Stellate Ganglion Block

Clinical Relevance

Some pain syndromes may stem from primary dysfunction in the nervous system itself. This pain is referred to as neuropathic pain, distinct from nociceptive pain, which is pain stemming from injury to non-nervous tissue. Further, neuropathic pain may have a component of pain that is maintained by the sympathetic branch of the autonomic nervous system, not only the somatic nervous system. Alterations or blockade of the sympathetic nervous system can be a useful treatment for these relatively rare painful syndromes. Sympathetic nervous system preganglionic fibers originate in the thoracic and lumbar segments of the spinal cord. Sympathetic nerves exit the cord as gray and white rami communicantes and coalesce to form the sympathetic trunk, which sits adjacent and lateral to the vertebral column. To reach the head and upper extremity, the trunk extends into the neck, where it forms the three cervical ganglia. In these ganglia, the pre- and postganglionic neurons synapse, and the postganglionic fibers join the brachial plexus and carotid and vertebral arteries. The most caudad of the cervical ganglia is enlarged and star shaped and thus termed the stellate ganglion. Local anesthetic blockade of the stellate ganglion will reliably block nearly all sympathetic function to the head, face, and arm. There are occasional sympathetic fibers traveling to the upper extremity along the T2 and T3 nerve roots, which provide the remaining sympathetic innervation to the arm.

The first reported block of the sympathetic trunk was by Sellheim in 1905, and this was followed later by Lawen, Kappis, and Finsterer. True indications and technique remained vague until White established some rudimentary guidelines in the early 1930s.¹ As regional anesthesia became more popular and our knowledge of pain syndromes increased, blockade of the stellate ganglion has seen increased application. The stellate ganglion block (SGB) is a simple, effective means of treating a wide variety of pain types that occur in the upper extremities, upper thorax, face, and neck. Incorporating systemic medications, physical therapy, and psychological therapy with SGB often produces better outcomes.

Indications

• Limb ischemia including Raynaud phenomenon, arterial vasospasm

• Complex regional pain syndrome (CRPS, also known as reflex sympathetic dystrophy)

• Neuropathic pain and vasospasm including Raynaud phenomenon

• Posttraumatic stress disorder and postmenopausal hot flashes are possible future indications.

SGB can be a part of treatment for many pain syndromes and symptoms; it leads to vasodilation in the upper extremity. Thus, pain syndromes like Raynaud disease and the Meniere triad have been alleviated via interruption of the sympathetic nervous system at the stellate ganglion. Treatment of pain secondary to upper extremity arterial thrombosis and frostbite has been documented. Furthermore, SGB can be efficacious in salvaging upper extremity ischemia caused by either extravasation of vasopressors or accidental intraarterial injection.²

SGB interrupts the sympathetic nervous system outflow to the upper extremity, which led to its historical use in the diagnosis and treatment of CRPS. There are two types of CRPS: CRPS-I, also known as reflex sympathetic dystrophy, has no specific nerve injury, whereas CRPS-II, also known as causalgia, can be attributed to injury to a specific nerve. SGB can ameliorate CRPS symptoms in the upper extremity, upper thorax, face, and neck.³ SGB has also been used to prevent postoperative recurrence of CRPS after upper extremity surgery in patients with resolved CRPS.⁴ Kakazu and Julka showed that SGB can effectively treat postoperative pain.⁵

SGB is most commonly used to treat chronic neuropathic pain,⁶ the rationale being that ephaptic connections can develop between the autonomic and somatic nervous system, especially after nerve injury.⁷ The link between the sympathetic efferent and somatosensory afferent nervous system has been demonstrated in both neuropathic and inflammatory conditions (Table e164-1). In addition, SGB has been used as a treatment for both acute herpes zoster and postherpetic neuralgia of the face and lower cervical/upper thoracic regions.^8,9 Similarly, SGB has been used for phantom limb pain. Despite these facts, recent reviews question the effectiveness of therapies designed to inhibit sympathetic function in patients with CRPS.^10,11 However, a recent systematic review of the topic found multiple trials demonstrating the effectiveness of SGB for CRPS and eventually scored it as a 2B+ therapy.¹²

There are two emerging indications for SGB: posttraumatic stress disorder (PTSD)¹³ and hot flashes in breast cancer patients.^14,15 PTSD is a growing problem in the United Sates owing to service members returning home from conflicts in Iraq and Afghanistan. Treatment of PTSD involves a multimodal approach, and the rationale for SGB is not obvious. However, SGB has connections to both the central systems responsible for anxiety, the hypothalamus and cardiovascular system, which mediate much of the systemic symptoms. Hot flashes after breast cancer treatment are common and cannot be treated with hormone replacement therapy. Lipov et al.¹⁴ initially described successful treatment of hot flashes with SGB, and Pachman et al. confirmed those results.¹⁵ Pachman’s study showed a 45% symptom reduction, but the mechanism remains unclear.