Study design: A cross-sectional study comparing the relationship of symptoms with anatomic impairment visible on lumbar magnetic resonance imaging in 408 symptomatic subjects.
Objective: To determine how various anatomic impairments, including the magnitude and location of nerve compression visible on lumbar magnetic resonance imaging, are associated with patient reports of pain, weakness, and dysesthesia.
Summary and background data: Anatomic impairments of the intervertebral disc, radicular canal, and associated soft tissues are prevalent in people with and those without low back pain or lower extremity radiculopathy. This has led to confusion in differentiating between symptom generators and benign variation visible on lumbar magnetic resonance imaging. Recent literature has suggested that the presence of nerve compression is an important finding in the prediction of symptoms. However, the threshold for meaningful nerve compression has not been described.
Methods: In this study, 408 participants undergoing a diagnostic workup for low back pain, radiculopathy, and/ or completed a survey and pain drawing. Participants underwent standardized lumbar magnetic resonance imaging using a 1.5-T scanner. Two classification systems describing the spatial distribution of symptoms were developed. An additional system to quantify the magnitude of nerve and thecal sac compression was created. All systems were assessed for reliability, after which comparisons among variables were performed using Chi2 as well as simple and multiple logistic regression analysis.
Results: The reliability coefficients for categorizing patients on the basis of pain drawing ranged from 0. 75 to 0.88. The S1-S2 segmental distribution was the most commonly reported location of symptoms, followed by L4-L5. The most common magnetic resonance imaging diagnosis was "unremarkable," followed by "disc impairment without nerve compression." Disc extrusion was present in 10.8% of participants. The reliability of classifying nerve compression visible on magnetic resonance imaging ranged from 0.27 to 1. Nerve compression was present in 37% of participants, and 18% had severe nerve compression. There were no significant associations between segmental distribution of symptoms and the presence of anatomic impairment. However, according to a collapsed classification scale, severe nerve compression and disc extrusion were predictive of pain distal to the knee (odds ratios, 2.72 and 3. 34). The self-report of weakness was associated mildly with severe nerve compression and disc extrusion, but not with other findings. Magnetic resonance imaging findings did not predict self-reports of dysesthesia.
Conclusions: The presence of disc extrusion and/or ipsilateral, severe nerve compression at one or multiple sites is strongly associated with distal leg pain. Mild to moderate nerve compression, disc degeneration or bulging, and central spinal stenosis are not significantly associated with specific pain patterns. Although segmental distributions of pain can be determined reliably from pain drawings, this finding alone is of little use in predicting lumbar impairment. The self-report of lower extremity weakness or dysesthesia is not significantly related to any specific lumbar impairments. [Key words: back pain, diagnosis, magnetic resonance imaging, nerve compression, pain drawing, pathology]