Intraoperative evaluation of local cerebral hemodynamic change by indocyanine green videoangiography: prediction of incidence and duration of postoperative transient neurological events in patients with moyamoya disease

Abstract

<jats:sec><jats:title>OBJECTIVE</jats:title><jats:p>Transient neurological events (TNEs) occur frequently in the acute phase after direct bypass surgery for moyamoya disease (MMD), but there is currently no way to predict them. FlowInsight is a specialized software for analyzing indocyanine green (ICG) videoangiography taken with a surgical microscope. The purpose of this study was to investigate whether intraoperative evaluation of local hemodynamic changes around anastomotic sites using FlowInsight could predict the incidence and duration of TNEs.</jats:p></jats:sec><jats:sec><jats:title>METHODS</jats:title><jats:p>From patients who were diagnosed with MMD in our hospital between August 2014 and March 2017 and who underwent superficial temporal artery–middle cerebral artery bypass surgery, we investigated 25 hemispheres (in 22 patients) in which intraoperative ICG analysis was performed using FlowInsight. To evaluate the local cerebral hemodynamics before and after anastomosis, regions of interest were set at 3 locations on the brain surface around the anastomotic site, and the mean cerebral blood flow (CBF), mean gradation (Grad), mean transit time (MTT), and mean time to peak (TTP) were calculated from the 3 regions of interest. Furthermore, the change rate in CBF (ΔCBF [%]) was calculated using the formula (postanastomosis mean CBF − preanastomosis mean CBF)/preanastomosis mean CBF. ΔGrad (%), ΔMTT (%), and ΔTTP (%) were similarly calculated.</jats:p></jats:sec><jats:sec><jats:title>RESULTS</jats:title><jats:p>Postoperative stroke without TNE occurred in 2 of the 25 hemispheres. These 2 hemispheres (in 2 patients) were excluded from the study, and data from the remaining 23 hemispheres (in 20 patients) were analyzed. For each parameter (ΔCBF, ΔGrad, ΔMTT, and ΔTTP) calculated by FlowInsight, the difference between the groups with and without TNEs was significant. The median values for ΔCBF and ΔGrad were significantly higher in the TNE group than in the no-TNE group (ΔCBF 30.13 vs 3.54, p = 0.0106; ΔGrad 62.05 vs 10.78, p = 0.00435), whereas the median values for ΔMTT and ΔTTP were significantly lower in the TNE group (ΔMTT −16.90 vs −7.393, p = 0.023; ΔTTP −29.07 vs −7.02, p = 0.00342). Comparison of the area under the curve (AUC) for each parameter showed that ΔTTP had the highest AUC and was the parameter with the highest diagnostic accuracy (AUC 0.857). The Youden index revealed that the optimal cutoff value of ΔTTP was −11.61 (sensitivity 77.8%, specificity 71.4%) as a predictor of TNEs. In addition, Spearman’s rank correlation coefficients were calculated, and ΔCBF, ΔGrad, ΔMTT, and ΔTTP each showed a strong correlation with the duration of TNEs. The larger the change in each parameter, the longer the TNEs persisted.</jats:p></jats:sec><jats:sec><jats:title>CONCLUSIONS</jats:title><jats:p>Intraoperative ICG videoangiography findings were correlated with the occurrence and duration of TNEs after direct bypass surgery for MMD. Screening for cases at high risk of TNEs can be achieved by ICG analysis using FlowInsight.</jats:p></jats:sec>

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

“…A variety of transient neurological events (TNEs) have been reported in the immediate postoperative period after STA-MCA bypass, which is most commonly employed in MMD treatment. TNEs occur in 14–77% of patients after MMD bypass surgery (3) and include extremity numbness, weakness, and episodic severe headaches (31–34), which could potentially have permanent neurological sequelae (31–34). The underlying causative mechanisms of TNEs are yet to be elucidated.…”

“…Percentage change of these parameters after bypass was calculated using the formula (ΔX = (Xafter - Xbefore)/Xbefore). They demonstrated that patients with ΔTTP ≤ −12, ΔCBF ≥ 8, or ΔGrad ≥ 30 have a higher risk of developing postoperative TNEs (3). Hemodynamic changes after bypass surgery, analyzed through ICG and FlowInsight, were predictive of postoperative TNE and correlated with their duration.…”

“…This stenosis may lead to occlusion of the vessel lumen and a consequent abnormal, compensatory collateral neovascularization at the base of the brain. Superficial temporal artery (STA)-middle cerebral artery (MCA) bypass is the main direct revascularization procedure performed, and it is effective in reducing the risk of ischemic and hemorrhagic strokes as well as in improving cerebral ischemia (1–3).…”

Imaging methods for surgical revascularization in patients with moyamoya disease: an updated review

“…A hypo-responsive CVR on postoperative basal or acetazolamide-challenged SPECT in patients with MMD suggests a poor prognosis such as remaining neurological deficits and ischemic attacks during follow-up [65]. Association of cognitive dysfunction with improvement with CBF changes measured by SPECT has been explored both in adult and pediatric patients with MMD [32,69].…”

Evaluation of Hemodynamic Change by Indocyanine Green-FLOW 800 Videoangiography Mapping: Prediction of Hyperperfusion Syndrome in Patients with Moyamoya Disease

“…However, postoperative hyperperfusion syndrome (HPS), such as aphasia, epileptic seizures, and even new cerebral hemorrhage or ischemia, is experienced frequently in the acute phase after such surgeries [ 4 ]. With the evidence of neuroimaging, multiple literatures [ 5 – 7 ] have discussed local hemodynamic dysfunction as one of the main causes of such neurologic deficits. Besides, hypotheses such as watershed shift and inflammation have also been suggested.…”