A new method to increase nociception specificity of the human blink reflex

Objective: The medullary R2 response of the blink reflex can be elicited by innocuous and noxious stimuli. The purpose of this study was to elicit a n ociception specific R2 response with a new surface electrode. Methods: In 10 healthy subjects the blink reflex was elicited using a stand ard (10-15 mA) and a new concentric surface electrode type (0.6-1.6 mA) whi ch produces a pin-prick-like pain. Results: After topical local anaesthesia with lignocaine/prilocaine pi was unchanged, R2 was attenuated by 12% after standard stimulation but was almo st abolished (-91%) with the new electrode type. Conclusion: Stimulation with low stimulus intensities but electrode-depende nt high current density allows preferential depolarization of superficial n ociceptive A-delta fibres. This new method is less traumatic than others an d is useful in the study of trigeminal nociception. (C) 2000 Elsevier Scien ce Ireland Ltd. All rights reserved.