Overview
Stellate ganglion blocks have been utilized for almost a century to treat a variety of medical conditions. Today, stellate ganglion blocks are most commonly used in the diagnosis and treatment of sympathetically maintained pain in the head, neck, and upper extremity. There are many painful and nonpainful conditions that may benefit from this interventional procedure. The more common indications include complex regional pain syndrome of the upper extremity and face and vascular disorders. This technique was first described as a blind procedure using landmarks. There have been a number of techniques described and developed using different imaging modalities and approaches to block the stellate ganglion.
The sympathetic nervous system plays an important role in neuropathic, vascular, and visceral pain, making it a good target for the treatment of a variety of disorders. The stellate ganglion is part of the sympathetic network formed by the inferior cervical and first thoracic ganglia.
It receives input from the paravertebral sympathetic chain and provides sympathetic efferents to the upper extremities, head, neck, and heart. Sympathetically maintained pain occurs in a variety conditions such as upper extremity or facial complex regional pain syndrome type I and II (formerly named regional sympathetic dystrophy [type I] and causalgia [type II]), vascular pain conditions, Raynaud’s disease, and refractory angina.
Stellate ganglion blocks have traditionally been performed blindly by palpating the anterior tubercle of the transverse process of C6 (Chassaignac tubercle) and directing a needle to the C6 transverse process while retracting the the carotid laterally. Once bony contact is made, the needle is slightly withdrawn to rest outside of the longus colli muscle. Large amounts of local anesthetic may be used in small aliquots after repeated negative aspiration.
This blind method has a relatively high failure rate, with numerous significant and even potentially fatal adverse effects. Due to the risk profile with blind procedures and advances in technology, this procedure is routinely performed with fluoroscopic or ultrasound guidance. Computed tomography (CT)-guided techniques have also been described in the literature. Image-guided stellate ganglion blocks have the advantages of increased safety and accuracy compared with blind injections. The needle can be accurately placed near the stellate ganglion, and, as a result, a safer and smaller amount of local anesthetic can be used, reducing the risk of adverse effects.
Anatomy
The cervical sympathetic chain is composed of the superior, middle, and inferior cervical ganglia. In approximately 80% of the population, the inferior cervical ganglion fuses with the first thoracic ganglion, forming the cervicothoracic ganglion also known as the stellate ganglion.
Understanding the surrounding anatomy of the stellate ganglion is critical for an effective block and to avoid serious and even life-threatening complications. The stellate ganglion lies anterolateral to the C7 vertebral body.
Structures lying anterior to the ganglion include skin, subcutaneous tissue, platysma, investing cervical fascia, sternocleidomastoid muscle, and the carotid sheath (containing the internal jugular vein laterally, carotid artery medially, and vagus nerve posteriorly). The lung apex lies anterior and inferior to the ganglion. Medial structures include the C7 vertebral body, esophagus, trachea, thoracic duct, recurrent laryngeal nerve, and thyroid gland. Posterolateral structures include the anterior scalene muscle with the phrenic nerve, brachial plexus and its branches, vertebral artery, and longus colli muscles.
The prevertebral fascia must be entered before these posterolateral structures become accessible. The inferior (serpentine) thyroid artery lies anterior to the vertebral artery at the seventh cervical level.
More commonly, however, is its location as it traverses the carotid artery posterior at C6, going laterally to medially into the thyroid gland. An important landmark located superior to the stellate ganglion is the anterior tubercle of the C6 vertebral body, Chassaignac tubercle (carotid tubercle). This is a commonly used landmark because it is easily palpated. Injection at this location allows for tracking of the local anesthetic down the prevertebral fascia to the stellate ganglion below.