671: Characterization of the Nociceptive Blink Reflex: Implications for Orofacial Pain and Headache

Topic: Experimental (Non-clinical) Human Studies
Subtopic: Non -specific to any diagnosis, Electrophysiology/Clinical neurophysiology (e.g. microneurography, EEG, MEG, OPMs, TMS), Assessment and Measurement of Pain/Nociception

Background and Aims: The nociceptive blink reflex (nBR) is a neurophysiological test that assesses brainstem-mediated responses and enables investigation of central pathways involved in trigeminal nociceptive processing. Its application may serve as an adjunctive tool in mechanism-based management of musculoskeletal orofacial pain, provided that robust reference values are established to identify neurophysiological alterations associated with distinct pain mechanisms. Characterizing nBR responses in healthy individuals is therefore essential to support clinical interpretation. The present study aimed to comprehensively characterize the psychophysical and electromyographic parameters of the nBR in a large sample of healthy adults.

Methods: The nBR was performed in healthy, pain-free participants in the supine position under temperature-controlled conditions (23-25 oC). Self-adhesive recording electrodes were placed over the inferior portion of the orbicularis oculi muscles. Electrical stimulation was delivered to the supraorbital (V1) and infraorbital (V2) regions of the trigeminal nerve bilaterally. Stimuli at 1.5, 2, and 3 times the pain perception threshold were administered in randomized series of 10 stimuli per intensity, with interstimulus intervals of 10–15 seconds. Pain threshold, pain intensity and unpleasantness, and R2 component amplitude, latency, and habituation were assessed. Data were analyzed using ANOVA and ANCOVA models (p<0.05).

Results: One hundred and ten participants (73 women; mean age 25.14±5.33 years) were included. Men exhibited significantly higher electrical pain thresholds (p=0.021). Thresholds also differed between trigeminal branches with higher values in V1 (p<0.001). Pain and unpleasantness varied significantly only across stimulation intensities (p<0.05). R2 amplitude showed significant main effects of sex, laterality, and stimulation intensity (p<0.05) and the influence of threshold as a covariate was restricted to V1 (p<0.001). R2 latency was influenced exclusively by laterality, with consistently higher values contralaterally. Habituation depended on stimulation intensity and was significant only in V2 (p<0.05).

Conclusions: This study provides a detailed characterization of the psychophysical and electromyographic parameters of the nBR in healthy adults. Differences between the V1 and V2 branches likely reflect anatomical and functional specialization within the trigeminal system. Observed sex-related effects highlight the importance of considering sex in the clinical application and interpretation of the nBR. These findings establish reference parameters and provide a foundation for future investigations in clinical populations with orofacial pain and headache.

References: Costa YM, Baad-Hansen L, Bonjardim LR, Conti PCR, Svensson P. Reliability of the nociceptive blink reflex evoked by electrical stimulation of the trigeminal nerve in humans. Clin Oral Investig. 2017;21(8):2453-63.

Kaube H, Katsarava Z, Kaufer T, Diener H, Ellrich J. A new method to increase nociception specificity of the human blink reflex. Clin Neurophysiol: official journal of the International Federation of Clinical Neurophysiology. 2000;111(3):413-6.

Katsarava Z, Ellrich J, Diener HC, Kaube H. Optimized stimulation and recording parameters of human 'nociception specific' blink reflex recordings. Clin Neurophysiol: official journal of the International Federation of Clinical Neurophysiology. 2002;113(12):1932-6.

Perrotta A, Anastasio MG, De Icco R, Coppola G, Ambrosini A, Serrao M, et al. Frequency-Dependent Habituation Deficit of the Nociceptive Blink Reflex in Aura With Migraine Headache. Can Migraine Aura Modulate Trigeminal Excitability? Headache. 2017;57(6):887-98.

This work was supported by Sao Paulo Research Foundation (FAPESP) grant number #2019/15826-8.

Presenting Author: Yuri Martins Costa
Submitting Author: Yuri Costa

Senior Author: Yuri Martins Costa

IASP 2026 Global Year theme of Neuropathic Pain: Yes

• Rhayane da Conceição Monteiro: DDS - Piracicaba Dental School
• Isadora Alves Lorenzo: DDS - Piracicaba Dental School
• Fernando Exposto: DDS, PhD. - Aarhus University
• Leonardo Rigoldi Bonjardim: DDS, PhD. - Bauru School of Dentistry
• Peter Svensson: DDS, PhD. - National University of Singapore