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When pain management with medications or by other conventional means is unsuccessful, interventional nerve blocks can be used to treat certain types of acute and chronic pain. In nerve blocks, a combination anesthetic and steroid solution is injected into nervous tissue to reduce inflammation and block the transmission of pain signals to the brain (Zhou, 2012).
Some nerve blocks target a specific segment of the nervous system known as the sympathetic nervous system. The sympathetic nervous system is involuntarily controlled and contains many neural pathways that communicate pain to the brain; it also controls many ‘fight or flight’ responses from the brain, such as increases in heart rate and pupil dilation, and most importantly, blood vessel constriction.
A Cervical Sympathetic Nerve Block (CSNB), or Stellate Ganglion Block, is an injection which targets clusters of sympathetic nerves, or ganglia, which participate in the communication of pain signals from the head, neck and upper extremities (Zhou, 2012). The CSNB is an important treatment for a condition known as complex regional pain syndrome (CRPS). CRPS affects the extremities with a variety of symptoms including pain, swelling, and skin and bone changes, and most commonly occurs after significantly stressful medical events such as a heart attack or stroke (Sheon & Abdi, 2011). The CSNB has been reported to provide effective pain relief for this condition, and may even help reverse the course of early disease. These nerve blocks have also been used to treat the painful symptoms of shingles and sympathetic dystrophy, as well as increase regional blood flow (Wedel & Horlocker, 2009).
Sympathetic cervical blockade can also be used diagnostically; if CSNB’s provide immediate pain relief following the completion of the sympathetic block, pain specialists can confirm that the chronic pain is sympathetically maintained. If pain relief does not occur, however, it can help point the pain specialist towards a more accurate diagnosis of the cause of chronic neck pain.
The spine is divided into four major regions; the cervical (neck), thoracic (upper back), lumbar (lower back) and sacral (hip/tailbone) regions. 33 vertebrae comprise the spine, divided into five regions: (1) cervical, which are found in the neck closest to the skull (identified as C1-C7), (2) thoracic, found along the upper back (identified as T1-T12), (3) lumbar, found along the lower back (identified as L1-L5), (4) sacral, which are contiguous with the pelvis or hip (identified as S1-S5), and (5) coccygeal, which are fused as the tailbone (Hansen, 2010). The vertebrae themselves are composed of many structures, beginning with a solid, circular body connected to two transverse processes on either side by thin bony structures termed pedicles. The transverse processes can be thought of bony projections toward each side which serve as points for muscle attachment.
The cervicothoracic, or stellate, ganglion is located near the seventh cervical vertebrae (C7), near where the first rib attaches to the spine and just under the subclavian artery (near the origination of the vertebral artery supplying blood flow to the brain) which travels out the upper extremities. Due to its location and proximity to major blood vessels, great care must be taken when injecting the ganglion so as not to inadvertently inject medication into the systemic blood circulation.
During a CSNB procedure, the patient is appropriately positioned and draped on a procedural table, and the site of injection is sterilized. A local anesthetic is then injected into the site to prevent discomfort during the primary procedure (ExitCare, 2012). The medication to be injected is prepared and generally consists of a corticosteroid to manage inflammation and pain long term, and an anesthetic to provide immediate disconnect of pain signals from being transmitted to the brain.
During a stellate ganglion block procedure, the side of the neck is numbed with a local anesthetic and a needle is inserted and guided just adjacent to the lowest cervical vertebrae (C7) (Zhou, 2012). To accomplish this, the patient lies on their back and slightly extends the neck allowing a doctor to feel for vertebral landmarks that will help determine proper needle insertion (Wedel & Horlocker, 2009). Once inserted, a physician would traditionally attempt to guide the needle to the correct position based on the vertebral landmarks, however without definitive guidance there is a significant risk of injecting the anesthetic solution into an artery or other critical neck structure causing complications. Instead physicians now use fluoroscopy, essentially a real-time x-ray, to safely guide the needle through internal tissues.
Depending on the condition being treated, a CSNB procedure is can be performed every 1-4 days, and can be repeated between six and twelve times. Pain relief can last several days; however treatment is discontinued after the first or second injection if pain relief isn’t quickly experienced (Sheon & Abdi, 2011). Due to the specific targeting of the sympathetic nervous system, some temporary discomfort may be experienced following the procedure including eyelid droopiness, red eyes, raised skin temperature or nasal congestion, which generally resolves within a few hours.
CSNB’s have been shown to be effective in relieving many chronic pain conditions, particularly in CRPS. As pain originating from sympathetic nervous system pathology is generally unresponsive to more conventional medical therapies with oral agents, sympathetic nerve blocks can be an effective alternative when all other treatments fail.
Complications associated with CSNB’s can include blocking the wrong nerves, fainting, seizures/convulsion, paralysis, heart attack, and in some cases death (Wedel & Horlocker, 2009). These complications are quite rare, however, and CSNB is associated with very little risk. And as with any medical procedure, bleeding and infection are always a risk, but are minimized through proper sterile technique and proper training and experience amongst the medical staff.
Due to the proximity of major blood vessels to the location of the stellate ganglion, complications associated with the injected medications can occur. If steroid medications are incidentally supplied to the bloodstream, temporary systemic side effects such as weight gain, high blood sugar, and a weakened immune system may be experienced.
Cervical sympathetic blockade is a minimally invasive treatment that has provided pain relief for many patients experiencing sympathetically-maintained chronic pain syndromes. It offers the opportunity to rapidly relieve painful symptoms in select patients, and return to normal activities of daily life.
- ExitCare. (2012). Sympathetic Nerve Block. Retrieved April 10, 2012, from MD Consult: http://www.mdconsult.com.ezproxy1.library.arizona.edu/das/patient/body/331985182-14/1303407258/10089/62183.html
- Hansen, J. (2010). Back. Retrieved April 7, 2012, from MD Consult. Netter’s Clinical Anatomy.
- Sheon, R., & Abdi, S. (2011). Prevention and management of complex regional pain syndrome in adults. Retrieved April 20, 2012, from UpToDate: http://www.uptodate.com.ezproxy1.library.arizona.edu/contents/prevention-and-management-of-complex-regional-pain-syndrome-in-adults?source=search_result&search=cervical+sympathetic+nerve+block&selectedTitle=2~150
- Wedel, D., & Horlocker, T. (2009). Nerve Blocks. Retrieved April 17, 2012, from MD Consult. Miller: Miller’s Anesthesia, 7th ed.: http://www.mdconsult.com.ezproxy1.library.arizona.edu/books/page.do?sid=1303407254&eid=4-u1.0-B978-0-443-06959-8..00052-2–s0880&isbn=978-0-443-06959-8&uniqId=331991798-2#4-u1.0-B978-0-443-06959-8..00052-2–s1180
- Zhou, Y. (2012). Interventional Pain Management. Retrieved April 18, 2012, from MD Consult. Daroff: Bradley’s Neurology in Clinical Practice, 6th ed.: http://www.mdconsult.com.ezproxy1.library.arizona.edu/books/page.do?sid=1303407254&eid=4-u1.0-B978-1-4377-0434-1..00051-7–s0130&isbn=978-1-4377-0434-1&uniqId=331991798-2#4-u1.0-B978-1-4377-0434-1..00051-7–s0150