The blood supply of the human spinal cord at birth: a report on a micro-dissection study of 27 foetal and neonate cadavers
The Vascular system of the human spinal cord at birth has been investigated, and a report is submitted on the detailed pattern of the arterial and arteriolar vessels in 27 cadavers. In 21 instances, the anterior median spinal arterial trunk and in 9 instances the postero-lateral spinal arterial trunks have been recorded. Selection of cadavers has been on the basis of the absence of obvious congenital deformity or disease of the spine and spinal cord. Particular attention has been paid to the feeder arteries which contribute to the main longitudinal channels, both anteriorly and posteriorly. The number of feeder vessels, their ;.., sources of origin .and their approximate size~ have been determined. In 21 specimens the anterior vessels have been recorded and charted in detail. (Plates I - VII). In 9 specimens the posterior vessels have been recorded and the detailed charts of 3 of the latter are presented. (Plate X, p.46). Material and Methods Newborn cadavers, obtained on average 3-5 days after death from various causes such as prematurity, cerebral trauma, pneumonia and pulmonary hyaline membrane have been used. In each case the body was warmed to room temperature, before the introduction into the right femoral artery of a plastic tubular cannula of appropriate gauge. Dilute Ammonia, 2-3 ml., was introduced to promote the flow of the injection material and the specimens were injected with latex under pressures which varied from 5 lbs per square inch to 20 lbs per square inch. The manometric readings of intra-arterial pressure were between 300 mms. Hg and 1200 mms. Hg, and the optimal pressure of delivery was 15 lbs per square inch. Both the arterial and the venous sides of the circulation were well-filled by the injection material, which in all instances was administered via the femoral artery. Rupture of vessel walls with leakage of injection material was not excessive. The number of cadavers rejected on account of inadequate filling or excessive leakage was less than 10 out of approximately 50 cadavers. The injection material consisted of a prevulcanised latex, "Revultex", coloured red with an appropriate dye, and stained through fine muslin before use to ensure freedom from solid particles which could cause obstruction of vessels of fine calibre. The injection material was allowed to penetrate the vascular tree for periods varying from 5 to 15 minutes and the cadaver was then embalmed, injecting the body cavities and infiltrating the limbs as far as possible with a standard embalming fluid consisting of: White Industrial Spirits, 45%; Glycerine, 35%; Formaldethyde, 15%; Thymol, q.s. The cadaver was preserved in a 50% solution of the embalming fluid, and dissections were commenced not less than 14 - 21 days after preparation. Use was made in all instances of the binocular surgical microscope, and magnifications of 10 or of 16 were found to be optimal. Photographic reproductions were made in colour, and the dissected specimens have been preserved. The findings in respect of the anterior arterial system of supply of the cord have been consistent with those of a number of workers, in particular Woollam and Millen (1958) of Cambridge. Additional findings have been reported in respect of the smaller arteries (arteries of the 4. 4th order) including the perforating arteries of the median sulcus. The value of a computerised "average" for the vascular pattern of the cord is disputed. In the opinion of the author, it is likely to be misleading to the clinician and to the surgeon. Reliance upon an average picture in an individual case is liable to be harmful; in the present series of 21 specimens, the average picture as offered by Suh and Alexander (1939) was, in some respects only, applicable to 1 case. The presence of arterio-arterial anastomoses as a common feature in the spine is reported, and the possible significance discussed. Reference is made to a "critical narrow zone" which the author has determined by the radiological examination of 50 vertebral columns in people of all ages. When the region of the "narrow critical zone" is related to the regional blood supply of the spinal cord, then a significant factor in the post-operative development of paraplegia in scoliosis cases has been found to emerge. Vascular factors have been sought in the etiology of idiopathic scoliosis, but not found.
Spinal cord, Blood supply, infancy and childhood
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