Abstract: Quantitative sensory testing is a popular tool for studying pain in the laboratory setting. Hand-held pressure algometers are commonly used to evaluate pain sensitivity in both healthy subjects and chronic pain patients. However, these hand-held algometers have innate limitations, including human error in manually applying a constant ramp of increasing pressure. The goal of this study was to develop and test a new computer-controlled pressure algometer (CCPA) that applies precisely controlled stimuli and records responses in real-time. Furthermore, we designed the CCPA to simultaneously record changes in heart rate, skin impedance, and blood pressure during pain testing. After collaboration with bioengineers to construct the new computerized algometer, we tested the CCPA and a hand-held algometer in 36 healthy subjects (14 females, 22 males; mean age 23 years) with no history of chronic or acute pain. Pressure pain thresholds and tolerance were recorded over the tibialis anterior muscle across two sessions separated by one week. Subjects indicated threshold and tolerance during CCPA testing by pressing two buttons on a remote control. The rate for CCPA output was 10 kPa/sec; the test administrator also attempted to achieve this rate with the hand-held algometer. For both algometers, females had significantly lower pressure pain thresholds and tolerance than males. When comparing the two algometers, pain thresholds were significantly lower when measured by the CCPA. In females, pain tolerance was also significantly lower when measured by the CCPA. Interestingly, we found a significant reduction in the variability of pain threshold responses when using the CCPA to test pain sensitivity. We are currently analyzing the physiologic data and will determine whether sympathetic nervous system responses to pressure pain stimuli are correlated with pain sensitivity measured with the CCPA. These preliminary results are encouraging and may suggest that the CCPA allows for more precise pain sensitivity measurements.
Lindley, E., Zimkowski, M., Patel, V., Rentschler, M., "Pain Sensitivity Testing Using a Novel Computer-Controlled Pressure Algometer that Simultaneously Records Sympathetic Nervoous System Responses to Pain Stimuli," Journal of Pain. 13(4): S9, 2012.