Patient Presentation
A 6-year-old male came to clinic for intermittent leg pain. He described it as an achy pain in both of his lower legs. He would motion with his hands up and down his shins when describing where the pain was. This occurred over the past several months, but had happened twice in the past week so his mother brought him in. The episodes occurred for several minutes but the family was unsure of the duration. It occurred in the evening but did not awaken the boy from sleep. His mother said that he would move or twitch his legs intermittently. There were no specific changes with exercise and he wanted to rest more when the pain occurred.. He had a normal gait and could participate in all activities. He had no limp and denied any other pains including headache. He denied any specific trauma. Doing nothing, rubbing the legs or a warm bath improved his discomfort.

The past medical history revealed an active boy who had a tibial toddler’s fracture from a fall at 3 years of age. The review of systems showed no weight loss, fevers, sweating, bruising/bleeding, specific joint or muscle pain, edema, skin rashes or other lesions or masses, nor any visual problems.The family history was positive for a maternal aunt and grandmother with restless legs syndrome. There were no other parasomnias though.

The pertinent physical exam showed a healthy appearing boy with growth parameters in the 75-90%. He had gained ~1800 grams over the past 9 months. His extremities had 1 shin bruise on his mid-shin. His legs appeared symmetric with good muscle bulk. His muscle tone and strength was normal in his lower extremities. He had full range of motion in both lower extremities without eliciting any pain. There was no edema. His pelvis, spine and upper extremities were normal. His examination was otherwise normal including only a few shotty anterior and inguinal nodes.

The diagnosis of bilateral intermittent leg pain consistent with growth pains was made. The pediatrician discussed the natural history of the problem, and recommended that they continue to treat him symptomatically and monitor him. “Kids can have restless legs syndrome and often it is hard to diagnose, but I feel pretty confident that this isn’t restless legs syndrome. Usually that is in only one leg and the kids want to move and not sit around. They also have less actual pain. He complains of both legs, wants to rest and has mainly pain when he describes it which is consistent with growing pains,” the pediatrician explained. At his next health supervision visit his mother reported that he had had a few other episodes but none that were different. His examination at that time was also normal.

Discussion
Restless legs syndrome (RLS) is also known as Willis-Ekbom disease.
RLS is a clinical diagnosis with criteria being:
1. An urge to move the legs usually accompanied by uncomfortable and unpleasant sensations in the lower extremities (Note: sometimes other body parts can be affected)
2. The urge to move begins or worsens when sitting or lying down
3. The urge to move is partially or totally relieved by movement (Note: relief by activity may not be noticable if severely affected but must have been previously present)
4. The urge to move the legs and any accompanying unpleasant sensations during rest or in activity only occur or are worse in the evening or night then during the day. (Note: worsening may not be noticable at night if severely affected but must have been previously present)
5. The symptoms are not accounted for by another primary medical or behavioral condition.

There must be a significant impact on sleep, cognition, mood, and/or behavior (especially in school or homelife) to make the diagnosis. For adults, all 5 criteria must be met. For children, all must be met but there are caveats depending on timing, severity and the child’s own cognition and language development. The descriptive words must be from the child themself and not the parent. Words children and adolescents use to describe their symptoms include: “boo-boos,” “oowies,” “creepy,” “crawly,” “tingling,” “tickle,” “spider in the legs,” “ants crawling and aching feeling,” “fidgety, restless, too much energy,” “legs need to stretch,” and “want or need to move.” Other criteria that supports the RLS diagnosis is periodic leg movements in sleep > 5 per hour or family history of the same, or a family history of RLS or PLMD in first-degree relatives.

Periodic leg movements in sleep (PLMS) can be associated with RLS but also is a separate entity. PLMS are periodic limb movements that are repetitive, stereotypical limb jerks. Episodes last from 0.5-10 seconds and are separated by 5-90 second intervals. When PLMS of more than 5 times/hour occurs along with sleep disturbance, this is called Periodic leg movements disorder (PLMD). There is considerable overlap with these entities and RLS supersedes the others. Therefore, “[i]t is possible to have a diagnosis of RLS with PLMS but not RLS and PLMD.” It is also possible for PLMD to precede RLS.

RLS may be unilateral or bilateral and although pain can be described by children it is not the main feature. Common mimics of RLS in children includes bruises, dermatitis, growing pains (very common, but is bilateral and pain is a main feature), myalgia/muscle soreness, positional discomfort, tendon/ligament strain or sprain, and transient nerve compression/numbness. Less common problems include arthritis, complex regional pain syndrome, leg cramps, myopathy, peripheral neuropathy, orthopaedic problems, radiculopathy, and sickle cell disease.

The exact cause of RLS is not known but it appears that genetics which involve the dopaminergic pathway are involved. Iron sores also appear to be part of the problem as well. RLS has been associated with other co-morbidities including attention deficit hyperactivity disorder, migraine headache, mood disorder and sleep disorders.

Iron therapy has been shown in some studies to be beneficial. Amount and length of treatment varies. Good sleep hygiene with appropriate room environment (relaxing, quiet, only for sleeping, no screens, etc.), consistent bed time, refraining from alcohol, tobacco or other medications that can cause sleep disruption are all advised. Regular exercise and good nutrition also are advised. There are medications for RLS for adults mainly dopaminergic medications.

Learning Point
RLS is estimated to affect 2-4% of children and adolescents. The number is likely to be an underestimate because of underrecognition by patients, families and health care providers, overlap with many other mimics, and difficulty in language used to describe symptoms by the children and adolescents. It is estimated that 25% of adults had onset of symptoms as a child or teenager. In adults RLS has an estimated prevalence of 4-10%

Questions for Further Discussion
1. What are indications for sleep studies? A review can be found here

2. What causes muscle cramps? A review can be found here

3. List some pediatric parasomnias. A review can be found here

Related Cases

Disease: Restless Legs | Sleep Disorders

Symptom/Presentation: Extremity Problems | Sleep Disturbance

Specialty: General Pediatrics | Neurology / Neurosurgery | Orthopaedic Surgery and Sports Medicine

Age: School Ager

To Learn More
To view pediatric review articles on this topic from the past year check PubMed.

Evidence-based medicine information on this topic can be found at SearchingPediatrics.com and the Cochrane Database of Systematic Reviews.

Information prescriptions for patients can be found at MedlinePlus for these topics: Restless Legs and Sleep Disorders.

To view current news articles on this topic check Google News.

To view images related to this topic check Google Images.

To view videos related to this topic check YouTube Videos.

Picchietti DL, Bruni O, de Weerd A, Durmer JS, Kotagal S, Owens JA, Simakajornboon N; International Restless Legs Syndrome Study Group (IRLSSG).
Pediatric restless legs syndrome diagnostic criteria: an update by the International Restless Legs Syndrome Study Group. Sleep Med. 2013 Dec;14(12):1253-9.

Simakajornboon N, Dye TJ, Walters AS. Restless Legs Syndrome/Willis-Ekbom Disease and Growing Pains in Children and Adolescents. Sleep Med Clin. 2015 Sep;10(3):311-22, xiv.

Angriman M, Cortese S, Bruni O. Somatic and neuropsychiatric comorbidities in pediatric restless legs syndrome: A systematic review of the literature. Sleep Med Rev. 2017 Aug;34:34-45.

Munzer T, Felt B. The Role of Iron in Pediatric Restless Legs Syndrome and Periodic Limb Movements in Sleep. Semin Neurol. 2017 Aug;37(4):439-445.

Author
Donna M. D’Alessandro, MD
Professor of Pediatrics, University of Iowa