| BACKGROUND AND OBJECTIVEMigraine is a common disorder affecting 6% of males and 18% of females. Nausea, vomiting, and photophobia, phonophobia are predominantly seen in migraine. Recurrent, disabling headaches produce significant functional limitations and impose large individual, societal, and economic burdens. The current therapeutic approaches to migraine are less than satisfactory for the limited efficacy, severe side effects and expensive cost. Recent studies demonstrate the obvious efficacy and slight side-effect of botulinum toxin type A in treating migraine. But its long-term effect and duration of treatment response are few reported. To evaluate its long-term effect, duration of treatment response and security in migraine prophylaxis, we performed a open-label study that enrolled 40 migraineurs who received BTX-A treatment with 6 to 30 months' follow-up. We hope that our study will add further evidence and clinical guidance for the BTX-A in treating migraine.MATERIALS AND METHODS1. SubjectsSubjects considered for participation were migraineurs who received BTX-A treatment in our hospital from March 2003 to September 2005, contained 8 males and 32 females. The mean age is 41.9±2.1, varied from 12 to 72. The duration of migraine is varied from 1 to 30 years (mean 10.8±1.2).2. MethodsBTX-A was injected into multiple sites of pericranial muscles according to the pain points with the dose varied from 35 to 100U. During a 3 months baseline period and the follow-up time after injection, subjects kept daily diaries recording migraine frequency, duration, and severity together with analgesic agent usage, concomitant symptoms and the occurrence of treatment-related adverse reactions. According above items observed, the treatment response was classified as "good response" (>50% improvement), "part response" (>25% improvement), no response(less than 25% improvement). Both "good response" and "part response" were considered to be treatment "responders". Recurrence was classified as >25% increase.3. Statistics analysisSPSS 13.0 software package was administered for statistics analysis.Hypothesis testing methods used included t test, Wilcoxon test and Pearson Chi-Square test. In the statistical analysis of this study, probabilities lower than 0.05 were taken as significant.RESULTS1. Treatment responseForty patients met the study criteria and were available for 6 to 30 months follow-up. During the period of follow-up, the patients showed significant reduction for the frequency, mean duration and severity of migraine attacks. The frequency of the 40 qualified study patients had decreased from 10.6±1.7 at baseline to 4.5±1.4 (PO.01). The headache severity decreased from 7.9±0.2 to 3.2±0.5 (PO.01) and the duration of attack decreased from 25.1±3.8 tol0.7±2.8 (PO.01). Overall, 77.5% of subjects were "responders" (greater than 25% improvement), of which 47.5% (n=19) show an over 75% improvement, 20.0% (n=8) show a 50% to 74% improvement, and 10.0% (n=4) show a 25% to 49% improvement in frequency, duration or severity of migraine attacks. 22.5% of subjects (n=9) were no-responders (less than 25% improvement). Furthermore, a reduced acute analgesic agents usage and decreased concomitant symptoms were observed (PO.01). 2. Duration of treatment responseThe subjects began to show therapeutic effect at 5 to 10 days after BTX-Ainjection, and the maximal effect was appeared at the first month. The duration of treatment response was 5.6±0.7mon, with the shortest duration 2 weeks and the longest duration 30 months.3. Side effectsOf the 40 patients studied, 2 showed muscle weakness related to raising head, 1 showed eyebrow ptosis, 3 showed dizziness and stiff facial expression. All the adverse effects were disappeared after 2 to 3 weeks without any management. It was also observed that decreased wrinkle on the forehead, procerus, and crow's-feet after BTX-A injection.4. Curative effect related factorsAge and duration of illness together with duration of migraine attack were the clinical factors significantly predictive of treatment response. Younger subjects were more likely respond to BTX-A than older subjects (mean age of responders was 39.5 years and mean age of no-responders 50.4 years, P=0.02<0.05). Patients who had migraines for less than 10 or 10 years had a response rate of 94.4% compared to the 63.6% response rate in subjects who had migraines for over 10 years(P=0.02<0.05). Subjects whose duration ofmigraine attacks for less than 12 or 12 hours had a response rate of 94.4% compared to the 63.6% response rate in subjects whose duration of migraine attacks for over 12 hours(P = 0.02O.05). However, total BTX-A dose,gender, severity and frequency of migraine attacks were not predictive of treatment response (P>0.05).Conclusion1. BTX-A is effective not only in decreasing the frequency, severity and duration of migraine attacks, but also in reducing acute analgesic agents usage and decreasing concomitant symptoms such as nausea, vomiting, and photophobia, phonophobia, with a 5.6-month mean duration of treatment response.2. BTX-A appears to be safe in treating migraine with only slight and reversible adverse effect.3. Our study demonstrates that age and duration of illness together with duration of migraine attack are the clinical factors significantly predictive of treatment response. However, total BTX-A dose, gender, severity and frequency of migraine attacks are not predictive of treatment response.
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