Color Doppler Ultrasonography of Lumbar Artery Blood Flow in Patients With Low Back Pain

Study Design. Prospective, clinical, noninvasive imaging study. Objective. To quantify normal lumbar artery hemodynamics and develop a reference range and lumbar artery hemodynamics in patients with low back pain. Summary of Background Data. Blood supply to the lumbar spinal tissues, intraosseous capillary circulation, and avascular intervertebral discs derives directly from the lumbar arteries. Pathology may affect this blood supply, impact nutrient delivery and contribute to low back pain and disc degeneration. However knowledge of hemodynamic characteristics of lumbar arteries is lacking. This could improve understanding into pathological tissue function and its relation to lumbar spine circulation in back disorders. Methods. Sixty-four patients with low back pain and 30 normal controls underwent lumbar spine imaging investigations with color Doppler ultrasonography. Doppler data on blood flow was obtained from arteries at S1 through to L1 bilaterally and angle-corrected peak systolic blood flow velocity (PSV) measured in all vessels. Aortic PSV was used to derive the normalized lumbar artery: Aortic PSV ratio (PSVR) for all subjects' levels L1 to S1 bilaterally. Results. In both the control and low back pain (LBP) groups blood flow PSV in the lumbar arteries increased incrementally from levels L1 to L4, declined to its lowest values at L5 and rose again at S1. Normalized lumbar artery blood flow PSVR in the LBP group is consistently higher at all levels (L1-S1) than in controls (P < 0.001). At level L5, lumbar artery blood flow PSVR was 46% higher in the LBP group than in controls. Conclusion. Color Doppler ultrasonography can reliably be used as a clinical tool to visualize and quantify blood flow in lumbar arteries of patients with low back disorders. Findings of increased blood flow PSVR in patients are consistent with the well-documented Doppler changes that occur during inflammatory hyperemia.