by Christopher J. Earley, M.D., Ph.D. Assistant professor in the neurology department at Johns Hopkins Bayview Medical Center, Baltimore, Maryland.
Clinically, Restless Legs Syndrome (RLS) is a primary disorder of sensation modulated by the state of arousal. Some describe a sensation of something crawling or moving in the legs, tickling them deep inside, or a deep uncomfortable ache, and a need or compulsion to move the legs. Moving the legs immediately resolves symptoms. However, within seconds or minutes, symptoms return. If not moved, legs often jump involuntarily.
The sensations come on with rest and are always relieved with walking. Rubbing or moving the legs will often offer relief, at least temporarily. Sensations always worsen at night or may only be felt then. If and when patients fall asleep, episodic, semi-rhythmic or periodic movements of one or both legs follow. These movements cause brief arousals without full awakenings, leading to tiredness on awakening and throughout the day. If severe, movements lead to frequent awakenings.
Without evening leg sensations, the disorder is called Periodic Leg Movements of Sleep (PLMS).
Numbers & Causes About 5% of those over 65 have significant RLS symptoms. The exact cause is unknown; most patients are idiopathic. Secondary causes are common and may account for 20 percent of cases.
The most common are iron deficiency, dialysis, pregnancy and underlying peripheral neuropathy.
Diagnostic Tests A polysomnograph will show PLMS and often the same type of movements before falling asleep. In patients with a clear, unambiguous history of RLS, it's not essential.
I strongly recommend that iron levels be checked before starting treatment. Iron deficiency is a common treatable cause.
Treatment With idiopathic RLS or PLMS, the treatment of first choice is carbidopa/levodopa 25/100. It will be effective in 95% of patients. Start with a half tablet at bedtime, then make half-tablet increments every three days if there are no side effects and inadequate benefit. Two to four tablets at night can be used without problems.
The primary problems seen with carbidopa/levodopa are
1) inadequate half-life, 2) rebound sensitivity and 3) RLS augmentation.
The primary complaint from the first two problems is early morning awakenings. Add another half to one tablet when patients awaken from sleep, or a slow-release preparation (Sinemet CR 50/200) at bedtime.
The most common problem (3/4 of patients) seen with Sinemet is RLS augmentation: an insidious advance in symptoms. Late nighttime problems will become early evening or afternoon problems. Symptoms may worsen at night, expanding to the trunk or upper extremities.
The augmentation can be sufficiently severe to present with classic akathisia, a diffuse inner restlessness with no clear diurnal variation. Symptoms will worsen as the Sinemet dose is increased, but original symptoms return within 48 hours of medication discontinuation.
If the side effects of carbidopa/ levodopa are intolerable, try a dopamine agonist: pergolide or bromocriptine. Pergolide (Permax) is started with a 0.05 mg. tablet two hours before bedtime. Increments can be made every three days by one tablet. Patients can increase this every three days until benefits are achieved or side effects preclude further increases. Most patients begin to benefit at about 0.15 to 0.25 mg. One rarely needs to go over 0.5 mg. per day.
The most common problems with pergolide are nausea (40%) and nasal congestion (15%). If patients experience these or augmentation, but otherwise respond well, consider bromocriptine (2.5 mg. tablets). Benefits may be equally good and side effects less severe. Unfortunately, in many cases, nausea and nasal congestion occur.
After dopamine agonists, try opiates (e.g., codeine). Most people do fairly well with opiates, but improvement is often less dramatic than with dopamine agents. Combining an opiate and a dopamine agonist may reduce side effects.
The third class of drugs is hypnotics. Clonazepam (Klonopin) was once the top choice in RLS treatment. It is now usually reserved for second- or third-line treatment. There is no indication that Clonazepam or other hypnotics (e.g., Zolpidem), are special in structure. Other benzodiazepines are as likely to be effective.
National Sleep Foundation 1522 K St., NW, Suite 510 Washington, DC 20005.
