Image-Guided Stellate Ganglion Blocks

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.[1, 2] 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 Once bony contact is made, the needle is slightly withdrawn to rest outside of the longus colli muscle.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.[3, 4] 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.[5]

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.[6, 7]

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.[6] 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.[8] 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.

Indications for stellate ganglion blocks are as follows:

• Pain syndromes: These conditions include CRPS type I (reflex sympathetic dystrophy [RSD]) and type II (causalgia), refractory angina, phantom limb pain, herpes zoster, and pain of the head and neck.

• Arterial vascular insufficiency: These conditions include Raynaud's syndrome, scleroderma, obliterative vascular diseases, vasospasm, trauma, and upper extremity arterial emboli. No benefit is seen in patients with venous insufficiency.[6, 7, 8, 9]

• Other:  Electrical storm, hyperhidrosis

Contraindications are as follows:

• Patient refusal

• Systemic or local infection

• Current coagulopathy

• Pathological bradycardia

• Glaucoma[6]

Image guidance allows for more precise needle placement and less local anesthetic use for an adequate block. Severe and possibly fatal consequences of intra-arterial injection and even local effects are not uncommon and have been reported in the literature.[9] Korevaar et al reported that the minimal toxic dose of local anesthetic injected intravascularly is approximately 4% of the minimum toxic intravenous dose.[10] Bupivacaine is associated with more adverse cardiovascular events than lidocaine. Although bupivacaine’s action may be more prolonged, the diagnostic value of the stellate ganglion block is the same with lidocaine. Finally, the epinephrine used with lidocaine can result in tachycardia if injected intravascularly and its vasoconstrictive effects confine the anesthetic locally and reduce its distribution. Note the following:

• Omnipaque, 1–1.5 mL (flouroscopic guidance)

• Lidocaine 1% with epinephrine, 10 mL

• Bupivacaine 0.25%, 10 mL[6, 9]

Equipment needs are as follows:

• 3-mL syringe – For contrast agent

• 10-mL syringe – For local anesthetic

• 22- or 25-gauge, 1.5-inch short-bevel needle

• Skin temperature monitor, typically placed on the finger

• Ultrasound probe, fluoroscopy, C-arm

• Appropriate equipment and medications for medical resuscitation[6, 9]

Ultrasound and fluoroscopic technique positioning is as follows:

• Position the patient supine

• Thin pillow under head to slightly extend the neck

• Head rotated slightly to the side contralateral to the block

• Mouth slightly opened[6, 9]

CT-guided technique positioning is as follows:

• Position the patient supine with his or her chin turned away slightly from the injection site.[6, 9]

Multiple imaging modalities, including ultrasound, fluoroscopy, and CT, have all been used to reduce adverse complications compared with the blind technique. Fluoroscopy and ultrasound are readily available and either is typically used instead of CT. Ultrasound provides greater delineation of soft tissue anatomy and uses the prevertebral fascia as its endpoint for injection.[8] Ultrasound guidance can reduce the amount of local anesthetic required to achieve blockade and can help reduce unintentional puncture of critical vascular and nerve structures.[11] Kapral was the first to describe ultrasound-guided nerve blockade in 1995.[12] Fluoroscopy is beneficial for visualizing bony anatomy; however, soft tissue structures are much more challenging to appreciate and there is additional radiation exposure to the patient’s thyroid.

Ultrasound guidance

Two main approaches have been described for stellate ganglion block: the C6 transverse process approach and the C7 anterior paratracheal approach.[6, 7]

C6 transverse process approach

The patient is first positioned as described above. The needle insertion site is located between the trachea and the carotid sheath. The C6 level is identified at the level of the cricoid cartilage. The Chassaignac tubercle is then identified. Placement of the ultrasound transducer helps retract the carotid sheath and sternocleidomastoid muscle laterally. Pressure is applied with the ultrasound transducer to reduce the distance between the skin and tubercle and to depress the dome of the lung to reduce risk of pneumothorax.

The needle is inserted towards to the Chassaignac tubercle, and, after contact, it is redirected inferomedially towards the body of C6. The needle is then withdrawn 1-2 mm to bring it out of the longus colli muscle while still staying within the prevertebral fascia. After negative aspiration, 1-2 mL of local anesthetic can be injected, and spread can be visualized with ultrasound. Once confirming that the injection was subfascial, the remaining local anesthetic can be given.[6, 7, 8, 9, 10]

C7 anterior paratracheal approach

The patient is first positioned as described above. The sternoclavicular junction is palpated, and the needle insertion site lies about 3 cm rostral. This landmark can help identify the C7 transverse process under ultrasound guidance. The needle is then inserted perpendicularly towards to the transverse process of C7. Once reached, the needle is withdrawn 1-2 mm. After negative aspiration, 1-2 mL of local anesthetic can be injected, and spread can be visualized with ultrasound. The remainder of the local anesthetic may be given. This approach is associated with a higher incidence of pneumothorax, so special attention must be made to avoid this complication.[6, 7, 8, 9, 10]

A successful block is seen by the onset of Horner syndrome (ptosis, miosis, anhidrosis) with affected extremity temperature increase greater than 3°F (typically seen within 3 min). After the procedure, the patient should be allowed to recover in the department for approximately 1 hour.[13]

Fluoroscopic technique

Using the fluoroscopic technique for stellate ganglion blockade encompasses many of the landmarks and patient positioning used for the ultrasound-guided technique. Fluoroscopy provides exceptional bony delineation compared with that of ultrasound. There are two common approaches using flouroscopy, a classic anterior approach and an oblique approach.[14] The anterior approach is the same as the landmark technique with the additon of flouroscopic guidance. The oblique approach involves obtaining a 25–30 degree oblique view on the ipsilateral side of the block to obtain a foraminal view of the lower cervical foramen. The needle is directed to the junction of the vertebral body and the uncinate process at either the C6 or C7 level. An additional procedural step seen with fluoroscopy is the use of Omnipaque contrast to confirm appropriate needle placement and to rule out intravascular or neuraxial injection. As discussed earlier, if the needle is located subfascially, one will see local spread of contrast between the tissue planes both cephalad and caudad. Additionally, if intravarterial injection occurs, immediate dissipation of contrast dye will be seen.[6] Note the image below.

Anteroposterior (AP) image demonstrates correct needle placement at the junction of the body and the transverse process of C6. Contrast material has been injected to document extravascular location of the needle tip. Image courtesy of Wade Wong, DO.

CT-guided technique

The patient is placed supine with his or her chin turned away slightly from the injection site. Using CT scanning or CT fluoroscopy identifies the head of the first rib, as well as the adjacent vertebral artery. Under sterile conditions, the skin and needle track are anesthetized, and a 25-gauge spinal needle is maneuvered onto the head of the first rib, as close to the vertebral body as possible.[1, 2, 15] The physician should take care to avoid the vertebral artery (see image below).

Computed tomography fluoroscopic image shows the correct placement of a 25-gauge needle on the head of the first rib.

The needle tip should be placed on the cortex to minimize the likelihood of intravascular placement, and a small amount of Omnipaque is injected to confirm an extravascular location of the needle tip (see image below).

Contrast material has been injected to confirm the extravascular location of the needle tip (same patient as in image above).

Once the needle is in place, a small amount of local anesthetic is injected; additional amounts are slowly added until a sympathetic block is elicited. The needle is withdrawn, and pressure is held for 5–10 minutes. The patient should be observed for at least 1 hour.

Complications of image-guided stellate ganglion blocks result from either direct injury from the needle, effect from the local anesthetic agent, or infection.

Injury to adjacent vascular structures, including the vertebral artery, carotid artery, and internal jugular vein, can result in hematoma formation, especially in patients with preexisting coagulopathy.

Intravascular/intrathecal injection of local anesthetic can result in arrhythmia, seizure, and cardiovascular collapse.

Local anesthetic can produce hoarseness and an elevated hemidiaphragm accompanied by dyspnea as a result of direct spread to the recurrent laryngeal and phrenic nerve, respectively. For this reason, bilateral stellate ganglion blockade not advised.

Pneumothorax, esophageal perforation, and chylothorax from thoracic duct injury can be seen owing to the close proximity of these structures to the stellate ganglion. These are uncommon when the block is done under image guidance.

Anesthetizing the stellate ganglion can also result in profound bradycardia, hypotension, and even heart block, owing to inhibition of sympathetic fibers

Additionally, soft tissue infection, osteitis, and neuraxial infection (meningitis) may be seen.

Neuraxial injection of local anesthetic into the epidural space, intrathecally and even the brachial plexus, can occur.[6, 9]