PainSci summary of Kobayashi 2003?This page is one of thousands in the PainScience.com bibliography. It is not a general article: it is focused on a single scientific paper, and it may provide only just enough context for the summary to make sense. Links to other papers and more general information are provided at the bottom of the page, as often as possible. ★★★★★5-star ratings are for sentinel studies, excellent experiments with meaningful results. Ratings are a highly subjective opinion, and subject to revision at any time. If you think this paper has been incorrectly rated, please let me know.
Kobay et al. surgically examined blood flow to a lumbar nerve root while the leg was in a painful position. (They peeked into twelve backs with a history of symptomatic disk herniations and nerve pain.) They found that “the intraoperative reverse straight leg raise test showed that the hernia compressed the nerve roots, and that there was marked disturbance of gliding, which was reduced to only a few millimeters,” and “during the test, intraradicular blood flow showed a sharp decrease [40 to 98%] at the angle that produced sciatica.”
Intriguing. It’s probably the physical distortion of the nerve root that caused the loss of circulation, and the combination of the two that was painful. Successful treatment seemed to back this up: “After removal of the hernia, all the patients showed smooth gliding of the nerve roots during the second intraoperative test, and there was no marked decrease in intraradicular blood flow.”
original abstract†Abstracts here may not perfectly match originals, for a variety of technical and practical reasons. Some abstacts are truncated for my purposes here, if they are particularly long-winded and unhelpful. I occasionally add clarifying notes. And I make some minor corrections.
STUDY DESIGN: An intraoperative straight-leg-raising (SLR) test was conducted to investigate patients with lumbar disc herniation to observe the changes in intraradicular blood flow, which then were compared with the clinical features.
OBJECTIVE: The legs of each patient were hung down from the operating table as a reverse SLR test during surgery, and intraradicular blood flow was measured.
SUMMARY OF BACKGROUND DATA: It is not known whether intraradicular blood flow changes during the SLR test in patients with lumbar disc herniation.
METHODS: The subjects were 12 patients with lumbar disc herniation who underwent microdiscectomy. The patients were asked to adopt the prone position immediately before surgery, so that their legs hung down from the operating table. A reverse SLR test was performed to confirm the angle at which sciatica developed. During the operation, the nerve roots affected by the hernia were observed under a microscope. Then the needle sensor of a laser Doppler flow meter was inserted into each nerve root immediately above the hernia. The patient's legs were allowed to hang down to the angle at which sciatica had occurred, and the change in intraradicular blood flow was measured. After removal of the hernia, a similar procedure was repeated, and intraradicular blood flow was measured again.
RESULTS: Intraoperative microscopy showed that the hernia was adherent to the dura mater of the nerve roots in all patients. The intraoperative reverse SLR test showed that the hernia compressed the nerve roots, and that there was marked disturbance of gliding, which was reduced to only a few millimeters. During the test, intraradicular blood flow showed a sharp decrease at the angle that produced sciatica, which lasted for 1 minute. Intraradicular flow decreased by 40% to 98% (average, 70.6% +/- 20.5%) in the L5 nerve root, and by 41% to 96% (average, 72.0% +/- 22.9%) in the S1 nerve roots relative to the blood flow before the test. At 1 minute after completion of the test, intraradicular blood flow returned to the value obtained at baseline. *After removal of the hernia, all the patients showed smooth gliding of the nerve roots during the second intraoperative test, and there was no marked decrease in intraradicular blood flow*.
CONCLUSIONS: This study demonstrated that the blood flow in the nerve root is reduced when the nerve root is compressed in vivo.
- “Significance of the small lumbar spinal canal: cauda equina compression syndromes due to spondylosis 3: Intermittent claudication,” CB Wilson, Journal of Neurosurgery, 1969.
- “Pathophysiology of nerve compression,” SE Mackinnon, Hand Clin, 2002.
- “Intervertebral foramen venous obstruction. A cause of periradicular fibrosis?,” J A Hoyland, A J Freemont, and M I Jayson, Spine (Phila Pa 1976), 1989.
- “The role of vascular damage and fibrosis in the pathogenesis of nerve root damage,” M I Jayson, Clinical Orthopaedics & Related Research, 1992.
These two articles on PainScience.com cite Kobayashi 2003 as a source:
- PS Trigger Points & Myofascial Pain Syndrome — A guide to the unfinished science of muscle pain, with reviews of every theory and self-treatment and therapy option
- PS Save Yourself from Low Back Pain! — Low back pain myths debunked and all your treatment options reviewed
This page is part of the PainScience BIBLIOGRAPHY, which contains plain language summaries of thousands of scientific papers & others sources. It’s like a highly specialized blog. A few highlights:
- Effectiveness of customised foot orthoses for Achilles tendinopathy: a randomised controlled trial. Munteanu 2015 Br J Sports Med.
- A Bayesian model-averaged meta-analysis of the power pose effect with informed and default priors: the case of felt power. Gronau 2017 Comprehensive Results in Social Psychology.
- The neck and headaches. Bogduk 2014 Neurol Clin.
- Agreement of self-reported items and clinically assessed nerve root involvement (or sciatica) in a primary care setting. Konstantinou 2012 Eur Spine J.
- Effect of NSAIDs on Recovery From Acute Skeletal Muscle Injury: A Systematic Review and Meta-analysis. Morelli 2017 Am J Sports Med.