Neuropathic pain assessment: update on laboratory diagnostic tools.

PURPOSE OF REVIEW: The purpose of this review was to provide an update on the diagnostic tools for neuropathic pain for clinical practice.

RECENT FINDINGS: The new definition of neuropathic pain by the International Association for the Study of Pain requires confirmation of a lesion or disease affecting the somatosensory system. In addition to traditional diagnostic procedures, for example, nerve conduction studies, skin biopsies depict morphological alteration and/or rarefication of the small intraepidermal nerve fibers and were recently used to identify small fiber abnormalities, for example, in patients with fibromyalgia or sarcoidosis. Quantitative sensory testing assesses the somatosensory function including both peripheral and central pathways. A recent consensus statement discussed its diagnostic value. Corneal confocal microscopy is a noninvasive method enabling in-vivo assessment of the small nerve fibers in the cornea and also seems to identify patients at risk for developing diabetic neuropathy at an early stage and to reflect the improvement of neuropathy after treatment. Further promising methods are the microneurography and nociceptive evoked potentials; however, they are technically challenging and their diagnostic value for clinical practice has yet to be confirmed.

SUMMARY: For diagnosing neuropathic pain, confirmation of a lesion or disease affecting the somatosensory system is needed. Better clinical phenotyping will hopefully enable individualized mechanism-based treatment of neuropathic pain.