title: Visual cortex excitability in migraine before and after valproate prophylaxis: a pilot study using TMS.
abstract: We examined the effect of standard migraine prophylaxis with sodium valproate on repeated measures of occipital excitability using transcranial magnetic stimulation (TMS). We predicted that, comparing pre- and post-treatment assessments, a reduction in clinical migraine parameters would be paralleled by a decrease in excitability measurements.A total of 31 migraine patients enrolled in the study, for assessment prior to and 1 month after commencement of sodium valproate prophylaxis. At each assessment, we used a standardized protocol to stimulate the occipital cortex with a 90-mm circular (coil A) and 70 mm figure-of-eight (coil B) coil. We recorded the threshold stimulation intensity at which subjects just perceived phosphenes. Subjects kept detailed records of headache parameters 1 month before and also during the study period. Valproate therapy significantly improved headache indexes, as expected. In MA subjects assessed with coil B, phosphene thresholds were significantly higher post-treatment than pre-treatment, but those for MO did not change. Modest correlations were observed in MA patients between increase in phosphene threshold and decrease in headache index. Although preliminary, the findings with coil B lend some support to the notion that effective migraine prophylaxis may be achieved through lowering cortical excitability by gamma-aminobutyric acid (GABA)-ergic intervention. Further investigation of the effect of sodium valproate or other similarly acting substances on cortical excitability in migraine is warranted.
authors.affiliation: Department of Neurology, Atrium Medical Center, Heerlen, The Netherlands. w.mulleners@freeler.nl
authors.forename: W M
authors.initials: WM
authors.lastname: Mulleners
authors.forename: E P
authors.initials: EP
authors.lastname: Chronicle
authors.forename: J W
authors.initials: JW
authors.lastname: Vredeveld
authors.forename: P J
authors.initials: PJ
authors.lastname: Koehler
mesh_terms: D000927:Anticonvulsants / Q000627:therapeutic use*; D004574:Electromagnetic Fields; D006801:Humans; D008137:Longitudinal Studies; D008881:Migraine Disorders / Q000175:diagnosis / Q000503:physiopathology* / Q000517:prevention & control*; D020325:Migraine with Aura / Q000188:drug therapy / Q000503:physiopathology; D010865:Pilot Projects; D014635:Valproic Acid / Q000627:therapeutic use*; D014793:Visual Cortex / Q000187:drug effects / Q000503:physiopathology*; D005680:gamma-Aminobutyric Acid / Q000502:physiology
chemical_list: D000927:Anticonvulsants; D005680:gamma-Aminobutyric Acid; D014635:Valproic Acid