An anesthesia medication being tested as a treatment for depression and PTSD could also be used to ease migraine pain in patients who may not have responded to other therapies.

Investigators administered ketamine infusions to 61 patients who were diagnosed with intractable migraine headaches over an average length of 5.1 days. Post treatment, nearly 75 percent of study participants reported a reduction in the intensity of their migraine pain.

The average migraine headache pain rating at admission was 7.5 compared to 3.4 on discharge with patients experiencing the lowest pain ratings by day four of treatment. The researchers reported adverse effects were generally mild.

"Ketamine may hold promise as a treatment for migraine headaches in patients who have failed other treatments," said study co-author Dr. Eric Schwenk, M.D., the director of orthopedic anesthesia at Thomas Jefferson University Hospital in Philadelphia, in a statement.

"Our study focused only on short-term relief, but it is encouraging that this treatment might have the potential to help patients long-term. Our work provides the basis for future, prospective studies that involve larger numbers of patients."

Ketamine is used to induce general anesthesia but can also provide powerful pain control in lower doses for patients suffering from a number of painful conditions.

"Due to the retrospective nature of the study, we cannot definitively say that ketamine is entirely responsible for the pain relief, but we have provided a basis for additional larger studies to be undertaken," added Dr. Schwenk.

Previous efforts to explore other potential indications for ketamine have primarily focused on off-label use in depression. Early results have been encouraging, but a study published in the Lancet Psychiatry in July 2017 said the risk of long-term ketamine treatment remain unclear. 

The findings of this migraine-related experiment were presented at the American Society of Anesthesiologists meeting taking place in Boston.