MR Aortography and Serum Cholesterol Levels in Patients With Long-Term Nonspecific Lower Back Pain

Leena I. Kauppila, MD, PhD; Raija Mikkonen, MD, PhD; Pekka Mankinen, MD; Kia Pelto-Vasenius, MD, PhD; Ilkka Mäenpää, MD

Disclosures

Spine. 2004;29(19) 

In This Article

Abstract and Introduction

Study Design: A cross-sectional analysis of the feeding arteries of the lumbar spine and cholesterol levels on patients with long-term nonspecific lower back pain.
Objectives: To evaluate whether occlusion of lumbar and middle sacral arteries or serum cholesterol levels are associated with lower back pain and/or with disc degeneration.
Summary of Background Data: Atherosclerosis in the wall of the abdominal aorta usually develops at the ostia of branching arteries and the bifurcation, and may obliterate orifices of lumbar and middle sacral arteries. Obstruction of these arteries causes ischemia in the lumbar spine and may result in back symptoms and disc degeneration.
Methods: MR aortography and cholesterol blood tests were performed on 51 patients with long-term lower back pain without specific findings (i.e., spinal or nerve root compression) in regular lumbar MR images. The patients ranged from 35 to 70 years of age (mean age, 56 years). Serum cholesterol and low-density lipoprotein (LDL) cholesterol levels were measured. To assess symptoms and disability NASS low back Outcome Instrument was used.
Results: Twenty-nine (78%) of 37 men and 11 (77%) of 14 women showed occluded lumbar and/or middle sacral arteries. The prevalence of occluded arteries was 2.5 times more than in subjects of corresponding age group in a Finnish necropsy material. Twenty-three (62%) men and seven (50%) women had significant disc degeneration. Disc degeneration was associated with occluded lumbar/middle sacral arteries (P = 0.035). Patients with occluded arteries or significant disc degeneration did not complain more severe symptoms than those without, whereas patients with above normal serum LDL cholesterol scored higher in neurogenic symptoms (P = 0.031) and complained more often severe pain (P = 0.049) than those with normal LDL cholesterol.
Conclusions: The study indicates that lumbar and middle sacral arteries are often occluded in patients with nonspecific long-term lower back pain. Occlusion of these arteries may also be associated with disc degeneration.

Epidemiologic and postmortem studies indicate that atheromatous lesions in the abdominal aorta may be related to disc degeneration and long-term back symptoms.[1,2,3] It has also been reported that some risk factors for atherosclerosis, such as low apo AI and high triglyceride, are associated with sickness absence because of back pain,[4] although this is not a consistent finding.[5] In an epidemiologic study on Finnish adults more than 29 years old, no association was found between low back pain and subsequent cardiovascular mortality, indicating that back pain is not associated with generalized atherosclerosis.[6] In these studies, the lack of distinction between different types of back pain was likely to bias the findings toward null.

The blood supply of the lumbar spine is derived from the aorta through the lumbar and middle sacral arteries. The upper four segments of the lumbar spine receive their blood supply from the four pairs of the lumbar arteries, which arise in the posterior wall of the abdominal aorta. The fifth lumbar segment is supplied partly by the middle sacral artery (arising in the bifurcation) and partly by branches of the iliolumbar arteries (arising from the internal iliac arteries).[7,8] Nutrition of the avascular intervertebral disc is by diffusion through the vertebral endplates from the blood vessels in the vertebral bodies above and below the disc.[9,10] Cholesterol plaques in the wall of the aorta obliterate orifices of lumbar and middle sacral arteries and may decrease blood supply of the lumbar spine and its surrounding structures. Structures with precarious nutrient supply, such as the intervertebral discs, may also suffer and gradually degenerate.[11,12,13]

Lumbar disc degeneration begins early in life. Severe macroscopic changes are already visible from the age of 30 onwards.[14] Atherosclerosis also manifests itself at middle age or even earlier in the abdominal aorta. Atheromatous plaques usually form at the orifices of branching arteries.[12,15] When occurring in or around ostia of lumbar or middle sacral arteries, they may reduce blood supply to the lumbar spine. Reduced blood flow causes hypoxia and tissue dysfunction. It also hampers removal of waste products, such as lactic acid. These changes in turn may irritate nociceptive nerve endings, causing pain, as well as lead to deterioration and atrophy of the structures involved.

The aims of this study were to assess whether occlusion of the lumbar and/or middle sacral arteries or serum cholesterol levels are associated with long-term nonspecific lower back pain and/or with disc degeneration.

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