Experimental study on the dynamics of lumbosacral nerve root circulation.
METHODS
Experimental investigation of the dynamics of nerve root circulation.


OBJECTIVE
To study the dynamics of lumbosacral nerve root circulation by using seriography in dogs.


BACKGROUND
The vascular distribution to the nerve root has been discussed mainly from the morphologic aspects, and no adequate elucidation has been presented concerning the kinetics of the blood supply to the nerve root.


METHODS
To investigate the direction of blood flow in the nerve roots, a series of photographs of the cauda equina were taken using a motor-driven camera immediately after 3 mL of india ink was injected through the aortic catheter manually. The changes in the blood flow direction caused by compression of the nerve root also were observed. After the dog was killed, the nerve roots were cleared by the Spalteholz technique to identify the vessels observed during the experiment.


RESULTS
The blood flow in the radicular arteries was descending in the proximal part and ascending in the distal part of the nerve roots. This observation supports the suggestion that there is a so-called watershed of the blood flow in the radicular arteries themselves. However, when the ascending radicular artery of the nerve root was cramped, the radicular blood flow on the proximal side was downward. The microangiograms also showed that there were abundant anastomoses of intrinsic vessels in the nerve roots.


CONCLUSIONS
There is no relatively hypovascular region in the nerve root that is vulnerable in the course of degenerative changes in the lumbosacral spine. Therefore, it is unlikely that the watershed represents a weak point of the blood flow in the nerve root.
Kobayashi
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S
Department of Orthopedics, Fujita Health University School of Medicine, Aichi, Japan.
Yoshizawa
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H
Nakai
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D000818:Animals; D002420:Cauda Equina / Q000098:blood supply; D004285:Dogs; D007700:Kinetics; D008161:Lumbosacral Region; D011843:Radiculopathy / Q000503:physiopathology; D013126:Spinal Nerve Roots / Q000098:blood supply* / Q000502:physiology