What Are Restless Leg Syndrome and Periodic Limb Movement Disorders?
Restless leg syndrome (RLS) is a disorder that causes unpleasant or tingling sensations in the legs, and less commonly, in the arms. This symptom tends to occur in the evenings and at night. It also worsens at rest and is usually relieved by movement. It is not related to emotional or psychological disorders. RLS can lead to trouble falling asleep, waking at night, daytime hyperactivity or sleepiness.
Periodic limb movement disorder (PLMD) is a sleep disorder resulting from frequent limb movements during sleep. A sleep study can help diagnose this disorder. Because occasional leg movements can occur in sleep, there are certain kinds of leg movements that are typical of PLMD. Children with PLMD are usually not aware of these movements, although parents may observe frequent leg movements during sleep. Most children with restless leg syndrome have PLMD. However children with PLMD may not have restless leg syndrome.
How Common Are These Conditions?
One study suggests that almost half of adults with restless leg syndrome have their first symptoms during childhood. Children with ADHD or children with iron deficiency anemia are at risk for restless leg syndrome and PLMD.
Symptoms of Restless Leg Syndrome and PLMD
The typical symptoms of restless leg syndrome consist of leg discomfort that worsens at rest and/or at night and is relieved by movement. Young children may have many non-specific complaints such as:
- The need to stretch their legs
- The feeling of ants crawling on their legs
- Legs tickling
- A feeling of spiders or pins and needles on their legs
- A lot of energy
- Funny feelings in the legs
Older children and adolescents may describe leg pain or tingling sensations in the legs.
These symptoms usually occur while lying down in bed, but they may occur while sitting in class at school or watching television. Some children rub or stretch their legs to get some relief. Other children may get up and walk around the house at night. Children may complain of growing pains, trouble falling asleep and waking up during the night. In fact, insomnia is often present in the early period of life in children with restless leg syndrome. Some parents may notice legs jerking and frequent movements during sleep.
Causes of Restless Leg Syndrome and PLMD
The definite cause of restless leg syndrome and PLMD is not known. Heredity, abnormal chemical substances in the brain called dopamine, and low iron levels may play a role. Both of these disorders often run in the family. Restless leg syndrome and PLMD are common in children with certain conditions such as iron deficiency, chronic renal failure and especially in children with attention deficit hyperactivity disorder (ADHD).
Diagnosis of Restless Leg Syndrome and PLMD
Diagnosing RLS and PLMD in young children is challenging due to their limited ability to describe symptoms. A recent study has suggested that it takes almost 10 years from the time children report having problems to the time of diagnosis. Doctors may use clues such as a family history of RLS and the presence of leg movements from a sleep study. Your child’s doctor needs to examine your child to rule out other conditions that may be mistaken for RLS such as nighttime leg cramps, sore leg muscles, dermatitis, growing pains and positional leg discomfort. The diagnosis of PLMD requires an overnight sleep study to document the presence of typical leg movements.
Your doctor may recommend a sleep study and other tests once RLS/PLMD is suspected. An overnight sleep test in a sleep laboratory is an important tool to evaluate leg movements that are typical of PLMD. In children, a sleep test may help diagnose RLS. In addition, your doctor may advise doing blood tests to check blood count and iron levels in your child. Other tests can be useful, but there is limited information for children.
Consequences of RLS and PLMD
RLS and PLMD can lead to several long-term consequences. RLS and PLMD can lead to daytime tiredness, sleepiness or hyperactivity. Children may have attention problems and may not be able to do well at school. Some children may be mistakenly diagnosed with ADHD. In fact, many studies have shown the complex relationship between RLS and PLMD and ADHD in children. In addition, recent studies have suggested that RLS and PLMD may lead to high blood pressure in both adults and children. Other studies have shown that RLS and PLMD in children could trigger unusual nighttime events such as night terrors or sleep walking.
Treatment of RLS and PLMD
There is limited information on the use of medications to treat RLS and PLMD in children. Certain medications that are widely used with adults have not been proven to work with children. If your doctor prescribes medications, your child will need to have regular follow-up visits to make sure your child does not develop significant side effects. Children who are taking iron supplements should have their blood tested on a regular basis for monitoring. Because RLS and PLMD are hereditary, parents and siblings should seek help if they have sleep problems.
Your child should avoid aggravating factors such as nicotine (smoking), caffeine and alcohol. In addition, certain medications (antidepressants, antihistamine in cold or allergy medications) can aggravate these conditions. Tell your doctor all the medications that your child is currently taking. It is important to practice regular sleep routines and good sleep hygiene. Below are suggestions for good sleep hygiene:
- Encourage regular sleep and wake schedules.
- Create a relaxing environment for unwinding before bedtime.
- Avoid heavy exercise and large meals close to bedtime.
- Limit exposure to bright light and stimulating activities such as video games, and frightening or exciting TV shows at bedtime.
- Avoid caffeine.
- Do not allow your child or teenager to fall asleep while watching television.