Ketamine has shown promise in patients with chronic migraine and other intractable headaches, but requires further investigation.
Researchers carried out a retrospective study to evaluate the analgesic effects of ketamine infusions on 61 patients with refractory headaches who had been admitted to hospital for aggressive intravenous therapy.
The mean headache pain rating at admission was 7.5 Â± 0.2 compared to 3.4 Â± 0.3 on discharge. There was a statistically significant difference between the initial, lowest and end pain ratings.
The mean length of infusion was 5.1 days and the day of lowest pain rating was day 4. Patients achieved their lowest pain rating at mean ketamine rates of 30.8 Â± 3.6mg/hour less than their pre-determined maximum dose of 1mg/kg/hour. Adverse effects were mild although one patient requested discontinuation.
Sub-anaesthetic ketamine infusions improved short-term analgesia for refractory headaches but research is needed to determine long-term outcomes, the researchers concluded at the Anesthesiology 2017 annual meeting (21 October 2017)
 Rangavijula A, Hernandez M, Dayan A et al. The use of ketamine infusions for refractory headaches: a retrospective analysis. Anesthesiology 2017 annual meeting, 21–25 October 2017. Abstract available here: http://asaabstracts.com/strands/asaabstracts/abstract.htm?year=2017&index=18&absnum=3491