A nerve destructive procedure is essentially any technique that damages a nerve so that it can no longer function. There are several different methods used to damage a nerve, including thermal(heat or cold), electrical, chemical, and surgical. To treat cancer pain, the goal is to damage a nerve so that it can no longer transmit pain message to the spinal cord. Theoretically, this would relieve all the apin coming from the area served by the nerve.
On the surface, it would appear that nerve destruction procedures would be an ideal way to relieve cancer pain coming from a single area. Unfortuately, like so many issues in modern medicine, it is not that simple It is natural to assume that nerve destruction is the equivalent of a permanent nerve block, but this is not so. The actual during of a nerve destruction procedure may only last a few weeks and usually lasts less than six months. This impermanence occurs for two simple reasons: nerve repair and cancer progression.
Visualize a single nerve cell as a yo-yo dangling from a finger. The actual yo-yo is the nerve cell body and the string is the nerve fiber. In a human the cell body is located in or near the spinal cord, and the nerve fiber extends out into the arm, leg, chest, or face. When a doctor destroys a nerve in your arm or leg, he is actually damaging a large number of nerve fibers. The cell body remain undamaged in the spinal cord.
After the nerve fiber is damaged, the cell bodies attempt to repair the injury by growing a new nerve fiber along the path of the nerve. The growth process is both very slow and very chaotic. Because a single peripheral nerve contains thousands of fibers, the individual nerve fiber usually does not reconnect to its original location exactly. In some cases, a nerve fiber may reconnect to a slightly different area. In other cases, the new nerve fibers are unable to travel down the nerve and instead from a tangled ball-like formation within scar tissue, called a neuroma. As abnormal connections or neuromas are formed, the patient may begin to experience pain again. This may or may not be similar to the original pain, and over time, it may even become more severe than the original pain.
In addition to nerve regrowth, there is the issue of cancer progression. If it is not cured, camcer eventually speads, invading new structures. It the tumor grows into area not covered by the original nerve destruction procedure, the pain obviously will return.
Despite these limitation, nerve destruction procedures can be very useful in certain situations. Deciding when such procedures should be used involves considering the life expectancy of the patient and the possibility of cancer cure, understanding the nerve pathways carrying the pain signal, and the patient’s ability to tolerate the predicted side effects. Nerve destruction should only be considered when the pain cannot be well controlled by using oral medications or other pain-relieving therapies. If there is significant chance that the paiful tumor can be cured, or at least reduced with radiation or chemotherapy, these methods should be tried before considering nerve destruction.
Nerve destruction is often very appropriate for patient who are in the terminal stages of cancer. Patients with advanced cancer often suffer severe pain that may require such high does of pain medication that they are always sedated. A nerve destruction procedure may allow the medication dose to be dramatically reduced, letting the affected person remain comfortable, yet alert enough to enjoy time with his loved ones. Since nerve destruction procedures often last for the life expectancy of a person with advanced cancer. Of course, predicting the duration of pain relief and life expectancy is as best educated guesswork, so repeat nerve destruction procedures may be necessary.
Since nerve destruction procedures only provide relief to a certain area of the body, they are not useful for patients suffering widespread pain involving large portions of their bodies. However, even such persons may have one or two areas that are much worse than pain in other area. Targetting these areas with nerve destruction techniques may reduce the pain level sufficiently to allow oral medications to provide of fective relief for the remaining pain.
In any case in which a nerve destruction procedure is being considered, a prognostic nerve block with local anesthetic should be performed first, so the patient can decide if a nerve destruction procedure is worthwhile. Some people fnd the numbness or weakness to be worse than the pain itself. Weakness, in particular, is often unacceptable to individuals who are already struggling to maintain some degree of personal freedom and self-care.