# Stellate Ganglion Block

## Introduction

The stellate ganglion block (SGB) is a sympathetic nerve block targeting the cervicothoracic sympathetic chain, most commonly performed at the level of C6 or C7. It is one of the oldest and most widely performed sympathetic blocks in pain medicine, with indications spanning complex regional pain syndrome (CRPS), phantom limb pain, vascular insufficiency of the upper extremity, and emerging applications in post-traumatic stress disorder (PTSD). Knowledge of the complex regional anatomy is essential to minimize the risk of serious complications.

## Anatomy of the Cervicothoracic Sympathetic Chain

The stellate ganglion — also called the cervicothoracic ganglion — is formed by the fusion of the inferior cervical ganglion and the first thoracic ganglion in approximately 80% of individuals. It sits anterior to the neck of the first rib and the transverse process of C7, posterior to the subclavian artery and the origin of the vertebral artery, resting on the longus colli muscle and covered by the prevertebral fascia. The ganglion measures approximately 1 cm wide, 2.5 cm long, and 0.5 cm thick.

Preganglionic sympathetic fibers from T1-T8 (primarily T1-T4) ascend through the sympathetic chain to synapse in the stellate ganglion. Postganglionic fibers then travel with the brachial plexus and cervical nerves to supply sympathetic innervation to the head, neck, and upper extremity. Several critical structures lie in close proximity: the vertebral artery (which passes through the foramen transversarium at C6), the recurrent laryngeal nerve, the phrenic nerve, the brachial plexus, the esophagus, and the pleural dome.

<image>Detailed cross-sectional anatomical illustration at the C7 level showing the stellate ganglion resting on the longus colli muscle anterior to the transverse process. Key structures labeled include: vertebral artery within the foramen transversarium, common carotid artery, internal jugular vein, vagus nerve, recurrent laryngeal nerve, esophagus, trachea, thyroid gland, anterior scalene muscle, phrenic nerve on the anterior scalene, brachial plexus trunks, and the pleural dome just caudal. The prevertebral fascia is shown covering the ganglion and longus colli.</image>

## Indications

### Established Indications

The most well-established indication is complex regional pain syndrome (CRPS) types I and II of the upper extremity, where the block serves both diagnostic (confirming sympathetically maintained pain) and therapeutic purposes. Other established uses include phantom limb pain of the upper extremity, acute herpes zoster and postherpetic neuralgia of the upper extremity and face, hyperhidrosis of the upper extremity and face, vascular insufficiency of the upper extremity (Raynaud disease, vasospasm, frostbite), and refractory angina pectoris and cardiac arrhythmias (ventricular tachycardia storm).

### Emerging Indications

Growing evidence suggests that SGB may reduce the sympathetic hyperactivation associated with PTSD symptoms. Hanling et al. (2016) and Rae Olmsted et al. (2020) studied military populations and demonstrated significant reductions in PTSD symptom scores (PCL-5) following SGB. The proposed mechanism involves resetting sympathetic tone by reducing elevated nerve growth factor levels in the stellate ganglion.

## Technique

### Landmark and Fluoroscopic Approach (C6 Level)

The patient lies supine with the neck slightly extended and head rotated slightly contralateral. The Chassaignac tubercle — the anterior tubercle of the C6 transverse process — is palpated between the carotid artery laterally and the trachea medially. Under fluoroscopic guidance (AP and lateral views), a 22-25 gauge needle is directed toward the junction of the C6 vertebral body and transverse process. On lateral fluoroscopy, the needle tip is confirmed to be anterior to the longus colli muscle and posterior to the prevertebral fascia. After negative aspiration, 0.5-1 mL of contrast is injected to confirm spread along the prevertebral fascia and exclude vascular uptake. A total of 5-10 mL of local anesthetic (0.25% bupivacaine or 1% lidocaine) is then injected incrementally.

### Ultrasound-Guided Approach

A high-frequency linear transducer is placed in the transverse plane at the C6 level. Key sonographic landmarks include the carotid artery, internal jugular vein, thyroid gland, longus colli muscle, C6 vertebral body and transverse process with the anterior tubercle (Chassaignac tubercle). The needle is advanced in-plane from lateral to medial, targeting the fascial plane over the longus colli muscle, subfascial to the prevertebral fascia. Real-time visualization allows avoidance of the carotid artery, vertebral artery, and esophagus. Ultrasound guidance has been shown to reduce the required volume of local anesthetic (to as low as 2-5 mL) and improve safety through direct visualization of vascular structures.

<image>Ultrasound-guided stellate ganglion block illustration showing a transverse sonographic view at the C6 level. The image demonstrates the longus colli muscle draped over the vertebral body, the carotid artery and internal jugular vein laterally, the thyroid lobe anteromedially, and the prominent anterior tubercle (Chassaignac tubercle) of the C6 transverse process. A needle is shown approaching in-plane from lateral to medial, with the tip positioned subfascially over the longus colli muscle. Local anesthetic spread is depicted as a hypoechoic layer lifting the prevertebral fascia off the longus colli.</image>

## Confirmation of Successful Block

A successful block is confirmed by the development of Horner syndrome — ipsilateral ptosis, miosis, anhidrosis, and enophthalmos — which indicates sympathetic blockade of the head and neck. A temperature increase of at least 1-2 degrees Celsius in the ipsilateral hand (measured by thermography or digital thermometer) confirms sympathetic blockade of the upper extremity. Ipsilateral nasal congestion and conjunctival injection are additional signs. It is important to note that Horner syndrome confirms blockade at the superior cervical ganglion level but does not guarantee complete stellate (T1) sympathetic blockade to the upper extremity.

## Complications

| Category | Complication | Mechanism | Prevention |
|----------|-------------|-----------|-----------|
| Common | Hoarseness | Recurrent laryngeal nerve block | Expected; resolves spontaneously |
| Common | Dysphagia | Pharyngeal muscle paresis | Expected; resolves spontaneously |
| Common | Horner syndrome | Sympathetic blockade | Expected sign of successful block |
| Common | Upper extremity weakness | Brachial plexus somatic block | Temporary; warn patient |
| Serious | Vertebral artery injection/seizure | Intra-arterial LA delivery to brain | Aspiration, contrast/US guidance |
| Serious | Pneumothorax | Pleural dome puncture (C7 > C6) | Use C6 level; image guidance |
| Serious | Airway compromise | Bilateral RLN palsy | Never perform bilateral blocks |
| Serious | Epidural/intrathecal injection | Needle enters foramen | Lateral fluoroscopy; proper depth |
| Serious | Esophageal perforation | Medial needle trajectory | Image guidance; lateral approach |

### Common

Common side effects include temporary hoarseness from recurrent laryngeal nerve blockade, dysphagia due to pharyngeal muscle paresis, Horner syndrome (which is expected rather than a true complication), and temporary upper extremity weakness from somatic blockade of the brachial plexus.

### Serious

Vertebral artery injection is a feared complication — even small volumes of local anesthetic injected intra-arterially can cause seizures due to direct cerebral delivery, making meticulous aspiration and use of contrast or ultrasound essential. Pneumothorax risk is higher with the C7 approach due to proximity to the pleural dome, and using the C6 level with image guidance reduces this risk. Bilateral blocks are contraindicated because bilateral recurrent laryngeal nerve palsy can cause vocal cord paralysis and airway compromise. Other serious but rare complications include epidural or intrathecal injection (if the needle enters the intervertebral foramen), esophageal perforation (associated with medial needle trajectory), and hematoma from vascular puncture of the carotid, vertebral, or inferior thyroid artery.

## Clinical Pearls

Bilateral stellate ganglion blocks should never be performed in a single session because of the risk of bilateral recurrent laryngeal nerve paralysis and airway compromise. The C6 level is preferred over C7 because the vertebral artery is anterior to the foramen transversarium at C7 (making it more vulnerable to needle injury) and the pleural dome is closer. Ultrasound guidance is increasingly considered the standard of care because it allows real-time visualization of vascular structures and reduces the required volume of local anesthetic. For CRPS, a series of 3-6 blocks is typically performed; if no improvement occurs after 2-3 blocks, sympathetically maintained pain is unlikely and the block series should be discontinued. For PTSD applications, a right-sided SGB is typically performed because the right stellate ganglion has been implicated in the sympathetic hyperactivation model, though bilateral approaches are under investigation.

## References

1. Elias M. Cervical sympathetic and stellate ganglion blocks. *Pain Physician*. 2000;3(3):294-304.
2. Narouze S, Vydyanathan A, Patel N. Ultrasound-guided stellate ganglion block successfully prevented esophageal puncture. *Pain Physician*. 2007;10(6):747-752.
3. Hanling SR, Hickey A, Lesnik I, et al. Stellate ganglion block for the treatment of posttraumatic stress disorder: a randomized, double-blind, controlled trial. *Reg Anesth Pain Med*. 2016;41(4):494-500.
4. Rae Olmsted KL, Bartoszek M, Mulvaney S, et al. Effect of stellate ganglion block treatment on posttraumatic stress disorder symptoms: a randomized clinical trial. *JAMA Psychiatry*. 2020;77(2):130-138.