Direct Origin of the Artery of the Cervical Enlargement from the Left Subclavian Artery

Donald L. Miller

Summary: An anatomic variation is described in which the principal radiculomedullary artery to the cervical spinal cord, the artery of the cervical enlargement, arises directly from the left subclavian artery. This anomaly is important clinically because it may be necessary to catheterize this vessel selec­

tively during spinal arteriography, and also because uninten­tional injection of this vessel can be associated with complica­

tions.

Index terms: Arteries, abnormalities and anomalies; Arteries,

anatomy; Arteries, spinal

The principal arterial supply to the anterior spinal artery in the cervical spinal cord is from anterior spinal branches of the vertebral arteries and from radiculomedullary branches of the ver­tebral artery and costocervical trunk (1-5). There is considerable variation in the precise origin of these branches (4-6). The thyrocervical trunk has been reported to supply branches to the spinal cord as well, via the ascending cervical artery (5), but an extensive series of thyrocervical trunk arteriograms suggest that this is rarely the case (7).

The largest radiculomedullary branch to the cord in the region of C5-C6 has been termed the artery of the cervical enlargement (ACE) by La­zorthes (8). This report describes an anatomic variation in which this vessel arises directly from the left subclavian artery (LSA).

Case Report

A 49-year-old woman underwent parathyroid arteriog­raphy to locate a parathyroid adenoma following an unsuc­cessful surgical exploration. Arteriography of the right and left thyrocervical trunks and internal mammary arteries is a standard part of this procedure. The right thyrocervical

Received March 5, 1992; accepted April 22.

trunk and internal mammary artery were catheterized and imaged in routine fashion . On the left, the internal mam­mary artery was examined and was unremarkable.

The catheter was then introduced into a vessel believed to be the left inferior thyroid artery. On fluoroscopy , injec­tion of contrast material into this vessel showed that it had a superior and medial course, similar to the ascending portion of the characteristic loop of the inferior thyroid artery.

Digital subtraction arteriography (DSA) of this vessel was performed with a gentle hand injection of contrast material. DSA images were monitored during the injection, and it was immediately obvious that the anterior spinal artery was opacified (Fig. 1). The catheter was pulled down and out of the vessel approximately 1.5 seconds after the beginning of the injection . The patient had no neurologic symptoms. A left subclavian arteriogram was performed, followed by catheterization and arteriography of the left thyrocervical trunk (Figs. 2 and 3). The costocervical trunk was clearly visible on both of these arteriograms, and it was clear that the catheter had not been in either the thyrocervical trunk or the costocervical trunk or in a branch of either trunk. There were no neurologic sequelae as a result of the procedure.

Discussion

Spinal arteriography requires adequate dem­onstration of the anterior spinal artery in the area of interest. When the cervical portion of the spinal cord is studied, it is common to catheterize selec­tively both vertebral arteries and both costocerv­ical trunks. Normally, this is sufficient. However, there is enormous variation in the anatomy of the branches of the subclavian artery (9). When an anatomic variant is present, such as the one described here, additional vessels may need to be examined. A subclavian artery arteriogram may

Diagnostic Radiology Department, Warren Grant Magnuson Clinica l Center, National Institutes of Health , and the Department of Radiology, Georgetown University Medica l Center, Washington, DC

Address reprint requests to Donald L. Miller, MD, Diagnostic Radiology Department, Building 10, Room 1 C660, National Institutes of Health, Bethesda , MD 20892.

AJNR 14:242-244, Jan/ Feb 1993 0 195-6 108/ 93/ 1401 -0242 © American Society of Neuroradiology

242

AJNR: 14, January / February 1993

....

....

A B

A B

help to suggest other possible sites of origin of radiculomedullary branches.

Knowledge of this variation is also important in order to avoid a complication. The anomalous

ORIGIN OF THE ACE FROM THE LSA 243

Fig. I. Select ive arteriogram of anomalous artery of the cervica l enlargement.

A, Earl y in the injection, the artery is visualized throughout its course (short arrows), and there is filling of the anterior spinal artery both superior and infer ior to the point of anastomosis with the ar­tery of the cervical enlargement (long arrows). Note that the artery of the cervical enlargement has no branches.

B, One second later in the in­jection, there is reflux into the left subclavian artery, outlining the su­perior aspect of the arterial lumen (long arrow). There is also opaci­fication of the costocervica l trunk (short arro ws). The anterior spinal artery is well seen.

Fig. 2. Selecti ve arteriogram of the left thy rocervical trunk .

A, The loop of the inferior thy­roid artery is well seen (long ar­row), as is the vascular blush of the left lobe of the thyroid gland (short arro ws). There is no filling of the anterior spinal artery.

B, A later image from the same study shows reflux into the left subclavian artery, with opacifica­t ion of the left costocervical trun k (short arrows) and the inferior th y­ro id vein (long arrows). There is no filling of the anterior spinal ar­tery, and the anomalous artery of cervical enlargement is not identi­fied.

artery of cervical enlargement in this patient has no other branches besides those to the anterior spinal artery, and a forceful , wedged, or pro­longed injection could produce severe damage to

244 MILLER

Fig. 3. Left subclavian arteriogram demonstrates both the anomalous artery of cervical enlargement (long arrows) and the inferior thyroid artery (short arrows). The anterior spinal ar tery is opacified (op en arrows).

AJNR : 14, January / February 1993

the spinal cord. This case serves as a useful reminder that selective arteriography of the prox­imal branches of the subclavian artery must al­ways be performed with extreme caution.

Acknowledgments

I thank Giovanni Di Chiro , MD, for reviewing the case and John L. Doppman, MD, for reviewing the manuscript.

References

I. Lippert H, Pabst R, Arterial variations in m an: classification and

frequency. New York: Springer-Verlag, 1985:94- 95

2. Williams PL, Warwick R. Gray 's anatomy. 36th British ed. Philadel­

phia: Saunders, 1980.

3. Domm isse GF. The blood supply of the spinal cord: a cr it ical vascular

zone in spinal surgery. J Bone Join t Surg 1974;56B:225- 235

4. Turnbull IM. Blood supply of the spinal cord: normal and pathologic

considerations. Clin 1'/eurosurg 1973;20:56- 84

5. Chak ravorty BG. Arterial supply of the cervica l spinal cord (wi th

special reference to the rad icular arteries). A nat Rec 1971; 1 70:

31 1-330

6. Doppman JL, Di Chiro G, Ommaya AK. Selecti ve arteriography of

the spinal cord. St. Louis: Warren Green, 1969:3-17

7. Mi ller DL, Doppman JL. Parathyroid angiography (letter). A nn Intern

/>'led 1987:107:942- 943

8. Lazorthes G. Blood supply and vascu lar pathology of the spinal cord.

In: Pia HW, Djindjian R, eds. Sp inal ang iom as: advances in diagnosis

and therapy. New York: Springer-Verlag, 1978: 1-17

9. Daseler EH, Anson BJ . Surgica l anatomy of the subclavian artery

and its branches. Surg Gynecol Obstet 1959;108: 149- 174