Chronic Pelvic Pain Management: An Anesthesiologist's Approach

From: Helen Dynda (olddad66@runestone.net)
Sun Sep 30 23:03:27 2001


[]]] Chronic Pelvic Pain Management: An Anesthesiologist's Approach http://www.pelvicpain.org/newsletter/1998_july.html#article

Pain is a complex, unpleasant sensory and emotional experience, which many patients suffer in the course of their lives. Fortunately, most of these instances re-solve spontaneously and are due to acute problems. However, particularly with musculoskeletal pain, the potential for a long-term problem is present; appropri-ate pain management can be essential in helping the patient return to full functioning. In addition to the nociceptive stimulus, cultural influences, the patient's own expectation, emotional factors such as fear and anxiety, loss of control, depression, primary/secondary and tertiary gain, and predisposing psychological fac-tors can all influence the amount of pain the patient reports.

Because different kinds of pain respond to different medications, it is important to try and delineate where the nociceptive impulse is coming from. Musculo-skeletal pain responds to different medications than does neuropathic pain, which again has a different group of medications than those helpful in bone pain. For organ and musculoskeletal pain, narcotics are of-ten the drugs of choice, along with nonsteroidal anti-inflammatory agents. Bony pain responds to nonster-oidal anti-inflammatory agents and steroids, with less response to narcotics. Neuropathic pain is treated by a diverse group of agents including Baclofen (a GABA-b agonist), sodium channel blocking agents such as antidepressants, anticonvulsants, and antiarrhythmics, and nonsteroidal anti-inflammatory agents. Often it is necessary to combine several neuropathic agents in order to get an acceptable therapeutic response. The idea of trying to find a single agent that will be effec-tive usually is doomed. Instead, multiple agents are combined in order to limit side effects and produce the best possible pain control.

Pain can also be the component of some psychological and psychiatric disorders. Consequently, patients with chronic pain who do not seem to be responding to the usual therapies deserve a thorough psychological evaluation in order to make sure that no other disease process is present.

With all types of chronic pain, it is important to have the patient focus on regaining function. Because pain leads to muscle spasms (which can increase pain and lead to protective disuse of the area), frequently pa-tients have loss of muscle tone, strength, and endur-ance with loss of joint mobility. Contractures may de-velop, bone calcium may decrease, and cardiorespira-tory fitness may be lost. Changes in motor and sensory function as well as autonomic functions with a reduc-tion in peripheral blood flow can be seen, and with prolonged pain psychological changes, such as depres-sion, anxiety, and anger usually develop. Therapy then not only needs to address the issues of pain control, but also improvement in function and restoration of the patient to as near normal functioning situation as possible.

It is important when treating a patient with a chronic pain problem to set goals and have the patient under-stand that pain relief, per se, while an admirable goal, is difficult to measure. Consequently, emphasis should focus on measured functional evaluations. With the goal of restoration of normal function (as much as pos-sible), specific active and passive exercises should be used, with generalized activity promoting an increase in aerobic fitness. Physical modalities such as dia-thermy, ultrasound, short-wave diathermy, TENS, and manipulation may be helpful to allow full mobilization of the joint. Nerve blocks may also be useful, not only as a diagnostic tool to help delineate which anatomic area is involved, but also as a therapeutic tool in mo-bilizing the patient and allowing aggressive physical therapy. Appropriate medications should also be se-lected for the patient.

Medications

Antidepressants - Antidepressants are a good choice for many musculoskeletal pain problems. In addition to their neuropathic pain contribution, they help pa-tients sleep, and can help with some of the depression that often develops as a result of a chronic pain condi-tion. Tricyclic antidepressants have been shown to be much more effective than the newer serotonergic anti-depressants (Zoloft, Paxil) in terms of relieving pain. However, both groups are effective in treating depres-sion. Amitriptyline has the highest incidences of side effects with desipramine having the lowest.

Nonsteroidal anti-inflammatory agents - NSAIDs have been shown to have a spinal mechanism of analgesia in addition to their anti-inflammatory effects (which may be more peripherally based). Additionally, NSAIDs may help decrease chronic mechanical hy-peralgesia and are helpful with many musculoskeletal and bony pain problems. The choice of which NSAID to use is largely patient dependent. Some of the newer NSAIDs have a decreased risk of GI upset that may be helpful, as well as a more convenient dosing schedule. However, the important thing is to find an agent that the patient can tolerate and which may be effective. Since the time frame for pain relief from NSAIDS is relatively long, these agents should be tried for at least a month.

Use-dependent sodium channel blocking agents - Sev-eral types of medication have been shown to block the sodium channels of nerves in a use-dependent fashion, that is, nerves that fire more frequently are blocked sooner. Since pain nerves are almost continuously fir-ing and are relatively small with little or no myelin, they are easily blocked. These medicines usually help neuropathic pain. The whole group of anticonvulsive agents has been shown to be helpful in treating neuro-pathic pain. Tegretol is helpful for lancinating inter-mittent peripheral neuropathic pain, a "peripheral nerve seizure". If the pain is more constant, Klonopin may be a better choice. Mexiletine has been a useful antiarrhythmic, which also has sodium channel block-ing properties. The ability of Mexiletine to help a pa-tient can be tested with an intravenous lidocaine infu-sion. Gabapentin and Topiramate are two newer anti-convulsant drugs that are often helpful.

Muscle relaxants - Baclofen is an interesting drug. It is a GABA-b agonist with significant muscle relaxant properties. However, it also appears to have good neu-ropathic pain properties. Other muscle relaxants can also be helpful. Flexeril, Robaxin, Soma, and orphen-adrine may all be useful depending on the particular patient. If one particular muscle relaxant is not effec-tive, it is often worth trying a second drug to see if the patient will tolerate it better.

Narcotics - Frequently, chronic pain patients are pre-scribed narcotics in an attempt to keep them func-tional. Since the longer a patient stays away from work, the less likely he or she is to ever return to work, it is important to get patients functional as soon as possible. If the decision is made to use narcotics, then a few simple guidelines should be kept in mind. Pa-tients should sign a narcotic contract, spelling out not only which narcotic agent will be used, but also the adjuvant drugs as well. Adjuvant drugs may be very helpful in potentiating the analgesia from a narcotic. Tramadol is a useful addition to the narcotic arma-mentarium, since it appears that the risk of dependence is significantly less with this agent. In addition, its se-rotonergic and norepinephrine effects appear to con-tribute to its analgesia. In my experience, a number of patients with neuropathic pain have responded favora-bly to this drug. For patients who are going to receive chronic narcotics, I prefer to give them on a set monthly rate. That is, by contract we decide on the appropriate number of pills for the month. This allows the patient to titrate the pills as needed. If the patient runs out before the month is up, it is important to make sure that the patient understands that, in fact, there will not be an additional amount of narcotic given. Ini-tially, while the dose is being titrated, you may find it more helpful to use small time intervals to help find the appropriate level. For patients taking more than 5-6 acetaminophen containing narcotics (Percocet, Vi-codin) a day, it is probably useful to consider going to a narcotic only compound to avoid the risk of aceta-minophen toxicity. Most patients who have degenera-tive joint disease, arthritis, or many other problems will do well on low doses of acetaminophen contain-ing narcotics. It is rare to need to give patients more than the equivalent of 100mg of oral morphine a day. When patients begin reaching the range of 40-100 mg of morphine equivalent medication, I believe that a psychological consult is probably advisable to make sure that this patient is an appropriate candidate for long-term narcotic use (that other factors which may be treatable are not present). If the multidisciplinary team is available, the patient should be evaluated be-fore the decision is made to continue this patient on relatively higher doses of narcotics long term. Metha-done, sustained-release oral morphine, Oxycontin, and Levo-Dromoran are all useful agents in patients who need a longer acting narcotic.

Clonidine has been shown to be helpful when given as a continuous epidural or spinal infusion. It appears to not only decrease pain, but improve urinary volume. In patients where it is helpful, a permanent pump can be implanted to provide a continuous infusion. Appropri-ate pain management can help pelvic pain patients im-prove their function and quality of life. Newer medi-cations under development may be even more helpful.


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