Reliability and repeatability of testing visual evoked potential habituation in migraine: A blinded case-control study.

Background Many studies have shown that migraine patients have an interictal habituation deficit of visual evoked potentials (VEPs). Some discordant results were attributed to non-blinded analyses and a lack of repeatability. Aims In this study, we compared blinded and non-blinded analyses of the same recordings and assessed test-retest repeatability. Methods VEP recordings of 25 healthy volunteers (HVs) and 78 episodic migraine patients (EMs; 52 interictal, 26 ictal) were analysed by two investigators, one of whom was blinded to diagnosis and headache phase. Twelve HVs and nine EMs had two recordings for test repeatability. Results In both blinded and non-blinded analyses, VEP habituation was normal in HVs and EMs during an attack, but deficient in EMs interictally. Intra-individual habituation percentages were highly correlated in two recordings separated by ≥7 days. Conclusions The studies showing a VEP habituation deficit in migraineurs between attacks are unlikely to be biased by non-blinding analysis or poor repeatability.