CVR impairment and the hemispheric volume flow rate in our patient cohort.

Complementary Tools in Cerebral Bypass Surgery

Cerebral revascularization surgery has been advanced by the refinement of several adjunctive tools. These tools include perioperative blood thinners, intraoperative spasmolytic agents, electrophysiological monitoring, and methods for assessing bypass patency or marking arteriotomies. Despite the array of options, the proper usage and comparative advantages of different complements in cerebral bypass have not been well-cataloged elsewhere. In this literature review, we describe the appropriate usage, benefits, and limitations of various bypass adjuncts. Understanding these adjuncts can help surgeons ensure that they receive reliable intraoperative information about bypass function and minimize the risk of serious complications. Overall, this review provides a succinct reference for neurosurgeons on various cerebrovascular bypass adjuncts.

Use of Indocyanine Green Angiography to Identify the Superficial Temporal Artery and Vein in Forehead Flaps for Facial Reconstruction

ABSTRACT

The superficial temporal artery (STA) frontal branch flap is susceptible to venous congestion because of its unpredictable and variable outflow. The authors applied indocyanine green angiography in identifying the superficial temporal vessels to help surgeons with proper flap designs to avoid severe complications. A retrospective review from 2015 to 2020 was conducted. All the patients who underwent indocyanine green angiography before forehead flap transfer for facial defect reconstruction were reviewed. The STA and vein were observed using indocyanine green angiography preoperatively. The relationship between the artery and vein was investigated. The venous anatomy was analyzed to guide the pedicle design. The survival of the flap and complications were assessed. A total of 12 patients were identified and included in this study. Indocyanine green angiography allows clear visualization of the detailed anatomy of the STA and vein. The frontal branch of the vein had great variations and generally diverged from the arterial branch. The tiny venae comitantes provided sufficient drainage for 2 small forehead flaps. The frontal branch of the vein entered the forehead and was used as the outflow channel in 4 patients. The parietal branch of the vein, which consistently gave off secondary tributaries to the superior forehead, was included in the pedicle in 6 patients. All flaps survived without complications. Indocyanine green angiography provided accurate localization of the superficial temporal vessels. This technique may be helpful in the precise planning forehead flap surgeries and in avoiding the risk of venous congestion.

Applications of Microscope-Integrated Indocyanine Green Videoangiography in Cerebral Revascularization Procedures

Indocyanine green videoangiography (ICG-VA) is a near-infrared range fluorescent marker used for intraoperative real-time assessment of flow in cerebrovascular surgery. Given its high spatial and temporal resolution, ICG-VA has been widely established as a useful technique to perform a qualitative analysis of the graft patency during revascularization procedures. In addition, this fluorescent modality can also provide valuable qualitative and quantitative information regarding the cerebral blood flow within the bypass graft and in the territories supplied. Digital subtraction angiography (DSA) is considered to be the gold standard diagnostic modality for postoperative bypass graft patency assessment. However, this technique is time and labor intensive and an expensive interventional procedure. In contrast, ICG-VA can be performed intraoperatively with no significant addition to the total operative time and, when used correctly, can accurately show acute occlusion. Such time-sensitive ischemic injury detection is critical for flow reestablishment through direct surgical management. In addition, ICG has an excellent safety profile, with few adverse events reported in the literature. This review outlines the chemical behavior, technical aspects, and clinical implications of this tool as an intraoperative adjunct in revascularization procedures.

Multimodal Monitoring Strategy Is Decisive in Elective Middle Cerebral Artery Aneurysm Clipping: A Case Report

BACKGROUND

The intraoperative use of neurophysiological monitoring (IONM) and indocyanine green video angiography (ICGVA) for aneurysm clipping have evolved during the last years. Both modalities are useful and safe by allowing greater rates of complete aneurysm occlusion with less intraoperative complications and postoperative neurologic deficits. We report a case of attempted aneurysm clipping in which the combined use of ICGVA and IONM was crucial for intraoperative decision-making.

CASE DESCRIPTION

A 62-year-old woman was operated for an incidental 6-mm aneurysm at the origin of the right fronto-opercular branch. During aneurysm clipping, IONM amplitudes dropped drastically, despite patency of the parent artery and perforators in ICGVA. Several attempts for clipping were made with recurring drops in IONM amplitudes, which forced us to leave the aneurysm untreated. The patient had a postoperative left-sided hemiparesis that improved on follow-up. Thereafter, the aneurysm was treated with stent-assisted coiling.

CONCLUSIONS

The combination of IONM and ICGVA during aneurysm surgery allows for a better assessment of vascular integrity and patient's postoperative outcome than ICGVA alone. Simultaneous evaluation of vessel patency and integrity of the somatosensory and motor pathways illustrates the complementarity of testing different modalities for intraoperative decision-making and for maximizing safeness in aneurysm clipping.

Usefulness of intraoperative Indocyanine green video angiography to select the recipient artery for bypass surgery in arteriosclerotic occlusion of the middle cerebral artery: a technical case report

BACKGROUND

In superficial temporal artery-to-middle cerebral artery (STA-MCA) bypass surgery, indocyanine green video angiography (ICG-VA) is usually used to verify bypass patency. Less-commonly reported is the ability to use this technique to evaluate candidate recipient vessels based on either collateral flow or identification of the distal branch of interest.

CASE PRESENTATION

An 82-year-old man presented with progressive cerebral infarction due to infarction of the M2 inferior trunk of the right middle cerebral artery. He underwent superficial temporal artery-middle cerebral artery bypass to prevent further ischemia 1 week after the initial stroke. In the surgery, M4 cortical arteries fed by the inferior trunk could not be identified as recipient arteries. Intraoperative ICG-VA showed delayed luminescence of some M4 arteries. Because the M4 arteries fed by the inferior trunk showed delayed retrograde flows from the anterior cerebral artery on preoperative digital subtraction angiography, the M4 arteries with delayed luminescence on ICG-VA were considered to be M4 arteries fed by the inferior trunk and selected as the recipient arteries.

CONCLUSIONS

ICG-VA shows differences in flow speed as delayed luminescence. This finding may be useful for detecting target vessels.

Role of Indocyanine Green Videoangiography in Identification of Donor and Recipient Arteries in Cerebral Bypass Surgery

The identification and preparation of a very good quality donor artery is a crucial step in every superficial temporal artery to middle cerebral artery (STA-MCA) bypass.For flow-preservation bypass performed for trapping of complex MCA aneurysms, the key element is the correct target of the recipient artery. When a cortical recipient artery (M4 segment of the MCA) is selected, this vessel must be a terminal branch of the artery whose sacrifice is necessary for definitive aneurysmal treatment.In this chapter we report on two techniques for (1) intraoperative mapping and preparation of good quality STA branch as the donor artery for STA-MCA bypass (mostly in the case the frontal branch of the STA needs to be used) and (2) selective identification of the correct superficial (M4 cortical) "recipient" artery in flow-preservation STA-MCA bypass performed for managing complex MCA aneurysms.Both techniques are based on the use of microscope-integrated indocyanine green videoangiography (ICG-VA), an intraoperative tool allowing observation and real-time assessment of blood flow in large and small vessels, with distinct evaluation of arterial, capillary, and venous phases.The two techniques contribute, respectively, to (1) reduce the risk of erroneous identification or injury of the donor artery in STA-MCA bypass procedures and (2) eliminate the risk of erroneous revascularization of a non-involved arterial territory in flow-preservation bypass surgery for managing complex MCA aneurysms.