Pain is the most common reason people in the United States visit their doctors each year. Although pain is highly subjective and difficult to describe, a working definition is ?an unpleasant sensory and emotional experience associated with actual or potential physical damage.? Its components are physical, cognitive, behavioral, emotional and perceptual.
Among people who have Parkinson?s disease (PD), pain is a major complaint. In fact, up to 85 percent of people with Parkinson?s report pain as a troubling symptom. Some of these people experience pain as an early symptom of Parkinson?s, before their disease has even been diagnosed. Yet, pain in Parkinson?s disease often remains undiagnosed and untreated. Thus, it is important to understand that pain can be part of the Parkinson?s experience and to learn ways to manage it.
Causes of Pain in Parkinson?s
Pain researchers use a classification system that is based on the separation of tissue pain receptors from the nerves that transmit pain signals. Pain can be classified as nociceptive, which relates to tissue damage, implicating the pain receptors in the skin, bones or surrounding tissues; as neuropathic, indicating pain arising in nerves; or as a mixed pain syndrome involving both nociceptive and neuropathic pain.
In Parkinson?s, most pain experiences seem to result from tissue that is injured or has the potential to be damaged: causes include persistent tremor, muscle rigidity, dystonia, musculoskeletal injury (i.e., sprains, bruises, bone fractures resulting from a fall etc.), burns and inflammation. The pain is typically well-localized to the affected body part; it may fluctuate with the medication dosing. Pain caused by dystonia can be diagnosed when there is visible twisting, cramping or posturing of the painful body part. The most common areas of the body where people with Parkinson?s experience pain are the neck, upper back and extremities.
In Parkinson?s, neuropathic pain is less common than nociceptive pain, and includes a number of conditions not directly related to PD, such as shingles, cancer pain, carpal tunnel syndrome, diabetic neuropathy, and peripheral neuropathy. The pain may present as burning, numbness and tingling, sharp sensations, or electric shock qualities. Pain due to nerve or root disease is most commonly caused by akathisia, an extreme inner restlessness.
Parkinson?s specialists gain insight from the perspective of the pain specialist, and often select treatments based on the nociceptive versus neuropathic classification. In practical terms, it often proves helpful to conceptualize the experience of pain in Parkinson?s as relating to one or more of the following five categories: pain from the muscles or skeleton, pain from nerves or spinal roots, pain related to sustained twisting or writhing, discomfort from akathisia and pain caused directly by changes in chemicals in the brain due to Parkinson?s.
The Impact of Pain
It is important to address pain because it may interfere with day-to-day activities, mood, sleep and overall enjoyment of life. Specific problems resulting from chronic pain may include sleep disturbance, malnutrition, social withdrawal, physical and functional decline, depression, anxiety and impaired cognition. Pain also accounts for increased overall health care costs.
A person?s perception of pain can be affected by emotional factors. Scientists have shown that depression, which affects approximately 40 percent of individuals diagnosed with Parkinson?s, plays an important role in the way people perceive pain. Similarly, tension and muscle stress caused by anxiety can compound pain. Cognitive processes ? how a person views pain and how he or she pays attention to it ? also influence the level of pain a person feels. A person who pays more attention to his or her pain and reacts to pain with a high level of stress will likely experience more pain than someone who tries to ignore the pain and considers it irrelevant to his or her daily life. Feeling helpless to control pain ? that is, believing that pain is uncontrollable or that there are no treatment options or health professionals available to assist in managing pain ? can also make pain seem worse.
Fortunately, many options exist for treating pain. How can you find which are right for you? The first step is to talk to your doctor who can assess your pain and then help to build a pain management plan.
Assessing and Managing Pain
Your doctor can assess pain through a clinical interview and neurological examination, sometimes performed in both the unmedicated state and when the Parkinson?s medications are working fully.
Your doctor may also ask you to describe the characteristics of your pain. For example, when do you feel pain? Where in the body is your pain? Does the pain feel hot or cold, stabbing or burning? You also may be asked to report how pain impacts your daily activities ? for example, walking or sleeping. The more information you can provide about your pain, the better your doctor will be able to diagnose and treat it.
Management options for pain in Parkinson?s include both the pharmacological (i.e., medications) and the non-pharmacological. A combination of both may offer the best pain control, and an interdisciplinary model of care can lead to optimal results for pain management. Some treatment options include:
botulin toxin injections
psychotherapy (emphasis on pain management)
Because of the relationship between dopamine and pain, dopaminergic medications such as levodopa can affect a person?s perception of pain. People with Parkinson?s who are in the ?on? levodopa state, when the medication is at peak effectiveness, report less pain than those in the ?off? state. Pain due to rigidity or dystonia can be relieved by dopamine drugs, but on the other hand, may cause dyskinesias. Therefore, effective management of levodopa medication for people with Parkinson?s may help to reduce pain.
Because certain thought processes and behaviors can alleviate or worsen pain, some people find psychotherapy helpful for managing their pain. Techniques such as cognitive-behavioral therapy (helping to control the psychological response to pain; teaching diaphragmatic breathing, visual imagery exercises, relaxation techniques, etc.), and biofeedback may help ease pain, but are unlikely to eliminate it completely.
A physical therapist can help you select and modify appropriate exercise routines. Of course, you should avoid activities or exercises that make your pain worse.