Figure 3From: Intra-oral orthosis vs amitriptyline in chronic tension-type headache: a clinical and laser evoked potentials study Laser evoked potentials in chronic tension type headache patients. Grand average of LEPs across 9 chronic tension type headache patients assigned to amitriptyline and 9 assigned to the oral appliance in basal conditions (T0) and after two months treatment (T1). The amitriptyline induced a reduction of the later positive wave, the P2.Back to article page