Murali Maheswaran, DO; Clete A. Kushida, MD, PhD

Disclosures

Medscape General Medicine. 2006;8(2):79 

In This Article

Differential Diagnosis of RLS

Rajaram and colleagues define growing pains as "Ill-defined limb discomforts in children that do not meet criteria for other diagnoses, such as arthritis, other bone and joint pathology, peripheral neuropathy, and radiculopathy."[4] Growing pains can be difficult to differentiate from RLS. A similar characteristic of both is the circadian pattern of the symptoms, which occur in the late afternoon to bedtime. Growing pains differ from RLS in that the unpleasant sensations are not partially or totally relieved by movements of the lower extremities. Typically, children may awaken in the middle of the night complaining of a "throbbing" pain in the legs. Onset usually occurs during early to late childhood, and the location of the pain is prominent in the front of the thighs, calves, or behind the knees. Symptoms may be alleviated with massage, ice packs, warm compresses, and acetaminophen or ibuprofen.

Motor tics may involve 1 or more muscle groups. Common simple tics involving 1 muscle group are eye blinks, facial twitches or grimacing, head shaking, shoulder shrugging, and neck or leg jerking. Tics are involuntary but can be temporarily suppressed with voluntary effort, although most children experience an urge to act out that grows as the tics build up. Commonly after voluntary suppression, a cluster of tics occurs, resulting in great relief for the individual. Typically, the diagnosis occurs at about age 7, and it is more common in boys. Tics are believed to be an inherited neurologic disorder that usually resolves by adulthood, although sometimes it may persist.

The exact relationship of ADHD, RLS, and PLMD is unknown, and there appears to be an overlap of symptoms and treatment. All 3 of these disorders can present with irritability, mood changes, hyperactivity, inattention, and motor restlessness. It has been demonstrated that RLS and PLMD frequently are seen in children diagnosed with ADHD. To further complicate the issue, RLS, PLMD, and ADHD all respond to dopaminergic agents, and dopaminergic deficits have been suspected as an etiology for both RLS and ADHD through brain imaging studies. ADHD may be overdiagnosed, and children suspected of this disorder should be evaluated for RLS, PLMD, and OSA by a sleep specialist or a pediatric neurologist.

This condition is more painful and cramp-like than RLS. It is usually associated with strenuous activity or exercise, typically is restricted to isolated muscle groups, and is not relieved by movement of the affected limb(s).

Unlike RLS, leg cramps are very painful, typically affect 1 leg, and are restricted to a specific muscle group(s). Symptoms are not relieved by leg movements and are alleviated by rest and alternate use of ice packs and warm compresses. Electrolyte disturbances and neuromuscular disorders may be an underlying etiology, especially in severe cases. Nocturnal leg cramps are also relatively common in children. Leung and colleagues[17] found that the incidence of nocturnal leg cramps increased at age 12 years and peaked at age 16 to 18 years; the overall incidence in the study group was 7.3% of healthy children.

This disorder results in complaints of knee pain that worsens after strenuous activity or activities that require excessive kneeling or movement of the knee. Typical age of onset is between 10 and 14 years of age and is believed to be caused by an abnormal strain of the patellar tendon that causes pain at the site of attachment at the knee cap. There is no circadian pattern. Ice packs alternating with warm compresses and medications such as acetaminophen and ibuprofen may provide temporary relief. For persistent pain, a referral to an orthopaedist may be prudent.

This condition is also known as patellofemoral pain, idiopathic anterior knee pain, or patellofemoral malalignment syndrome. It is a diagnosis of exclusion that typically results from malalignment or maltracking of the patella femoral joint, which causes damage to the underside of the patella. The worst pain occurs with the knee in full flexion. Unlike RLS, pain is at the knee joint and movement precipitates the pain. Nonsteroidal anti-inflammatory drugs, ice massage or heat, avoiding activities that cause pain such as leg squats or bike riding, and orthopaedist-prescribed reconditioning techniques such as straight leg raises or orthotics may be appropriate treatments.[18]

Arthralgias comprise many medical disorders that involve joint pain. Unlike RLS, swelling and tenderness may be present at the affected joint(s) and the pain may be more severe. Systemic involvement of muscles and nerves may arise and, depending on the medical disorder, may mimic some of the complaints seen in RLS.

SDB and PLMD can cause fragmented sleep and impaired sleep quality, which in turn result in daytime symptoms (eg, irritability, mood changes, lack of concentration, restlessness) similar to those seen in children with RLS. However, children with SDB or PLMD may present with symptoms such as hyperactivity, conduct disorders, and enuresis, which are different from those seen in adults. The most common cause of SDB in children is adenotonsillar hypertrophy.

This syndrome consists of a subjective feeling of inner restlessness followed by an urge to move. Unlike RLS, this condition is usually a drug-induced adverse effect of antipsychotics and may occur at any time during the day. The treatment of choice is withdrawal or reducing the dose of the offending agent. If this fails, lipophilic beta blockers such as propranolol have been shown to be effective. Other medications that are used occasionally include benzodiazepines, clonidine, amantadine, amitriptyline, and opioids.

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