Hot Flash Severity May Be Reduced by Nerve Block Injection

Larry Hand

February 06, 2014

A nerve-blocking injection into the neck may be an alternative treatment for hot flashes for women who would prefer not to get hormonal treatments because of safety reasons or personal preferences, according to an article published online February 5 in Menopause.

David R. Walega, MD, from the Department of Anesthesiology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, and colleagues conducted a randomized sham-controlled trial comparing the effects of stellate ganglion blockade (SGB) vs sham injection. The trial involved 40 postmenopausal women aged 30 to 70 years who were experiencing moderate to severe vasomotor symptoms (VMS), including hot flashes and night sweats.

The participants kept daily diaries, from which they were confirmed to have 25 or more VMS a week for at least 2 weeks before being assigned at random to either 5 mL 0.5% bupivacaine or 5 mL preservative-free saline.

After injections, women kept diaries for 6 more months and rated their symptoms from mild to very severe. Researchers also fitted the women with skin conductance monitors that time-stamped events and transmitted data to a computer for analysis by researchers.

Exactly how SGB works is still unclear, but the treatment is "based on the interruption of the sympathetic nervous system" and may affect blood flow and moderate norepinephrine levels in some brain areas. SGBs have been primarily performed by pain management physicians, and in recent years, image-guided SGBs have increased the safety of the procedure.

The researchers used fluoroscopic imaging with contrast dye to identify the correct vertebra to contact, using a 22-gauge, 1.5-inch needle for the injections.

Objective Results

There were no significant differences between groups for overall VMS frequency. However, the SGB group did experience a significant reduction in frequency of moderate to very severe VMS (event rate ratio, 0.50; 95% confidence interval [CI], 0.35 - 0.71; P < 0.001), as well as a significant reduction in objective VMS (event rate ratio, 0.71; 95% CI, 0.64 - 0.99; P < 0.05). No serious study-related adverse events were reported.

"Although women in the sham control group showed a 34% placebo effect on reported VMS from baseline to month 3, objective monitoring showed no improvement in VMS in the sham control group during that same time frame compared with a 21% reduction in objective VMS in the SGB group," the researchers write.

"The finding that SGB significantly reduces objectively measured VMS provides further evidence of efficacy. A larger trial is warranted to confirm these findings," the researchers conclude.

Dramatically Different

"Stellate ganglion block is a dramatically different approach to treating moderate to severe hot flashes. That's what's exciting about this paper," Margery Gass, MD, a gynecologist at the Cleveland Clinic Center for Specialized Women's Health and executive director of the North American Menopause Society in Ohio, told Medscape Medical News.

"Of course, these are among the early results, so many questions remain," she cautioned, including duration of benefit and whether other doses or injectable drugs are more or less effective. "People will be interested in the degree of rebound of hot flashes, because we see that with hormone therapy, as well. Will the return of hot flashes be similar to that with hormone therapy, or could it be less?"

Long-term patient satisfaction will also be a factor, she added. Whether it will become a practical clinical application depends on how effective it turns out to be after being studied in larger populations and how it affects the amount of bother from hot flashes, a US Food and Drug Administration consideration.

A considerable number of women want to avoid hormone therapy, which is not recommended for women who have had breast cancer or other significant health problems, she added, and SGB may be an alternative, but it is a procedure that should be done by highly qualified practitioner.

"In terms of clinical practice, it will boil down to cost and acceptability to the patient as a viable alternative," Dr. Gass said.

This research was supported by the Department of Obstetrics and Gynecology, Northwestern University. One coauthor has reported receiving grant funding from the National Institute of Child Health and Development and the National Institutes of Health Office of Research on Women's Health; another coauthor has reported receiving honoraria from Shionogi for consulting and speaking engagements and from Noven Pharmaceuticals for speaking engagements; and another coauthor has reported receiving honoraria from Noven and DepoMed for consulting. The other authors and Dr. Gass have disclosed no relevant financial relationships.

Menopause. Published online February 5, 2014. Abstract

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