Impaired glutamatergic neurotransmission in migraine with aura? Evidence by an input-output curves transcranial magnetic stimulation study

Objective: An imbalance between activity of inhibitory and facilitatory intracortical circuits could play a central role in migraine etiology. We used input-output curves to achieve further information about intracortical excitability of motor cortex in migraine with aura.

METHODS:
Input-output curves were measured in the right abductor pollicis brevis muscle at rest in 12 patients suffering from migraine with aura and 8 healthy subjects. Stimuli were delivered at intensity ranging from 100% to 160% of resting motor threshold with 10-second inter-stimulus intervals. Seven patients were studied before and during treatment with levetiracetam.

RESULTS:
Results showed a greater motor-evoked potential amplitude in response to increasing intensity of stimuli in patients compared to controls (P < .02). This increased facilitatory effect was abolished by levetiracetam (P < .005).

CONCLUSIONS:
Our findings support the hypothesis of an interictal cortical hyper-responsivity in migraine patients that appears to be normalized by levetiracetam. This effect could support the potential therapeutic role of levetiracetam in migraine with aura prevention.