Prospective Assessment of a Protocol using Neuromonitoring, Early Limb Reperfusion and Selective Temporary Aneurysm Sac Perfusion to Prevent Spinal Cord Injury During Fenestrated-branched Endovascular Aortic Repair

Abstract

Introduction - Spinal cord injury (SCI) is a devastating complication of thoracoabdominal aortic aneurysm (TAAA) repair. The aim of this study was to analyze the outcomes of a standardized protocol using continuous neuromonitoring, lower limb (LL) reperfusion and selective temporary aneurysm sac perfusion (TASP) to prevent SCI in patients undergoing fenestrated-branched endovascular repair (F-BEVAR). Methods - Patients enrolled in a prospective, non-randomized single-center study between 2014 and 2017 underwent a SCI prevention protocol for TAAAs or >5-cm supraceliac coverage, including staged thoracic endovascular aortic repair (TEVAR) for Extent I-II TAAAs, cerebrospinal fluid (CSF) drainage, permissive hypertension (mean arterial pressure [MAP] >80 mmHg), LL reperfusion and neuromonitoring. A >75% decrease in motor evoked (MEP) and somatosensory evoked potential (SSEP) amplitude triggered standardized maneuvers. Selective TASP was indicated in patients with persistent decline or delayed recovery (>10 min) in MEP/SSEPs despite maneuvers. End-points adjudicated by independent clinical event committee and included mortality and rates of immediate and delayed (>6 hours) SCI. Results - SCI prevention protocol was indicated in 166 of 232 patients (72%) treated by F-BEVAR for pararenal aneurysms in 22 patients, Extent IV TAAAs in 59 and Extent I-III TAAAs in 85 (Figure). CSF drainage was successful in 162 patients (98%) and stable neuromonitoring was achieved in all patients. Eighty-eight patients (53%) had changes in neuromonitoring starting 50±37 minutes after introduction of the aortic device. Changes in neuromonitoring improved with maneuvers in all except for 10 patients (11%) who had persistent decline in MEP/SSEPs after LL reperfusion. All 10 patients had TASP by leaving a renal-mesenteric branch or contralateral iliac gate incomplete. There was one 30-day or in-hospital mortality (0.4%) due to a subarachnoid hemorrhage from CSF drainage. Ten patients (4%) developed SCIs, including 6 paraplegia and 4 paraparesis. SCIs were immediate in 4 and delayed in 6 with an incidence of 1% for pararenal, 0% for Extent IV, 13% for Extent III and 10% for Extent I-II TAAAs. The probable cause of SCI was hemodynamic compromise in 6 patients, embolic in 2 and epidural hematoma in 2. SCIs occurred in 1/78 patients (1%) with normal neuromonitoring and in 9/88 patients (10%) who had decline in MEP/SSEPs (P=0.02). Among the 10 patients with TASP, neurologic exam was normal in 8 and showed SCI in 2. TASP closure was completed in all patients at 22±16 days, with one SCI 2 days after completion. All 3 patients with post-TASP SCI had complete recovery to ambulatory status. Overall, 2 patients (1%) had permanent paraplegia, which was immediate and probably embolic in both. Factors associated with SCI included extent I-III TAAAs, change in neuromonitoring and need for TASP. Conclusion - This prospective non-randomized study showed that a standardized protocol was associated with low rate of permanent paraplegia (1%). The predominance of SCIs among patients with Extent I-III TAAAs confirms that this protocol may be avoided in lower risk patients (e.g. pararenal and Extent IV TAAAs) due to potential risk of spinal and cerebral hemorrhagic complications from CSF drainage. Although TASP does not completely prevent SCI, it may optimize recovery to ambulatory status. Further investigation is needed to evaluate the benefits of TASP to prevent permanent paraplegia.