On the relationship between nociceptive evoked potentials and intraepidermal nerve fiber density in painful sensory polyneuropathies

Abstract

This study analyzed the relationship between the density of intraepidermal nerve fibers (IENF) and the characteristics of either nociceptive laser-evoked potentials (LEPs) or contact heat-evoked potentials (CHEPs) in patients with painful sensory polyneuropathy with the aim to determine which parameters of LEPs and CHEPs more reliably reflect IENF loss. A total of 96 patients and 35 healthy volunteers took part in the study. Based on clinical examination, nerve conduction tests, and quantitative sensory testing, we identified 52 patients with small-fiber neuropathy (SFN), 40 with mixed (small-fiber and large-fiber) neuropathy (MFN), and 4 who were excluded from the analysis because of no evidence of involvement of small fibers. The latency of the N2 was delayed for both LEPs and CHEPs in patients with MFN and for CHEPs only in patients with SFN. The amplitude of the vertex N2/P2 potential was similarly reduced in both types of neuropathy, but LEPs were more frequently absent than CHEPs in MFN patients (68% vs 40%). In general, latency and amplitude of LEPs and CHEPs were well correlated with IENF density. SFN patients were characterized by abnormal EPs and slightly decreased but morphologically abnormal IENF. MFN patients were characterized by frequently absent LEPs and CHEPs and a rather severe IENF loss. The correlation between nociceptive evoked potentials (laser-evoked potentials and contact heat-evoked potentials) and skin biopsy aids in the diagnosis of painful neuropathies.

Rapid Automated Diagnosis of Diabetic Peripheral Neuropathy With In Vivo Corneal Confocal Microscopy

“…36 This is likely for two main reasons: NCS offer a robust and objective means of assessing neuropathy, while WT is a subjective measurement of small fiber function. Cassanova et al 37 in their study found that even patients with no IENFs had consistent responses in WT and concluded that it is possible for partially damaged nerve endings to still generate a propagated action potential. We speculate that a similar association may exist for the corneal subbasal nerves.…”

Chemotherapy‐induced neuropathies—a growing problem for patients and health care providers

“…Latency and amplitude nociceptive‐evoked potentials are associated with the density of intraepidermal nerve fibers. Nociceptive evoked potentials with skin biopsy may be used in the diagnosis of painful neuropathy (Casanova‐Molla, Grau‐ Junyent, Morales, & Valls‐Solé, 2011). …”

Diabetic neuropathy

“…However, LEPS may cause skin injuries in laser-stimulated areas, while CHEPS, in addition to being more sensitive and specific, is noninvaise and able to generate reproducible evoked potentials. There is still no standardization for both methods for the clinical practice 61 .…”