Pain in Parkinson’s Disease

Pain is an unfortunately common problem in Parkinson’s disease.

Of course, pain is common in the general population, especially among older people. A recent American study found that pain affected about twice as many people with Parkinson’s Disease than those of the same age and gender without PD. About 50% of Parkinson’s Disease patients in that study suffered from painful disorders. Men and women seem to be about equally affected. A very well described scenario is the patient who is followed for a painful frozen shoulder for a year or so before a tremor develops leading to a diagnosis of PD. Pain clearly plays a major role in quality of life. Everyone with chronic pain enjoys life less, leading to a vicious cycle in which pain causes depression or isolation which in turn leads to more pain.

Parkinson patients suffer from the same pain problems that other people have, often amplified by the motor dysfunction, but they also have additional pain problems which are unique to PD.

One recent review classified the types of pain Parkinson’s Disease patients have into: musculoskeletal, in which the pain results from problems with the muscles , bones or joints; dystonic, which is due to abnormal muscle contractions caused by the Parkinson’s Disease or the medications used to treat it; radicular pain, which is feels like the pain caused by pinched nerves; central pain, which is presumed due to abnormalities in the brain, and is a continuously present pain that cannot be explained otherwise; and discomfort related to an unpleasant urge to move.

Lower back pain and back of the neck pain are most common

Pain occurs for a number of reasons and it’s not always clear what the cause is, making it difficult to figure out how best to treat it. I believe that most common pain problems in Parkinson’s Disease are the same as in the general population, but amplified. Low back pain and back of the neck pain are probably the most common pain conditions in PD. The reason Parkinson’s Disease patients have so many problems with their low back and their neck is their posture. Parkinson’s Disease causes a stooped posture. Some of this happens with age anyway, particularly in women after menopause when their bones soften, but is always worse from the PD. All Parkinson’s Disease patients have some degree of stooped posture and many also tilt to one side. Because of the stooped posture, the muscles in the lower back have to pull much harder to keep the spine upright.

Strengthening exercises or stretching may be helpful

Imagine that the spine is like a telephone pole or the mast of a sailboat. If the pole is not exactly upright, even a slight tilt requires a great force to keep it from tilting further and falling. In the human body, this means that the lower back muscles are under great stress. It also means that the tension on the back bones (vertebral bodies) is much increased as well. This worsens whatever problems, like arthritis, that are already present. The same process applies to the neck, although the forces are less great. Strengthening exercises or stretching may be helpful. Almost everyone over the age of 60 has arthritis in their spine. Luckily most don’t have pain from it, but those who do will have it worsened by the spine curvature caused by the PD.

Joint pain from arthritis or other disorders is exacerbated by Parkinson’s Disease because the biomechanics of walking and other movements are altered, causing patterns of stress that the joints did not evolve to deal with. Thus there are abnormal stresses on joints that are partially damaged, making the damage either worse or less likely to heal. These changes in motor control and posture put excessive and abnormal strains on the joints, and tend to make “normal” arthritic pain worse. This causes more problems in Parkinson’s Disease than in others because exercise is so important for long term health and function. If a Parkinson’s Disease patient exercises by walking, the joint pain gets worse and is less likely to heal, but if she doesn’t walk, she loses ground, making her walking worse.

PD patients also frequently have an aching discomfort in their muscles, particularly in the thighs and shoulders. I think this is due to the rigidity, or stiffness, that is part of the Parkinson’s Disease syndrome, but I’ve seen many patients with this pain and no apparent stiffness on examination, hence not explained. It is common and it often, but not always, responds to alterations of the usual Parkinson’s Disease medications for movement. Exercise and stretching may be helpful as well and should always be tried first before increasing medications.

Muscle cramps are common in PD. Sometimes this is associated with dystonia, an abnormal posture that typically affects the toes or feet, causing them to develop an abnormal posture, like having the big toe curl up or down, and the smaller toes sometimes following suit. Sometimes the whole foot curls in. This is often painful, due to excess muscle contractions and usually resolves with stretching the involved joint, but may recur when the limb is used again.
Radicular pain is generally a sharp, stabbing or electrical sensation that travels along the route of a nerve. This is often due to a pinched nerve, which may happen in Parkinson’s Disease as well as in non-PD patients, but is increased by the abnormal spine curvature in PD. Most patients with this type of pain don’t actually have a pinched nerve. Usually it is due to arthritis or muscle injuries, but the pain feels identical to that of a pinched nerve.

Central pain is very poorly understood. This type of pain is thought to be generated in the brain and is therefore unlikely to respond to physical therapy. The pain may be anywhere, involving an arm, or a leg, the abdomen or the genitals. It is often necessary to do a large number of tests to exclude tumors in the GI tract or kidneys, because the pain is located in the viscera, yet no explanation can be found. The only “good” thing about this is that one can worry less that a cancer is being missed and blame the problem on the PD.

Akathisic discomfort is a troubling sensation, not clearly painful, but disturbing, of a strong need to move, keeping the affected patient from ever getting comfortable. It is a form of restlessness similar to restless legs syndrome but present throughout the day.

Complicating all of these problems are the routine aches and pains of everyday living. Who can say what’s due to Parkinson’s Disease and what isn’t? We have no tests for any of these pain syndromes. In occasional Parkinson’s Disease patients, the pain improves with their L-Dopa dose and returns when the effects wear off. These patients are thought to have “non-motor off” periods, that is, a fluctuation of symptoms that are not the problems that the Parkinson’s Disease medications are used to treat, like tremor, slowness , gait and rigidity. These patients, in addition to, or instead of, having fluctuations of their motor response to Parkinson’s Disease meds, also have fluctuations in their mood, or sweating, or fatigue or pain.

Despite the high frequency of pain in PD, some studies have shown that Parkinson’s Disease patients are LESS pain sensitive than others. One study showed that when equally painful procedures were performed on Parkinson’s Disease and non-PD patients, the Parkinson’s Disease patients reported less pain on the various pain scales, than the non-PD patients. Another study found that after deep brain stimulation in the subthalamic nucleus, a center in the brain important in motor function but not known to be involved in pain, Parkinson’s Disease patients had a reduction in pain problems.

Pain is a challenge in PD. We can’t measure it and often cannot find its cause. It is, however, often treatable, and reducing pain improves quality of life.

Treating the pain

As is true for most medical conditions, there is no single treatment for “pain in PD”, and it must always be kept in mind that what works for one person may not work for another. Pain, in particular, has so many different facets, that it is impossible to make specific recommendations. The first recommendation is to avoid adding new medications, if possible. The second recommendation is to avoid letting pain control your life. Of course, recommendation number two often leads to violation of recommendation number one.

Identify the Cause of the Pain

The first step in treating pain is to try to identify the cause. As I noted in the last essay, there are many different causes of pain for people with PD. If we look at the most common pain problems, low back and neck pain, we can see that there are many different causes for each. Many doctors order x-rays of the spine for these conditions, and they may be needed. The main problem with x-rays of the spine is that they always show arthritis, which is because virtually everyone over the age of 60 has arthritis in the spine. Whether that’s the cause of the pain or not is usually not clear.

However, x-rays will show if there’s a compression fracture (collapse/compression of a backbone), or a tumor. Since older women frequently develop compression fractures even without a fall, this can be important because we know then that the pain is likely severe, but time limited, and will resolve in a month or two. This makes it easier to treat with strong medication, like narcotics, because there is less concern for addiction. X-rays do not show discs, but disc herniation is much less common in older people so it’s of less concern.

Physical Therapy

Most low back and neck pain is probably due to muscle strain, and this is not likely to get better. The best approach therefore is to use physical therapy and possibly devices like canes or walkers to help redistribute weight when walking. The cardinal rule I use when referring a patient to therapy is: if you’re not committed to doing the exercises between therapy sessions and after the therapy ends, it’s probably not worth getting the therapy.

Alternative treatments

Many of my patients use massage therapy and some use acupuncture, Reiki or other treatment. Most who use massage report that it makes them feel great, but only for an hour or two. The ones who try acupuncture continue using it if it helps and stop if it doesn’t. It has not been adequately studied in Parkinson’s Disease to make a recommendation. My rule for massage, acupuncture and “alternative” treatment approaches is that it’s ok to try anything that isn’t harmful and if it works for you, it’s great. You should clarify at the beginning of a treatment trial how long it should be before you feel some benefit. It’s not fair to try something but not give it a fair chance.

Chiropractors focus entirely on spine pain and may be very helpful. Since many medical doctors are not very familiar with PD, I assume that many chiropractors probably aren’t either. Therefore it will be helpful to find one who is familiar with PD. Probably the best way to do this is through a Parkinson’s Disease support group in your area.

Treatment through medication

When medications are required to control back or neck pain, as is often the case, there are few studies to guide choices. Epidural injections, particularly for low back pain are very popular. These are injections into the spinal canal, but outside the spinal cord, with steroids and lidocaine (numbing medication) and can sometimes be extremely helpful for months at a time. Sometimes they work for a few days, sometimes not at all. They are very unpredictable. The data in support of this treatment is very unpersuasive. It has been accepted by the FDA as approved, but it is unclear how helpful this is although many spine specialists recommend it routinely. The American Academy of Neurology believes that it is probably useful for spine pain that radiates down a leg but not for pain that stays in the back.

NSAID’s (non-steroidal anti-inflammatory drugs) are what are most commonly used. They are safe, except for occasional stomach irritation, can be used long term, and do not alter brain function. There are many to choose from, and for unknown reasons, some work better for some people than others. They are non-specific, meaning they are helpful for pain, whether the cause is arthritis, trauma, muscle strain, or anything else but are useful for reducing inflammation, hence act to reduce pain in two ways, reducing the inflammation causing the pain, and reducing the pain directly.

In recent years a few medications, gabapentin (Neurontin), duloxetine (Cymbalta) and Lyrica (pregabalin) have been increasingly used to treat chronic painful conditions like fibromyalgia, diabetic and other nerve pain, and, as doctors have become more comfortable using them, their use has become increasingly widespread. Their value in treating back and neck pain in Parkinson’s Disease is unknown and their side effects have not been studied. It is therefore not possible to suggest guidelines on whether or not to use them, what doses to use, etc.

One important thing to keep in mind is that these are not “pain” medications in the sense that aspirin, acetaminophen (Tylenol) and the NSAID’s reduce all pain. These newer drugs seem to be useful to treating specific types of pain, not all pain. Unlike the NSAID’s and acetaminophen, they cannot be used on an “as needed” basis. That is, they can’t be taken only when the pain is bothersome. They must be taken all the time, and must be taken for several weeks, often at increasing doses, to determine if they are helpful or not. Since these medications may have brain side effects, like reduced balance and attention, they need to be monitored and stopped if side effects develop.

No side effects are permanent so that these medications are safe. Lidocaine patches are approved for this type of pain, although not tested in PD. They are often unavailable because of insurance denials due to expense. They can only be worn 12 hours at a time, and then must be kept off for 12 hours, so people use them during the day or at night.

Narcotics are the last resort unless they are a stopgap measure, with some other treatment starting. Aside from the side effects of constipation and possible delirium, they may become addicting and often need to be slowly increased, causing increasing problems with constipation, confusion and occasionally depression.

Other pain syndromes are less common. In Parkinson’s Disease patients who experience pain as an “off” sensation, that is, the pain develops when the Parkinson’s Disease medications are wearing off, the treatment is to increase the “on” time.

In the first article on pain, I mentioned the very common problem of aching muscles, particularly in the thighs and the shoulders. I am unsure how to treat this problem but generally advocate a trial of stretching as well as strengthening exercises, with the assistance of a physical therapist or personal trainer. When this doesn’t work or can’t be done, I often try increasing the Parkinson’s Disease medications to see if the discomfort may be a direct result of Parkinson’s Disease rigidity. If these approaches don’t work I suggest NSAID’s.

Pain of any type is associated with depression when chronic and depression is often associated with pain. Sometimes treatment of depression may alleviate some of the pain, or at least its impact on quality of life.

Although there are pain clinics in Rhode Island, none, to the best of my knowledge, have a “behavioral” orientation, which incorporates programs that teach patients to live with their pain and not allow it to take over their lives. The behavioral approach may involve medications for pain, but equally value treatments for the psychological aspects. This is an important “unmet need” for all RI patients with chronic pain