The effect of spinal distraction on regional spinal cord blood flow in cats

Abstract

Distraction is considered to be a factor in many spinal cord injuries. With a specially designed distraction apparatus and the 14C-antipyrine autoradiographic technique, the effect of distraction on spinal cord blood flow (SCBF) in cats was studied. Distraction was performed at L2-3 at a rate of 0.25 cm/10 min, and the spinal evoked response (SER) was monitored by stimulating the sciatic nerve and recording at T-13. The SCBF was assessed in five control animals, four animals in whom the SER was markedly altered by distraction, and five animals after the SER had been abolished and an additional 0.5 cm distraction applied. Control cats had gray- and white-matter flows of 44.5 +/- 1.4 (SEM) and 10.5 +/- 0.4 ml/100 gm/min, respectively. Distraction to the point of marked SER alteration caused a 50% loss of SCBF at and caudal to the distraction site. An additional 0.5 cm distraction produced total abolition of SCBF at the distraction site and for a considerable distance rostral and caudal to it. Thus, it is shown that spinal distraction causes cord ischemia similar to that seen with other types of spinal cord injury. In addition, distraction severe enough to cause loss of the SER has already produced severe cord ischemia.

Hypotension-Induced Loss of Intraoperative Monitoring Data During Surgical Correction of Scheuermann Kyphosis: A Case Report

“…4 Distraction has been known to induce spinal cord injury by reducing spinal blood flow in feline studies, and the effect is postulated to increase in patients who are already compromised by kyphoscoliosis and global hypotension. 6,22 Same-day circumferential spinal fusion accompanied by unilateral segmental vessel harvest was performed in another case with a postoperative neurologic deficit.…”

“…5,7 If the main supply to this region originates from the ARM, its interruption may lead to paraplegia. 6,14,40,41 The only other significant source of blood supply to this area is the lateral or middle sacral artery or both, a branch of internal iliac artery. It may become critically important when the ARM is deficient or occluded.…”

Spinal cord traction, vascular compromise, hypoxia, and metabolic derangements in the pathophysiology of tethered cord syndrome

“…12,14,36,40 A decrease in the diameter of the lumen of spinal vessels, due to traction, substantially reduced the total spinal blood flow, causing local ischemic insult. 6,12,14,36,40 If detethering of the cord is performed within 2-8 weeks of the initial insult, blood flow and spinal evoked potentials may return to normal. Longer delays may result in irreversible changes.…”

“…6,36 Dolan and colleagues 6 used tracers, autoradiography, and a distraction apparatus in cats to assess the spinal blood flow under various mechanical tension scenarios. Spinal evoked potentials were also used in parallel to monitor the electrophysiology of the neurons.…”

The Role of Somatosensory Evoked Potentials in the Evaluation of Spinal Cord Retethering

“…Somatosensory evoked potentials (SEPs) have been shown in animal experiments to deteriorate with traction of the spinal cord or distraction of the spinal column [8][9][10][11], A previous report suggested that SEPs correlate well with clinical changes and are useful in evaluating retether ing [12], The purpose of this report is to reexamine the relationship between changes in SEPs and neurological worsening and to evaluate the usefulness of SEPs in the early detection of clinically significant retethering.…”