Normative Values for Contact Heat and Cold Evoked Potentials.

Area of Science:

• Neuroscience
• Clinical Electrophysiology
• Sensory Physiology

Background:

• Small fibre neuropathy (SFN) and spinothalamic tract (STT) dysfunction assessment requires reliable neurophysiological tools.
• Contact heat evoked potentials (CHEP) and cold evoked potentials (CEP) offer objective measures of small fibre function.
• Establishing normative data is crucial for clinical application.

Purpose of the Study:

• To establish normative values for CHEP and CEP in healthy adults across different age groups.
• To provide a reference dataset for evaluating SFN and STT function.
• To compare CHEP and CEP parameters between upper and lower limbs and across age groups.

Main Methods:

• Healthy participants (n=80, aged 26-75) underwent thermal quantitative sensory testing and sensory nerve conduction studies.
• CHEP and CEP were recorded from the forearm and foot using a contact thermal stimulator (60°C heat, 10°C cold, 200ms duration).
• Age-grouped descriptive statistics were computed, and results were compared across age groups, stimulation sites, and sex.

Main Results:

• Upper limb CEP demonstrated high detection rates (>90%) across all ages.
• N2P2 amplitudes for both CHEP and CEP were larger in upper limbs compared to lower limbs (p<0.05).
• N2P2 amplitudes decreased with age for both CHEP and CEP (p<0.01), while latencies remained consistent.

Conclusions:

• Normative data for CHEP and CEP were successfully established, supporting their clinical integration.
• CHEP and CEP serve as objective, non-invasive tools for assessing small fibre and STT function.
• Age-related amplitude decline, particularly in the feet, highlights the importance of age-matched normative values.