Chronic Pain Primer
Definition of Chronic Pain
CHRONIC PAIN (non-cancer pain) generally refers to intractable pain that exists for three or more months and does not resolve in response to treatment. There is some variation in terms of the required pain duration, in that some conditions may become chronic in as little as one month, while some pain specialists adhere to the six-month pain duration criteria employed in the past.
Chronic Pain VS "Psychogenic Pain"
Perhaps no other issue has done as much damage to individuals with chronic pain as this one. Many health care professionals fail to recognize the complexity of pain and believe that it can be dichotomized based on the presence or absence of physical findings, secondary gain, or prior emotional problems. As a result, countless individuals have been informed that "The pain is all in your head". And if these same individuals react with anger and hurt, we (health care staff) are ready to compound the problem by labeling the individual as hostile, demanding, or aggressive.
In actuality, the correspondence between physical findings (e.g., MRI, CT, or X-ray results) and pain complaints is fairly low (generally, 40% to 60%). Individuals may have abnormal tests (e.g., MRI shows a "bulging disk" or a herniation) with no pain, or substantial pain with negative results. This is because chronic pain can develop in the absence of the gross skeletal changes we are able to detect with current technology. Muscle strain and inflammation are common causes of chronic pain, yet may be extremely difficult to detect. Other conditions may be due to systemic problems (e.g., HIV-related pain or sickle cell pain), trauma to nerves (e.g., post-thoracotomy pain), circulatory difficulties (e.g., diabetic neuropathy), CNS dysfunction (e.g., central pain syndromes), or many others. Yet, in each of these cases we may be unable to "see" the cause of the problem. Instead, we have to rely on the person’s report of their pain, coupled with behavioral observations and indirect medical data. This does not mean that the pain is psychogenic. Rather, it means that we are less able to detect or understand its cause.
In actuality, healthy individuals feigning pain for secondary gain purposes are relatively rare. And in most cases, clear monetary motives will be evident. Additionally, the presence of secondary gain does not at all indicate that an individual’s pain is less "real". In this country most individuals with chronic pain receive at least some type of benefit (not necessarily monetary) for pain complaints. Therefore, exaggeration of pain or related problems is to be expected. Unfortunately, many less aware practitioners use the presence of secondary gain or pain amplification as an indication that the person’s pain is not "real".
Factors Influencing the Experience of Pain
Pain is a complex response by the organism to a number of factors.
As pain duration increases, more of these factors begin to influence the experience of pain. Thus, successful chronic pain treatment often involves multiple specialties delivering a range of interventions for a variety of related problems.
Chronic Pain Assessment
The presence of chronic pain does not always mean that the individual with pain is in distress. Surprisingly, pain may be experienced, but may not be perceived as unpleasant. Therefore, when measuring chronic pain, one needs both quantitative, qualitative, and distress measures.
Quantitative measures are used to judge the "amount" of pain. The best quantitative measure is a scaled self-report of pain. Many of these scales exist. They include verbal descriptive scales, nonverbal scales, scales for children, and number scales. The easiest and perhaps best-validated quantitative measure is the pain Visual Analog Scale (VAS), using either a 0-100 or 0-10 reference line. A typical 10-point VAS, and the version we use, follows:
Place a vertical mark across the line at a point which shows what your
current pain level is.
NO PAIN UNBEARABLE
The line length is 10 cm. Scoring the response simply involves measuring the distance between the "no pain" endpoint and the individual’s response, in centimeters (e.g., a score of 5.2).
Measures of tissue damage, autonomic levels, and reports of others have not been found to be very reliable or accurate quantitative measures. In fact, correlations between medical staff estimates of an individual’s pain level and the person’s own rating generally are quite low. Behavioral measures of pain (e.g., facial expressions, postural changes, etc.) are accurate but usually require much more time to score.
Qualitative measures are used to differentiate between possible etiologies. Suggestions for gathering some qualitative pain information follow:
Distress measures provide us with information as to how much the pain interferes with the person’s life. The more it interferes, the more unpleasant it is perceived. Distress measures include assessment of emotional distress, marital/family dysfunction due to pain, financial pressures due to pain, and a variety of other indicators.
In order to effectively diagnose and treat chronic pain we typically need to incorporate measures from all three of these pain domains (i.e., quantitative, qualitative, and distress) at a minimum. At present there are no universally accepted means of measuring these pain domains.
Chronic Pain Syndromes
In deciding how to treat chronic pain, it is important to distinguish between CHRONIC PAIN and a CHRONIC PAIN SYNDROME. A chronic pain syndrome differs from chronic pain in that people with a chronic pain syndrome, over time, develop a number of related life problems beyond the sensation of pain itself. It is important to distinguish between the two because they respond to different types of treatment.
Most individuals with chronic pain (estimates are about 75% nationally) do not develop the more complicated and distressful chronic pain syndrome. Although they may experience the pain for the remainder of their lives, little change in their daily regimen of activities, family relationships, work, or other life components occurs. Many of these individuals may never seek treatment for pain. Those that do often require less intensive, single-modality interventions.
The 25% who do develop chronic pain syndromes tend to experience increasing physical, emotional, and social deterioration over time. They may abuse pain medications (usually narcotics and/or muscle relaxants), and typically require more intensive, multimodal treatment to stop the cycle of increasing dysfunction. Based on past VA experience, and the prevalence of other complex problems among individuals served by the VA, it is likely that the percentage of veterans with chronic pain who develop a chronic pain syndrome is higher than in the general population.
There are at present no empirical methods of determining whether or not a chronic pain syndrome is present. Distinctions between the two are based on clinical judgments. Generally, the more of the above symptoms the individual reports or the more severe the symptoms are, the more severe the chronic pain syndrome is. However, the above are symptoms of a chronic pain syndrome only when they are primarily or mostly due to the pain itself. For example, individuals with a history of substance abuse or depression which preceded their chronic pain would not meet the requirement that their symptoms be primarily due to their pain.
How Do Chronic Pain Syndromes Develop?
As individuals try to cope with chronic pain, they adopt predictable patterns of behavior which appear to provide short-term relief. Unfortunately, the long-term effects of these patterns tends to be increased pain and more daily impairment. Typically this results from the chronic pain cycle:
pain > less activity > weaker muscles > more pain > less activity > weaker muscles
The deterioration is exacerbated by Kinesiophobia, or avoidance of certain movements or activities due to fear of reinjury or re-experiencing the pain. Kinesiophobia leads to more protective behaviors, or changes in posture, gait, or movement that reduce the pain for the short term. Unfortunately, over time they may lead to increased muscle weakness, reduced circulation, muscle spasms and inflammation, reduced flexibility, and, in some cases, muscle atrophy.
Models of Treatment
There are four primary models of chronic pain service delivery, which are based on the results of the International Association for the Study of Pain (IASP) Task Force on Guidelines for Desirable Characteristics for Pain Treatment Facilities. These models are represented both in the private sector and in the VA.
Single service clinics or modality-oriented clinics are outpatient clinics that provide a specific type of treatment for pain but do not provide comprehensive assessment or management. Most often they are staffed by individuals from a single discipline with some expertise in a range of pain interventions falling within their areas of specialty training. Examples include a nerve block clinic, a transcutaneous nerve stimulation (TENS) clinic, or a biofeedback clinic. In general, these approaches are best suited for individuals with chronic pain, but without a chronic pain syndrome. The goal of treatment is pain reduction.
The next level of intervention occurs within a pain clinic. These outpatient clinics specifically focus on the diagnosis and management of individuals with chronic pain. They are staffed by individuals from one or more disciplines with specialized training in chronic pain. They may focus only on selected pain problems (e.g., a "headache clinic", or a "back pain clinic"), or on more general pain conditions. They may refer to outside consultants or staff for services not available within the clinic. They are most appropriate for individuals with more severe pain but without a chronic pain syndrome. However, those with mild chronic pain syndromes also may be appropriate.
As we increase in treatment intensity and complexity, we next come to the multidisciplinary (or interdisciplinary) pain clinic. This level of intervention includes a specific outpatient or inpatient program of treatment which typically includes at a minimum physical restoration, medical, educational, and psychological services delivered by an identifiable team of individuals from a range of disciplines with extensive training and experience in chronic pain interventions. These pain programs are most suited for those with mild to moderate chronic pain syndromes who require more global and intensive treatment of their pain and their related areas of dysfunction. Goals include improvement in pain, activity level, flexibility, strength, endurance, and psychosocial functioning.
The final type of treatment delivery is provided through a multidisciplinary (or interdisciplinary) pain center. The pain center is the largest and most complex type of pain treatment model, and typically is associated with a medical school or teaching hospital. Such centers offer treatment of both acute and chronic pain using a dedicated, interdisciplinary staff working in a team setting. Staff specialize in pain treatment. Unlike the multidisciplinary pain clinic, pain centers also must engage in active pain-related research and staff education. Pain centers are most appropriate for individuals with moderate to severe chronic pain syndromes, and for those with less severe pain syndromes but very complex and refractory pain problems. They also are most appropriate for individuals with chronic pain whose rehabilitation is complicated by concurrent medical or emotional problems that require closer monitoring and the immediate availability of emergent and supportive services. The Chronic Pain Rehabilitation Program at James A. Haley Veterans Hospital is the only program in the VA that currently meets the pain center criteria and is CARF-accredited.
Examples of Popular Pain Treatment Modalities
Unfortunately, popularity of a treatment does not guarantee its effectiveness. It is up to the individual practitioners to determine whether a given treatment is potentially effective for the condition, and to ascertain if professional or state guidelines or standards of care governing the treatment of certain pain conditions exist.