Ferraro D et al. – The deficient habituation of the vertex N2/P2 complex was partly restored after successful treatment of medication–overuse headache, reflecting a modification in pain–processing pathways.

• LEPs were recorded to stimulation of both the right hand and the right perioral region in 14 patients and in 14 healthy subjects.
• The habituation of both the N1 and the vertex N2/P2 components was assessed by measuring the LEP amplitude changes across 3 consecutive repetitions of 30 trials each.

• In the 8 patients who had clinically improved after treatment, the N2/P2 amplitude habituation was significantly higher after treatment than before treatment following both hand (F = 43.2, P < .0001) and face stimulation (F = 6.9, P = .01).
• In these patients, the N2/P2 amplitude habituation after treatment was not different from that obtained in healthy controls (P = .18 and P = .73 for hand and face stimulation, respectively).
• On the contrary, in the patients who did not improve, the N2/P2 amplitude still showed reduced habituation after both hand (F = 3.1, P = .08) and face (F = 0.7, P = .4) stimulation.