Image-Guided Lidocaine Injections for Headache

Pauline Anderson

March 06, 2015

Injection of local anesthetic into part of the trigeminal nerve under fluoroscopic guidance is being used to treat migraine and other headaches.

A new study showed that numbing the sphenopalatine ganglion (SPG) with the aid of fluoroscopy improved headache pain by about a third, said lead researcher Kenneth Mandato, MD, assistant professor, Interventional Radiology, Albany Medical Center, New York.

Intranasal image-guided SPG blocks "can diminish the pain and disability associated with chronic headaches and has the potential to be an alternative to traditional therapy," the researchers conclude.

The research was presented at the Annual Scientific Meeting of the Society of Interventional Radiology.

Image-Guided Procedure

The study included 112 patients, mostly women (79%), with a mean age of 44.5 years, who had been diagnosed with migraine (n = 98) or cluster headaches (n = 14). The patients had been receiving a stable medication regimen for more than a week.

To quantify the degree of debilitation, researchers assessed patients using a visual analogue scale (VAS), with scores that could range from 1 to 10 (most severe). At baseline, the mean VAS score was 8.25. All patients had a VAS score greater than 4 for at least 15 days of every month.

Image-guided, intranasal sphenopalatine ganglion injection involves an initial numbing in the nose with a lidocaine spray while the patient sits up. Then, while the patient is lying down, the doctor, using fluoroscopy, threads a small catheter up one nostril to the back of the nose and injects a very small amount (2 mL) of concentrated (4%) lidocaine hydrochloride (Xylocaine, Astra Zeneca) into the SPG while the patient inhales. The doctor then repeats the injection via the other nostril.

The entire procedure takes only about 15 or 20 minutes and is painless for most patients.

The study showed that after the procedure, the mean VAS score decreased to 4.10 (P < .001) at day 1 and to 4.40 (P < .001) on day 7, and that at day 30, it was 5.25 (P < .001).

This, said Dr Mandato, represents a 36% reduction in score after a month.

The 13 patients with cluster headache who responded did so to a modest to significant level, said Dr Mandato. Of the migraine responders, 91 responded at this level.

That patients still had headache relief after a month suggests that the effects last longer than the actual numbing. "That's the interesting part of this whole thing," said Dr Mandato. "Just like lidocaine used on the skin, the effect only lasts a few hours, but we're finding that even though the numbing aspect goes away, it seems to stop the bad headache cycle."

The SPG target, a nerve complex outside the brain, "has connections to many of the headache pathways," said Dr Mandato. He explained that lidocaine inhibits lipid bilayer depolarization, preventing the migraine stimulus from completing the neurologic circuit that leads to the headaches.

The study also found that after the injection, 88% of patients required less medication for ongoing pain relief.

It's unclear why seven patients in the study, all but one with a migraine diagnosis, didn't respond to the treatment. Nothing obvious set them apart from the responders, said Dr Mandato, adding that the protocol was the same and that they had a similar proportion of men and women.

Adverse Effects Rare

There were very few adverse effects. One patient had a stomachache from swallowing medicine, and another got a sinus flare-up. "These were very rare and more of a nuisance than a significant problem," said Dr Mandato.

Theoretically, patients with headache could get the injection repeatedly. It's also not a difficult procedure to learn. "The learning curve is not steep," said Dr Mandato.

Lidocaine is used to treat headache in other ways: for example, in nasal sprays and drops and injections into muscles. But the current procedure is superior in that it is a more direct approach, said Dr Mandato.

The study didn't include patients with tension-type headaches or headaches related to problems with the cervical spine because, said Dr Mandato, "it has never been shown that headache related to neck pain or muscular tension has any connection to this nervous pathway."

Dr Mandato now wants to follow these headache patients to see how durable the results are at 6 months. He would also like to see the results validated prospectively in a blinded study.

Nerve Blocks Not New

Commenting on the study for Medscape Medical News, Lawrence Newman, MD, president of the American Headache Society and director of the Headache Institute, Mount Sinai Roosevelt Hospital Center, New York, New York, said that nerve blocks have been used to treat headaches for decades.

For example, he said, some anesthesiologists and neurologists put lidocaine on a long cotton swab and place it up the nostril to the SPG area. There are also products that facilitate the injection of lidocaine through a tube.

"The only new thing here is doing it under fluoroscopy," said Dr Newman. "The study is useful in that headache doctors are always looking for different ways to help their patients, but this is not ground-breaking by any means."

He noted that the study was open label and "you can't give any validity to a technique unless it's double-blind."

Another drawback to the fluoroscopy-guided approach, said Dr Newman, is that it exposes the patient to radiation.

Dr Mandato and Dr Newman have disclosed no relevant financial relationships.

Society of Interventional Radiology Annual Scientific Meeting. Abstract #77. Presented March 1, 2015.

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