Blood Supply to the Spinal Cord.

To the Editor:

In the July 2000 issue of Physical Therapy, Mautes et al, in an article titled "Vascular Events After Spinal Cord Injury: Contribution to Secondary Pathogenesis,"[1] described the blood supply to the spinal cord. The authors stated that a segmental spinal artery enters the intervertebral foramen and divides into 3 branches outside the spinal canal at each segmental level of the spinal cord: the anterior and posterior longitudinal spinal canal arteries and the radicular artery.

Furthermore, Mautes et al described the radicular artery continuing along the nerve root and dividing into an anterior radicular artery and a posterior radicular artery. They stated that, after penetrating the dura mater, the anterior and posterior radicular arteries join the 3 major arteries on the surface of the spinal cord to provide the blood supply to those areas. Mautes et al cited references by Crock and Yoshizawa[2] and Domisse[3] in their description of the extrinsic blood supply to the spinal cord.

Although Mautes and colleagues' description of anterior and posterior arteries coursing along the spinal nerve roots to join the longitudinal arteries on the surface of the spinal cord may be correct for an embryo during the fourth month of life,[4] we believe that they have misrepresented these authors' works by implying that this situation applies to humans after that stage. We believe that their description does not reflect currently accepted (or long-held) views and is misleading. As Lazorthes et al stated, "The classical description of a vertical arterial pathway composed of an anterior and two posterior longitudinal spinal arteries reinforced at each level by rami radiculares was corrected by the observations of Adamkeiwicz[6] in 1882, Kadyi[7] in 1889, and Tanon[8] in 1908."[5](p253)

Current accounts of the extrinsic blood supply to the spinal cord in standard anatomical references[9-13]--based both on these early studies and on recent studies[14-16] and utilizing a new, more precise, internationally developed and recognized anatomical terminology[17] that may now be universally applied--describe more clearly and accurately the vascularization of the spinal cord in humans and other primates and mammals.

The arteries supplying the spinal cord arise from branches of the vertebral, ascending cervical, deep cervical, intercostal, lumbar, and lateral sacral arteries.[9-13] The anterior and posterior spinal arteries originate primarily from the vertebral arteries and run longitudinally from the medulla of the brain stem to the medullary cone of the spinal cord. By themselves, the portions of the anterior and posterior spinal arteries arising from the vertebral arteries can supply only the superior portion of the spinal cord. It has been shown, however, that the circulation to much of the rest of the spinal cord depends on segmental medullary and radicular arteries running along the spinal nerve roots.[9-13]

The anterior and posterior segmental medullary arteries are derived from the spinal branches of the ascending cervical, deep cervical, posterior intercostal, and lumbar arteries. The medullary segmental arteries are located chiefly where the need for a good blood supply to the spinal cord is greatest--the cervical and lumbar enlargements. These arteries enter the vertebral canal through the intervertebral foramina and reinforce the anterior and paired posterior spinal arteries. It is the segmental medullary arteries that primarily provide additional vascularization to the spinal cord.[9-13]

The dorsal and ventral radicular arteries are also derived from the spinal branches of the ascending cervical, deep cervical, posterior intercostal, and lumbar arteries. These arteries course along most nerve roots (all except those supplied by a segmental medullary artery) and supply blood to the dorsal and ventral roots of the spinal nerves and their coverings. The dorsal and ventral radicular arteries typically do not reach the anterior or posterior spinal arteries.[9-13] Most radicular arteries are small and supply only the nerve roots; however, some radicular arteries may supply the superficial parts of the gray matter in the dorsal and ventral horns and spinal cord. Segmental medullary arteries are the larger vessels that, after supplying or dorsal or ventral root, continue on to reach and anastomose with the spinal arteries, thus providing the additional extrinsic blood supply to the spinal cord.[9-13] In fact, it is the segmental medullary arteries such as the named great anterior segmental medullary artery (artery of Adamkiewicz[6]) that reinforce circulation to two thirds of the spinal cord and the lumbosacral enlargement.[9]

David G Greathouse, PT, PhD Professor and Chairman School of Physical Therapy Belmont University Adjunct Professor Department of Cell Biology Vanderbilt University Nashville, Tenn

John S Halle, PT, PhD Associate Professor School of Physical Therapy Belmont University Nashville, Tenn

Arthur F Dalley II, PhD Professor Department of Cell Biology Vanderbilt University Nashville, Tenn

References

[1] Mautes AEM, Weinzierl MR, Donovan F, Noble LJ. Vascular events after spinal cord injury: contribution to secondary pathogenesis. Phys Ther. 2000;80:673-687.

[2] Crock HV, Yoshizawa H, eds. The Blood Supply of the Vertebral Column and Spinal Cord in Man. New York, NY: Springer; 1977.

[3] Domisse GF. ed. The Arteries and Veins of the Human Spinal Cord From Birth. New York, NY: Churchill Livingstone Inc; 1975.

[4] Schoenen J. Clinical anatomy of the spinal cord. Neurol Clin. 1991;9:503-532.

[5] Lazorthes G, Gouaze A, Zadeh JO, et al. Arterial vascularization of the spinal cord: recent studies of the anatomotic substitution pathways. J Neurosurg. 1971;35:253-262.

[6] Adamkiewicz AA. Die Blutgefasse des Menslichen Ruckenmarkes, II: Die Gefasse der Ruckenmarksoberflache. S B Heidelberg Akad Wiss. 1882;85:101-130.

[7] Kadyi H. Uber die Blutgefasse des Menschlichen Ruckenmarkes. Lemberg, Poland: Gubryonowisz & Schmidt; 1889.

[8] Tanon L. Les Arteres de la Moelle Dorsolumbaire [thesis]. Paris. 1908.

[9] Moore KL, Dalley AF II, eds. Clinically Oriented Anatomy. 4th ed. Baltimore, Md: Lippincott Williams & Wilkins; 1999.

[10] Williams PL, Bannister LH, Berry MM, et al, eds. Gray's Anatomy. 38th British ed. New York, NY: Churchill Livingstone Inc; 1995.

[11] Agur AMR, Lee MJ, eds. Grant's Atlas of Anatomy. 10th ed. Baltimore, Md: Lippincolt Williams & Wilkins; 1999.

[12] Netter FH. Atlas of Human Anatomy. 2nd ed. East Hanover, NJ: Novartis; 1997.

[13] Haines DE, ed. Fundamental Neuroscience. New York, NY: Churchill Livingstone Inc; 1997.

[14] Gillilan LA. The arterial blood supply of the human spinal cord. J Comp Neurol. 1958;110:75-103.

[15] Turnbull IM. Blood supply of the spinal cord: normal and pathological considerations. Clin Neurosurg. 1973;20:56-84.

[16] Murray MJ, Bower TC, Carmichael SW. Anatomy of the anterior spinal artery in pigs. Clin Anat. 1992;5:452-457.

[17] Federative Committee on Anatomical Terminology. Terminologia Anatomica: International Anatomical Terminology. Stuttgart, Germany: Thieme; 1998.

Authors' Response:

In our article in the July 2000 issue, we described the blood supply to the human spinal cord. We provided a short overview of the extrinsic and intrinsic vessels of the spinal cord. First, a schematic illustration of the segmental supply to the spinal cord was given. Thereafter, we characterized important anatomical features of the blood supply to the human spinal cord. Our description of the blood supply to the spinal cord is, in our opinion, accurate according to the citations used in our article.[1-11] For a better understanding of the blood supply to the spinal cord, we recommend Thron's text on the vascular anatomy of the spinal cord.[11]

Angelika EM Mautes, PhD Head Neurosurgical Research Laboratory Saarland University Medical School Homburg, Germany

Martin R Weinzierl, MD Medical Faculty Department of Neurosurgery University of Technology Aachen, Germany

Frances Donovan, PhD Postdoctoral Fellow Department of Anatomy University of California San Francisco, Calif

Linda J Noble, PhD Professor and Vice Chair Department of Neurological Surgery University of California 521 Parnassus Ave Room C224 San Francisco, CA 94143-0520

References

[1] Crock HV, Yoshizawa H, eds. The Blood Supply of the Vertebral Column and Spinal Cord in Man. New York, NY: Springer; 1977.

[2] Domisse GF, ed. The Arteries and Veins of the Human Spinal Cord From Birth. New York, NY: Churchill Livingstone Inc; 1975.

[3] Jellinger K. Experimental studies on the question of the vertebral artery supply of the spinal cord. Acta Neuropathol. 1966;6: 201-208.

[4] Brockstein B, Johns L, Gewertz BL. Blood supply to the spinal cord: anatomic and physiological correlations. Ann Vasc Surg. 1994;8:394-399.

[5] Adamkiewicz A. Die Blutgefabe des menschlichen Ruckenmarks: Die Gefabe der Ruckenmarksoberflache. Sitzungsberichte der Akademie der Wissenschaften in Wein--Mathematisch-Naturwissenschaftliche Klasse--Abteilung 3. 1882;84:101-130.

[6] Zivin JA, De Giorlami U. Spinal cord infarction: a highly reproducible stroke model. Stroke. 1980;11:200-202.

[7] Suh TH, Alexander L. Vascular system of the human spinal cord. Arch Neurol Psych. 1939;41:659-677.

[8] Gillilan LA. The arterial blood supply of the human spinal cord. J Comp Neurol. 1958;110:75-103.

[9] Di Chiro G, Fried LC. Blood flow currents in spinal cord arteries. Neurology. 1971; 21:1088-1096.

[10] Viraswami V. A Study of the Blood Supply of the Spinal Nerve Roots in Man and the Rabbit With an Experimental Analysis of the Collateral Circulation Following Ligation of Arteries [PhD thesis]. London, England: University of London; 1963.

[11] Thron AK, ed. Vascular Anatomy of the Spinal Cord. New York, NY: Springer-Verlag New York Inc; 1988.