***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: OBJECTIVE We evaluated the efficacy of  prophylactic valproic acid treatment ( 6 months ) on the frequency of migraine attacks and the number of migraine headache days with respect to serum levels . BACKGROUND Valproic acid , a GABAergic drug , has been shown to be effective for migraine prophylaxis . Results from several dose- and serum level-adjusted studies have recommended valproic acid doses within a range of 500 to 1500 mg per day for migraine prophylaxis . DESIGN AND METHODS In this prospect i ve open-label study , 52 patients received valproic acid doses of 300 to 1200 mg per day ; 45 patients were treated per protocol .  Valproic acid serum levels increased linearly in relation to the valproic acid dose and were between 21 and 107 microg/mL at the end of the treatment period . Patients were divided into two groups : those with valproic acid serum levels less than 50 microg/mL ( group 1 ) and those with serum levels greater than 50 microg/mL ( group 2 ) . RESULTS The frequency of migraine attacks was significantly reduced in group 1 from 3.5 + /- 0.9 to 2.0 + /- 0.9 attacks per month . Migraine headache days also decreased ( 6.4 + /- 3.5 to 4.6 + /- 2.9 days per month ) . In the high serum level group , a reduction of migraine attacks from 3.5 + /- 0.9 to 2.8 + /- 1.0 attacks per month and only a slight decrease in headache days ( 6.4 + /- 3.5 to 6.1 + /- 2.4 days per month ) was observed . The outcome of group 1 ( low serum level ) was significantly better than that of group 2 with respect to both parameters ( P<.05 ) . Side effects were generally mild and temporary . CONCLUSIONS Due to the lack of additional benefit from higher valproic acid doses ( more than 600 mg per day ) , we recommend daily valproic acid doses of 500 to 600 mg with a target serum level less than 50 microg/mL for the prophylactic treatment of migraine Aim : Scientific evidence regarding exercise in migraine prophylaxis is required . Therefore this study aim ed to evaluate the effects of exercise in migraine prevention . Methods : In a r and omized , controlled trial of adults with migraine , exercising for 40 minutes three times a week was compared to relaxation according to a recorded programme or daily topiramate use , which was slowly increased to the individual ’s highest tolerable dose ( maximum 200 mg/day ) . The treatment period lasted for 3 months , and migraine status , quality of life , level of physical activity , and oxygen uptake were evaluated . The primary efficacy variable was the mean reduction of the frequency of migraine attacks during the final month of treatment compared with the baseline . Results : Ninety-one patients were r and omized and included in the intention-to-treat analysis . The primary efficacy variable showed a mean reduction of 0.93 ( 95 % confidence interval ( CI ) 0.31–1.54 ) attacks in the exercise group , 0.83 ( 95 % CI 0.22–1.45 ) attacks in the relaxation group , and 0.97 ( 95 % CI 0.36–1.58 ) attacks in the topiramate group . No significant difference was observed between the groups ( p = 0.95 ) . Conclusion : Exercise may be an option for the prophylactic treatment of migraine in patients who do not benefit from or do not want to take daily medication We included 43 patients with migraine without aura in a triple-blind , placebo- and dose-controlled , crossover study of the prophylactic effect of slow-release sodium valproate ; 34 patients completed the trial . The number of days with migraine was 3.5 per 4 weeks during treatment with sodium valproate and 6.1 during placebo ( p = 0.002 ) . The severity and duration of the migraine attacks that did occur were not affected by sodium valproate when compared with placebo . Fifty percent of the patients were responders , ie , their initial migraine frequency was reduced to 50 % or less during sodium valproate as compared with 18 % during placebo . The number of responders increased during the trial to 65 % in the last 4 weeks of the active treatment period . There were no serious side effects requiring withdrawal of patients from the study . We conclude that sodium valproate is an effective and well-tolerated prophylactic medication for migraine without aura ABSTRACT The present study was performed to evaluate the efficacy of low-dose topiramate and compare it with sodium valproate that is prevalently prescribed as a migraine prophylaxis . This was a r and omized , double-blind , parallel-group clinical trial on 56 patients who completed the course of study .  Topiramate and valproate were administered at 50 mg/day and 400 mg/day , respectively , during the follow-up period . Frequency , intensity , duration , associated symptoms with headaches , analgesics use , as well as drugs ’ side effects were studied . Participants completed MIDAS and HIT-6 question naires before and after treatment . Frequency , intensity , and duration of migraine headaches as well as MIDAS score and symptomatic medications decreased significantly between repeated follow-up visits in both groups . Responder rate for patients treated with topiramate and valproate were 71.6 % and 64.3 % , respectively , and the difference between the two groups was not statistically significant . The reduction of headache severity in the topiramate group was significantly more than that in the valproate group ( p = .027 ) . During the study , no statistically significant reduction in associated symptoms with migraine were observed in both the groups . Topiramate dose of 50 mg/day with fewer side effects in comparison with its higher doses may be an appropriate substitution for first-line migraine prophylaxis such as valproate CONTEXT Small open-label and controlled trials suggest that the antiepileptic drug topiramate is effective for  migraine prevention  . OBJECTIVE To assess the efficacy and safety of topiramate for migraine prevention in a large controlled trial . DESIGN , SETTING , AND PATIENTS A 26-week , r and omized , double-blind , placebo-controlled study was conducted during outpatient treatment at 52 North American clinical centers . Patients were aged 12 to 65 years and had a 6-month history of migraine ( International Headache Society criteria ) and 3 to 12 migraines a month but no more than 15 headache days a month during a 28-day prospect i ve baseline phase . INTERVENTIONS After a washout period , patients meeting entry criteria were r and omized to topiramate ( 50 , 100 , or 200 mg/d ) or placebo . Topiramate was titrated by 25 mg/wk for 8 weeks to the assigned or maximum tolerated dose , whichever was less . Patients continued receiving that dose for 18 weeks . MAIN OUTCOME MEASURES The primary efficacy measure was change from baseline in mean monthly migraine frequency . Secondary efficacy measures included responder rate ( proportion of patients with > or = 50 % reduction in monthly migraine frequency ) , reductions in mean number of monthly migraine days , severity , duration , and days a month requiring rescue medication , and adverse events . The month of onset of preventive treatment action was assessed . RESULTS Of 483 patients r and omized , 468 provided at least 1 postbaseline efficacy assessment and comprised the intent-to-treat population . Mean monthly migraine frequency decreased significantly for patients receiving topiramate at 100 mg/d ( -2.1 , P = .008 ) and topiramate at 200 mg/d ( -2.4 , P<.001 ) vs placebo ( -1.1 ) . Statistically significant reductions ( P<.05 ) occurred within the first month with topiramate at 100 and 200 mg/d . The responder rate was significantly greater with topiramate at 50 mg/d ( 39 % , P = .01 ) , 100 mg/d ( 49 % , P<.001 ) , and 200 mg/d ( 47 % , P<.001 ) vs placebo ( 23 % ) . Reductions in migraine days were significant for the 100-mg/d ( P = .003 ) and 200-mg/d ( P<.001 ) topiramate groups . Rescue medication use was reduced in the 100-mg/d ( P = .01 ) and 200-mg/d ( P = .005 ) topiramate groups . Adverse events result ing in discontinuation in the topiramate groups included paresthesia , fatigue , and nausea . CONCLUSION Topiramate showed significant efficacy in migraine prevention within the first month of treatment , an effect maintained for the duration of the double-blind phase BACKGROUND Open-label trials and small controlled studies report topiramate 's efficacy in migraine prevention . OBJECTIVE To assess the efficacy and safety of topiramate as a migraine-preventive therapy . DESIGN A 26-week , r and omized , double-blind , placebo-controlled study . SETTING Outpatient treatment at 49 US clinical centers . Patients Patients were aged 12 to 65 years , had a 6-month International Headache Society migraine history , and experienced 3 to 12 migraines per month , but had 15 or fewer headache days per month during the 28-day baseline period . INTERVENTIONS Participants were r and omized to placebo or topiramate , 50 , 100 , or 200 mg/d , titrated by 25 mg/wk to the assigned dose or as tolerated in 8 weeks ; maintenance therapy continued for 18 weeks . MAIN OUTCOME MEASURES The primary efficacy assessment was a reduction in mean monthly migraine frequency across the 6-month treatment phase . Secondary end points were responder rate , time to onset of action , mean change in migraine days per month , and mean change in rescue medication days per month . RESULTS Four hundred eighty-seven patients were r and omized , and 469 composed the intent-to-treat population . The mean + /- SD monthly migraine frequency decreased significantly for the 100-mg/d group ( from 5.4 + /- 2.2 to 3.3 + /- 2.9 ; P < .001 ) and the 200-mg/d group ( from 5.6 + /- 2.6 to 3.3 + /- 2.9 ; P < .001 ) vs the placebo group ( from 5.6 + /- 2.3 to 4.6 + /- 3.0 ) ; improvements occurred within the first treatment month . Significantly more topiramate-treated patients ( 50 mg/d , 35.9 % [ P = .04 ] ; 100 mg/d , 54.0 % [ P < .001 ] ; and 200 mg/d , 52.3 % [ P < .001 ] ) exhibited a 50 % or more reduction in monthly migraine frequency than placebo-treated patients ( 22.6 % ) . Adverse events included paresthesia , fatigue , nausea , anorexia , and taste per version . CONCLUSION Topiramate , 100 or 200 mg/d , was effective as a preventive therapy for patients with migraine Abstract Twenty-three patients , aged 18‐66 years and suffering from migraine with or without aura , were r and omly selected to receive either vigabatrin or matched placebo tablets first for 12 weeks in a double-blind crossover study . Alternative treatment was given after a 4-week washout period . The dose of medication was titrated to a maximum of 4 tablets ( 2 g vigabatrin ) daily according to patients ' tolerance during the first six weeks of each treatment . No further dosage adjustment was made . Apart from rescue medication for migraine , no other drug was permitted . Four patients dropped out and four were excluded for non-compliance . Compared to placebo , vigabatrin decreased the frequency ( p=0.017 ) and severity ( p=0.024 ) of headache modestly . However , it reduced the duration ( p=0.019 ) of headache and migraine index ( p=0.012 ) considerably by 40 % and 59 % , respectively . No serious adverse effects were observed . Serum vigabatrin levels showed no correlation with the clinical effects Objective To evaluate the efficacy and safety of extended-release divalproex sodium compared with placebo in prophylactic monotherapy treatment of  migraine headache .  Methods This was a double-blind , r and omized , placebo-controlled , parallel-group study . Subjects with more than two migraine headache attacks during a 4-week baseline were r and omly assigned in a 1:1 ratio at each center to receive either extended-release divalproex sodium or matching placebo once daily for 12 weeks . Subjects initiated treatment on 500 mg once daily for 1 week , and the dose was then increased to 1,000 mg once daily with an option , if intolerance occurred , to permanently decrease the dose to 500 mg during the second week . Reduction from baseline in 4-week migraine headache rate was the primary efficacy variable . Migraine headaches separated by a < 24-hour headache-free interval were counted as single migraines in calculating migraine headache rates . 
    Output:
    
Results Mean headache frequency  on topiramate and sodium valproate is significantly lower than placebo .
Likewise , topiramate and divalproex demonstrated favorable results for the proportion of subjects with ≥50 % reduction of migraine attacks .
For topiramate , 100 mg and 200 mg outperformed 50 mg , but this was paralleled by a higher adverse event rate .
For valproate/divalproex , a dose-effect correlation could not be established .
There was no unequivocal evidence of efficacy for any of the other antiepileptics .
Conclusion Topiramate , sodium valproate and divalproex are effective prophylactic treatments for episodic migraine in adults .
In contrast to previous reports , there is insufficient evidence to further support the use of gabapentin