Restless Legs and Periodic Limb Movement Syndromes
Restless legs syndrome (RLS) is a daytime disorder that occurs in individuals who have an irresistible urge to stretch or move the legs to ease discomfort, itching, or pain. Many who suffer with RLS claim to feel creepy or crawling sensations in their legs. Any annoying symptoms are generally temporarily relieved by voluntary movement, but the condition is often relentless.
Symptoms may flare up on a plane, or in a car, and in particular just after lying down to sleep. It appears to have a circadian fluctuation, usually peaking around midnight.
An associated condition is the periodic limb movement disorder (PLMD), which is a nocturnal disorder affecting the legs usually but occasionally the arms or arms and legs. This disorder may require a sleep test for certain diagnosis, though the comments of a sleeping partner are useful and at times sufficient for a diagnosis. PLMD involves a periodic quick movement of the ankle, foot or toe, and occasionally the knee or arm. The movement may not disturb the person and the EEG may show no disturbance but at times it is a cause of arousal and even wakenings.
These conditions commonly coexist. Approximately 80% of those with RLS have PLMD, but only 30% of those with PLMD have restless legs. In both conditions, the pathologic cause is believed to be related to a deficiency in the brain neurotransmitter dopamine. The medical treatment is also similar. There is a secondary form of these conditions related to either serum iron (ferritin) or folate deficiency, chronic kidney failure or peripheral neuropathy. It is now known that there is a familial predisposition to develop them in 50% of cases. During pregnancy, there is a definite increase in incidence of these disorders. This may relate to low iron or folate levels. Also, caffeine consumption, SSRI antidepressant medication, antihistamine, and amphetamine or other stimulant therapy worsens restless legs.
At least four categories of medications have been successfully used to treat RLS and PLMD: dopamine agonists (pramipexole, ropinorole), benzodiazepines (clonazepam) and anticonvulsants (gabapentin) are commonest treatments, and occasionally hydrocodone is used.