Approaches to a stellate ganglion block
Multiple approaches have been used to block the stellate ganglion and include the use of ultrasound, MRI, and/or plain fluoroscopic guidance.
- Surface landmark technique - (using the C6 anterior approach)
The patient is in the supine position with the head in a slight extension. The head is turned towards the opposite side, away from where the block is to be performed. The cricoid cartilage is palpated to ascertain the C6 level. At the C6 level, we palpate for the C6 transverse process, which is also known as the Chassaignac tubercle. In most individuals, the tubercle is 3 to 4 cm cephalad to the sternoclavicular joint at the medial border of the sternocleidomastoid. The needle is advanced in the anteroposterior direction until it hits the tubercle. The needle is withdrawn about 2mm to come out of the longus colli muscle. A test dose of about 1 mL is administered after negative suction, then subsequently administer 8 to 10 mL of local anesthetic administration.
- Fluoroscopy-guided technique
This technique offers the advantages of providing better bony delineation. It also involves the administration of contrast, which assures that the needle tip is in the appropriate fascial plane. If a striated appearance shows on the administration of the contrast media, it means that the needle tip is probably intramuscular. Immediate dissipation of the dye indicates that the needle tip is intravascular in position.
- Ultrasound-guided C6 transverse approach
The carotid sheath and the sternocleidomastoid muscles are retracted laterally with the help of the ultrasound transducer. Gentle pressure is applied to reduce the distance between the skin and the tubercle. Needle insertion is towards the Chassaignac tubercle. After contacting the tubercle, the needle is withdrawn about 1 to 2 mm to bring it in the area of the prevertebral fascia. After negative aspiration, the local anesthetic (approximately 2 mL) is injected, and the spread is carefully visualized with the use of the ultrasound. Once the visualization confirms subfascial drug deposition, the clinician can administer the remainder of the local anesthetic.
- Ultrasound-guided C7 anterior approach
This method carries a slightly higher risk of pneumothorax and vertebral artery injury. However, it provides a much more consistent blockade as the needle lies closer to the ganglion. A smaller volume of local anesthetic can bring about a more consistent block with this technique. It is particularly useful in cases of failed blocks at the C6 level. The C7 approach always needs imaging as the C7 vertebrae have a vestigial tubercle which is not readily palpable.