Hume Memorial Lecture
Prevention of spinal cord complications in aortic surgery

Presented at the 26th Annual Meeting of The Society for Clinical Vascular Surgery, Coronado, California, March 25–29, 1998.
https://doi.org/10.1016/S0002-9610(98)00133-0Get rights and content

Abstract

Paraplegia or paraparesis after operations on the thoracic and abdominal aorta is a devastating event, both for the patient and the surgeon. While its incidence varies from under 1% with operations at the top and bottom of the aorta, its occurrence in the midportion of the aorta, just above the diaphragm, even in the best of hands exceeds 10%. Over a decade ago, Crawford et al (J Vasc Surg. 1986;3:389–404) introduced the use of inclusion and sequential clamping techniques for thoracoabdominal aneurysmectomy, lowering both morbidity and neurologic sequelae. Although these techniques have been widely adopted, newer ancillary adjuncts have been recommended by a number of investigators. This paper summarizes the possible causes of paraplegia secondary to the various operations on the aorta and analyzes the status and value of the various ancillary techniques in its prevention.

Section snippets

Anatomy

Knowledge of the arterial blood supply of the spinal cord is essential to an understanding of the pathophysiology of paraplegia occurring after operations on the aorta. The spinal cord, like the entire central nervous system, has a maximum ischemic time of 8 minutes, as estimated from the animal model.4 Three spinal arteries, one anterior and two posterior, arise cephalad from branches of the vertebral arteries and run lengthwise, ending in a conus plexus of lumbosacral branches (Figure 1). 5

Coarctation

This congenital aortic lesion is generally recognized and repaired in infancy or childhood by excision of the coarcted area with end-to-end anastomosis or patch aortoplasty. Enlarged intercostals around the lesion usually provide adequate collateral flow during aortic cross-clamping. However, if the coarcted area is not very stenotic, the collaterals may not have enlarged enough to be adequate during cross-clamping to supply the distal cord with the resulting complication of paraplegia.

Traumatic rupture of the descending thoracic aorta

Thoracic isthmic aortic rupture after blunt trauma results in a posterior tear or complete aortic separation, which may be held in place by adventitial tissue just distal to the ductus arteriosus. Early recognition and timely operation may allow direct repair of a tear, but often an interposition graft is necessary.12, 13 Some surgeons use the “clamp and go” technique without an adjunct bypass.14, 15, 16 Although the incidence of paraplegia with cross-clamp times of over 30 minutes exceeds 10%,

Localized descending thoracic aneurysm

The first successful resection of a thoracic aneurysm of the descending aorta was performed by Lam and Aram24 in 1951 (Figure 3). An internal Lucite tube was used to conduct blood through an aortic homograft as it was inserted in place of the aneurysm (Figure 4). The procedure required 24 minutes of cross-clamping to insert the temporary Lucite bypass with resulting partial paraplegia. This operation was not only the first reported thoracic aortic resection with grafting, but also the first

Thoracoabdominal aneurysmectomy

The first thoracoabdominal aneurysmectomy (type 4) was performed by Etheredge et al25(Figure 5) in 1954 by use of a homograft, using a temporary aorto-aorta shunt and inserting the celiac and superior mesentery arteries (SMAs) separately into the graft (Figure 6). An aortogram 11 years later showed wide patency of all anastomoses. Subsequently, many surgeons have made numerous contributions to the successful expansion of the field to include aneurysmectomy of the entire descending and

Infrarenal aortic surgery

In 1957, Adams and von Geertruyden55 presented a review of paraplegia after aortic surgery, in which they stated that it does not occur in infrarenal surgery. However, in the discussion of the paper, McCune mentioned two such cases. Both patients had ruptured abdominal aortic aneurysms he observed that extended into the external iliac arteries, so that it was impossible to reestablish either hypogastric artery. He also speculated that the hypogastric vessels may supply some circulation to the

Comments

Although advances in the surgical management of diseases of the aorta over the past decade have lowered the incidence of postoperative paraplegia, its incidence remains unacceptably high. Although use of both the inclusion and segmental clamping techniques has been widely accepted, additional ancillary modalities continue to be debated. Further experience with the use of evoked potentials, selective spinal cord cooling, deep hypothermia with circulatory arrest, and selective angiography to

Conclusions to minimize paraplegia

  • 1.

    Coarctation

    In an infant or child, measure clamped distal aortic pressure. If it is below 50 mm Hg, use simple aorto-aorta bypass. In an adult, use left heart bypass with centrifugal pump, without heparin.

  • 2.

    Localized Descending Aorta Aneurysm or Traumatic Tear

    Employ left heart bypass with centrifugal pump, without heparin.

  • 3.

    Extensive Thoracic or Thoracoabdominal Aneurysm

    • 3.1.

      Obtain preoperative selective angiogram of artery of Adamkiewicz, if available.

    • 3.2.

      Employ inclusion and sequential clamping.

    • 3.3.

      Employ

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