The stellate ganglion is a bundle of sympathetic nerves located at the base of your neck, just in front of the seventh cervical vertebra (C7). It serves as a relay station in your body’s “fight or flight” nervous system, sending nerve signals to your head, neck, arms, and upper chest. Present in about 80% of people, it forms when two smaller nerve clusters fuse together during development. In the other 20%, those clusters remain separate.
Where It Sits and How It Forms
The stellate ganglion is created by the fusion of the inferior cervical ganglion and the first thoracic ganglion, two collections of nerve cell bodies in the sympathetic chain that runs alongside the spine. It sits in front of the neck of the first rib and extends upward to the bottom of the C7 vertebra’s bony projection. That puts it deep in the neck, nestled among major blood vessels, the esophagus, and the trachea. When the two ganglia don’t fuse, which happens in roughly one in five people, the term “stellate ganglion” typically refers to just the inferior cervical ganglion sitting next to C7.
What It Controls
The stellate ganglion is part of your autonomic nervous system, specifically the sympathetic branch that handles involuntary “background” functions. Sympathetic nerve fibers from the upper thoracic spine travel upward through the sympathetic chain and pass through this ganglion on their way to the head, neck, heart, and arms. Through these connections, it helps regulate heart rate, blood pressure, sweating, blood vessel diameter in the arms and face, and pupil size. You never consciously direct any of these processes, but the stellate ganglion is involved in coordinating them.
Because it sits at a crossroads between the brain and the upper body, the stellate ganglion also plays a role in how pain signals are transmitted. When sympathetic nerves become overactive after an injury or illness, they can amplify pain in the regions they supply. That relationship between sympathetic nerve activity and pain is the basis for most medical procedures targeting this structure.
The Stellate Ganglion Block Procedure
A stellate ganglion block (SGB) is an injection of local anesthetic around the ganglion, temporarily shutting down the sympathetic nerve signals that pass through it. The procedure is typically performed with ultrasound guidance so the clinician can see the needle’s position relative to the surrounding blood vessels and other structures in real time. You lie on your back with your neck slightly extended, and the injection is placed at the C7 level. The whole process usually takes less than 30 minutes.
A successful block produces a set of predictable signs on the side of the injection: a drooping eyelid, a constricted pupil, and reduced sweating on that side of the face. This trio of changes is called Horner’s syndrome, and it’s actually the confirmation that the block worked. It’s temporary and resolves as the anesthetic wears off. You may also notice warmth in the arm on the injected side, a sign that blood flow has increased as the sympathetic “squeeze” on blood vessels relaxes. Some people experience temporary hoarseness or a feeling of a lump in the throat because of the ganglion’s proximity to the voice box nerves.
Pain and Vascular Conditions
The most established use of the stellate ganglion block is managing pain in the head, neck, upper chest, and arms, particularly pain driven by overactive sympathetic nerves. Complex regional pain syndrome (CRPS), a condition where pain persists and intensifies long after an initial injury, is one of the primary reasons clinicians perform SGBs. The block interrupts the abnormal sympathetic signaling that fuels the pain cycle. It can also improve circulation to the arm, making it useful for certain vascular conditions where blood flow to the hand or fingers is restricted.
PTSD and Mental Health Applications
One of the most talked-about uses of the stellate ganglion block in recent years is for post-traumatic stress disorder. The rationale is that PTSD involves a chronically overactivated sympathetic nervous system, and temporarily blocking the stellate ganglion may help “reset” that heightened state. A systematic review and meta-analysis found that SGB reduced scores on a standard PTSD assessment scale by a statistically significant margin compared to control groups. The treatment also showed potential benefits for anxiety and depression that often accompany PTSD.
The side effects associated with SGB tend to be mild compared to long-term psychiatric medications, which is part of its appeal. However, the optimal number of injections, which side to inject, and how long the benefits last are still being worked out. Some patients experience relief after a single injection, while others need repeated treatments.
Hot Flashes and Menopause Symptoms
Stellate ganglion blocks have shown notable results for severe hot flashes, particularly in women who can’t take hormone therapy, such as breast cancer survivors. The data varies across studies, but the pattern is consistent: symptoms drop significantly after treatment. One study reported a 90% reduction in hot flash frequency and a 93% reduction in nighttime awakenings up to 12 weeks after the procedure. Another found a 52% reduction in moderate to severe hot flashes over four to six months in women who received SGB, compared to just 4% in a sham control group.
Relief after a single block typically lasts two to five weeks. Repeat injections tend to produce longer-lasting effects. In some cases, a second block provided relief for 4 to 18 weeks, and a third extended that to 15 to 48 weeks. Not everyone responds equally: one study classified roughly half its participants as responders (with 40% to 90% symptom reduction) and the other half as nonresponders (0% to 11% reduction).
Loss of Smell and Taste After COVID-19
A newer and still preliminary application involves using SGB to treat persistent loss of smell and taste following COVID-19. In a case series of six patients with long-lasting smell and taste dysfunction, five experienced considerable improvement after a series of stellate ganglion block injections, with 83% reporting significant gains. The improvements ranged from moderate to near-full recovery, and taste tended to return before smell. Most positive outcomes occurred after injections were given on both sides of the neck. One patient saw no benefit. These are early findings from a small group, but they point to the ganglion’s broad influence over head and neck function.
What Can Go Wrong
Because the stellate ganglion sits in a crowded neighborhood of critical anatomy, the procedure carries some risk. The most common effects, like Horner’s syndrome, hoarseness, and a feeling of warmth, are expected and temporary. More serious but rare complications can include accidental injection into a blood vessel, nerve damage, or pneumothorax (a collapsed lung), since the top of the lung isn’t far below the injection site. Ultrasound guidance has significantly improved the safety profile by letting clinicians visualize the needle in real time.
Interestingly, bilateral effects sometimes happen even when only one side is injected. Research has shown that increased hand warming and facial blood flow occur on both sides of the body in about 50% of cases after a one-sided block. This suggests that the sympathetic blockade can spread to some degree, though it’s rarely enough to cause visible Horner’s syndrome on the opposite side.