Neurolytic blocks refer to the blocks in which the target nerves are lysed (undergo change in structure) by injecting neurolytic agents. The commonly used neurolytic agents include absolute alcohol, phenol, glycerol. The neurolytic blocks are commonly given in cancer pain such as pancreatic cancer, bowel cancer, pelvic malignancy, oral cancer and non cancer pains such as trigeminal neuralgia. There is a chance of alcohol induced neuritis after administration of neurolytic blocks.
The common neurolytic blocks are as follows:
Coeliac plexus block- The celiac plexus is formed by three ganglion and is situated anterior to the aorta at T12 and L1 level. As the nerve supply of most of the visceral organs goes through the visceral plexus, it is used to manage the pain of intra-abdominal malignancy such as pancreatic cancer.
There are various approaches to block the Coeliac plexus including fluoroscopic guided, ultrasound guided and CT guided which have been used successfully. A transient fall in blood pressure is common after celiac plexus block.
- Splanchnic nerve neurolysis – This is done for similar indications as the celiac plexus block i.e upper abdomen malignancy.
- Superior hypogastric neurolysis – This is done in cases of pelvic malignancy under fluoroscopic guidance. Usually a trans-discal approach is taken to deposit the neurolytic agent anterior to the L5-S1 interspace after checking the spread with radio-opaque dye.
- Ganglion impar neurolysis – This is done in cases of perineal cancers. The procedure is similar to ganglion impar block, only difference being that neurolytic agent is injected after checking the spread with radio-opaque dye.