The measurement of pain threshold in man by means of electrical stimuli. A critical appraisal.

The problem of pain threshold measurement in man is critically considered. The advantages of electrical stimuli in determining the cutaneous pain threshold are discussed. The conducting properties of the skin to electric current are carefully examined: in fact, such properties must be taken into account when electrical stimuli are applied to the skin. A series of investigations on pain threshold measurement by means of electrical stimuli are reported. The different sensations induced by stimulating the skin with different kinds of electrodes and different types of stimuli were analysed: trains of 5 square waves of 0.5-2 msec at the frequency of 250 Hz, applied to the skin by means of unpolarizable electrodes, were selected as the best suited stimuli for practical application. This kind of stimulation was applied in physiological and clinical investigations. The measurement of pain threshold by electrical stimuli was especially useful for the clinical examination and for the study of pathogenetic mechanisms of painful diseases.