393 Sonolucent Cranioplasty for Real-Time Ultrasound Monitoring of Extra-to-Intracranial Bypass: Early Multicenter Experience of 44 Cases

Abstract

INTRODUCTION: The new sonolucent cranioplasty implant (clear polymethyl methacrylate, PMMA) adds functionality besides reconstruction during and after surgery. One possible application uses transcranioplasty ultrasound (TCUS) technique after PMMA cranioplasty to assess graft patency of extracranial-intracranial (EC-IC) bypass procedures. METHODS: Multicenter analysis of consecutive EC-IC bypass patients from 5 US centers between 2019-2022 with closure post bypass using the translucent PMMA cranioplasty implant. RESULTS: Forty-four patients (median-age 53, 68.2% females) were included. The most common indication for bypass was Moyamoya disease/syndrome (77.3%) and superficial temporal artery to middle cerebral artery (STA-MCA) bypass was the most common procedure (79.5%). Pre-treatment modified Rankin Scale of 0 and 1-2 was noted in 11.4% and 59.1% of the patients, respectively, with hypertension being the most common comorbidity (72.7%). Intraoperative imaging for bypass patency involved utilizing combination of modalities in all patients, with intraoperative doppler being the most commonly utilized monitoring modality (90.9%) followed by indocyanine green (ICG) and catheter angiography (86.4% and 61.4%, respectively). Qualitative TCUS assessment of the graft patency was feasible in all cases without technical difficulties. Post-operative inpatient TCUS confirmation of the bypass patency was recorded in 56.8% of the cases, and outpatient TCUS surveillance for monitoring bypass patency through the implant was recorded in 22.7% of the patients. There were no cases of bypass failure noted in this cohort necessitating retreatment. Similarly, no implant-related complications were encountered in the cohort. Major complications requiring additional surgery occurred in 2 patients (4.6%) including epidural hematoma requiring surgical evacuation (2.3%) and post-operative surgical site infection (2.3%) that was unrelated to the implant. CONCLUSIONS: This multicenter study supports the safety and feasibility of using the sonolucent PMMA implant in the setting of EC-IC bypass surgery with the goal to monitor bypass patency using TCUS.