Increased baseline temperature improves the acquisition of contact heat evoked potentials after spinal cord injury

Abstract

Objective: To investigate the effect of increasing the skin surface baseline temperature for contact heat evoked potentials (CHEPs).

Methods: CHEPs were studied in healthy subjects and subjects with chronic cervical spinal cord injury (SCI) using a conventional 35°C (condition 1) or increased 42-45°C baseline temperature (condition 2). A third condition was used to standardize the contact heat stimulus duration from the different baseline temperatures. Changes in peak latency and N2P2 amplitude of the CHEPs and rating of perceived intensity were examined between conditions.

Results: In healthy subjects, increasing the baseline temperature for contact heat stimulation significantly increased the rating of perceived intensity (conditions 2 and 3), as well as the amplitude of CHEPs (condition 2 only). Following SCI, an increased baseline temperature facilitated perception of contact heat stimulation and evoked potentials could be recorded from dermatomes that were insensitive to contact heat from a conventional baseline temperature.

Conclusions: Enhancing the acquisition of CHEPs can be achieved by increasing the baseline temperature. This effect can be attributed, in part, to shortening the stimulation duration.

Significance: After SCI, increasing the baseline temperature for CHEPs in dermatomes with absent or diminished sensation improved the neurophysiological resolution of afferent sparing.