Visual cortex excitability in migraine before and after valproate prophylaxis: a pilot study using TMS

Area of Science:

• Neuroscience
• Neurology
• Pharmacology

Background:

• Migraine is a common neurological disorder characterized by recurrent headaches.
• Cortical excitability changes are implicated in migraine pathophysiology.
• Sodium valproate is a standard migraine prophylaxis treatment.

Purpose of the Study:

• To investigate the effect of sodium valproate on occipital cortical excitability in migraine patients.
• To determine if reduced clinical migraine parameters correlate with changes in cortical excitability.

Main Methods:

• 31 migraine patients underwent transcranial magnetic stimulation (TMS) assessments before and after 1 month of sodium valproate prophylaxis.
• Occipital cortical excitability was measured using phosphene threshold determination with circular and figure-of-eight coils.
• Headache parameters were recorded by patients throughout the study.

Main Results:

• Sodium valproate significantly improved headache indexes.
• Phosphene thresholds, indicating cortical excitability, were significantly higher post-treatment in migraine with aura (MA) patients assessed with a figure-of-eight coil.
• No significant changes in phosphene thresholds were observed in migraine without aura (MO) patients or MA patients assessed with a circular coil.
• A modest correlation was found between increased phosphene threshold and decreased headache index in MA patients.

Conclusions:

• Sodium valproate therapy is effective in improving migraine symptoms.
• The findings suggest that sodium valproate may reduce cortical excitability, particularly in MA patients, supporting the role of gamma-aminobutyric acid (GABA)-ergic mechanisms in migraine prophylaxis.
• Further research is warranted to explore the effects of sodium valproate and similar agents on cortical excitability in migraine.