Diagnosing Restless Leg Syndrome

Health Professional, Medical Reviewer

You notice your legs are moving uncontrollably during the night. Specifically you experience jerking motions, tremors, and even leg cramps that painfully awaken you. You also observe a slow, peculiar, and purposeful movement of your legs. Sound familiar? If you assume the diagnosis is Restless Legs Syndrome you may indeed be correct. But how do you know this is different from simple cramps and movements that you might feel after a hard workout or some kind of trauma or injury?

While tremors and cramps are caused by instability in the neuromuscular connections, or they can be due to fast movements of (intracellular) sodium across the muscle membrane, true or classic Restless Legs Syndrome is a totally different entity, with its own unique mechanism.

Restless Legs Syndrome (RLS) is caused by a deficiency of dopamine, a chemical in the part of the brain that controls sleep-wake clock (the hypothalamus). Dopamine is one of the brain's key neurotransmitters, which are substances that make communication between nerves and neurons possible. Deficiency of dopamine will cause movement disorders, with the most well-known movement disorder being Parkinson’s disease.

RLS has some similarities with Parkinson’s disease, but it also has its own unique characteristics.   Because the low dopamine level occurs in the hypothalamus, where the sleep-wake cycle is controlled, there is a nocturnal pattern to the condition. People report feeling a particular need to get up and walk, which does provide relief.

The urge to move the legs is a strong sensory phenomenon, and not something that happens unconsciously. The international RLS study group created the acronym _URGE _ to describe it:

U rge to move the legs, sometimes accompanied by uncomfortable sensations deep in the legs

R est induced, meaning the urge to move gets worse during inactivity, like sleep

G ets better with activity like walking, but symptoms can reappear as soon as you stop movement

E vening and nighttime are the common times for the symptoms to appear

Since RLS occurs in the evening, while the body is typically at rest, relief is generally provided when there is movement. But when RLS interferes with sleep and causes daytime somnolence, it is then classified as a disorder.** Determining RLS in Children**

There is no specific diagnostic test for RLS, and a sleep study is not specific for this condition.  It is strictly diagnosed clinically - by taking a detailed history from the patient. It can therefore be very challenging to make the diagnosis in children.

Children can express symptoms differently than adults do when afflicted with RLS, and they may have difficulty articulating detailed symptoms.  Daytime sleepiness in children could be caused by RLS, but a doctor may have difficulty identifying RLS as the cause.  As clinicians, we know that children with uncontrolled asthma or obstructive sleep apnea (due to enlarged tonsils) who don't sleep well, may also be restless in the daytime or have disruptive behavior in school. Many times, thse children get a misdiagnosis like ADD or ADHD and receive treatment or severe discipline. But when in fact, their behavior could be a direct result of a condition like RLS.

It is crucial that the pediatrician extract a history from the child, in his own words. Asking the parents may result in a child’s actual complaints being lost in translation. Some commonly used words and terms that children will use to describe RLS:

  • Creepy-crawly
  • Ants crawling on my legs
  • Jittery
  • Feels like worms moving
  • Soda burning in my veins
  • Itchy bones
  • “I need to move.”

Treatment involves medications similar to those used in Parkinson’s disease. Levodopa is the first line medication recommended by the American Academy of Sleep Medicine.  Patients need to know that the medications can stop working resulting in symptoms getting worse, a process known as** Augmentation**. Doctors need to monitor patients and possibly use second line drugs like** Pramipexole** (Mirapex) and** Ropinirole** (Requip), both of which are similar to Levodopa.

When it comes to RLS in children, the only approved drug is called Gabapentin.  All of these medications are ill advised for use in pregnant women.  That’s important to know, because this condition can commonly occur in the third trimester pregnancy.  In this case, codeine or oxycodone, are the only approved medications, and their use requires a deep discussion between the pregnant patient and her physician.

Other triggers for RLS can be medications such as antidepressants, prolonged inactivity such as long trips, and alcohol. When treating children, some measures will include mind-engaging activities during long trips. In some cases of RLS, there is a deficiency of Iron (Iron is a coenzyme in the reaction that forms dopamine), so a blood test to check iron levels should be routinely done and if levels are low, iron can be replaced if needed.

This disease can be complicated to diagnose, but it is a treatable condition.  Treatment is key to giving the patient a better quality of sleep and overall, a better quality of life.