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INTRUDER OF THE NIGHT

It deprives people from sleep, disrupts family life, prevents One from sitting through an entire movie, and thrusts sufferers in Perpetual motion. Relatively unknown even to the average medical doctor, Restless Legs Syndrome (RLS) is a common sleep disorder affecting 5 to 10% of the population with varying degrees of intensity. A surprising 12 million Americans live with this disorder - as many as diabetes- and most RLS patients have lived with it for years, even decades, before finding a doctor who can put a label on their problem.

Restless Legs Syndrome is a central nervous system disorder. Psychiatric factors or stress does not cause it, although these conditions, along with diet and other environmental factors may contribute to it. A high incidence - 30% of primary RLS - occur in families, suggesting that familial RLS is a genetic disorder although the exact mode of inheritance is still unknown.

RLS symptoms are described as an irresistible urge to move the legs (and sometimes the arms), often accompanied by uncomfortable sensations in the calves. Patients often experience a creepy/crawly feeling, sometimes associated with an aching, tingling, cramping or moderate burning pain. Discomfort is relieved by temporarily moving the limb such as stretching, bending, rubbing the legs, tossing, turning in bed, or getting up and pacing the floor. On the other hand, discomfort worsens while relaxing, sitting and lying down, especially at night upon falling and staying asleep. As a result, patients suffer from insomnia and non-restorative sleep.

The chronic sleep deprivation allied to daytime sleepiness deeply affect the ability to work, engage in social activities and may contribute to mood swings. Commonly unrecognized by physicians, most patients are often diagnosed in their 50's and 60's although their symptoms can appear between the late twenties and early forties. Many patients suffering from genetically inherited RLS can trace their symptoms back to childhood. They were thought to have had "growing pains" or considered "hyperactive" because they couldn't sit still and were constantly "fidgeting."

Secondary conditions such as iron deficiencies, neurological lesions and pregnancy may create transient to longer-lasting symptoms of RLS. Recent studies have shown that anemia and low levels of iron (measured by ferritin levels lower than 50 mcg/L) can aggravate RLS symptoms. Chronic conditions such as diabetes, spinal cord and peripheral nerve lesions, kidney failure, thyroid disease, alcoholism, Parkinson's disease, rheumatoid arthritis, and intake of caffeine-containing beverages such as coffee, tea, and soft drinks may in some induce longer-lasting RLS symptoms. It has also been demonstrated that during the last few months of pregnancy, up to 15% of women develop RLS, whose symptoms generally, but not always, vanish after delivery. Many RLS patients also report that their symptoms wax and wane during the menstrual cycle. Additionally, RLS symptoms may be worsened by medications such as tricyclic antidepressants, selective serotonin reuptake inhibitors (SSRIs), lithium, dopamine antagonists, antihistamines, decongestants, anti-emetics and gastrointestinal medications.

Approximately 80% of RLS patients experience Periodic Limb Movement Disorder (PLMD) while sleeping or lying awake. This condition is described as involuntary limb jerks, brief muscle twitches, and upward flexion of the feet, knee or hip. PLMD may occur independently of RLS and is particularly common in the elderly, affecting 35% of people age 65 and older. It is defined as 5 or more involuntary movements per hour with each "move" lasting 0.5 to 5 seconds. Episodes seem more numerous in the first half of the night but can also recur throughout the entire night. Patients often complain of difficulty initiating sleep, associated with intense movements causing numerous awakenings, leading to non-restorative sleep and daytime sleepiness. PLMD may also be accompanied by other sleep disorders, such as sleep apnea. PLMD has been associated with low levels of vitamin B-12 and/or folic acid. PLMD should be differentiated from nocturnal leg cramps, akathesia (motor restlessness) and myoclonus (brief contractions of one or a muscle group.)

As previously noted, the incidence of RLS/PLMD increases with age. The exact cause of both disorders remains unknown and active debate is still taking place in regard to the pathophysiology of RLS and PLMD. Some researchers hypothesize that patients presenting with both disorders are suffering from low levels of iron and may not be able to properly synthesize dopamine, a potential important neurotransmitter for sleep. Recent studies also suggest an association between Attention Deficit Hyperactivity Disorder (ADHD) and RLS and PLMD. For additional information on the latest scientific breakthroughs, please refer to the Research Corner on page 6.

The diagnosis of these two disorders is primarily based on the patient's history, followed by a neurological and vascular examination to identify secondary causes and rule out other disorders. Additionally, vitamin and ferritin levels should be tested and a sleep study should be conducted to diagnose the severity of the disorders.

Prior treatment options included benzodiazepines and opiates. However, their effectiveness in often inadequate and the addictive potential for these classes of medications is obviously a concern. More recent treatments have centered on dopaminergic agents such as L-Dopa with carbidopa (Sinement) and bromocriptine (Parlodel) by enhancing the brain chemical dopamine. More selective dopaminergic agonists such as pergolide (Permax) and pramipexole (Mirapex) have recently been developed and appear promising in treating RLS.

Any medication should be started at the lowest dose and gradually increased until symptoms resolve. If the patient develops intolerance or severe side effects, rotating to another treatment might prove helpful. As with any sleep disorder, belonging to a support group should help patients to better cope with their disorder.

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