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Updated: Apr 11, 2026
A Novel Approach for Documenting Phosphenes Induced by Transcranial Magnetic Stimulation
Published on: April 1, 2010
Correlation between habituation of visual-evoked potentials and magnetophosphene thresholds in migraine: A
Anna Ambrosini1, Ennio Iezzi2, Armando Perrotta3
1IRCCS Neuromed, Headache Unit, Italy anna.ambrosini@neuromed.it.
Introduction:
In migraine most studies report an interictal deficit of habituation of visual-evoked potentials (VEP-hab) and reduced thresholds for phosphene induction (PT) by transcranial magnetic stimulation (TMS). We searched for a possible correlation between VEP-hab and PT in migraine patients and healthy controls to test whether they reflect the same pathophysiological abnormality.
Methods:
We assessed PT and VEP-hab measured as the percentage change of N1/P1 amplitude over six blocks of 100 responses in 15 healthy volunteers (HV) and in 13 episodic migraineurs without aura (MO) between attacks. Results were compared using Mann-Whitney U test. Interrelationships were examined using Spearman's correlation.
Results:
In MO patients VEP-hab was reduced compared to HV (p = 0.001), while PT were not significantly different between HV and MO. There was no correlation between PT and VEP-hab in either group of participants.
Conclusions:
We confirm that in interictal migraine VEP habituation is deficient, but magnetophosphene threshold normal. VEP-hab and PT were not correlated with each other in healthy controls or in migraineurs. This finding suggests that they index different facets of cortical excitability in migraine, i.e. a punctual normal measure of the cortical activation threshold for PT and a dynamic response pattern to repeated stimuli for VEP habituation.
