Efficacy of IV ketamine in treating Refractory Migraines in the Clinic

Ketamine is a antagonist of NMDA-subtype glutamate receptors, thought to play a role in pain transmission. Remarkably little information exists on this receptor subtype and any potential role in migraine pathophysiology, although central sensitization and allodynia play a part in the migraine process. We chose to study this agent IV in the headache clinic to treat refractory migraines and other headaches in our search for additional agents to offer patients.

30 patients (21=f, 9=m) were treated for refractory migraines in the clinic with IV ketamine. A total of 48 infusions were administered. 18 patients had co-existent pain problems. An IV was placed and pulse oximetry was used in each patient. 0.4mg ketamine/kg was administered by IV infusion over 90 minutes. If there were no side effects, another 0.4mg/kg was administered over the same time. Patients rated their migraines on a 0-10 VAS. 8 patients received a 3rd infusion using the same dosage.

Beginning migraine severity was 6.61/10 and this reduced to 3.4/10 after treatment (p<.001). Average ketamine infusion time was 142 min and the average dose of ketamine was 71 mg. Side effects were transient “spaciness” in 5 patients and a sense of exhilaration in 4 more. No person fell asleep during treatment.

We conclude that IV ketamine for treating refractory migraines is a very effective new form of treatment with implications for migraine pathophysiology. It is quite efficacious, is tolerated well and has minimal transient side effects It should be studied in a double-blind fashion.