Thermal deficit in lumbar radiculopathy. Correlations with pain and neurologic signs and its value for assessing symptomatic severity.

STUDY DESIGN

The relationship between areas of thermal deficit and areas exhibiting other symptoms and neurologic signs, and the significance of the magnitude of thermal deficit in lumbar radiculopathy were analyzed.

OBJECTIVES

To determine the clinical significance and value of thermal deficit as a sign of lumbar radiculopathy.

SUMMARY OF BACKGROUND DATA

Thermal deficit has been discussed as a factor in the diagnosis of involved nerve roots. However, it has not been previously correlated with any particular symptoms or signs.

METHODS

Sixty-eight healthy subjects and one hundred nine patients with lumbar radiculopathy due to intervertebral disc herniation underwent thermography. Sensitivity, specificity, and the agreement rate of thermal deficit to symptoms and neurologic signs were calculated in ten body regions. Total temperature difference of the affected limb was compared with the Japanese Orthopaedic Association scoring system.

RESULTS

The agreement rates of thermal deficit with pain, muscle tenderness, motor weakness, and sensory disturbance were 60.9, 69.3, 71.8, and 71.8%, respectively. Sensitivity and specificity of thermal deficit to symptoms and signs were approximately 30% and 80%, respectively. The correlation coefficient of temperature decrease of the affected limb and the Japanese Orthopaedic Association score was 0.57, indicating a moderate correlation.

CONCLUSIONS

Thermal deficit should be considered an independent sign of lumbar radiculopathy. The relatively high specificity suggests that a normal temperature may indicate an asymptomatic region. Symptomatic severity of lumbar radiculopathy may be assessed by measuring the magnitude of thermal deficit in the affected limb.