What is restless leg syndrome?
Restless leg syndrome (RLS) is a disorder of the nervous system that leads to painful sensations in the legs and an uncontrollable need for movement of the legs, especially at night, which can affect the quality of sleep.
This syndrome is most common in adults over the age of 50, especially in women, but can also occur in children, especially in combination with Attention Deficit Hyperactivity Disorder (ADHD).
The unpleasant sensations occur mainly at rest, in the evening, or at night and are relieved by movement of the legs, which may prompt the patient to get up and walk around the room to calm the discomfort. The consequences are not negligible, both for sleep and for social and professional life.
Restless legs syndrome is thought to be caused by low levels of dopamine, a chemical that enables the transmission of information between nerve cells (“neurons”) in the spinal cord.
What are the signs of restless leg syndrome?
Restless legs syndrome is essentially characterized by an unpleasant feeling in the legs that leads to an urge to move them. Characteristically, the unpleasant sensations come on or intensify during resting periods in the evening or at night, as well as during the day, and these unpleasant sensations disappear completely or partially when the legs are moved.
The unpleasant sensations are usually in the form of tingling, prickling, itching, burning, tightness, or a feeling of electric shock, but are sometimes poorly described by the patient. Sometimes legs can be painful too.
These signs may be more pronounced in one leg than the other. In severe cases, they may also affect the arms.
These unpleasant sensations are usually accompanied by involuntary movements during sleep that especially disturbs the person laying next to the patient in bed.
What are the causes of restless legs syndrome?
There are traditionally 3 forms of restless legs syndrome: genetic, secondary to a disease or medication, and without a known cause (“idiopathic”).
- In the genetic form, the brain and nerves are usually undamaged and in almost 90% of cases, there is a family history. Four genes predispose to restless legs syndrome.
- In the form when restless leg syndrome is secondary to another condition, iron deficiency (with or without anemia), nerve disorders in the legs (sciatica, polyneuritis), other diseases (diabetes, rheumatoid arthritis, chronic renal failure, multiple sclerosis) are sometimes found to be the causes.
- The idiopathic form is a diagnosis that should only be made after the elimination of the previous two major categories.
Various medications may be associated with restless legs syndrome (neuroleptics, antidepressants, antihistamines).
Excessive use of alcohol, coffee, tobacco, and stress may also be associated with this syndrome.
During pregnancy, 20-30% of women complain of signs of restless legs syndrome and these disorders disappear after delivery.
What are the complications of restless legs syndrome?
This condition can have two main consequences: Disruption of sleep and social life.
- The person with restless legs syndrome has difficulty falling asleep and wakes up several times during the night to move their legs or even to get up and walk. This can cause insomnia in the affected person and discomfort in the person sharing the bed with them. Eventually, fatigue can occur during the day with sleepiness, difficulty concentrating, and even mood disturbances (irritability and depression).
- Restless legs syndrome can become embarrassing in social situations where one must sit still for a period of time (meetings, shows, long car or airplane rides, etc.) and can also lead to sleep deprivation.
- It is possible to experience signs of restless legs syndrome several times a year without suffering from a true syndrome.
How is restless leg syndrome diagnosed?
A doctor’s consultation is often sufficient to diagnose restless leg syndrome, but a blood test is usually required. Sometimes other tests are needed, but mainly to rule out other conditions.
During the doctor’s visit, the physician will examine the nature of the unpleasant sensations, their severity, the circumstances in which they are triggered, and their periodicity. Four criteria are essential to confirm the diagnosis:
- Unrestrained need to move the legs, associated with or caused by “unpleasant” sensations in the lower limbs.
- Impatience or unpleasant sensations that are present or worsen only at rest, especially when lying or sitting.
- Unpleasant sensations that are partially or completely improved (at least temporarily) by movement.
- Occurrence or worsening of unpleasant sensations in the evening or at night.
The presence of involuntary movements during sleep may help with the diagnosis.
The physician will also ask the patient about the presence of similar cases in the family, medical history (diabetes, chronic renal insufficiency…), and the medications that are taken, especially antihistamines, which are often used without prescription.
And a detailed neurological examination usually concludes the consultation.
A blood test (serum ferritin level) is usually requested to check for iron deficiency.
In severe cases, a sleep analysis is performed to assess the effects of the sleep disorder, and a neurologist or sleep specialist may be asked for an opinion.
If in doubt, an electromyogram may be requested to look for early peripheral nerve damage (polyneuritis).
What could be confused with restless leg syndrome?
Nocturnal cramps may be confused with restless legs syndrome, but in this case, there is an obvious contraction of a muscle or muscle group.
Some neurological conditions can resemble restless legs syndrome: This is the case with sciatica. This may also be the case with early polyneuritis, in which there is “paresthesia” in the areas innervated by the affected nerves.
Venous insufficiency can also cause uncomfortable sensations in the legs that predominate at the end of the day, but these sensations are usually accompanied by swelling of the legs, even varicose veins, and are greatly relieved by lying down and elevating the legs.
Arterial damage in the lower limbs can also cause unpleasant sensations at night, but during the day there are usually painful cramps and a significant decrease in the pulse rate in the lower limbs.
What can be done about restless leg syndrome?
Simple gestures and a healthy lifestyle are usually enough to alleviate the signs of this disease.
The first step is to identify the elements that can cause or worsen restless legs syndrome, and in particular medication (neuroleptics, antidepressants, antihistamines). If this is the case, it will be necessary to try to modify the treatments by changing the drugs, for example.
For good sleep hygiene, it is recommended to go to bed and get up at regular times, limit activities in the bedroom and avoid disruptive activities.
You can also move your legs, try taking a warm bath before going to bed, massage your legs and stretch your lower limbs.
Moderate exercise can also be part of preventive treatment at night.
Reduction of obesity has also been associated with an improvement in the syndrome.
It is also advisable to limit the consumption of alcohol, tobacco, coffee, and tea.
What is the treatment for restless leg syndrome?
Treatment is mainly based on simple gestures and a healthy lifestyle. However, in more severe forms, medications will be necessary, either to improve the restless legs syndrome or to treat its causes.
Treatment with iron is necessary in cases where iron deficiency has been demonstrated, even if anemia is not present. Iron deficiency occurs in 25% of restless legs syndrome cases, and there is an inverse relationship between symptom severity and blood iron levels.
In the forms that affect sleep and social or professional life, drugs that facilitate the transmission of nerve impulses using dopamine can relieve unpleasant sensations and sleep disturbances. The doctor may prescribe a drug from the family of non-ergot dopamine agonists (pramipexole, ropinirole, rotigotine, and apomorphine). These products compensate for the relative lack of dopamine in the nervous system.
Dopaminergic drugs are often very effective, but the doses prescribed depend on the intensity of the symptoms.
In cases where the disorder is intermittent, dopaminergic agonists are taken during episodes of restless legs syndrome. They can also be prescribed preventively in situations that systematically provoke symptoms. If the symptoms are regular and frequent, the medication is taken continuously.
In any case, to avoid side effects, dopaminergic drugs are prescribed in moderate doses, which are gradually increased.
Anticonvulsants (mainly gabapentin) are an alternative to dopaminergic agonists when the latter are not well-tolerated, but they are especially effective in neuropathic pain.
Opioid analgesics have been used successfully but carry a risk of dependence and addiction.
Benzodiazepines (clonazepam) have also been used. Their importance is obvious in sleep, but they have not been shown to be effective in the neurological disorder itself, and particularly in involuntary leg movements during the night.
Pregnancy and the treatment of restless legs syndrome
Up to 30% of pregnant women complain of restless legs syndrome, especially in the third trimester, and pregnancy can also aggravate a pre-existing syndrome.
In almost all cases, the symptoms of the syndrome remain mild and disappear after delivery. However, more than half of the women affected in a first pregnancy will be affected again in subsequent pregnancies. In addition, women who suffered from restless legs syndrome during pregnancy are four times more likely to develop the chronic form later in life.
Iron deficiency, which is common during pregnancy, is thought to be partially responsible for this, but other factors may also predispose pregnant women to the disease.
In the vast majority of cases, there is no need for treatment beyond iron supplements and lifestyle changes. The signs usually disappear soon after delivery.
Magnesium has been suggested in this situation, although its effectiveness has not been scientifically proven.
Other treatments commonly used in restless legs syndrome are contraindicated during pregnancy.
In the most severe cases, analgesics (paracetamol-codeine combination) can be used.