Differences Between Primary and Secondary RLS
Restless Legs Syndrome (RLS) can be frustrating because it’s one of those disorders other people really can’t see. People with RLS experience an overwhelming urge to move the legs, accompanied by unpleasant sensations, often at night. It’s not a mental disorder and it isn’t all in your head. RLS is a neurological condition, but there is no specific test for it. Your doctor will rely heavily on your symptoms in order to make a diagnosis.
Once your doctor suspects RLS, there are tests to help determine whether it’s primary or secondary RLS. This is important to know, because although the symptoms are the same, the treatment may be different.
Primary RLS has no known cause
Most people with RLS have primary RLS, for which there is no known cause. Another name for this type of RLS is idiopathic RLS. Primary RLS tends to run in families, suggesting a genetic or hereditary link. One study found 70% of children with RLS had at least one parent who also had the condition. So, yet another name for primary RLS is familial or hereditary RLS.
Researchers have found clues about the genetics of primary RLS. Genetic researchers in one study identified a gene present in about 50% of RLS cases. But having the gene doesn’t necessarily mean you’ll end up with RLS. Rather, it likely increases your risk of developing the condition. Other research suggests RLS may be a developmental disorder, due to an association between RLS and a gene for limb development.
Other medical conditions may cause secondary RLS
Experts have associated several medical conditions with RLS; if you have one or more of these conditions in addition to RLS, you have secondary RLS. Your doctor can order blood tests, nerve studies, and vascular studies to determine whether a secondary cause is likely. Conditions that may cause secondary RLS include:
Stress, sleep deprivation, and other environmental factors
Medications may also contribute to RLS. This includes drugs to treat nausea, antipsychotic medicines, antidepressants that increase serotonin, and antihistamines.
Treating primary and secondary RLS takes different approaches
In secondary RLS, treating the underlying cause, such as iron deficiency, may help relieve RLS symptoms. If your doctor thinks a medication is contributing to your RLS symptoms, switching to another drug may be in order. And for pregnancy, symptoms usually disappear within four weeks of delivery. This may be all that is necessary to manage secondary RLS.
But most people have the primary form of RLS, with no known cause. For them, treatment involves finding a way to control the symptoms. This may include:
Lifestyle changes—decreasing caffeine, alcohol and tobacco; maintaining a regular sleep routine; exercising moderately; massaging the legs; and using heat or cold to soothe the legs
Medications—there are FDA-approved drugs to treat RLS and various other drugs that can help relieve the symptoms
These treatments may also help those with secondary RLS when treating the underlying condition doesn’t work or isn’t possible.
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- National Heart, Lung, and Blood Institute Working Group on Restless Legs Syndrome. Restless legs syndrome: detection and management in primary care. Am Fam Physician. 2000 Jul 1;62(1):108-114.
- Restless Legs Syndrome (RLS) Treatment. National Sleep Foundation. http://sleepfoundation.org/sleep-disorders-problems/restless-legs-syndrome/treatment
- Restless Legs Syndrome Fact Sheet. National Institute of Neurological Disorders and Stroke. http://www.ninds.nih.gov/disorders/restless_legs/detail_restless_legs.htm