Brain : a journal of neurology
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The quantitative somatosensory thermotest (QST) assesses the function of afferent channels concerned with sensory submodalities served by small calibre fibres. Measured ramps of ascending or descending temperature are applied to the skin through a Peltier contact thermode, and detection thresholds are recorded as the subject signals the onset of a particular sensation. The present study describes underlying principles, methodological aspects and normal reference values for the QST. ⋯ Furthermore, while most methods of sensory testing only document normality or deficit, the QST permits additional documentation of hyperalgesia, a positive sensory phenomenon that implies unusual pathophysiologies such as sensitization of receptors, central hyperexcitability, disinhibition or, possibly, ectopic nerve impulse discharge. This psychophysical test does not specify the level within afferent channels, between skin and brainmind, where the abnormality resides. It is recommended that the QST for all four thermal specific and thermal pain functions be incorporated in routine neurological assessment.