Ketamine improved pain scores in patients with migraines and other refractory headaches, according to findings presented at the Anesthesiology Annual Meeting.
“The burden of migraine headaches on patients, their families and the health care system as a whole is substantial,” Eric Schwenk, MD, director of orthopedic anesthesia at Thomas Jefferson University Hospital in Philadelphia, told Healio Family Medicine.
Researchers retrospectively reviewed demographics, medications, initial and daily pain ratings, the amount of ketamine infused daily and adverse effects of 61 patients who received ketamine infusions for migraines or other intractable headaches. The infusion protocol was a “soft upper limit” of 1 mg/kg per hour but could be increased at the attending physician’s discretion. According to a press release, the ketamine was administered for 3 to 7 days.
“These patients had tried everything else and not gotten much relief,” Schwenk said.
Researchers hypothesized that patients would have a reduction in headache pain by two or more points by the end of their admission with less ketamine than the maximum allowed under the study’s protocol. Pain scores ranged from zero to 10, with 10 the “worst pain imaginable,” and were reported as mean values with standard error of the mean.
Schwenk and colleagues found that at admission, mean pain score was 7.5 and at discharge, the mean score was 3.4. There was a statistically significant difference between the initial, lowest and end pain ratings (P < .001). The lowest pain rating occurred on day 4, the mean length of infusion was 5.1 days, and patients achieved their lowest pain rating at mean ketamine rates 30.8 mg/hour less than the study protocol’s soft upper limit.
Adverse effects included sedation, blurry vision, nausea/vomiting, visual and auditory hallucinations, vivid dreams; and hypotension. Only one patient requested that infusions be stopped, according to researchers.
Schwenk discussed how primary care physicians can address possible concerns that patients may have about using ketamine as a pain treatment.
“The doses used for migraines and other painful diseases are much lower than the doses used for anesthesia. It is only given in controlled environments with trained personnel monitoring patients and asking frequently about side effects,” he said. “Though ketamine does have the potential to cause hallucinations and vivid dreams in some patients, it also has a long track record of being used without many problems. These side effects are typically treated by adjusting the dose and sometimes with an additional medication.”
Schwenk added that more research that explores ketamine as a pain management mechanism is needed.
“It is important that larger, prospective studies be done so that doctors have the evidence necessary to consider ketamine as a last-resort treatment for migraine and other refractory headaches. Until these studies are performed, insurance may not cover these treatments and the word will not get out about how effective ketamine is,” he said.
Reference: Rangavajjula A, et al. Abstract: A1065. Presented at: Anesthesiology Annual Meeting. Oct. 21–Oct. 25, 2017; Boston.
Schwenk reports no relevant financial disclosures. Healio Family Medicine was unable to determine the other authors’ relevant disclosures prior to publication.