CHAPTER 3. MECHANICAL TREATMENT OF PAIN

3.01 Mechanical Treatment of Pain; Introduction

3.02 Tumor Surgery

3.03 Surgical Nerve Intervention and Anesthetic Blocks

3.04 Radiation

3.01 Mechanical Treatment of Pain; Introduction

In a majority of patients, pain medication along with physical therapy and supportive counseling adequately controls the pain of terminal disease, but at times it fails or produces unacceptable side effects. In the ten percent or less of patients in whom this happens, other more invasive interventions may be employed to relieve pain. Surgical procedures, for instance, may be used in selected patients to remove tumors of large size just to reduce the obstruction or compression produced by the tumor mass. Alternatively, neurosurgery is undertaken to interfere with or cut the nerve pathways which carry the pain sensations. More commonly, and increasingly in recent years, methods to implant devices for drug delivery in and around nerve structures are being used with great effectiveness by highly skilled anesthesiologists, who have tended to become the leaders in developing these approaches because of their knowledge about placement of needles and catheters within the body. Because these methods often involve considerable risk and require highly skilled providers, the availability of physicians with the appropriate expertise and the presence or absence of payment coverage frequently determine whether they are undertaken. Of course, even more important in this decision is the location and type of pain being experienced and the general condition and life expectancy of the patient.

3.02 Tumor Surgery

Surgery directed at tumor removal remains one form of physical intervention which may be helpful for pain relief even when total removal of the tumor for cure is not possible. Before such surgery is undertaken, however, it is important for everyone involved to clearly understand the limited objective of the undertaking, pain relief. This is particularly important when dealing with illnesses in which second surgical procedures may be appropriate on occasion in search of a cure, as discussed below.

In deciding to undertake a surgical procedure purely for pain relief, knowledge of the natural history of various cancers is critical. For example, a woman who previously underwent a lumpectomy for breast cancer may develop a recurrence of the cancer in the same breast or in the lymph nodes on the same side under the arm. In either of these situations, removal of the recurrent tumor with or without additional chemotherapy may still be attempted with the hope of achieving a cure. To the contrary, if the spread of the cancer was to the brain, even though surgery might be undertaken to remove the brain metastasis, it would not be undertaken with the hope of achieving a cure.

Under these two different circumstances, decisions regarding surgery are very different. First, when cure is still possible, highly aggressive surgery may be indicated, but when cure is no longer possible, less invasive alternative approaches are usually preferable. If, for instance, surgery for pain relief is going to be directed at decreasing tumor bulk, the ability to achieve this same goal through the use of radiation may well be preferable with less risk for the patient in most situations.

Second, even when cure is not possible and surgery is being undertaken purely for palliation, the surgeon should consider the potential for additional spread of the tumor and should remove as much of the tumor as can be safely accomplished to help decrease the risk of recurrent pain in the future.

Third, when surgery for palliation alone is being considered, rapid care may not always be in the patientís best interest. If cure is not possible, it may be wise to delay surgical intervention as long as medication successfully controls pain, for such delay is likely to improve the immediate quality of life and may allow greater total benefit from the surgical procedure when it is finally performed.

Such a delay in surgical intervention is, in fact, somewhat of a shift in the course of suggested medical therapy. In the past when use of opioid narcotics was generally frowned upon, given a choice of surgical or medical intervention, surgery was often employed as a means of reducing the need for narcotics. Recently, however, as we have learned how to use narcotics more effectively in the treatment of cancer pain, this has reversed, surgery being delayed until drug therapy fails. Even more recently, this switch in medical theory has been further intensified with the increased use of methods permitting local use of narcotics through needles and catheters placed locally around tumors, within blood vessels, within the spinal canal, or in the brain itself. Employment of these techniques has greatly extending the usefulness of medicinal pain therapy further limiting the need for surgical pain relief.

3.03 Surgical Nerve Intervention and Anesthetic Blocks

In the past, peripheral neurectomy (surgery directly cutting pain carrying nerves) was common, but this approach has been largely replaced by newer drug therapies and/or surgical techniques designed to interfere with the transmission of the nerve impulses through the spinal cord to the brain. Neurectomy may, however, still be used in certain specific situations, such as tumors involving the chest wall or the face.

The most commonly used surgical procedure of this kind, commonly referred to as a "cordotomy," is most helpful with pain from the legs or lower body and involves cutting specific pathways in the spinal cord. It, like neural blockade discussed below, requires significant expertise and is quite expensive. Somewhat similar is a procedure which cuts not within the spinal cord but the nerve roots just as they enter into the spinal cord. This procedure, called a "dorsal rhizotomy," is usually used when pain is coming from an arm or leg which has already lost most or all of its function. Recently, new procedures have been developed which may permit these same procedures to be undertaken without actual surgical incisions, either through telescopic type surgery using radio frequencies instead of cordotomies, or by the introduction of chemicals through needles positioned just outside the spinal canal with radiographic guidance instead of rhizotomies.

Like the positioning of needles for chemical rhizotomies, many of the new approaches to pain therapy rely on placement of catheters in far corners of the body by radiologists or anesthesiologists with special expertise in these fields. These procedures, which allow the infusions of opioid narcotics or anesthetics within the fluids bathing the spine (intraspinal fluid) or the brain (intraventricular fluid) has the advantage of producing profound pain relief in properly selected patients without causing significant side effects or interfering with other nerve functions. In practice, use of such techniques usually involves continuation of the general pain killers by mouth or patch in addition to the local application, making coordination between the various physicians involved more complicated.

Similarly, in a procedure called "neural blockade," otherwise intractable pain may be relieved by the relatively brief application of a local anesthetic or nerve poison at crucial points in the nervous system. This procedure is most commonly employed in patients with cancers within the abdomen, such as the pancreas, when narcotics are unable to provide adequate relief without undue side effects. The procedure itself usually involves a trial in which a local anesthetic is injected through a needle into the area of nerve transmission to see if there is temporary relief of pain. If this occurs, and there are no apparent harmful effects, other nerve destroying chemicals, such as alcohol or phenol, may then be used to produce more lasting effects. Alternatively, a thin walled catheter may be left in the area through which pain medications can be repeatedly administered to block nerve transmission of pain sensations. Unfortunately, undertaking such procedures requires great expertise and is often an expensive undertaking at a time when life expectancy is short.

A less commonly employed technique for relief of generalized pain such as may occur from multiple bone metastases is destruction of the pituitary gland at the base of the brain. This can be accomplished either surgically or by local injection of chemicals like alcohol. This is a risky procedure with significant, unpredictable side effects, but one that may be used to avoid the necessity of sedation for pain relief.

As the reader should appreciate, use of these procedures can be highly limited by the need for physicians with great expertise in the precise placement of the needles and catheters, in addition to requiring the availability of special hospital units set up to undertake the procedures. As a result, many of these more sophisticated approaches to pain management are limited by lack of local expertise. Even more upsetting is the situation in which the expertise is available, but lack of financial backing causes the patient to suffer needlessly.

3.04 Radiation

The use of x-ray therapy to treat tumor pain has decreased along with recent developments enhancing the effectiveness of drug treatment and nerve blocks, etc., but remains an important part of pain relief, especially when it is caused by metastases to bone. In the presence of bone metastasis, radiation therapy is also likely to be helpful in preventing future fractures when x-rays and scans suggest a high risk for fracture of the bone in the future. Fortunately the radiologic procedure referred to as a "bone scan" is easy to perform and is very reliable in identifying metastases, while also being highly predicative of the ability of radiation therapy to reduce bone pain and prevent fracture.

Radiation therapy is likely to also be helpful in shrinking large tumors which are causing pain by local pressure effects and in relieving pain which results from spread of cancer to nerve networks, such as at the "brachial plexus," a meshing of nerves at the base of the neck giving rise to the more peripheral nerves which provide sensory and motor function to the arms.

Although radiation can cause both early and late side effects, they are usually avoidable by careful dosing by skilled radiotherapists. Early side effects are usually very dose related and have the advantage of being short lived, so the patient typically only suffers for a short period of time even when side effects do occur. Late side effects usually take many years to develop, which is not of concern when dealing with terminally ill patients.

In addition to direct radiation therapy, many drugs have now been developed which carry radioactive material and localize in specific tumors, thus allowing direct radiation to the cancer itself. Such "radiopharmaceuticals," as they are called, are now being used under specific indications in at least thyroid, breast, and prostate cancers.

 


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Chapter 8 Chapter 9 Chapter 10 Chapter 11 Chapter 12 Chapter 13 Chapter 14 Chapter 15 Chapter 16 Chapter 17

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