The Link Between Restless Leg Syndrome and Chronic Pain
Restless leg syndrome (RLS) is a common and sometimes devastating condition. I see it quite frequently in many of my chronic pain patients. In fact, it contributes to quite a bit of chronic pain, because of the difficulty it causes in terms of getting a good night's rest, and because it in and of itself can be rather painful. And there are diseases associated with chronic pain which can result in so-called secondary RLS.
Restless Leg Syndrome is a nighttime condition that has a huge impact on daytime functioning for those afflicted.
The diagnosis of RLS is mostly arrived at through interviews with the patient, and basically involves four important features:
There is a compelling need to move, usually associated with unpleasant sensations in the legs, which have been described variously as painful, electric or "creepy-crawly."
These sensations of RLS are worse or exclusively present at rest.
These sensations are at least partially and temporarily relieved by activity.
The sensations of RLS follow a circadian pattern, which in this case translates into being worse late in the evening.
Interestingly, other body parts may be affected, but usually the problems begin with the legs. The other body parts which have been reported to be involved in rare patients include the genitals, hips, back, and even the neck and chin.
There is one question that can best screen for RLS: "When you try to relax in the evening or sleep at night, do you ever have unpleasant, restless feelings in your legs that can be relieved by walking or movement?" However, this in and of itself will not give an immediate diagnosis of Restless Leg Syndrome. Conditions that mimic RLS include anxiety disorders, arthritis, peripheral arterial disease, muscle diseases, neuropathies, and, of course, night cramps, along with many other conditions.
A doctor has to pay close attention to those characteristics more specific to Restless Leg Syndrome in order to avoid confusing other diagnoses with RLS. These include the following:
RLS symptoms are more persistent, lasting at least 5 or 10 minutes, while those of other illnesses can last only a few seconds.
RLS symptoms can quickly be relieved with activity.
RLS symptoms can be helped with more continuous activity; simple positional change is not enough.
RLS discomfort is comes about by being at rest, and does not require a particular position.
Features that support a diagnosis of RLS include periodic limb movements, a family history of RLS, and a response to the so-called dopaminergic medications. Features associated with a diagnosis of RLS include a chronic and progressive course, sleep disturbance, and a normal neurologic examination.
There are no specific lab tests that can diagnose RLS. And a sleep study is usually not needed to make the diagnosis of Restless Leg Syndrome. However, it is important to look for any causes of secondary RLS before the doctor assumes the patient has only primary RLS. Obviously, this is important so that the patient has a potentially serious illness treated; it would be a tragedy to miss the diagnosis of an illness that is causing an RLS-type picture because the doctor was only focusing on the symptoms of RLS. Well-established causes of secondary RLS (that is, diseases or conditions that can result in RLS) include iron deficiency, pregnancy, rheumatoid arthritis, and the effects of kidney failure.
The general approach to the treatment of RLS involves eliminating factors that can cause RLS; for example, anti-nausea drugs, antidepressants such as the selective serotonin receptor inhibitors and tricyclics, antihistamines, caffeine, alcohol and nicotine. Patients should have regular sleep and wake times and avoid activities that cause irritation immediately prior to sleep. A brief walk before bedtime can be helpful, as can massage or a hot bath.
Medications for occasional RLS include carbidopa, opioids, dopamine agonists and sedatives. Daily Restless Leg Syndrome can be treated with dopamine agonists, Ropinirole, Pramipexole, Pergolide, opioids, anti-seizure drugs, Clonazepam, to name a few. In those cases where nothing seems to be effective in RLS, some experts have had success with strong opioids such as methadone.
I believe it is very important to screen for RLS in the chronic pain population. We might find something that can be treated, and this in turn may help the pain.