Quantitative sensory testing (QST) is used to assess neurological function in chronic pain patients (Felix & Widerstrom-Noga, 2009). QST measures thresholds for mechanical detection, vibration detection, cool and warm detection and cold and hot pain sensations. Assessment of thresholds can be used to evaluate the involvement of different nervous system functions (Nathan et al,1986). The test is used to quantify the neurological dysfunction associated with neuropathic pain.

Procedure: The QST is performed by administrating six different threshold tests including, the mechanical detection threshold, the vibration detection threshold, the cool and warm threshold detection and the cold and hot pain threshold at eight standard test sites on the various dermatomes (Felix & Widerstrom-Noga, 2009). Threshold values are recorded at either the first or last detectible level of intensity. If the maximum stimulus is reached without the patient indicating sensation, the maximum value is recorded as threshold.

Advantages: QST has been used extensively to asses the functional integrity of the somatosensory system among various populations (Felix & Widerstrom-Noga, 2009). Preliminary evidence indicates high reliability among SCI participants. A significant correlation was found between average thermal pain thresholds (ATPT) and the severity of self reported pain. The scale was not developed specifically for the SCI population, although preliminary research shows it can be used within this group without any adaptations.

Limitations: For SCI, at test sites where stimuli cannot be distinguished, either maximum or minimum threshold levels are recorded which may lead to floor or ceiling effects. Only the ATPT is significantly correlated with self-reported measures of pain, indicating potentially low validity of the other QST thresholds. In addition, SCI patients have reported sensations that are not due to the stimulus (Felix & Widerstrom-Noga, 2009). Only one study has assessed the QST’s psychometric properties.

Interpretability: For each location, the high and low threshold detection values for each of the six stimuli are recorded. The high and low scores are averaged and can be compared to data from ‘un-injured’ populations. Threshold measurements for pressure and vibration can evaluate large-fiber and dorsal column function, while thresholds for thermal detection and pain can be used to assess small-fibre and spinothalamic tract function (Nathan et al, 1986).

Acceptability: For each QST threshold, several measurements need to be taken in different dermatomes. Thresholds are to be measured both for increasing and decreasing intensity. Patient burden is extensive; testing must be in person at a clinic or hospital. Although time to complete the entire QST is not mentioned, it may be substantial.

Feasibility: QST requires several pieces of equipment to ensure accurate threshold detection. Clinicians need to be trained in the use of each piece of equipment. Though there are instructions that are to be read to the patient prior to each test, these were not found in the original publication ((Felix & Widerstrom-Noga, 2009).

Clinical Summary: Thermal pain thresholds may be particularly useful when used in combination with self-report measures of neuropathic pain for the development of pain management strategies. QST may not feasible as a general test used across clinical sites due to the necessary equipment, but may be feasible for specific clinics that focus on pain and pain management.

Psychometric Summary:

Note: +++ = Excellent; ++ = Adequate; + = Poor; TR=Test retest

References

• Felix ER and Widerstrom-Noga EG. Reliability and validity of quantitative sensory testing in persons with spinal cord injury and neuropathic pain. JRRD. 2009;46:69-83.
• Nathan PW, Smith MC, Cook AW. Sensory effects in man of lesions of the posterior columns and some other afferent pathways. Brain. 1986;109(5):1003-41.