Endovascular repair and open repair surgery of thoraco-abdominal aortic aneurysms cause drastically different types of spinal cord injury

J. Huw Williams ,M. Basso ,Jayanth Rajan,Mostafa Eltobgy,Alexander A. Efanov,Hosam F. El-Sayed ,Sarah A. Moore ,Jean‐Jacques Michaille ,Kareem B. Rasul,Hesham Kelani,Eric C. Bourekas ,Mohamed Ehab Ramadan,Raphael A. Malbrue,Gerard J. Nuovo ,Michael Oglesbee,Hamdy Awad,Michael Knopp,Katherine Binzel,David Mast,Esmerina Tili,Valerie Bergdall,Adel A. Mikhail

doi:10.1038/s41598-021-87324-6

Abstract

Both endovascular repair (EVR) and open repair (OR) surgery of thoraco-abdominal aortic aneurysms cause spinal cord (SC) injury that can lead to paraparesis or paraplegia. It has been assumed that mechanisms responsible for SC damage after EVR are similar to those after OR. This pilot study compared the pathophysiology of SC injury after EVR versus OR using a newly developed EVR dog model. An increasing number of stents similar to those used in patients were inserted in the aorta of three dogs to ensure thoracic or thoracic plus lumbar coverage. The aorta of OR dogs was cross-clamped for 45 min. Behavior assessment demonstrated unique patterns of proprioceptive ataxia and evolving paraparesis in EVR versus irreversible paraplegia in OR. MRI showed posterior signal in lumbar SC after EVR versus central cord edema after OR. Histopathology showed white matter edema in L3–L5 localized to the dorsal column medial lemniscus area associated with loss of myelin basic protein but not neurons after EVR, versus massive neuronal loss in the gray matter in L3–L5 after OR. Metabolome analysis demonstrates a distinctive chemical fingerprint of cellular processes in both interventions. Our results call for the development of new therapeutics tailored to these distinct pathophysiologic findings.

Highlights

Both endovascular repair (EVR) and open repair (OR) surgery of thoraco-abdominal aortic aneurysms cause spinal cord (SC) injury that can lead to paraparesis or paraplegia
The incidence of SC injury associated with paraparesis or paraplegia following EVR surgery varies from 0.26 to 20%, depending on the nature, location and extent of the aortic aneurism, the presence or absence of comorbidity, the extent and location of stent coverage, and the strategy used for data collection[1,2,3,4,5,6,7,8,9,10]
We have shown that ischemia/reperfusion caused by transient aortic cross-clamping initiates a series of secondary events involving blood-spinal cord (SC) barrier damage, followed by vascular leakage and the development of central cord edema that results in gray matter damage and neuronal d eath[13]

Summary

Introduction

Both endovascular repair (EVR) and open repair (OR) surgery of thoraco-abdominal aortic aneurysms cause spinal cord (SC) injury that can lead to paraparesis or paraplegia. This pilot study compared the pathophysiology of SC injury after EVR versus OR using a newly developed EVR dog model. We have previously established a dog model of OR where transient cross-clamping of aorta results in gray matter damage and p araplegia[11]. We have shown that ischemia/reperfusion caused by transient aortic cross-clamping initiates a series of secondary events involving blood-spinal cord (SC) barrier damage, followed by vascular leakage and the development of central cord edema that results in gray matter damage and neuronal d eath[13]. The purpose of this work is to detail the pathophysiology of SC injury following EVR versus the pathophysiology after OR in our two dog models

Objectives

Results

Conclusion