Repeatability of dermatomal warm and cold sensory thresholds in patients with sciatica.

Area of Science:

• Neurology
• Pain Management
• Quantitative Sensory Testing

Background:

• Afferent small A-delta and C-fibers are crucial for thermal sensation.
• Nerve dysfunction assessment often relies on quantifying thermal thresholds.
• Sciatica involves nerve dysfunction affecting the lower extremities.

Purpose of the Study:

• To evaluate the test-retest repeatability of thermal detection thresholds.
• To assess repeatability in patients with unilateral sciatica across affected and non-affected dermatomes.
• To determine the clinical utility of dermatomal thermotesting in sciatica.

Main Methods:

• Nineteen patients with unilateral sciatica (L5 or S1) participated.
• Thermal detection thresholds (warm and cold) were measured at six sites across L4, L5, and S1 dermatomes.
• Testing was repeated within 1-2 hours, and the coefficient of repeatability (CR) was calculated.

Main Results:

• Warm threshold repeatability was similar between symptomatic and non-symptomatic sides.
• Cold threshold CR was significantly higher in the affected foot dermatome (P=0.04).
• Warm thresholds exhibited greater variability (CR 4.7-5°C) than cold thresholds (CR 2.1-2.2°C).
• Sensitivity for detecting abnormalities was higher on the foot compared to the lateral calf in L5 sciatica.

Conclusions:

• Dermatomal thermotesting demonstrates acceptable repeatability, especially at proximal lower extremity sites.
• The test is a potentially valuable tool for longitudinal monitoring of sciatica patients.
• Thermal threshold quantification aids in assessing nerve function and treatment follow-up in sciatica.