FRCA Notes

Stellate Ganglion Block

The relevant curriculum items here are knowldege of both the "stellate ganglion" and "blocks including...[those] used to treat chronic pain conditions".

Resources


The stellate ganglion

  • Also known as the cervicothoracic ganglion
  • Formed by fusion of the inferior cervical and first thoracic sympathetic ganglia:
    • Present in 80% of people
    • In the remaining 20% the inferior cervical ganglion stands alone
    • Variable shape: spindle (47%), dumbbell (27%) or star (24%) although classically described as a 2cm star-shaped structure

  • Lies anterior to the transverse process of C7 and the neck of the first rib, at the root of the neck
  • Sits just anterior to the prevertebral fascia, which separates it from longus colli

Relations

Relation Structures
Anterior Skin and subcutaneous tissue, sternocleidomastoid, carotid sheath, subclavian artery, vertebral artery, phrenic nerve
Posterior Prevertebral fascia, longus colli, transverse process of C7, neck of the first rib
Medial Vertebral body of C7, oesophagus, trachea, thyroid, recurrent laryngeal nerve, thoracic duct (left)
Lateral Anterior scalene, brachial plexus roots, superior intercostal vessels, ventral ramus of T1
Inferior Pleural dome over the lung apex

Sympathetic pathway

  • Central origin: paraventricular nucleus of the hypothalamus, descending to the lateral horn of T1-T3

  • Preganglionic fibres leave via the anterior roots and white rami communicantes, ascend the sympathetic chain and synapse in the ganglion

  • Postganglionic fibres supply:
    • Head and neck along the common carotid artery
    • Upper limb via the grey rami to the brachial plexus
    • Heart and lungs via the cardiac and pulmonary plexuses

  • The left stellate ganglion plays the predominant role in cardiac sympathetic innervation
  • The nerve of Kuntz is an alternative sympathetic pathway to the arm that bypasses the stellate ganglion and is a cause of block failure for upper limb indications

Mechanism of the block

  • Local anaesthetic interrupts ipsilateral postganglionic sympathetic outflow with effects lasting up to around 72hrs
  • Effects lasting weeks to months are attributed to central neural remodelling, e.g. reduced noradrenaline release in the amygdala and hypothalamus

Chronic pain

  • CRPS types 1 and 2 of the upper limb
  • Herpes zoster and post-herpetic neuralgia of the face and neck
  • Refractory angina and chest pain
  • Phantom limb pain
  • Other sympathetically mediated pain of the upper limb, head, neck and thorax

Vascular insufficiency of the upper limb

  • Raynaud's phenomenon and scleroderma
  • Obliterative vascular disease
  • Vasospasm, trauma and embolic events
  • Frostbite
  • Inadvertent intra-arterial injection of irritants

Other

  • Hyperhidrosis
  • Post-traumatic stress disorder

Emerging perioperative and critical care uses

  • Refractory ventricular arrhythmias and electrical storm (≥3 episodes of sustained VT/VF within 24 h)
  • Prevention of postoperative atrial fibrillation after cardiac and thoracic surgery
  • Cerebral vasospasm after subarachnoid haemorrhage
  • Return of gut function and attenuation of the stress response after abdominal surgery
  • See the evidence section below; most of these remain under investigation

Absolute

  • Patient refusal
  • Allergy to the drugs used
  • Infection at the injection site

Relative

  • Coagulopathy or anticoagulation due to proximity of large vessels (although evidence suggests very few bleeding complications even if anticoagulated)
  • Recent myocardial infarction (although may be beneficial for coronary blood flow)
  • Pathological bradycardia
  • Glaucoma
  • Contralateral phrenic nerve palsy (as inadvertent ipsilateral phrenic block may precipitate respiratory distress)
  • Local neoplasm or distorted anatomy
  • Bilateral block in a non-intubated patient due to risk of bilateral recurrent laryngeal or phrenic nerve block and airway compromise

General principles

  • Consent, including the expected Horner's syndrome and hoarseness
  • Full monitoring, IV access and resuscitation equipment (including lipid emulsion) available
  • Usually performed awake, so that Horner's syndrome can be assessed and nerve or vascular complications recognised

  • Most approaches target C6 (Chassaignac's tubercle) rather than C7:
    • Further from the pleura, reducing the risk of pneumothorax
    • At C7 the vertebral artery lies unprotected anterior to the transverse process before entering the C6 foramen
    • Injectate spreads caudally along the prevertebral fascia to reach the ganglion

Landmark (anterior paratracheal) approach

  • Supine with the neck slightly extended
  • Chassaignac's tubercle (anterior tubercle of C6) is palpated at the level of the cricoid cartilage, approximately 2-3 cm above and 2 cm lateral to the suprasternal notch
  • Sternocleidomastoid and the carotid artery are retracted laterally with the fingers

  • The needle is passed directly backwards between the trachea and the carotid sheath until it contacts the tubercle
  • Withdraw 1-2 mm so that the tip lies anterior to the prevertebral fascia and outside longus colli
  • Test dose of 0.5 ml with repeated aspiration, then 5-10 ml of local anaesthetic injected slowly

Ultrasound-guided approach

  • Supine, head rotated 45° away from the side to be blocked
  • High-frequency linear probe placed transversely on the anterolateral neck at the level of C6
  • C6 is identified by its prominent anterior tubercle and smaller posterior tubercle
  • Identify: carotid artery, internal jugular vein, thyroid, trachea, oesophagus, anterior scalene (lateral), longus colli and the C6 nerve root

  • Target: the fascial plane between the prevertebral fascia overlying longus colli and the posterior carotid sheath
  • Lateral-to-medial in-plane needle passing behind the carotid artery:
    • Advancing past the anterior scalene avoids the brachial plexus roots and phrenic nerve
    • Colour Doppler identifies vessels in the needle path, e.g. the inferior thyroid artery
    • Aspirate during advancement and before injection
  • Injection should be seen opening the plane between the prevertebral fascia and carotid sheath

Image-guided approaches

  • Fluoroscopy: landmarks guide the approach and contrast confirms spread on AP and lateral views
  • CT: allows a needle to be directed onto the head of the first rib, permitting smaller volumes

Drugs and volumes

  • Diagnostic block: lidocaine 1%
  • Therapeutic block: bupivacaine or levobupivacaine 0.125-0.5% or ropivacaine 0.2%

  • Volume: 5 - 15 ml depending on approach
    • With ultrasound, 5ml of 0.25% bupivacaine is sufficient
    • Failure rate of 5ml (0%) is less than 2ml (21%)
    • Higher volumes risk spread to other nearby structures

  • Neurolysis (e.g. alcohol) and radiofrequency ablation are used for prolonged effect in selected patients
  • Continuous catheter techniques are being investigated for electrical storm

Laterality

  • Unilateral block is usual
  • Left-sided block is preferred for cardiac indications
  • Bilateral block is generally considered safer in intubated patients

Horner's syndrome

  • Ipsilateral ptosis, miosis and anhidrosis; also enophthalmos, conjunctival injection and nasal congestion
  • An expected effect and the most practical marker of a successful block
  • Occurs in 84-100% of blocks, usually within 2 minutes
  • Not specific: can also result from blockade of the middle cervical ganglion, without sympathetic block to the upper limb

Other signs

  • Rise in ipsilateral hand skin temperature of 1.5-2°C
  • Negative sweat test or loss of skin conductance response
  • Increase in perfusion index of around 60% in the ear lobe or upper limb
  • Increased limb blood flow; reduced pain

Limitations

  • No consensus on the most reliable marker
  • In one study 87% developed Horner's syndrome, but only 28% met all four endpoints (Horner's, skin temperature, blood flow and skin resistance)
  • For electrical storm, reduction in arrhythmias occurred whether or not Horner's syndrome developed
  • Diagnostic blocks are prone to false positives (spread to somatic nerves, systemic local anaesthetic absorption, placebo) and false negatives (incomplete block)

Cardiovascular

  • Reduced cardiac sympathetic tone: slower conduction, prolonged atrial effective refractory period and raised VF threshold
  • Reduced inducibility and duration of atrial fibrillation with shortened QTc in animal models
  • Minimal effect on cardiac output and blood pressure compared with neuraxial sympathectomy
  • Ipsilateral vasodilation and increased upper limb and carotid blood flow
  • Possible bradycardia

Respiratory

  • Small reductions in FEV1, FVC and peak flow
  • Improved PaO2/FiO2 ratio after cardiac and oesophageal surgery without affecting shunt fraction

Neurological

  • Increased ipsilateral cerebral blood flow and reduced cerebral vasospasm
  • Reduced EEG activity and may reduce anaesthetic requirements
  • Improved postoperative sleep quality

Gastrointestinal

  • Increased gut blood flow with faster return of bowel function

Endocrine

  • Attenuated surgical stress response, e.g. lower cortisol, adrenaline and noradrenaline
  • Reduced inflammatory markers, e.g. IL-6 and CRP

  • Generally considered safe
  • Serious complications occur in around 1.7/1,000 procedures, mostly seizures
  • A systematic review of reported adverse events found that around half followed landmark-guided blocks

Common side-effects

  • Hoarseness from recurrent laryngeal nerve block is the most common: up to 25%, resolves spontaneously
  • Haematoma
  • Dysphagia, light-headedness, transient headache, somnolence, dry mouth

Needle trauma

  • Vascular puncture: carotid artery, internal jugular vein, vertebral artery, inferior thyroid artery; haematoma or haemothorax
  • Pneumothorax
  • Oesophageal or tracheal perforation
  • Chylothorax from thoracic duct injury (left side)
  • Nerve injury e.g. vagus nerve, brachial plexus roots

Spread of local anaesthetic

  • Intravascular injection: carotid or vertebral artery injection causes seizures with very small volumes
  • Local anaesthetic systemic toxicity
  • Phrenic nerve block: elevated hemidiaphragm, dyspnoea
  • Brachial plexus block
  • Neuraxial (epidural or intrathecal) spread, including high spinal
  • Bilateral sympathetic block or bilateral Horner's syndrome

Other

  • Infection: soft tissue abscess, osteitis, meningitis
  • Rarely: transient locked-in syndrome, persistent ptosis, vasovagal reaction, asystolic cardiac arrest


Technique Characteristics
Stellate ganglion block Targeted unilateral sympathetic block of the head, neck, upper limb and heart
Minimal haemodynamic effect
May be acceptable in anticoagulated patients
Thoracic epidural Bilateral sympathetic and somatic block
Significant hypotension and relatively high failure rate
Restricted by anticoagulation
Thoracic paravertebral block Unilateral analgesia with limited segmental sympathetic block
Risk of pneumothorax
Surgical thoracic sympathectomy Used for severe hyperhidrosis and refractory angina
Invasive and irreversible, not suitable perioperatively
IV regional sympathetic block Guanethidine injected into an exsanguinated, tourniquet-isolated limb
Depletes noradrenaline from postganglionic nerve terminals