Quantitative assessment of cutaneous sensory function in subjects with neurologic disease.

Based upon techniques devised for the behavioral study of cutaneous sensation in monkeys, a method has been developed which studies quantitatively cutaneous sensation in man. The techniques is analogous to the von Békésy method of audiometry and employs a subject-operated stimulus and signalling divice. In tests utilizing electrical stimulation of the skin surfaces the subject serves as his own control for comparison of one cutaneous zone with another and from one trial session to another. A permanent, written record of stimulus and nonverbal perceptual response is produced in this instrumental method which permits statistical analysis of responses. The analysis includes determination of cutaneous sensory thresholds, limits of stimulus intensity during detection, duration of perception, detection cycle rates, and persistence indices. This instrumental method of cutaneous sensory assessment is quantifiable, free of verbal bias, and repeatable in terms of defined stimulus strengths. In applied clinical studies, patients with peripheral nerve lesions show elevations of perceptual thresholds, reduced numbers of detection-disappearance cycles per unit time, prolonged, contorted decay slopes, and occasionally persistence of perception in the absence of stimulation. Patients with central lesions have variable threshold abnormalities, but little slowing of cycle rate or perceptual persistence. These quantitative sensation parameters can be evaluated longitudinally during the course of an illness and its treatment. The method has potential use in the investigation of basic aspects of sensation and its interactions with behavior.