Low doses of certain Parkinson's disease medications are proving effective in controlling Restless Leg Syndrome (RLS), a disorder that causes unpleasant crawling and aching sensations and an urge to move the legs.

"People often think they are having leg or arm cramps, and this can lead to improper treatment," said Dr. William Ondo, a neurologist at Baylor College of Medicine's Parkinson's Disease Center and Movement Disorders Clinic.

The symptoms, which are worse at night and with inactivity, begin slowly and develop over a number of years. Patients often have problems sleeping, and many experience involuntary and rhythmic leg movements while sleeping. Because RLS involves abnormal movements, researchers at Baylor and other medical centers have examined the effectiveness of drugs used for the movement problems of Parkinson's disease.

"These medications, called dopamine agonists, stimulate the cells normally acted on by dopamine, the brain chemical necessary for normal movement," Ondo said. "Symptom improvement is so consistent that it is clear that RLS somehow affects the patient's cells that use dopamine."

The recent studies revealed that low doses of dopamine-mimicking medications, like pramipexol and ropinirol, are highly effective. Other drugs of this type including pergolide and bromocriptine are also effective.