Attenuated Laser Evoked Potentials in Sarcoidosis Patients in Clinical Remission

Abstract

Background: Burning sensations and pain in hands and feet occur frequently in patients with sarcoidosis. Even when features of the granulomatous inflammation have resolved and the disease is in clinical remission, pain complaints may persevere. We hypothesized that pain may be related to dysfunctioning of the A δ nociceptive processing which is responsible for transporting pain signals. Methods: Laser Evoked Potentials were recorded in patients with sarcoidosis in clinical remission (n = 62) of whom 27% reported complaints of burning pain in hands and/or feet, and a group of healthy volunteers (n = 28). Electroencephalographic recordings following laser stimulation were evaluated in terms of N2P2-amplitude, N2P2-amplitude per ms, and N2- and P2-latencies. Results: Sarcoidosis patients in clinical remission (irrespective of burning pain complaints) showed no significant increase in N2P2-amplitude and in N2P2- amplitude per ms at stimulus intensity 2.0 Watt, while healthy controls did show a significant increase. Post hoc analysis revealed that sarcoidosis patients with burning pain complaints showed the smallest N2P2- amplitude per ms at stimulus intensity 2.0 Watt (P = 0.028). Age did not explain the differences. No differences between groups were found on the N2- and P2-latencies. Conclusions: This is the first study investigating small fiber processing in sarcoidosis patients by Laser Evoked Potentials. A δ nociceptive processing was found to be reduced in patients in which clinical signs of sarcoidosis have resolved, particularly in those reporting complaints of burning hands and/or feet. The latter data are suggestive for clinical as well as subclinical neuropathy in sarcoidosis patients after clinical remission of the disease. J Neurol Res. 2012;2(5):189-197 doi: https://doi.org/10.4021/jnr150w