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Severity of symptoms and signs in relation to magnetic resonance imaging findings among sciatic patients

PainSci » bibliography » Karppinen et al 2001
Tags: etiology, counter-intuitive, sciatica, pro, back pain, pain problems, spine, butt, hip

PainSci commentary on Karppinen 2001: ?This page is one of thousands in the 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 wherever possible.

This cross-sectional study of patients with one-sided sciatica was looking for causes other than the usual suspect: “generated by nerve root compression.” They looked for the size of the herniation, signs of inflammation (nerve root enhancement), and how much nerve roots were being compressed. The degree of these signs did not correlate with the severity of symptoms. The authors concluded that “a discogenic pain mechanism other than the nerve root entrapment generates the subjective symptoms among sciatica patients” and that you cannot figure out which sciatica patients are having the roughest time by their MRI results alone.

~ Paul Ingraham

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: A cross-sectional study in sciatic population.

OBJECTIVES: To evaluate the separate roles of nerve root entrapment-based on magnetic resonance imaging-and other discogenic pain mechanisms on disability and physical signs among symptomatic sciatic patients.

SUMMARY OF BACKGROUND DATA: Data symptoms of sciatica are generally understood to be generated by nerve root compression, but other pain mechanisms of sciatica have been suggested.

METHODS: The authors obtained magnetic resonance scans from 160 patients with unilateral sciatic pain. The patients reported the intensity of their back and leg pain and their back-specific disability. Clinical examination and magnetic resonance imaging (1.5 T) was performed on every patient. The degree of disc displacement, neural enhancement, and nerve root compression was evaluated from magnetic resonance scans. The correlations of symptoms and signs with magnetic resonance imaging findings were calculated.

RESULTS: The degree of disc displacement in magnetic resonance imaging did not correlate with any subjective symptoms, nor did nerve root enhancement or nerve compression. Magnetic resonance imaging classification was associated, however, with straight leg raising restriction. In regression analysis, straight leg raising restriction was best explained with a simple classification of nonherniations versus herniations.

CONCLUSIONS: The results suggest that a discogenic pain mechanism other than the nerve root entrapment generates the subjective symptoms among sciatic patients. The findings of this study thus indicate that magnetic resonance imaging is unable to distinguish sciatic patients in terms of the severity of their symptoms.

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