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Complex Regional Pain Syndrome Diagnostic Tests
Quantitative Sensory Testing (QST)
Quantitative sensory testing (QST) assesses damage to the small nerve endings, which detect changes in temperature, and the large nerve endings, which detect vibration. QST is typically used to assess the severity and location of nerve damage and to determine if a neuropathy is responding to treatment. (23)
QST uses a computer testing system to measure how the nerves involved react to vibration and changes in temperature. These test results are then compared to unaffected patients and the patient's unaffected side. The patient will feel mild vibrations, as well as hot and cold sensations. The procedure is non-invasive. (5,23) The subjective responses of the patient to the superficial stimuli are also measured, and in the case of CRPS, provide information pertaining to peripheral nerve function and sensory abnormalities (3,5). Although QST detects such abnormalities, they are not specific to CRPS, making QST useful for confirming symptoms, but not diagnosis (3).
The Vaneker et al study found that those who initially responding as “cold” patients (having more pain with cold stimulation than warm) upon initial CRPS diagnosis had more pain during electrical stimulation and disease progression eight years later (24). These patients also had poorer clinical pain outcomes over time than the “warm” patients, possibly making QST a good indicator of disease progression (24).
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Updated December 20, 2007 |
