Contact heat evoked potentials: Normal values and use in small-fiber neuropathy

Introduction: Contact heat evoked potentials (CHEPs) may be an objective, non-invasive diagnostic tool in small-fiber neuropathy (SFN). This study establishes normal CHEP values and examines their applicability in SFN patients. Methods: Standardized CHEPs were administered at the wrist and ankle. The N2 and P2 latencies and N2-P2 peak-peak amplitude were recorded by electroencephalography. We examined healthy subjects (n=97), stratified by age and gender, and SFN patients with abnormal intraepidermal nerve fiber density (n=42). CHEP reproducibility and interobserver values were also investigated. Results: CHEP normative values were determined. There was a 9-16% increase in latency per centimeter of height with increasing age. Amplitudes were higher in women than men, and decreased (17-71%) with aging. Test-retest reproducibility and interobserver values were >0.61 and >0.96, respectively. CHEPs were abnormal in 73.8% of the patients. Conclusion: In this study we have established normal values, reliability, and clinical applicability of CHEPs in SFN