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ASRA: Ketamine Can Treat Stubborn Migraines -

Infusion may work when nothing else does!

 

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SAN DIEGO -- Ketamine, the anesthetic-turned-club-drug-turned-depression-therapy, has had a complicated history. And growing more so all the time: a pain physician told colleagues here that the ketamine infusions may be just the ticket for patients whose migraines and other headaches just won't quit. "It's non-conventional, not a first-line treatment. It has to be a last resort," cautioned Magdalena Anitescu, MD, PhD, of the University of Chicago, at the American Society of Regional Anesthesia Pain Medicine meeting. To complicate matters, insurance coverage may be a hassle, patients need recovery time after infusions, and patients might have trouble fitting regular treatments into their schedules.

Still, Anitescu said she's had success with ketamine infusions for patients with refractory migraines and other forms of chronic pain. "I tell patients that there's a 50-50 chance you may be get better," said Anitescu, who spoke at an ASRA presentation and in an interview with MedPage Today.

Ketamine, a short-acting dissociative anesthetic, is perhaps best known as a club drug ("Special K") that produces hallucinations. But it is also widely used as an anesthetic in animals and humans. Over the past quarter-century, it transformed into a popular sedative for children in the emergency setting. Researchers have studied its use as a treatment for postoperative pain, refractory pain, and depression. The drug is currently under FDA review for on-label use as a treatment for depression; researchers are now exploring its use as a rapid-acting emergency treatment for suicidal ideation. In 2012, Anitescu and a colleague retrospectively examined the records of 49 patients who'd undergone 369 outpatient ketamine infusions from 2004-2009, including eight with refractory headaches. All patients reported significant pain reduction. "In half of our patients, relief lasted for up to 3 weeks with minimal side effects," the researchers reported.

Anitescu recommended turning to ketamine for headaches when "nothing else helps" -- not Botox or nerve blocks or other treatments. Lidocaine infusions are another option for refractory pain, she said, but she tends to use ketamine more often when patients have centralized pain. In a 2012 retrospective study into ketamine infusions, Anitescu and a colleague wrote that the drug appears to relieve pain by interacting with the N-methyl-D-aspartate (NMDA) receptor: "Reversal of central sensitization by NMDA-receptor antagonists such as ketamine is believed to reduce pain and may reduce the amount of opioid analgesics patients need as well."

While ketamine is among the more well-known club drugs, Anitescu said patients don't tend to resist it because of its reputation since they don't know much about it. "I tell them what the side effects are -- we do a very low dose -- and that it's an LSD derivative," she said. "I let them decide." The treatment can be used for central pain syndrome and other pain conditions, Anitescu said. Insurance coverage can be dicey, she said, since ketamine infusions are still considered an experimental treatment. And she cautioned that regular infusions -- every 4-6 weeks in some cases -- can be an inconvenience for patients. At clinics, infusions can be time-consuming since patients need to be monitored after the procedure, she said.

Administration of ketamine may become easier, however. Last year, researchers reported promising findings regarding the use of oral ketamine at home as a treatment for chronic pain. Intranasal formulations are in development as well, although the possibility of abuse -- it is a street drug, remember, with dissociative hallucinogenic effects at sufficient doses -- remains a challenge. Researchers have also explored the use of ketamine infusions to treat other forms of pain. In a 2014 report, researchers summarized systemic reviews of ketamine's use for neuropathic pain; the reviews found limited high-quality research, especially regarding long-term treatment. Still, the researchers wrote that "we believe in the significant benefits of ketamine intravenous infusions in the treatment and management of a specific subgroup patients with CRPS. We have had very limited success with non CRPS neuropathic pain."

by Randy Dotina
November 22 2016
Contributing Writer, MedPage Today