ABSTRACT
Contact heat evoked potentials (CHEPs) have become an acknowledged research tool in the assessment of the integrity of the nociceptive system and gained importance in the diagnostic work-up of patients with suspected small fiber neuropathy. For the latter, normative values for CHEP amplitude and latency are indispensable for a clinically meaningful interpretation of the results gathered in patients. To this end, CHEPs were recorded in 100 healthy subjects over a wide age range (20-80 years) and from three different dermatomes of the lower extremities (L2, L5, and S2). A normal baseline (35-52 °C) and increased baseline stimulation (42-52 °C) were applied. Statistical analysis revealed significant effects of stimulation site, stimulation intensity, and sex on CHEP parameters (N2 latency, N2P2 amplitude, and NRS). Significant positive correlations of body height with N2 latency, and pain ratings with N2P2 amplitudes were observed. This is the first time that normative values have been obtained from multiple dermatomes of the lower extremities. The present dataset will facilitate the clinical application of CHEPs in the neurophysiological diagnosis of small fiber neuropathy and by discerning pathological findings help establish a proximal-distal gradient of nerve degeneration in polyneuropathies.
Subject(s)
Datasets as Topic/standards , Evoked Potentials, Somatosensory/physiology , Hot Temperature , Lower Extremity/physiology , Adult , Aged , Aged, 80 and over , Healthy Volunteers , Humans , Middle Aged , Nerve Degeneration/etiology , Nerve Degeneration/pathology , Pain/etiology , Physical Stimulation , Polyneuropathies/diagnosis , Polyneuropathies/etiology , Sex Factors , Skin/innervation , Young AdultABSTRACT
OBJECTIVE: To investigate test-retest reliability of contact heat evoked potentials (CHEPs) from lower extremities using two different stimulation protocols, i.e., normal and increased baseline temperature. METHODS: A total of 32 able-bodied subjects were included and a subset (Nâ¯=â¯22) was retested. CHEPs were recorded from three different dermatomes of the lower extremity (i.e., L2, L5, and S2). Test-retest reliability of CHEPs acquisition after simulation in various lower limb dermatomes using different stimulation protocols was analyzed. RESULTS: The study revealed an improved acquisition of CHEPS employing the increased baseline protocol, particularly when stimulating more distal sites, i.e., dermatome L5 and S2. Based on repeatability coefficients, CHEP latency (N2 potential) emerged as the most robust CHEP parameter. Although CHEP amplitudes (N2P2 complex) and pain ratings were decreased in the retest, amplitudes still showed fair to excellent intraclass correlation coefficients using normal baseline or increased baseline temperature, respectively. CONCLUSIONS: This is the first study to demonstrate that CHEPs acquisition from the lower extremities is improved by increasing the baseline temperature of the thermode. SIGNIFICANCE: This study highlights the usability of CHEPs as a viable diagnostic method to study small fiber integrity.
