Data Collection. Baseline data will be recorded as above (including HDI and Headache Diary). Pain, nausea and sedation scores will be recorded pre-infusion and then immediately post infusion Each subject will be given a daily headache diary to keep for the 30 days following the infusion. Subjects will be contacted by telephone at 24 and 72 hours post infusion and weekly thereafter to remind them to complete their headache diaries. At 30 days post-infusion the patients will complete a follow-up HDI by telephone or mail and their diaries collected.