The sympathetic blocks are given for diagnosing and relieving sympathetic mediated pains in CRPS, ischemia induced pains and certain other indications such as coccydynia (ganglion impar block), discogenic pain (L2 ramus communicans block). These blocks are also given like other nerve blocks under fluoroscopic guidance. Some of the commonly given sympathetic blocks are
Stellate ganglion block
Stellate ganglion block is useful in the treatment of a variety of painful conditions of the head, neck, upper extremities and upper thoracic dermatomes. The stellate ganglion lies in front of the neck of first rib and extends to the interspace between C7 and Tl. There are different approaches to blocking the stellate ganglion including landmark based, ultrasound and fluoroscopic guided. Fluoroscopic guided oblique approach is used commonly. The appearance of horners syndrome with classic changes in the eye on the same side of block confirms the correct administration of block. The stellate ganglion Radiofrequency lesioning is also used rarely in recurrent cases.
The sphenopalatine ganglion is found in a small space beneath the floor of cranial cavity called pterygopalatine fossa. It is suspended from the maxillary branch of trigeminal nerve in this fossa. The Sphenopalatine ganglion block is used for relief of facial pain and headache in conditions such as sphenopalatine and trigeminal neuralgia, cluster and migraine headaches and atypical facial pain. The different techniques to block this ganglion include intranasal topical local anaesthetic application, intraoral and extraoral approach, which are done under fluoroscopic guidance.
The Greater splanchnic, lesser splanchnic and least splanchnic nerves carry pain sensations from the viscera. Splanchnic nerve block is given in cases of malignancy of upper abdominal origin or even in upper abdominal pain of non malignant origin. Being found in a narrow compartment in lower thoracic region on each side of the vertebral bodies, Splanchnic nerves are amenable to radiofrequency lesioning which can provide relief from medium to long term.
Lumbar Sympathetic block
Lumbar sympathetic block is given in cases of circulatory insufficiency in legs in conditions such as diabetic gangrene, buergers disease, sympathetic mediated pains in CRPS 1&II and in discogenic pain. This is done to block the lumbar sympathetic ganglion which rune as a vertical chain on each side anterolateral to the vertebral body. The level of block is chosen by the site of pain. If a diagnostic lumbar sympathetic block provides relief, then radiofrequency neuroablation can be done for long term relief at same levels.
Superior hypogastric block
The superior hypogastric plexus is situated anterior to the L5-S1 intervertebral disc. It is indicated in pelvic pain due to various gynaecological conditions, non gynaecological causes such as interstitial cystitis and pelvic malignancy. It can be done with various approaches medial, lateral or transdiscal, all under the guidance of C Arm fluoroscope.
Ganglion Impar block
Ganglion impar marks the end of two sympathetic chains and is situated anterior to the sacro-coccygeal junction. It is indicated in sympathetically mediated pains in the perineum, rectum, genitalia and coccygodynia. There are many approaches but is easily approached by transdiscal approach through sacro-coccygeal junction. Radiofrequency lesioning or neurolysis may be done if local anaesthetic block provides pain relief.