Preparing the spinal cord - priming or preconditioning? A systematic review of experimental studies

Objectives. Paraplegia is devastating complication associated with thoracic and thoracoabdominal aortic aneurysm repair. Vast evidence has been gathered on pre-, peri- and postoperative protective adjuncts aiming to minimize spinal cord ischemia. This review focuses on the pretreatment phase of open surgical or endovascular aortic procedures and gathers the experimental data on the interventional preconditioning and priming methods that increase the spinal cord ischemic tolerance. Design. By the start of March 2021, a systematic review was performed in PubMed, Scopus and Web of Science core collection to identify the articles that reported (i) either an ischemic preconditioning, remote ischemic preconditioning or priming method prior to (ii) experimental spinal cord ischemia performed in endovascular or open surgical fashion mimicking either thoracic, abdominal or thoracoabdominal aortic aneurysm procedures. (iii) The outcomes were reported via neurological, motor-evoked potential, somatosensory-evoked potential, histopathological, immunohistochemical, physiological analysis, or in different combinations of these measurements. Results. The search yielded 7802 articles, and 57 articles were included in the systematic review. The articles were assessed by the evaluated species, the utilized pretreatment, the measured protective effects, and the suggested underlying mechanisms. Conclusions. The reviewed articles showed several possible mechanisms in ischemic and remote ischemic preconditioning for prevention of spinal cord ischemia. The main suggested method for priming was arteriogenetic stimulus. Future studies should confirm these hints of arteriogenetic stimulus with more precise quantification of the protective recruitment process.