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.
In the case of pancreatic cancer and other types of abdominal malignancies, if this block proves to be effective in controlling the pain, it can be repeated, using alcohol, phenol, or radiofrequency, in an effort to provide longer duration of relief. The duration of relief from these longer-lasting blocks will often outlive the patient’s expected lifespan, hence they are known as “permanent blocks”. Their main advantage is that of providing those patients with a significant improvement in quality of life, which is often lost as the disease progresses and the patient gets closer to their end of life. Most of the time, this occurs due to the use of strong narcotics that may keep the patient over sedated, obtunded, and often disoriented. Contrary to common belief, these treatments should not be used as “last resort”. In fact, the sooner they are used, the more effective they may be. Currently, ongoing studies are looking at life expectancy issues, since some preliminary reports have suggested that early intervention with these modalities may actually increase the mean life expectancy on these patients.