By Genevra Pittman NEW YORK, April 24 (Reuters Health) - The main ingredient in Botox may be modestly helpful for people with chronic migraines, a new report suggests, but the wrinkle treatment doesn't seem to offer much relief for those whose headaches are less frequent. Patients who started out having headaches almost daily reported two fewer headaches per month when they were given injections of botulinum toxin A.