Restless legs syndrome and periodic leg movement

Restless legs syndrome (RLS) and periodic leg movements in sleep (PLMS) are relatively common conditions that usually affect older adults. RLS and PLMS commonly occur together and are generally treated in the same manner. They may be associated with underlying medical conditions, such as diabetes or kidney diseases. A number of different treatments are available which have been shown to be effective in both RLS and PLMS.

Restless legs syndrome

RLS is usually described as creeping sensations in the legs, accompanied by a strong desire to move the legs. These symptoms are worse at rest. They usually occur in the evening and may get worse as the evening progresses. As a result, patients with RLS may have difficulty falling asleep.

RLS affects approximately 5-15% of the population. This chronic movement disorder may begin at any age, but the symptoms typically become more pronounced in the above 40 age group. In fact, symptoms tend to become worse and more frequent as the sufferer grows older.

More females are affected than males, and females tend to report more symptoms as well. Although the name suggests a leg movement disorder, the restlessness and discomfort may spread to involve the arms in about 20-30% of more severely affected patients. One in five patients may report the abnormal sensations to be painful.

About 80% of patients with RLS also experience PLM in sleep.

Periodic leg movements in sleep

PLMS consists of frequent rhythmic movements of the legs and feet during sleep. People with PLMS are often described as restless sleepers and they may feel tired during the day due to the sleep disruption caused by the leg movements in sleep. PLMS is easily diagnosed by an overnight stay in hospital for a sleep study.

PLMS is a term used to describe a series of complex, involuntary, repetitive and stereotypic upward movements involving upward motion of the big toe, downward and fanning motion of the other toes and accompanied by bending of the ankle, knees and thighs. PLMS is measured in the sleep laboratory using electrodes placed on the skin on the front of the legs (anterior tibialis muscles). Leg movements are scored as PLMS if occurring in a sequence of four or more movements lasting 0.5 to 5 seconds each episode and recurring every 20-40 seconds.

Do you have restless legs syndrome?

If you frequently experience the following symptoms, you may have RLS with or without accompanying PLMS.

An irresistible urge to move the legs, usually accompanied or caused by unpleasant sensations in the legs such as tingling, crawling, creeping, cramping, burning or even pain.
Beginning or worsening of these symptoms when resting or inactive such as when sitting down to watch television, travelling in a car or aeroplane, or lying down to sleep at night.
A partial or total relief with movement (such as stretching or getting out of bed to walk), rubbing of the legs, or having a bath.
Worsening of the symptoms in the evening or at night.
Involuntarily kicking or twitching of the legs in sleep.

If you do have RLS, you are not alone. Approximately five out of every 100 people will experience RLS at some point in their life.

Who gets restless legs syndrome and periodic leg movements in sleep?

No one knows the exact cause of these disorders as yet. However, research has indicated that people with RLS have problems with a brain chemical called dopamine and a decrease in the level of iron in an area of the brain that controls movements, called substantia nigra.

RLS can be a primary or secondary disorder. 'Primary RLS' is when no specific causes are found and 'Secondary RLS' is when certain conditions or medications cause RLS or worsen the symptoms.

Primary RLS

RLS may run in families; more than 40% of patients have a family history of the disorder. There is ongoing research looking for genes that may be responsible for RLS.

Secondary RLS

Some of the more common factors that may cause secondary RLS are:

Low body iron stores, which are most commonly the result of bleeding or dietary deficiency and can result in anaemia.
End-stage kidney failure often the result of dialysis and partly related to iron deficiency.
Pregnancy—particularly in the third trimester, also possibly from iron deficiency; up to 25% of women may develop RLS during pregnancy, most resolve after giving birth but RLS may persist later in life.
Nerve damage from diabetes, alcohol, kidney failure or other conditions.
Arthritis of the lower back causing a pinched nerve.
Antidepressants such as the selective serotonin reuptake inhibitor (SSRI) group and venlafaxine.
Anti-nausea medications such as metoclopramide (Maxolon) and prochlorperazine (Stemetil) as they block the action of dopamine in the brain.

In most cases, RLS symptoms may decrease or disappear when the associated factors are treated or removed.

What tests are needed?

Your physician will go through your medical history and medication list in detail, examine you physically, and order a blood test.

The aim of all this is to:

Confirm the diagnosis of RLS.
Exclude other disorders that may mimic RLS (e.g. anxiety, other neurological disorders).
Look for associated factors that may be reversible.

Who needs treatment?

This depends on the severity and frequency of the symptoms. In all patients, associated factors should be treated or removed where possible as this may decrease or abolish symptoms of RLS.

Mild or infrequent symptoms

Medications are generally not required in mild cases. Simple remedies such as the following may be adequate:

Decrease caffeine, avoid alcohol and nicotine.
Exercises focusing on stretching or bending (e.g. yoga).
Hot or cold packs to affected limbs.
Hot or cold baths.
Massage or rubbing of limbs.
Mental alerting activities (e.g. crossword puzzles).

In those with reduced iron stores, iron supplementation may be considered after exclusion of potential causes (e.g. bleeding, dietary deficiency, kidney failure). Concurrent supplementation with vitamin C to aid iron absorption may be helpful.

Severe or frequent symptoms

The most common medications for RLS and PLM are:

Dopaminergic agents, which increase the level of dopamine in the brain. These are the medications of choice for treatment of RLS and PLM and are taken an hour or two before bed.
Dopamine precursors were the earliest medications used; examples are Sinemet and Madopar. These medications can be quite effective. However, because they are short-acting, a phenomenon called 'augmentation' occurs commonly (65-80% of cases). Augmentation typically occurs several months after starting treatment and is characterised by symptoms appearing earlier and earlier in the day, and often intensifying in severity. Higher doses of these medications typically worsen rather than resolve augmentation.
Dopamine agonists are newer medications that do not commonly cause augmentation. Earlier agents such as cabergoline contained a substance called 'ergot.' Because of rare reports of thickening of the heart valves and lining of the lungs ergot-containing medications are no longer recommended for RLS . Newer medications such as ropinirole and pramipexole do not contain ergot and are now preferred. Doses are commenced low and increased gradually to reach a steady level, tailored to the individual patient’s response. Side effects such as nausea and headaches are usually mild and transient.
Benzodiazepines have a relaxing effect and slow down the central nervous system. They promote sleep and reduce RLS symptoms. Clonazepam is the most commonly used benzodiazepine for RLS. Its success in treating RLS is limited by its likelihood to cause side effects (next-day drowsiness) and reduced efficacy (tolerance) in long-term use.
Opioids are pain-killing, relaxing medications. Similar to the benzodiazepines, the potential for abuse is low when used in patients with RLS. Codeine is the most common opioid used for RLS. Aperients may be needed for those that develop constipation with opioids.
Anticonvulsants may be effective especially in patients who experience painful sensations with RLS. Gabapentin is most commonly used for these patients. Potential side effects are next-day drowsiness and unsteadiness, particularly in higher doses. As gabapentin may cause a rare, but potentially serious, blood reaction, some blood tests are performed in the course of using this drug.

Can restless legs syndrome or periodic leg movements affect my sleep?

People with RLS may complain of varying degree of leg discomfort during the daytime. Some people may even experience problems with memory and concentration. However, many people are affected most significantly at bedtime as the symptoms are worse with inactivity and at night, and this makes it difficult to fall asleep. It is not uncommon for them to get up several times to walk around until symptoms are partially relieved.

On the other hand, PLMS occurs when the person is already asleep and can range in intensity from mild twitches to violent kicks. Although the peak of PLMS activity typically occurs in the early part of sleep, leg movements may be present for the entire night in more affected individuals. In the laboratory, PLMS is considered severe if it occurs 50 times or more per hour—especially if movement causes frequent brief awakenings (arousals) at least 25 times per hour. Generally, people with PLMS are not consciously aware of these awakenings, but if they occur very frequently, sleep may be severely disrupted resulting in excessive daytime sleepiness. PLMS may also result in the bed partner being kicked, sometimes violently, and wearing out of bedsheets on some occasions.

Can RLS/PLM cause sleep apnoea?

The answer is no, although the two conditions may interact.

Obstructive sleep apnoea (OSA) is a condition where patients stop breathing very frequently during sleep, sometimes hundreds of times each night. Patients with OSA may sometimes have leg jerks during the night as a consequence of the upper airway repeatedly closing and opening. These leg jerks will disappear when the patient’s OSA is treated with continuous positive airway pressure (CPAP).
Conversely, PLM, particularly if severe, can disrupt sleep and worsen mild OSA. Successful treatment of PLM can result in an improvement in OSA in such a case.

A sleep study can therefore be of value in certain patients, if another cause of sleep disturbance such as OSA is suspected, and needs to be confirmed.