Ketamine has been in clinical use for over 30 years. It has an excellent safety profile and profound analgesia. In the operating room, we really like it for specific populations. It’s related to the drug PCP and it does have some psychomimetic effects which is actually one of the reasons it’s not more widely clinically used. Ketamine is starting to be used more and more in the chronic pain population because of its relatively profound analgesic properties. Recent evidence is showing that ketamine might be a therapeutic option for chronic refractory migraine. Migraine, as anybody in the field knows, is relatively poorly understood. What we do know is that serotonin plays an important role, that calcitonin gene-related peptide plays an important role, that central sensitization plays an important role, and that glutamate plays an important role. Ketamine can work on all of these areas to help modulate migraine in patients that are refractory to first and second line therapies.
There are certainly contraindications for ketamine treatment. For example, ketamine can increase your cardiac output. A patient with coronary artery disease who couldn’t withstand the increased cardiac demand or myocardial oxygen consumption wouldn’t be a good candidate. Ketamine can also induce psychosis if the patient is schizophrenic. There are other effects like increased ocular pressure, so patients with glaucoma are not indicated. And it can cause increased intracranial pressures, so anybody with an intracranial mass or intracranial hypertension would not be a good candidate. My practice is to have every ketamine patient screened by a cardiologist and a psychiatrist or psychologist beforehand, and as long as there are no other red flags, with those two clearances, I’m comfortable proceeding.