Functional assessment of neuropathic pain

Abstract

The assessment of the nervous system in patients with neuropathic pain is particularly challenging. Conventional electrophysiological testing, such as nerve conduction studies and somatosensory-evoked potentials, may prove normal as these techniques only evaluate large fibre function (A beta). In a clinical setting, two evaluation methods may prove useful to examine the nociceptive system or to explore small fibre function (A delta et C). First, quantitative sensory testing, derived from psychophysics, explores different sensory modalities (tactile, thermal and vibratory sensations) corresponding to different types of nerve fibres. Second, CO2 lasers allow for powerful and selective thermal stimuli to evoke brain potentials that are specifically related to the cutaneous activation of A delta and C nociceptors. Finally, other assessments of the nervous system, such as nociceptive reflexes and microneurography, are available for use in a more experimental setting.