Light-induced sensory dysregulation in migraine: Evidence from blink reflex habituation analysis

Abstract

Background & Objective: Migraine involves altered brainstem sensory processing and photophobia affects 90% of patients. The blink reflex (BR) evaluates trigeminal-brainstem circuits non-invasively, but photic stimulation effects on BR habituation remain unexplored. This study aimed to investigate BR habituation changes following photic stimulation in episodic migraine patients versus healthy controls.

Methods: Thirty episodic migraine patients (ICHD-3 criteria) and 30 age-gender-matched controls underwent BR testing during interictal periods. Primary outcomes were changes in R1 amplitude and R2 areas (ipsilateral/contralateral) after standardized photic stimulation (6 Hz, 1200 cd/m², 60 seconds). Delta values (Δ = post-pre) were compared using Mann-Whitney U tests with Bonferroni correction.

Results: Baseline BR parameters were comparable between groups. Controls showed physiological habituation with increased R1 amplitude (median Δ = +42.3 μV) and reduced R2 areas (ipsilateral: -41.2 μV·ms, contralateral: -118.5 μV·ms). Migraine patients demonstrated impaired habituation with minimal R1 changes (+3.8 μV) and paradoxical R2 area increases (+2.4 and +31.7 μV·ms). All differences were significant (p < 0.001) with large effect sizes (r = 0.72-0.86).

Conclusion: Migraine patients exhibit profound BR habituation deficits following photic stimulation, reflecting brainstem sensory inhibition dysfunction. This approach may serve as an objective biomarker for migraine-related brainstem pathology.