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Page 2 of 14 Monaco et al. Vessel Plus 2023;7:23 https://dx.doi.org/10.20517/2574-1209.2023.113

INTRODUCTION
Spinal cord ischemia (SCI) is one of the most devastating complications in the repair of thoraco-abdominal
aortic aneurysms (TAAA) in both the open and endovascular approaches. When it occurs, it carries a poor
prognosis, leading to patients’ reduced quality of life, high complication and mortality rate, and prolonged
[1,2]
duration of intensive care unit (ICU) and hospital stays . The incidence of SCI in the repair of TAAA
ranges between as low as 2%-3% and 10%, while the one-year survival of those who suffer this complication
[3,4]
is as low as 40% . SCI encompasses a spectrum of severity that extends from temporary or permanent
paraparesis to paraplegia with or without autonomic dysfunction. SCI can manifest at various time points.
Approximately 15% of cases occur intraoperatively, meaning the injury takes place during the surgical
procedure. Around 50% of cases fall into the intermediate category, with symptoms manifesting within 48 h
following the procedure. The remaining 35% are classified as late SCI, with symptoms arising more than 48
[5]
h after surgery . These timing distinctions reflect the underlying pathophysiology of SCI. Intraoperative
SCI is directly linked to the interruption of blood flow, while postoperative SCI is influenced by
hemodynamic management, particularly through the establishment and stabilization of the collateral blood
flow.

Intermediate paraplegia, which occurs within 48 h after surgery, is more insidious in nature. Its
development is intricately tied to the recruitment of the collateral network that is supplied by the
hypogastric and intercostal arteries, as well as branches of the subclavian artery. The management of SCI is
grounded in a deep understanding of its pathophysiology and requires a multimodal approach [Figure 1]. In
fact, multiple strategies are implemented for preventing and addressing SCI, including the placement of
cerebrospinal fluid (CSF) drainage, distal aortic perfusion, optimization of blood pressure, restoration of
blood flow in collateral network vessels, embolization and reimplantation of segmental arteries according to
the monitoring of motor (MEP) and somatosensory-evoked potentials (SSEP).

By employing these strategies, anesthesiologists and surgeons can work towards minimizing the occurrence
and severity of SCI and maximizing the chances of neurological recovery . The present review discusses the
[6]
evolution of strategies that can be applied to maximize spinal cord perfusion and decrease the risk of SCI
during thoracoabdominal aortic aneurysm repair.

VASCULAR ANATOMY OF THE SPINAL CORD
The spinal cord (SC) vasculature consists of very small vessels running in intricate, three-dimensional
planes with substantial regional and inter-individual variability. SC vasculature was originally visualized
with routine contrast-enhanced CT scanning back in 1994, yet information about the SC circulation has, for
the most part, been gained from post-mortem studies. The first accurate anatomical descriptions were
provided in 1881 by Adamkiewicz and Kady. They described the vascular system of the SC as consisting of
one anterior and two posterolateral anastomotic trunks running longitudinally. Inflow vessels to the SC
include: the subclavian artery (through the vertebral artery), the thyrocervical trunk, and the costocervical
trunk; several segmental feeders from the intercostal and lumbar arteries; the hypogastric arteries (through
the lateral sacral and iliolumbar arteries). Arteries directly nourishing the SC (intrinsic arterial system) are
divided into two different systems: a central (centrifugal) system fed by the sulcal arteries; and a peripheral
(centripetal) system, the pial plexus (or pial network), which gives origin to perforating branches. The pial
network forms an impressive secondary anastomotic system along the entire length of the SC between the
anterior and posterolateral longitudinal vessels. The anterior spinal artery (ASA) is ultimately an
anastomotic channel between ascending and descending branches of neighboring anterior radicular arteries.