A neurolytic block is the injection of alcohol or phenol around a group of nerves to provide long lasting relief (after a previous diagnostic block has provided effective temporary relief). Alcohol or phenol will damage these nerves and will, therefore, grant longer pain alleviating effects than a temporary, local anesthetic drug (e.g., Novocain).
After the nerves have been damaged, they will try to repair themselves over the course of several months to several years, and, eventually, this process or nerve regeneration could result in a patient experiencing greater pain than originally experienced before the neurolytic block. Therefore, these blocks are usually only performed for the treatment of (terminal) cancer pain after other treatment modalities have been tried.
Even though this block is considered permanent, it may not be. It may last for several weeks or months. If the pain returns, this block can be repeated. The procedure is the same as with a temporary local anesthetic block. The only difference is the medication used. This procedure is commonly performed to provide pain relief to patients with pancreatic cancer, ovarian cancer, colon cancer etc.
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