The stellate ganglion is part of the sympathetic nervous system. It is located in the neck and is involved in regulating blood flow, sweating and certain pain responses in the upper limb, face and upper chest. When this system does not work properly, it can keep chronic pain going on its own. For this reason, temporarily “switching off” the stellate ganglion with a local anaesthetic can serve as both a diagnostic and a therapeutic method.
Who is the block for, and why?
A stellate ganglion block (SGB) is considered mainly for patients with:
- complex regional pain syndrome (CRPS) of the upper limb, where sympathetic overactivity worsens pain, swelling and impaired blood flow,
- phantom limb pain or chronic pain after an upper limb injury or surgery, when sympathetic involvement is suspected,
- vasomotor circulatory disorders of the upper limb (e.g. Raynaud’s phenomenon, or ischaemia caused by vasospasm),
- certain forms of chronic head and facial pain with a vasomotor component,
- in some cases, excessive sweating (palmar hyperhidrosis) or hot flushes.
The block is also increasingly considered for newer, still-emerging indications, where the evidence is less established than for CRPS:
- Dysautonomia – a general imbalance between the sympathetic and parasympathetic nervous systems. It may show up as abnormal regulation of heart rate, blood pressure or sweating, whatever the underlying cause.
- Long COVID – in patients with persistent dysautonomic symptoms after COVID-19, such as palpitations, exercise intolerance or impaired temperature regulation.
- POTS (postural orthostatic tachycardia syndrome) – as a therapeutic trial to ease symptoms linked to sympathetic overactivity when changing body position.
- PTSD (post-traumatic stress disorder) – a growing number of reports suggest that a right-sided block may ease hyperarousal symptoms such as hypervigilance, sleep disturbance and anxiety. The mechanism is not fully understood. Here the method complements psychiatric treatment and psychotherapy and does not replace them.
- Fibromyalgia – in some patients with persistent, widespread pain and accompanying sleep disturbance or sensory hypersensitivity, as a therapeutic trial to reduce the component driven by sympathetic overactivity. As with long COVID and PTSD, the evidence is limited, and the method supplements treatment rather than forming its basis.
- Depression with an anxiety component – isolated reports suggest the block may relieve anxiety and tension accompanying depression, in a similar way as in PTSD. As with the other indications in this group, it does not replace psychiatric treatment or psychotherapy and can only complement them.
What these conditions have in common is the suspicion that some of the patient’s symptoms are driven by an overactive sympathetic nervous system. The block makes it possible to test this and may bring relief at the same time.
Why is the procedure always performed on one side, not both at once?
The stellate ganglion lies right next to many important structures in the neck, including major blood vessels, the recurrent laryngeal nerve, the oesophagus and the pleura. Blocking both ganglia at the same time would pose a serious risk to breathing and circulation. For example, paralysis of both laryngeal nerves at once could compromise the airway.
For this reason, the procedure is always performed on one side only, the side matching the symptoms. If both sides of the body need treatment, the procedures are spaced out and performed at separate visits.
Which medications are used?
The block uses local anaesthetics, most often bupivacaine or ropivacaine. They are injected near the ganglion under imaging guidance (X-ray or ultrasound), which allows the doctor to precisely and safely avoid the surrounding structures. Dexamethasone may be added to the anaesthetic. It is an anti-inflammatory steroid intended to extend the pain relief beyond the duration of the anaesthetic alone.
What can you expect after the procedure?
A correctly performed block temporarily switches off sympathetic activity on the treated side of the body. This may result in:
- reduced pain and swelling in the limb (in CRPS),
- improved blood flow and a warmer limb,
- less excessive sweating.
Beyond the effects felt in the limb, patients sometimes report more general effects that reach beyond the arm or hand. These reflect the stellate ganglion’s wider influence on the sympathetic nervous system throughout the body:
- a sense of calm and reduced tension and hypervigilance, especially in patients with PTSD, anxiety or depression with an anxiety component,
- better sleep quality in the days following the procedure,
- fewer palpitations and hot flushes, which matters for patients with POTS or dysautonomic symptoms of long COVID,
- a slight, temporary drop in heart rate and blood pressure, an expected consequence of reduced sympathetic tone,
- redness and warmth on the treated side of the face (part of Horner’s syndrome, described below).
The effect may build up gradually. A single block can bring temporary improvement. For some conditions, such as CRPS, a series of several procedures is performed to achieve longer-lasting relief.
Horner’s syndrome as confirmation that the block worked
A typical, expected sign of a correctly performed block is Horner’s syndrome. It involves a temporary drooping of the eyelid, a constricted pupil and slight redness or warmth of the face on the treated side. This is not a complication. It confirms that the medication reached exactly the right place, near the sympathetic fibres that also supply the eye. These signs resolve on their own within a few hours as the anaesthetic wears off.
Summary
A stellate ganglion block is performed on one side only, for safety reasons. It is used in patients with pain or circulatory disorders of the upper limb and face that have a sympathetic origin. Horner’s syndrome after the procedure is a good sign, because it confirms the medication was delivered precisely. The doctor decides whether a patient qualifies for the procedure, and how many blocks are needed, based on the medical history and clinical picture.
