الفهرس 
Pathophysiology of migraine
Mechanisms of migraine headacheOnly 14 pages are availabe for public view
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Abstract
Migraine is a primary headache disorder ranked as the third most prevalent and the seventh disabling condition affecting about 14.7% of people with a high societal and individual burden. Both subtypes of migraine, migraine with aura and migraine without aura may evolve from an episodic to a chronic form which affects 2–3% of the general population and causes the greatest disability.
Although well accepted diagnostic criteria exist for migraine, it is still a complex disorder that remains both under-diagnosed and misdiagnosed.
Currently available evidence suggests that migraine is a disorder of brain excitability characterized by deficient regulation of the excitatory inhibitory balance mostly due to thalamo-cortical dysfunction during cortical activity. The mechanisms underlying this cortical dysexcitability might lead to the interictal dysfunction in sensory information processing that progressively increases in the period between attacks and in particular conditions, ignition of cortical spreading depression occurs followed by activation of the trigeminovascular pain pathway.
The treatment of migraine headaches include acute therapy, with the goal of terminating and aborting attacks and daily preventive therapy which is indicated in one third of patients with migraine.
Despite recent drug developments, there is a great need for more efficacious and specific prophylactic migraine treatment. Available pharmacological treatments are often incompletely effective and have troublesome side effects and alternative therapies are therefore wanted.
One of those alternative therapies is Transcranial magnetic stimulation (TMS) used as a neuromodulatory tool with the ability to modulate cortical excitability. TMS showed encouraging results when used in single pulse protocol as an abortive therapy that can disrupt the phenomena of cortical spreading depression and that paved the way for investigators to implement studies to assess the efficacy of the repetitive pulse protocol in migraine prophylaxis and their results were mixed.
This placebo controlled study examined the efficacy of 5Hz repetitive transcranial magnetic stimulation versus sham stimulation in achieving significant response (>50% reduction in headache frequency) as a primary outcome applied over the left dorsolateral prefrontal cortex; an area that is thought to be involved in modulating pain pathways.
The study included 60 migraine patients (30 in each treatment group) who are recruited from headache and general neurology clinics in Ain-Shams University hospitals. Patients were asked to keep a baseline migraine dairy one month before being randomized to either group. Patients were assessed at 2 time points (baseline and 1 month after sessions) by migraine dairy ,disability scale (Hit-6),depression scale (BDI),anxiety scale (HAS), daytime sleepiness (Epworth) scale and also motor threshold and latency were assessed together with EEG.
The study results showed that active rTMS significantly improved total headache days frequency in 46.4% of patients, migraine days frequency in 57.1% of patients and attack frequency in 53.6% of patients in active group as compared to sham (22.2%, 26.9%, and 22.2% respectively) which was statistically significant and maximum improvement was in the first 2 weeks.
As regard to secondary outcomes, the headache severity (14.3% vs. 7.4%), attack duration (17.9% vs. 3.7%) functional disability (78.6%vs.44.4%) and rescue analgesics (-8 overuser vs. -3 overusers) were improved in both the rTMS and sham stimulation groups compared to baseline, but the improvement was more marked in the active rTMS group.
Lastly, no statistically significant change was found in BDI, HAS, Epworth scales compared to baseline in both groups and no significant difference between both groups was found in TMS parameters and EEG after one month.