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Nerve Block Injection Helps Reduce Hot Flashes


It’s like an inner inferno suddenly erupts, leaving you drenched in sweat and red in the face from heat and embarrassment. No wonder women who suffer from menopausal hot flashes—and that includes about 80% of us at some point in our lives—are desperate for relief. The treatment options leave a lot to be desired, however. Hormone therapy helps but has been linked to increased risk for breast cancer and heart disease…oral medications that reduce hot flashes (gabapentin, clonidine) can have intolerable side effects…and botanical therapies such as black cohosh and phytoestrogens haven’t proved to be very effective.

A real breakthrough: A treatment usually used to control nerve pain or heavy sweating helps reduce hot flashes, too—and the effects of a single treatment last for six months or more, according to a new study.


To understand the study, you need a little (I promise) physiology lesson. The stellate ganglion is a collection of nerves located in front of the vertebrae at the base of the neck, connecting to the arms and face. These nerves are part of the sympathetic nervous system that activates our fight-or-flight response when we’re stressed, so they’re not involved with sensation or movement. When a tiny amount of local anesthetic is injected into this bundle of nerves, a procedure called a stellate ganglion block, it temporarily inactivates the nerves. Doctors typically administer the injection to relieve nerve pain in the head, neck, chest or arm…ease angina…or help control very excessive sweating in those same areas.

Some earlier studies suggested that stellate ganglion blocks also reduced vasomotor symptoms (hot flashes, night sweats) in women—so researchers put it to the gold-standard test by doing a randomized, placebo-controlled study. Participants included 40 women who experienced an average of 10 hot flashes daily, with most hot flashes rating as moderate to very severe. (Side note: We’re not talking about 10 quick little surges of mild warmth. A moderate hot flash lasts up to 15 minutes and involves sweating, clammy skin, dry mouth, tense muscles, racing heart and/or heat in part or all of the body. A severe hot flash lasts up to 20 minutes, feels like a “raging furnace” and is accompanied by weakness, headache, extreme perspiration, anxiety and/or panic attacks. A very severe hot flash is a “boiling eruption” that lasts up to 45 minutes and is characterized by rolling perspiration, heart irregularities, dizziness, nausea, cramps and difficulty breathing!)

Study procedure: Half of the women were randomly assigned to receive the actual stellate ganglion injection. The other half got a placebo—a sham procedure in which a bit of saline was injected beneath the skin close to, but not actually into, the stellate ganglion. All injections were done using an imaging technique called fluoroscopic guidance (like an X-ray “movie”) so that the needle went precisely where it was supposed to go. Only the anesthesiologist giving the injections knew which patients got the real block and which ones got the sham.

All study participants kept diaries to record the frequency and severity of their hot flashes, starting two weeks before the procedure and continuing for six months after. In addition to this subjective measure, the researchers also arranged for an objective measure of vasomotor symptoms—at the start of the study and again three months later, each participant wore a skin conductance monitor for 24 hours to measure how much she perspired.

Here are the results, based on…

The objective skin tests: Compared to the start of the study, vasomotor symptoms at three months after the procedure were reduced by 21% in the block group…but were not reduced at all in the sham group.

The women’s subjective diaries: For the first three months after the procedure, the women’s self-reported symptoms were reduced by about the same amount in both groups—despite the fact that the skin tests showed actual reductions only in the block group—suggesting that a strong placebo effect was at work in the sham group. However, that placebo effect seemed to wear off over time. Compared to the start of the study, the frequency of self-reported moderate-to-very-severe hot flashes occurring in the four to six months after the procedure fell by 52% in the block group but by only 4% in the sham group…while the intensity fell by 38% in the block group but only 8% in the sham group.

How does the procedure work? That’s not fully understood, but it could be that the block induces changes in blood flow to regions of the brain that regulate body temperature…and/or that it modulates norepinephrine or nerve growth factor, neurotransmitters that seem to change before and during a hot flash.

The women in this study continued to show benefit from the stellate ganglion block throughout the six-month study. Additional research is needed to determine just how long the effects of a single injection last—they might last even longer than six months.

If you are interested in trying this treatment: Ask your doctor to refer you to an anesthesiologist who is experienced at doing stellate ganglion blocks. You certainly don’t want just anybody injecting your neck, given the many critical nerves and blood vessels there—possible risks include seizure, collapsed lung, nerve damage and temporary numbness or weakness from the neck down. However, injuries are very rare when the procedure is done by a well-qualified practitioner, the study researchers said. In this study, the only side effects of the treatment were temporary ones that lasted just a few hours—drooping eyelids, eye redness, warmth in the face, hoarseness—which are normal and expected with a stellate ganglion block.

For much, much more on menopause: Be sure to check out our 24-article guide, Menopause Central: Your Guide to Part 2 of Your Life.

Source: David R. Walega, MD, associate professor of anesthesiology, Feinberg School of Medicine of Northwestern University, Chicago. His study was published in Menopause. Date: May 6, 2014 Publication: Bottom Line Health
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