Quantitative thermal sensory testing and sympathetic skin response in primary Restless legs syndrome - A prospective study on 57 Indian patients

Abstract

Patients with restless leg syndrome present with sensory symptoms similar to peripheral neuropathy. While there is evidence of abnormalities of dopaminergic pathways, the peripheral nervous system has been studied infrequently. We studied conventional nerve conduction studies, quantitative thermal sensory testing and sympathetic skin response in 57 patients with primary restless leg syndrome. Almost two third patients demonstrated abnormalities in the detailed testing of the peripheral nervous system. Sbtle abnormalities of the peripheral nervous system may be more common than previously believed.

Association between restless legs syndrome and peripheral neuropathy: A systematic review and meta‐analysis

“…A study measuring the quantitative sudomotor axon reflex test (QSART) (which tests the peripheral axon reflex mediated by the postganglionic sympathetic sudomotor axon) showed similar values in iRLS patients to controls, suggesting that alterations in QTST found in the same group of patients could be related to alteration of somatosensory processing rather than to small fibre abnormalities [82]. Sympathetic skin response (SSR) (a method used to assess both peripheral and central autonomic nervous system dysfunctions) has been found as non‐recordable in 30% of a series of iRLS patients, all of them showing abnormalities in QTST [83].…”

“…The results of CuSP [79,81] could suggest the presence of small nerve fibre dysfunction but, because CuSP is also modulated by supraspinal influences, the possible contribution of the latter should be considered as well [89]. The normality of QNART [20] and QSART [82] in patients with iRLS suggests that alterations in QTST found in patients with this condition should not be related to small sensory fibre dysfunction, whereas the abnormalities of SSR found in patients with iRLS in another study suggest the opposite [83]. Studies with LEP were consistent both with central and peripheral sensory dysfunction in patients with RLS [84].…”

Restless Legs Syndrome; Inflammation, Electroneuromyography Findings, and Disease Severity

“…Although the results of studies using cutaneous quiescent period (CuSP) suggest the presence of small nerve ber dysfunction in RLS patients, it should be noted that CuSP is also modulated by supraspinal effects (24,25,26). Shukla et al revealed that patients with iRLS show abnormal thermal thresholds and sympathetic skin response (SSR) with the possibility of signi cantly widespread abnormalities in small peripheral nerve bers (27). Studies with laser-evoked potentials have shown central and peripheral sensory dysfunction in patients with RLS.…”

Impact of Restless Legs Syndrome on Cardiovascular Autonomic Control

“…Of note, while recent studies have observed differences in skin sympathetic response and partial pressure of oxygen in the calves of persons with RLS, autonomic control of the skin correlates poorly with sympathetic vascular control. [36][37][38] Additionally, anecdotal reports have suggested that reduced leg blood flow contributes to PLMS. 39,40 All values mean ± SE (range).…”