COMMENTARIES

CLOGGED LUMBAR ARTERIES – A CAUSE OF LOW BACK PAIN AND DISC DEGENERATION

Leena I. Kauppila, M.D., Ph.D.
Department of Rehabilitation, Helsinki University Central Hospital
Jorvi Hospital
Turuntie 150
02740 Espoo, Finland
E-mail: leena.kauppila@hus.fi; kauppila.p@kolumbus.fi

Leena I. Kauppila



Background: Blood Supply to the Back

Each vertebral segment from the upper thoracic down to the fourth lumbar receives a pair of arteries arising from the rear wall of the abdominal aorta. In the lumbar region there are four pairs of lumbar arteries supplying the first through the fourth lumbar segments. The fifth lumbar segment is supplied by branches of the middle sacral artery, which originates in the aortic bifurcation, and also by tributaries of the iliolumbar arteries branching from the internal iliac arteries.

Atherosclerosis in Low Back Pain

The abdominal aorta, especially at the orifices of branching arteries and the aortic bifurcation, shows the earliest and most pronounced changes of atherosclerosis. A study of 17,300 aortas from males and females aged 10 to 99 by M.A. Vihert [1], found early lesions by the age of 10 to 14. By the age of 20, about 10% of the population showed substantial fibrous plaques in the abdominal aorta. The highest frequency of atherosclerotic plaques was in men aged 30 to 45 and in women 5 to 10 years later. By the age of 55, nearly everyone showed advanced atherosclerotic deposits in the abdominal aorta.
In another study of 774 orifices of the lumbar and middle sacral arteries of 36- to 69-year-old males, 18% of the ostia of these arteries were severely stenotic or occluded. This study, which assessed atheromatous lesions in the abdominal aorta and the stage of disc degeneration from lumbar radiographs, also indicated that disc degeneration increases with advanced atherosclerotic manifestations in the abdominal aorta, and especially with stenosis of the orifices of the segmental arteries above and below the disc [2].
In a third study of 140 autopsy lumbar aortographs of 16- to 89-year-old males and females, the mean age for men with occluded or narrowed lumbar arteries was 50 years, and for women 59 years [3,4]. Subjects with one or more occluded/narrowed arteries were more likely to have suffered from chronic low back pain during their life than were those without such findings. Most of the stenotic changes were seen at the orifices or in the first parts of the arteries [5].
A follow-up study of 606 members of the population-based Framingham cohort indicated that advanced aortic atherosclerosis ? presenting as calcific deposits in the posterior wall of the aorta ? increases a person's risk for development of disc degeneration and is also associated with the occurrence of back pain [6].
To further investigate the role of atherosclerosis in chronic low back pain, a magnetic resonance (MR) aortography and cholesterol blood tests were performed on 51 patients with long-term lower back pain without specific findings, such as spinal stenosis or disc herniation. In this patient group, the prevalence of occluded lumbar and middle sacral arteries was 2.5 times higher than in corresponding age and gender matched population-based autopsy material. Furthermore, this study indicates that patients with above normal low density lipoprotein (LDL) cholesterol complained of more severe back symptoms and they had more often occluded arteries than those with normal LDL cholesterol [7].

Adaptation to Reduced Blood Supply

If arterial obstruction occurs slowly, it may pass with relatively mild symptoms or even with no symptoms at all, whereas a more speedy process may cause more severe symptoms. Gradual occlusion of an artery may allow time for tissues to develop collateral pathways and to adapt to diminished blood supply.
The blood supply of the lumbar spine is principally segmental. Segmental arteries are, however, connected by several small anastomoses. Obliteration or stenosis of lumbar and middle sacral arteries is often followed by the widening of these anastomoses, and also by the formation of new arterial pathways. The existence of anastomotic networks and the ability of their arteries to enlarge may explain why necrotic changes, frequently seen in advanced atherosclerosis of the lower extremities, are hardly ever seen in the lumbar region. However, blood supplied via anastomoses cannot totally compensate for a normal vascular supply, with consequential hypoxia, tissue dysfunction, and failure to remove waste products. These changes in turn may irritate nociceptive nerve endings, causing pain, as well as lead to deterioration and atrophy of the structures involved. The intervertebral disc with its precarious nutrient supply may be one of the first structures to suffer damage from insufficient blood flow, thus linking occluded arteries with disc degeneration.

References
1. Vihert AM. Atherosclerosis of the aorta in five towns. Bull Wld Hlth Org 1976;53:501-8.
2. Kauppila LI, Penttilä A, Karhunen PJ, Lalu K, Hannikainen P. Lumbar disc degeneration and atherosclerosis of the abdominal aorta. Spine 1994;19:923-29.
3. Kauppila LI, Tallroth K. Postmortem angiographic findings for arteries supplying the lumbar spine: their relationship to low-back symptoms. J Spin Dis 1993;6:124-29.
4. Kauppila LI. Can low-back pain be due to lumbar-artery disease? Lancet 1995;346:888-89.
5. Kauppila LI. Prevalence of stenotic changes in arteries supplying the lumbar spine. A postmortem study on 140 subjects. Ann Rheum Dis 1997;56:591-95.
6. Kauppila LI, McAlindon T, Evans S, Wilson PW, Kiel D, Felson DT. Disc degeneration/back pain and calcification of the abdominal aorta. A 25-year follow-up study in Framingham. Spine 1997;22:1642-49.
7. Kauppila LI, Mikkonen R, Mankinen P, Pelto-Vasenius K, Mäenpää I. MR aortography and serum cholesterol levels in patients with long-term nonspecific lower back pain. Spine 2004;29:2147-52.

 

 

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