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Neurolytic Procedures
Celiac Plexus Block Fluoroscopy Technique
DARADIA: The Pain Clinic
Fluoroscopy-guided celiac plexus block technique — the same approach is used for neurolysis with phenol or alcohol instead of local anesthetic.
Neurolytic Mechanisms and Methods
Neurolytic procedures achieve analgesia by destroying afferent neural pathways or sympathetic ganglia that transmit pain signals. The two broad categories are thermal ablation (radiofrequency) and chemical neurolysis (phenol, alcohol, glycerol).
Shared Pathophysiology: Wallerian Degeneration
All neurolytic techniques produce Wallerian degeneration, which is the progressive breakdown of the nerve axon distal to the site of the destructive lesion. If the axolemma (the nerve's outer membrane) remains structurally intact, regeneration of the nerve fiber will occur over approximately 3 to 6 months, leading to return of sensation. The clinical duration of effect therefore depends on the extent to which the technique disrupts axolemmal integrity.
Thermal Ablation (Radiofrequency Neurotomy)
- Uses radio waves to generate a focused heat lesion at the target nerve
- Typical parameters: 80-85 degrees C for 60-90 seconds
- Creates a lesion roughly 1 cm long by the diameter of the electrode shaft
- Advantages: More controlled lesion size, lower complication profile than chemical agents
- Limitations: Nerve regeneration tends to occur sooner because axolemmal architecture is better preserved
- Duration of effect typically ranges from months to about a year before repeat treatment is needed
Chemical Neurolysis: Phenol
- Concentration used clinically: typically 6-10%
- Mechanism: causes protein coagulation and denaturation of neural tissue
- Often prepared in a viscous formulation (such as glycerin base) that limits spread to surrounding structures
- Produces necrosis and demyelination in addition to Wallerian degeneration, resulting in longer-lasting effects
- Less painful on injection compared with alcohol
Chemical Neurolysis: Absolute Alcohol
- Mechanism: extracts lipids from neural membranes and causes protein precipitation, leading to extensive tissue necrosis
- More potent tissue destruction than phenol, with correspondingly longer duration of effect
- Significant disadvantage: alcohol is an irritant and causes pain on injection, often requiring concurrent local anesthesia or sedation
- Commonly used for celiac plexus neurolysis in cancer pain management
Chemical Neurolysis: Glycerol
- Less commonly used in spinal procedures
- Most frequently applied for Gasserian ganglion rhizolysis in trigeminal neuralgia
- In trigeminal applications, glycerol injection has demonstrated efficacy lasting up to five years in roughly half of treated patients
Celiac Plexus Neurolysis Technique
- Patient positioning: Prone
- Imaging guidance: CT or fluoroscopy (EUS is an alternative for the gastroenterologist-performed approach)
- Approach: Bilateral posterior paravertebral approach at the T12-L1 level
- Target: The celiac plexus, located around the celiac artery and root of the superior mesenteric artery, formed by the greater, lesser, and least splanchnic nerves
- Diagnostic block first: A test block with local anesthetic is performed to confirm the pain source before committing to neurolysis
- Neurolytic agent: Typically absolute alcohol or phenol injected bilaterally
- Monitoring: Watch for hypotension and diarrhea in the immediate post-procedure period; observe for at least one hour
Other Common Sympathetic Neurolysis Sites
| Target | Location | Primary Indications | |--------|----------|--------------------| | Stellate ganglion | Needle target: Chassaignac's tubercle (C6 anterolateral transverse process); injectate diffuses caudad to the cervicothoracic ganglion at C7-T1 | Head, neck, upper extremity sympathetically mediated pain, CRPS | | Celiac plexus | Anterior to aorta at T12-L1 | Pancreatic cancer pain, upper abdominal visceral pain | | Lumbar sympathetic chain | Anterolateral to L2-L3 vertebral bodies | Lower extremity pain, vascular insufficiency, CRPS | | Superior hypogastric plexus | Anterior to L5 vertebral body | Pelvic visceral cancer pain, chronic pelvic pain | | Ganglion impar | Anterior sacrum at sacrococcygeal junction | Perineal pain, coccydynia, rectal cancer pain |
Key Points
- •All neurolytic techniques produce Wallerian degeneration of the nerve axon distal to the lesion site
- •Nerve regeneration occurs in approximately 3-6 months if the axolemma remains intact
- •Thermal ablation (RFN) has lower complication risk but shorter duration compared with chemical neurolysis
- •Phenol (6-10%) causes protein coagulation; it is often mixed in a viscous base to limit tissue spread
- •Absolute alcohol extracts lipids and precipitates proteins, producing more extensive destruction but causing pain on injection
- •Chemical neurolysis produces necrosis and demyelination beyond simple Wallerian degeneration, resulting in longer-lasting effects
- •Celiac plexus neurolysis uses a bilateral posterior approach at T12-L1 under CT or fluoroscopic guidance
- •Glycerol is most commonly used for Gasserian ganglion rhizolysis in trigeminal neuralgia, not spinal procedures
- •Five major sympathetic block/neurolysis sites: stellate ganglion, celiac plexus, lumbar sympathetic chain, superior hypogastric plexus, and ganglion impar
References
- Rowe DS (1998). Neurolytic techniques for pain management. Jacksonville Medicine.
- Loukas M, Klaassen Z, Merbs W, et al. (2010). A review of the thoracic splanchnic nerves and celiac ganglia. Clinical Anatomy.