Double pattern of relationship between skin temperature, thermoregulation and sensory nerve conduction

Electroneurographic and thermographic investigations were done in 32 persons. Sensory nerve conduction velocity, amplitude of sensory nerve potential, subjective and objective sensory thresholds were determined during stimulation of each finger. The maximal and minimal skin temperatures for each finger were evaluated from thermograms taken from the dorsal and palmar surface of the hand before and after standard cooling test. The measurements were done in a thermostabilised room at 19-21 degrees C effective ambient temperature. The second degree correlations between the electroneurographic and thermographic parameters were calculated. The statistical analysis revealed the presence of a double correlation pattern depending on the homoiothermic or poikilothermic thermoregulatory ability of the finger. The differentiation threshold criterion for the poikilo- and homoiothermic group assignment was the minimal rest temperature of the finger equal to 28 degrees C. The correlations in the poikilothermic fingers were very strong and much stronger than in the homoiothermic fingers. Correlations with temperatures were strong both at rest as well as after cooling. Correlations for the sensory nerve potential amplitude likewise for the objective and subjective thresholds were stronger than for the conduction velocity. Sensory nerve potential amplitude increases and subjective and objective thresholds decrease with finger temperature. The obtained results suggest that sensory nerve conduction is related not only to the actual tissue temperature but also to local thermoregulatory ability.