Quantitative sensory testing

Abstract

Abstract-Objective:This assessment evaluates the clinical utility, efficacy, and safety of quantitative sensory testing (QST). Methods: By searching MEDLINE, Current Contents, and their personal files, the authors identified 350 articles. Selected articles utilized computer operated threshold systems, manually operated threshold systems, and electrical threshold devices. The authors evaluated the use of normal values and the degree of reproducibility between the same and different systems. Articles were rated using a standard classification of evidence scheme. Results: Because of differences between systems, normal values from one system cannot be transposed to others. Reproducibility of results was also an important concern, and there is no consensus on how it should be defined. The authors identified no adequately powered class I studies demonstrating the effectiveness of QST in evaluating any particular disorder. A number of class II and III studies demonstrated that QST is probably or possibly useful in identifying small or large fiber sensory abnormalities in patients with diabetic neuropathy, small fiber neuropathies, uremic neuropathies, and demyelinating neuropathy. Conclusions: QST is a potentially useful tool for measuring sensory impairment for clinical and research studies. However, QST results should not be the sole criteria used to diagnose pathology. Because malingering and other nonorganic factors can influence the test results, QST is not currently useful for the purpose of resolving medicolegal matters. Well-designed studies comparing different QST devices and methodologies are needed and should include patients with abnormalities detected solely by QST. NEUROLOGY 2003;60:898 -904 Quantitative sensory testing (QST) systems have been developed to assess and quantify sensory function in patients with neurologic symptoms or in those at risk of developing neurologic disease. QST measures the detection threshold of accurately calibrated sensory stimuli. Vibratory, thermal, or painful stimuli are often chosen because they relate to distinct neuroanatomic pathways with discrete fiber populations.1-3 It should be appreciated, however, that natural stimuli rarely activate single types of receptors but rather activate different combinations of receptors. 1Quantitative sensory tests are psychophysical in nature, requiring cooperation from the patient. While the sensory stimulus is an objective physical event, the response represents the subjective report from a patient or control subject. If abnormal, the result may signal dysfunction anywhere along the sensory pathway between the receptor apparatus, the primary sensory cortex, and the association cortex. Furthermore, psychological factors figure prominently in sensory function perception. Thus, QST differs from nerve conduction and evoked potential testing in which the stimulus generates an evoked response that is generally independent of cooperation from the subject. 4QST devices. QST systems are separable into devices that generate specific physical...

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