Causes and Symptoms of Restless Leg Syndrome

Health Professional

We started our discussion about restless legs syndrome (RLS) in my recent blog, so let's continue where we left off.

Mild symptoms of RLS occur in 5-15% of the general population, which makes it the second or third most common sleep disorder. Of these cases, only about 2-3% are considered clinically severe enough to require treatment. It appears to occur more commonly in females and can even affect children. Due to the difficult to describe leg sensations that are felt, children may be wrongly diagnosed with "growing pains" or even attention deficit hyperactivity disorder (ADHD). RLS symptoms occur more commonly as we age. Individuals who experience symptoms at a younger age tend to worsen as they get older, though there cases when the disease resolves spontaneously when the sufferer gets older.

Sleep disturbance is a major complaint in patients and is usually the main reason why they seek medical help. Though the disease sounds relatively benign it can have significant consequences. RLS can impact life dramatically, for both the patient and the bed partner.

When RLS is severe, it can produce extreme chronic sleep deprivation, with sufferers only getting a few hours of nightly sleep, often spending the hours pacing around their house. In fact, one interesting case was reported that the RLS sufferer was so tired and sleep deprived that he often fell asleep while doing his nighttime pacing and bruising themselves. The RLS was only discovered when the patient was seen in the hospital after a particularly traumatic fall. The sleep loss caused by RLS can lead to problems with concentration, memory, and attention. In addition to sleep disruption, RLS can lead to daytime and evening discomfort and an inability to sit still, which affects other activities such as meetings, classes, or plane rides.

This background gives us a good idea of how RLS can affect work, social, and leisure activities.

What causes RLS? In many cases RLS is idiopathic (a medical term meaning the disease arises spontaneously or from an undetermined cause), but often it can be seen as a secondary problem due to another medical condition.

Although a definitive cause of RLS is not known in idiopathic RLS, there does seem to be a tendency for it to run in families, particularly in patients who start having symptoms earlier in life (<45 years old).    There have been some recent discoveries of specific genes that are more common in patients with idiopathic RLS. Overall, a person with RLS is 3-6 times more likely to have a family history of the disorder than an individual who does not have RLS.

Secondary RLS can be caused by some fairly common medical conditions, including low blood iron stores (anemia), neuropathy (a nerve disease) which frequently occurs due to sciatica and diabetes, end-stage kidney disease, pregnancy, Parkinson's disease, and varicose veins. If it is caused by these conditions, treatment of the main disease usually causes improvement in the RLS. RLS also occurs as a side effect of certain medications, most notably antidepressants (like Prozac, Zoloft, etc.).

We will hopefully continue on this fascinating topic in my next blog.

(Much of this discussion was taken from a consensus statement entitled, "Restless Legs Syndrome: Diagnosis and Treatment Strategies for the Primary Care Provider".)