Indications des potentiels lasers dans l'exploration de la douleur neuropathique

Among non-invasive laboratory tests, laser-evoked potentials (LEPs) are the best tool for assessing dysfunction of small sensitive fibers and lesions of the spino-thalamic pathways. LEPs are useful to diagnose small-fiber neuropathy, especially when pain topography is atypical, in absence of obvious etiology, and when nerve conduction tests are normal. The analysis of nociceptive thresholds and the acquisition of late potentials enable routine exploration of Aδ fibers. The exploration of C fibers is more difficult in practice except for the face. LEPs are also required in case of central neuropathic pain without any spinal or brain MRI abnormalities and without SEP abnormalities. LEPs are sometimes the only test showing a dysfunction of the spino-thalamic pathway. LEPs can also discriminate pure psychogenic pain and patients with certain neuropathic pain.