title: Factors associated with favorable outcome in botulinum toxin A treatment for chronic migraine: A clinic-based prospective study.
abstract: BACKGROUND
  Botulinum toxin A (BTA) responders have elevated levels of calcitonin gene-related and vasoactive intestinal peptides, which are potent vasodilators. We aimed to investigate neurovascular features as a predictor of BTA treatment response in patients with chronic migraine.
  
  
  METHODS
  We prospectively recruited South Korean patients who were diagnosed with chronic migraine and underwent BTA injection at a university hospital from December 2013 to January 2015. Interictal transcranial Doppler (TCD) test was performed before BTA treatment when patients did not experience moderate-to-severe headache attacks. Botulinum toxin A was injected per the Phase III REsearch Evaluating Migraine Prophylaxis Therapy (PREEMPT) protocol. Treatment response was determined after 4-6 weeks of follow-up. Pretreatment clinical and neurosonologic features of responders and non-responders were analyzed.
  
  
  RESULTS
  Of the 83 enrolled patients, 70 who completed initial and follow-up evaluations were included for this study. Forty-two (60.0%) patients were classified as responders. 50% responders were 31 (44.2%). Longer disease duration was associated with poor treatment outcome (p=0.019). The ratio of the mean velocity of middle cerebral artery to that of ipsilateral internal carotid artery (MCA/ICA index) was significantly higher in responders than non-responders (p=0.027) and remained significant after controlling for covariates (p=0.025).
  
  
  CONCLUSIONS
  Shorter disease duration and higher pretreatment MCA/ICA index on TCD are associated with good early outcomes of BTA treatment.
authors.affiliation: Department of Neurology, Neuroscience Center, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea.
authors.forename: Mi Ji
authors.initials: MJ
authors.lastname: Lee
authors.affiliation: Department of Neurology, Neuroscience Center, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea.
authors.forename: Chungbin
authors.initials: C
authors.lastname: Lee
authors.affiliation: Department of Neurology, Neuroscience Center, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea.
authors.forename: Hanna
authors.initials: H
authors.lastname: Choi
authors.affiliation: Department of Neurology, Neuroscience Center, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea. Electronic address: cspaul@naver.com.
authors.forename: Chin-Sang
authors.initials: CS
authors.lastname: Chung
mesh_terms: D000328:Adult; D019274:Botulinum Toxins, Type A / Q000008:administration & dosage*; D002908:Chronic Disease; D005260:Female; D006801:Humans; D007273:Injections, Intramuscular; D008297:Male; D008875:Middle Aged; D008881:Migraine Disorders / Q000175:diagnosis* / Q000188:drug therapy*; D009465:Neuromuscular Agents / Q000008:administration & dosage*; D011446:Prospective Studies; D016896:Treatment Outcome
chemical_list: D009465:Neuromuscular Agents; D019274:Botulinum Toxins, Type A
keywords: Asian; Botulinum toxin A; Chronic migraine; Transcranial Doppler