By Erika Manis. MD
Sleep Medicine

Do you experience an urge to move your legs that is worse or only present at night, that starts when inactive or still and is better with movement? If so, you may have restless leg syndrome (RLS). 

It is a clinical diagnosis, meaning there is no test besides endorsing these symptoms. The sensation can be hard to describe (“an itch you can’t scratch,” “ants in your pants,” “heebie-jeebies in your legs”) but is not typically considered painful. It can occur intermittently or be chronic and run in families. Individuals with RLS may have trouble going to sleep due to the need to pace or stretch their legs at night or difficulty with prolonged commutes by car or plane. It may be commonly comorbid in patients with chronic kidney disease, neuropathy, or during pregnancy.

It is often associated with periodic limb movements of sleep (PLMS), a bicycling movement of the legs, and a repetitive triple flexion response involving the great toe, ankle, and knee while sleeping. This may occur beyond your awareness, noted only by a bed partner. Still, it can cause daytime sleepiness or, more commonly, insomnia, which is referred to as periodic limb movement disorder (PLMD). People with PLMS may describe their bed sheets as being in disarray or requiring frequent replacement. 

However, you can have PLMS without it causing dysfunction, including RLS, for which it is not treated as a typical sleep study finding, particularly with age. A periodic limb movement index (PLMi) determined by anterior tibialis electromyography (EMG) on a polysomnogram (an in-lab sleep study) of > 15 per hour of sleep in adults is used for diagnosis.

Treatment for RLS and PLMD is approached similarly. First and foremost, avoidance of known triggers is recommended. Common triggers for RLS and PLMD are alcohol, tobacco, caffeine, certain antidepressants and antipsychotics, and antihistamines. Untreated sleep-disordered breathing can exacerbate sleep-related movement disorders, for which compliance with positive airway pressure, if indicated, is encouraged. Although not too close to bedtime, exercise and massage can be helpful. 

Iron deficiency, even without anemia, due to its relationship with dopamine, has been found to cause or worsen RLS/PLMD, including limited response to medication, for which fasting morning iron studies, specifically ferritin, are routinely obtained. Iron supplementation, oral or IV, may be indicated. If additional pharmacotherapy is required, a class of medications referred to as alpha 2 delta ligands, including gabapentin and pregabalin, is now preferred due to concerns for augmentation with dopamine agonists such as ropinirole and pramipexole. 

Gabapentin enacarbil is FDA-indicated and may be better absorbed, but is often cost-prohibitive. The longer someone has been on dopamine agonists, the higher the dose, and the shorter the formula is acting, the more likely their RLS is to progress, which is referred to as augmentation, for which discontinuation is advised. Benzodiazepines, specifically clonazepam and opioids, are also sometimes used.