Stellate Ganglion Block

Key facts

Who it is for

What the stellate ganglion does and why a droopy eyelid means success

The stellate ganglion sits in front of the C7 vertebra and the first rib, just behind the carotid artery. It is the relay station for all the sympathetic nerves to the arm, hand, face and eye on that side: the nerves that narrow blood vessels, trigger sweating and fine-tune the eye. In CRPS and other sympathetically maintained pain these fibers become cross-wired with pain fibers, so every sympathetic signal fuels the pain and the limb turns cold, blotchy and swollen.

Placing 5–10 mL of local anesthetic on the ganglion, or on the sympathetic chain at C6 just above it, interrupts that output for several hours. The hand warms as its blood vessels open, and if the pain is sympathetically maintained it drops within minutes. The block does not numb the skin or weaken the arm, which is what makes the result easy to read.

Horner's syndrome is the expected sign. Because the same ganglion supplies the eye and face, a successful block always produces, on the injected side, a droopy upper eyelid, a smaller pupil, a red eye, a stuffy nose and a dry, warm face. This is called Horner's syndrome. It looks alarming and it is exactly what we want to see: without it, the block did not reach the ganglion and the pain result cannot be trusted. It resolves as the anesthetic wears off, usually within 4–8 hours. The same anesthetic spread commonly reaches the recurrent laryngeal nerve beside the ganglion, causing a hoarse voice and a feeling of a lump in the throat or difficulty swallowing for a few hours; that is why you cannot eat or drink until it passes and why we never block both sides on the same day.

Test, then series. We treat the first block as a test. If your hand warms by at least 1.5°C, Horner's appears and your pain drops by 50% or more, your pain is sympathetically maintained and we schedule a series: typically 3–6 blocks, 1–2 weeks apart, each the day before an occupational or physical therapy session so the therapist can work the hand while it is pain-free. If the hand warms and Horner's appears but the pain does not budge, the pain is sympathetically independent and we move to other treatments, most often spinal cord or DRG stimulation.

Ultrasound or fluoroscopy. We use ultrasound at the C6 level, which shows the carotid artery, the vertebral artery, the thyroid and the esophagus, so the needle can be steered around them; fluoroscopy at C7 is an alternative. Either way, a small test dose goes in first and we watch you for the signs of anesthetic in an artery before giving the rest.

What happens on procedure day

1. Check-in with an empty stomach (no food for 4–6 hours). We review your pain score, blood-thinner list, heart and lung history, and confirm the side. A skin temperature probe is taped to both hands and an IV line placed as a precaution.
2. You lie on your back with a small roll under the shoulders and the chin slightly up, mouth open a little so you do not swallow or talk during the injection. Blood pressure, heart rhythm and oxygen level are monitored continuously.
3. The front of the neck is cleaned with chlorhexidine. Under ultrasound we identify the C6 vertebra, the carotid artery, the vertebral artery and the longus colli muscle; the target lies on the surface of that muscle. A tiny lidocaine wheal numbs the skin.
4. A thin needle is advanced under live ultrasound to the target, avoiding the vessels. We draw back to check for blood and inject a 0.5–1 mL test dose, then wait 30–60 seconds while asking you to report any ringing in the ears, metallic taste, dizziness or numb lips.
5. The remaining 5–10 mL is injected slowly, in increments, with you reporting how you feel after each. Total needle time is under 5 minutes. Pressure and a brief ache in the neck are normal.
6. You sit up slowly. Over the next 10–20 minutes the eyelid droops, the eye reddens, the voice may go hoarse and the hand warms; we record the temperature on both sides and ask you to move the hand and rate your pain.
7. You are observed for 30–45 minutes, mainly watching the neck for any swelling and confirming you can swallow water. You go home with a driver, a diary, and a therapy appointment for the next day.

After the procedure

Day 0. Expect Horner's syndrome (droopy lid, small pupil, red eye, blocked nostril) for 4–8 hours, a hoarse voice and a lump-in-the-throat feeling for 1–3 hours, and a warm, flushed hand. Do not eat or drink until your voice is normal and you can swallow water without coughing; start with sips of cold water. Do not drive. Use the pain-free hours to move the hand and arm gently. A sore neck and a small bruise are normal.

Days 1–3. Therapy the next day is the point of the block. Pain usually returns over one to several days; note in your diary how long the relief lasted and what you could do. A dull ache in the neck for 2–3 days is common.

Week 1–2. Bring the diary to the next block; the interval is set by how long relief lasted. If relief is lengthening with each block, the series continues.

When we judge the response. The test block is judged the same day from the temperature record, Horner's and your diary. The series is judged after 2–3 blocks. Call 911 for a swelling neck, trouble breathing, or a seizure. Call us the same day for hoarseness lasting more than 24 hours, a droopy eyelid lasting more than 24 hours, fever, chest pain, or new arm weakness.

What the evidence shows

Stellate ganglion block has been part of CRPS care for more than 70 years and is recommended in ASIPP and international CRPS guidelines as an early adjunct to physical therapy and medication. The randomized trial base is small: a Cochrane review of local anesthetic sympathetic blockade found low-quality evidence and could not confirm long-term pain reduction from blocks alone. Observational series and the guidelines agree on short-term relief that enables rehabilitation, with better outcomes when treatment starts early. For upper-extremity vascular pain and early herpes zoster pain, evidence comes from case series. Ultrasound guidance has been shown to reduce the volume needed and the rate of hoarseness and vascular puncture compared with the blind landmark technique.

PTSD and long COVID. Stellate ganglion block has been studied for post-traumatic stress disorder, with one randomized sham-controlled trial in active-duty service members showing a modest improvement in symptom scores at 8 weeks after two blocks, and for long-COVID symptoms such as smell loss and fatigue in small case series. These uses are off-label, not endorsed by psychiatric or infectious-disease guidelines, and typically not covered by insurance. We do not present them as established treatments; if you are asking about them, we will tell you honestly whether we offer the block for that purpose and what the evidence supports. Gulf Coast Pain & Spine performs stellate ganglion blocks under ultrasound in Houston and Webster, and in Pearland when that office opens in November 2026.

Alternatives and what comes next

For CRPS of the arm the block is one part of a plan that includes occupational and physical therapy, a nerve-pain medication, and sometimes a short course of oral steroid early on. The sympathetic block hub explains the whole family; for the leg the equivalent is the lumbar sympathetic block. If a series of blocks helps but does not hold, or the pain is sympathetically independent, spinal cord stimulation and dorsal root ganglion stimulation are the next step and have stronger trial evidence for CRPS than repeated blocks. Pulsed radiofrequency of the stellate ganglion is used in some centers to extend relief; chemical neurolysis of the stellate ganglion is avoided because of the risk of permanent Horner's and vocal cord weakness. For facial pain, the sphenopalatine ganglion block is often the better-matched target. If a well-performed block with Horner's gives no relief, sympathetic treatment is not your answer, and that result saves you further blocks.

Safety and preparation

• Blood thinners: this is a high-risk site for bleeding under ASRA guidance because a hematoma can compress the airway. Warfarin, DOACs (apixaban, rivaroxaban, dabigatran, edoxaban), clopidogrel, prasugrel and ticagrelor are held for 2–7 days depending on the drug, arranged with the prescriber; we will tell you whether aspirin needs to stop. Never stop a blood thinner on your own.
• Diabetes: the block uses anesthetic only, so blood sugar is unaffected. Tell us if you take insulin, since you will be fasting beforehand.
• Infection or fever: any fever above 100.4°F, a throat or neck infection, or skin infection on the neck postpones the block.
• Allergies (contrast, steroid, local anesthetic): ultrasound blocks use no contrast dye; fluoroscopic blocks use a small amount. Tell us about any reaction to lidocaine, bupivacaine or ropivacaine so we can substitute.
• Pregnancy: an ultrasound-guided block avoids X-ray and can be done when clearly needed; tell us if you are or could be pregnant.
• Sedation and driving: sedation is minimal or none so you can report symptoms instantly. You still need a driver and must not drive for 24 hours because of the eye and throat effects.
• Fasting: no solid food for 4–6 hours before the block and clear liquids up to 2 hours before, because swallowing is temporarily affected afterward.
• Heart, lung and eye: tell us about heart rhythm problems, a slow pulse, a pacemaker, recent heart attack, COPD, prior lung surgery, glaucoma, or any prior vocal cord or diaphragm problem; each can change whether or how we do the block.

Risks and side effects

Frequently asked questions

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