But before beginning any kind of treatment plan, migraineurs and headache specialists should weigh the drug’ s benefits and risks.
THE UPSIDES
Topiramate was introduced to the United States in 1996 as an anti-seizure medication( also known as an anticonvulsant or anti-epileptic). 4 Similarities between epilepsy and migraine suggested the drug could work for headache. For instance, both migraine and epilepsy affect how neurons fire and both are associated with hyperexcitability in neurons. 5
In cortical spreading depression, which may be related to migraine pain, neurons in the brain’ s outer layer( the cortex) become hyperexcited. The hyperexcitability then moves in a wave across the brain. People who have migraine with visual aura can actually see this effect, as blinking lights or geometric patterns move through their field of vision with the same timing as the cortical waves, about two to five millimeters per minute. 6
A study published this year in the journal Cephalalgia examined topiramate’ s effect on cortical waves. Researchers induced cortical spreading depression in groups of anesthetized rats( some had been treated with topiramate daily for six weeks, while others had never received the drug). Among the untreated rats, waves of hyperexcitability traveled across their brains unimpeded. But in rats treated with topiramate, cortical spreading depression faded significantly and the time between wave episodes increased. 7
Headache specialists recommend a certain dosage and regimen to receive the full benefit of the drug.
“ When topiramate is selected, the average dose for the average person looking to prevent their headaches is
2012 MIGRAINE PREVENTION GUIDELINES
In the 2012“ Guidelines for Prevention of Episodic Migraine,” preventive medications were organized into five categories:
• Level A drugs have been established as effective for the treatment of episodic migraine, based on clinical trials.
• Level B drugs are labeled“ probably effective” and should be considered for migraine prophylaxis.
• Level C drugs“ may” be considered for preventive treatment.
• Level U includes drugs that have insufficient data.
• A separate category was created for drugs considered ineffective.
In the updated guidelines, Level A drugs now include three beta-blockers( metoprolol, propranolol and timolol), anti-epileptic drugs( e. g., topimarate and sodium valproate) and the herbal treatment butterbur. Amitriptyline, which was in Level A in 2000, has been downgraded to Level B. It is accompanied by the herbal treatment feverfew, vitamin B2, venlafaxine( an antidepressant), and several NSAIDs( e. g., ibuprofen). Level C drugs included coenzyme Q10( coQ10) and several NSAIDs as well( e. g., flurbiprofen). Among the drugs considered ineffective for migraine prevention were the anti-epileptic drug lamotrigine as well as oxcarbazepine and telmisartan.
Other guidelines— such as those for chronic migraine, pregnant women or pediatric migraineurs— were outside the scope of the study. Researchers working on the updated guidelines also excluded onabotulinumtoxin A( Botox ®) because the AAN has previously identified it as ineffective for treatment of episodic migraine. 1
Despite researchers’ conclusions about the efficacy of various preventive medications, the authors of the updated prevention guidelines have noted,“ A majority of migraine sufferers who would benefit from prevention therapies do not receive them.” According to one study sponsored by the National Headache Foundation in 2005, some 43 percent of migraineurs have never used preventive therapies, despite having migraine frequencies that would benefit from treatment. 15 A lack of physician awareness and confidence in the quality of medication guidelines could be to blame, the guideline authors suggest.
4. National Institutes of Health.“ Topamax.” Dailymed. nlm. nih. gov. January 2012. 5. Haut et al.“ Chronic Disorders with Episodic Manifestations: Focus on Epilepsy and Migraine.” Lancet Neurology. 2006; 5( 2): 148-157. 6. Mulleners et al.“ Visual Cortex Excitability in Migraine with and Without Aura.” Headache. 2001; 41( 6): 565-572. 7. Unekawa et al.“ Suppressive Effect of Chronic Peroral Topiramate on Potassium-induced Cortical Spreading Depression in Rats.”
Cephalalgia. 2012; 32( 7): 518-527.
32 HEAD WISE | Volume 2, Issue 4 • 2012