Clinical Use Of Intraoperative Neuronavigation And FLOW 800 With Indocyanine Green Videoangiography In Cerebral Arteriovenous Malformation Surgery

Objective: To demonstrate the usefulness of intraoperative functional neuronavigation and FLOW 800 with indocyanine green videoangiography during microsurgical resection of cerebral arteriovenous malformations (AVMs).Materials and Methods:A series of 40 consecutive cases of AVMs underwent microsurgery aided by intraoperative functional neuronavigation at our hospital were retrospectively analyzed. Preoperative assessment included functional magnetic resonance (fMRI) and diffusion tensor imaging (DTI) to identify the relationship between lesions and eloquent areas. The results of images were integrated into three-dimensional datasets to achieve intraoperative microscopic-based functional neuronavigation during AVMs resection. Intraoperative MRI and electrophysiological monitoring were also used. Indocyanine green videoangiography was performed at predissection, postclipping of the feeders, and postresection of the nidus. FLOW 800 software presented a color map and ICG intensity-time curve. Analysis was performed using time to half-maximum fluorescence intensity (T1/2) to evaluate the transit time between the cortical artery and the cortical vein. Postoperative digital subtraction angiography (DSA) was re-examined routinely to evaluate the extent of resection. Clinical outcome was evaluated with the modified Rankin Scale.Results:Of the 40 patients,29 were male and 11 were female, with age ranging from 4 to 62 years (mean age 32.5 years). There were 3 Spetzler-Martin grade IV AVMs,8 Grade III AVMs,16 Grade Ⅱ AVMs and 13 Grade I AVMs. Eighteen AVMs were adjacent to eloquent areas including the eloquent cortex and fiber bundles which were successfully activated preoperatively. Seven AVMs were involved in Broca’s areas, 8 were involved in Wernicke’s areas,6 were involved in motor areas,4 were involved in sensory areas,3 were involved in visual cortex,7 were involved in arcuate fasciculus, 10 were involved in corticospinal tract,11 were involved in sensory tract and 11 were involved in optic radiation. All patients underwent surgery with the aid of intraoperative navigation, intraoperative MRI (iMRI) was used in 12 patients. Operations involved in motor areas and corticospinal tract were performed under continuous electrophysiological monitoring. Twenty-two patients without eloquent areas-related AVMs had successfully located the lesions. Total resection was achieved in 34 cases (85.0%) including 14 AVMs in eloquent areas. No surgery-related mortality occurred.A total of 40 ICG videoangiographies were successfully performed in 11 patients. The average number of ICG injections per operation was 3.64 (range,3～6). Feeders were visualized in 10 patients, the nidus were visualized in 11 cases, and drainers were visualized in 9 cases. FLOW 800 analyses were achieved in all patients. Transit time between the cortical artery and the cortical vein reduced from 4.74±1.32s at predissection of the nidus to 3.90±1.35s seconds at postclipping of the feeders (P＜0.05) and 2.58±0.93s seconds at postresection of the nidus (P<0.05).The postsurgical follow-up period varied from 3 months to 70 months (mean 22.5 months). Six patients with residual AVMs were treated subsequently with radiosurgery. 3 AVMs were successfully obliterated with radiosurgery. Two AVMs were within the 3-year latency period after radiosurgery. One patient had a new hemorrhage 1.5 years after radiosurgery and underwent embolization. Of the 11 patients presenting with seizures,9 patients were seizure-free during the followed-up period. The mean mRS score in three months after surgery was 1.4 and postoperative mRS was 2.6, compared with a mean preoperative mRS score of 1.2.82.5% of the patients returned to normal work and life during the followed-up period.Conclusion:Three-dimensional visualization of lesions and adjacent eloquent areas including functional cortex and fiber tract with preoperative fMRI and DTI aids the neurosurgeon in selecting suitable patients and designing a feasible approach for resection. Intraoperative microscope-based functional neuronavigation helps to accurately design the skin flap, surgical trajectory, thus avoiding damage to functional areas and neurologic compromise. ICG videoangiography helps identify the vascular patency and architecture. FLOW 800 software enables an objective and quantitative analysis presented visually as a color map and ICG intensity-time curve to analyze blood flow dynamics at various stages of resection.