1. A description of the symptoms should be provided in the child’s own words
2. Periodic limb movement disorder may develop before symptoms of RLS
3. The interviewer must be familiar with words typically used by children and adolescents to describe symptoms of RLS
4. Language and cognitive development determine the applicability of the RLS diagnostic criteria, rather than age
5. The interviewer must be mindful that adult specifiers for clinical course may not be applicable to the pediatric patient
6. Symptoms of RLS must be of clinical significance
Periodic limb movements occurring with a frequency greater than 5 per hour in the child or a first-degree family member supports the diagnosis of RLS. The diagnosis of pediatric RLS is also supported if the child has a first-degree family member with RLS [1].
In children, an increase in symptoms during the evening or at night may not be reported. The majority of children with RLS, 66 %, report daytime leg discomfort. One explanation is the number of hours children sit during the school day [1].
Restless legs syndrome affects 1.9 % of children 8–11 years of age and 4 % of children 12–17 years of age [10]. During early childhood, most children are thought to have mild symptoms that do not require medical care, and therefore RLS goes unreported [11]. Most people seeking medical treatment for RLS are adults, but 25 % of adults diagnosed with RLS report the onset of symptoms between 10 and 20 years of age [9]. In addition, adult patients with RLS frequently report onset in childhood that remitted during adolescence only to return in adulthood often with recurrent onset in pregnancy. Among adults with RLS, many studies report a higher prevalence of RLS in women compared to men [12]. There is no significant gender difference among children.
Restless legs syndrome is associated with insomnia, impaired comprehension, impaired semantic/phonemic fluency, poor sleep quality, and decreased ability to sustain focused attention [9]. The neurocognitive deficits associated in short- and long-term memory, working memory, attention and executive functions, and semantic/phonemic fluency improve after 3 months of therapy with dopaminergic agents [13].
There is an overlap between RLS and attention deficit hyperactivity disorders (ADHD). Pullen et al. found 25 % of children with RLS met diagnostic criteria for ADHD [14]. Sleep deprivation does not solely explain the association between RLS and ADHD. Both disorders involve disruption in the dopaminergic system [15]. It has long been hypothesized that RLS involves dopamine dysfunction [16]. Most patients with RLS benefit from dopaminergic agents. It is also known that children with ADHD benefit from stimulants and these stimulants increase cerebral levels of dopamine [17]. Ernst et al. [18] studied dopaminergic pathways of children with ADHD. The researchers used dopamine tracers with positron emission tomography scans and documented decreased dopaminergic function in the brains of children with ADHD.
Children with RLS are more likely to suffer mood disorders than children who do not have RLS [19]. Pullen et al. studied 239 children with RLS. Sixty-four percent of children with RLS had one or more comorbid psychiatric disorders. Mood disturbances occurred in 29.1 %. Attention deficit hyperactivity disorder occurred in 25 %. Anxiety disorder occurred in 11.5 % and 10.9 % had behavioral disturbances. A gender difference was observed. Male children were more likely to have ADHD and disruptive behavior disorders. Female children had a higher incidence of mood disturbances and anxiety disorders [14].
A higher incidence of obstructive sleep apnea syndrome and parasomnias has been reported. Similar to adults, children with chronic renal disease have a high incidence of RLS. In adults, the incidence of RLS increases in the presence of type 2 diabetes and peripheral neuropathy. Children with these disorders may be at increased risk for developing RLS but scientific evidence has not been established.
The prevalence of growing pains among children is unknown, but a conservative estimate is that growing pains affect 4.7 % of children [20]. Halliwell et al. estimate that children with growing pains represent 7 % of office visits in a general pediatric medical practice [21]. Accurately differentiating growing pains from RLS is challenging [22]. One reason is the lack of universally accepted diagnostic criteria for diagnosing growing pains. Walters et al. reviewed the suggested diagnostic criteria for growing pains published by Evans et al. and Peterson [23–25]. Walters et al. documented an overlap in the symptoms of growing pains and RLS [20] (See Table 11.2). Halliwell et al. suggest important symptoms that differentiate the two disorders: growing pains are always described as painful, they do not affect the arms, and symptoms resolve around 12 years of age [21]. However, these distinctions do not help in cases of childhood RLS where isolated leg pain may occur in a not insignificant minority of children with RLS according to Picchietti et al. [9, 10]. The literature reviewed recently by Walters et al. [20] suggests that children with growing pains do not have symptoms made worse by rest, do not have a desire to move the legs to get relief by activity, nor do they get any relief by activity, whereas the exact opposite is true of RLS. However, these contentions have not been formally studied and could well be the basis of further investigational research [20].
Table 11.2
Shared symptoms of RLS and growing pains (GP)
1. Pain occurs in the legs |
2. Onset of symptoms starts between 3 and 12 years of age |
3. The unpleasant sensations are worse in the evening or at night or only occur at night or in the evening |
4. There are no significant limitations in activity or weight bearing |
5. Pain usually affects the anterior thigh, calf, and posterior knee. The pain is felt in the muscles and not in the joints |
6. The pain is intermittent with some pain-free days and nights |
7. Physical examination is normal |
8. Diagnostic tests such as erythrocyte sedimentation rate, radiograph, and bone scan are within normal values |
9. Pain persists at least 3 months |
10. There is no associated lack of well-being |
Treatment of RLS involves non-pharmacologic and pharmacologic therapies. In all cases, non-pharmacologic therapies may help reduce or eliminate symptoms at least temporarily. Non-pharmacologic treatments are considered first-line therapy and should be considered prior to initiation of prescription medications. When medically possible, consider discontinuing medications that trigger RLS symptoms: antihistamines, antidepressants, antiemetics, and antipsychotics [26]. Discontinuing commonly prescribed medications such as selective serotonin reuptake inhibitors (SSRI), metoclopramide, and diphenhydramine may improve RLS symptoms [27]. Abstinence from alcohol and caffeine may be helpful [28].
Massaging the legs may reduce discomfort. Massage increases dopamine levels and this may explain efficacy. Exercise is associated with decreased RLS symptoms. Avoid prolonged standing or sitting. Avoid artificial sweeteners, caffeine, and alcohol. Over-the-counter supplements and vitamins have been used to treat RLS in adults with variable results. Iron supplements have been found to reduce symptoms in children with low iron or low ferritin levels. Simakajornboon et al. induced the reduction of symptoms for a period of 1–2 years in children who were iron deficient. Children were administered 3 mg of elemental iron/kg/day for 3 months. Iron was then tapered over a period of 1 year [27]. Vitamin C enhances iron absorption [29]. Lee et al. found an association between low folate levels and RLS in pregnant women [30]. Folate (B9) synthesizes tetrahydrobiopterin. Sagheb et al. reported that a combination of vitamin C and vitamin E or either alone was found to decrease severity of RLS [31]. Melatonin may help induce sleep, but there is no evidence of decreased melatonin levels in patients with RLS [32]. There is no evidence supporting the use of homeopathic therapies as treatment for RLS [26].
The usefulness of magnesium is controversial. Horynyak et al. reported improvement in RLS symptoms in patients given 300 mg of elemental magnesium each evening for 4–6 weeks [33]. Walters et al. measured serum and CSF magnesium levels in patients with RLS and controls and found no statistically significant difference between the groups [34]. It is possible that magnesium may affect RLS symptoms at the muscular level because magnesium is associated with muscle relaxation and dilation of blood vessels [35]. Improved blood circulation is also thought to be the mechanism for the beneficial effects of exercise.
The pharmacologic choices for children are limited. Dopaminergic agents have documented effectiveness in treatment of adult RLS. But dopaminergic agents are not FDA approved for use in children with RLS. In a multicenter double-blind study, carbidopa/L-DOPA (25/100 CR) was found to effectively treat RLS/PLMs in children, and few side effects occurred [36]. Pramipexole and ropinirole are selective dopamine agonists and less likely to cause side effects such as augmentation compared to carbidopa/levodopa. Either pramipexole or ropinirole can be used to treat RLS in children. Start with the lowest available dose and titrate upward as needed weekly. In adults the maximum dose is 1.5 mg and may be effective at lower doses [29].
Clonidine has been reported to effectively treat RLS in children. Gabapentin and clonazepam have been shown to reduce symptoms, but clonazepam may increase symptoms of ADHD [27]. The Pediatric RLS Severity Scale offers a mechanism to document improvement of symptoms after treatment [37].
Periodic Limb Movements
Periodic limb movements (PLMs) are common but periodic limb movement disorder (PLMD) is not. PLMs are repetitive kicking movements in sleep usually of the legs, but have been reported to involve the arms. PLMD is defined as the presence of PLMS when there is accompanying fatigue or sleep disruption that can definitely be related to the PLMS. Even though PLMS are common in RLS (occur in up to 80 % of adult RLS patients), PLMD cannot be diagnosed in the presence of any other sleep disorder such as RLS which might account for the sleep disruption and daytime fatigue. PLMD is usually a diagnosis of exclusion since PLMS are a very common finding on polysomnography done for unrelated purposes such as ruling out sleep apnea. Insomnia as a cause of sleep disruption and daytime fatigue is also common and may be coincidental to the PLMS. A good history will usually reveal that the insomnia is due to something other than the PLMS in which case a diagnosis of PLMD cannot be made. Similarly hypersomnia is not uncommonly seen in a sleep disorders practice. A good sleep history may also reveal that the fatigue or hypersomnia is due to sleep apnea, medications, and other medical or psychiatric problems rather than any accompanying PLMS. A multiple sleep latency test (MSLT) may reveal evidence of idiopathic hypersomnia or narcolepsy as a cause of the hypersomnia. Again, in these cases, if PLMS co-occur, the diagnosis of PLMD cannot be made. Although excessive sleepiness and sleep disturbance has been reported in the past, newer data do not find significantly elevated Epworth sleepiness scale scores or multiple sleep latency test (MSLT) values in subjects with PLMS [1].
Periodic limb movements are common in adults but rarely occur in children [38]. PLMs occur most often during sleep, but can occur during wakefulness as an accompaniment of RLS. Movements involve the stereotypic extension of the great toe frequently with simultaneous flexion of the ankle, knee, and hip. Movements last at least 0.5 s but not longer than 10 s. Arousals may precede, coincide with, or follow PLMs [1].
Periodic limb movement disorder requires the presence of periodic limb movements at a frequency of greater than 5 per hour in children and greater than 15 per hour in adults. Periodic limb movements must be associated with sleep disturbance or impairment of mental, physical, social, occupational, educational, behavioral, or other areas of important functioning [1]. The diagnosis of periodic limb movement disorder requires polysomnography or actigraphy. The polysomnogram montage should include surface electrodes on both legs and preferentially recorded on separate channels. The electrodes are placed longitudinally and symmetrically around the middle of the muscle 2–3 cm apart or one-third of the length of the anterior tibialis muscle, whichever is shorter. A periodic limb movement is defined as an 8 uV elevation above baseline in the EMG channel with a duration ≥0.5 s and ≤10 s. A series of four or more limb movements defined as ≥ 4 limb movements must be recorded. The limb movements must occur between 5 s and not longer than 90 s. The duration of each individual limb movement is anywhere from 0.5 to 10 s. In addition to occurring commonly in RLS, PLMS also occur commonly in obstructive sleep apnea, REM sleep behavior disorder, and narcolepsy and as a side effect to medications [39]. For aforementioned reasons, PLMD cannot be diagnosed in the presence of any of these conditions [1]. The etiology of PLMs is unknown but several hypotheses exist. One hypothesis implicates dopamine. According to Montplaisir et al., “there is a high occurrence of PLMs in RLS/WED, REM behavior disorder (RBD) and narcolepsy. Data suggest that these conditions are associated with impaired central dopaminergic transmission. Neuroleptics and gamma-hydroxybutyrate, medications that decrease dopamine, have been reported to trigger PLMs” [39].
The incidence of PLMs in children increases in the presence of obstructive sleep apnea syndrome. Hartzell et al. [40] quantified the frequency and severity of sleep disorders in a population of hypertensive pediatric patients. The researchers found 64 % of the children had obstructive sleep apnea and or PLMD [40]. Qubly et al. [41] studied 139 infants with obstructive sleep apnea and found 42 % also have periodic limb movements [41].
Asymptomatic periodic limb movements may be helpful in establishing a diagnosis of RLS/WED or narcolepsy in patients who do not clearly meet diagnostic criteria for RLS/WED or narcolepsy.
Treatment of periodic limb movement disorder is similar to the treatment of RLS. Asymptomatic periodic limb movements do not warrant treatment.
See Fig. 11.1 for examples of periodic limb movements in sleep.
Fig. 11.1
Periodic limb movements in sleep (PLMS) (three epochs at 30, 60, and 120 s). The burst duration of a single leg movement is ≥0.5 s and ≤10 s. Four or more limb movements in a row 5–90 s apart are needed for any of the movements to be counted as PLMS. In the first 30 s epoch, the two movements meet the burst duration and movement interval criteria for PLMS but would not be counted as PLMS unless there were at least four such movements 5–90 s apart. One would need to search the pages directly before and directly after to look for at least an additional two movements. PLMS can be discriminated from HFT and ALMA because the burst duration of PLMS is much longer (0.5–10 s), and the interval between PLMS is also much longer (5–90 s apart)
Sleep-Related Rhythmic Movement Disorder
These commonly manifest in children as repetitive body rocking or repetitive head banging (jactatio capitis nocturna). Sleep-related rhythmic movements are also referred to as stereotypies [42]. Sleep-related rhythmic movements are only considered a disorder if the movements are associated with clinical symptoms. Sleep-related rhythmic movements involve large muscle groups in any part of the body but most commonly the head, torso, and legs. The movements are nonfunctional, repetitive, stereotyped behaviors that predominantly occur during sleep or at the transition from wakefulness to sleep. Movements may occur during quiet wakefulness [1].
Rhythmic movements are distinguished from tremors and other types of movements by a frequency of 0.5–2 Hz and duration of less than 15 min. Nevertheless, some reports exist of head banging lasting for 30 min to 1.5 h [43]. The movements are fixed in fashion, form, amplitude, and location. Movements stop with distraction [44].
The diagnostic criteria for sleep-related rhythmic movement disorders include all of the following: repetitive, stereotypic, and rhythmic motor behaviors of large muscle groups. Movements occur during times of sleepiness or around naps or bedtime and must interfere with sleep or impair daytime functioning or be associated with or have a high probability of associations with self-inflicted injury [1].
Although sleep-related rhythmic movements are common, sleep-related movement disorder which implies impairment of sleep, daytime function, or bodily injury is rare. Peak age of onset of the benign form of the condition occurs before a child’s first birthday and decreases with increasing age. Almost 60 % of infants have sleep-related rhythmic movements, but the disorder occurs in only 5 % of children who have reached 5 years of age. Sleep-related rhythmic movements can persist into adulthood in normal adults, but more commonly persistence occurs in children with neurological or developmental disorders.
Each patient has his/her own pattern of stereotypic behavior. Although body rocking or rolling or head banging is the classic forms of the condition, the behaviors vary widely, and more than one type of movement may occur in the same patient. In younger children, the behaviors may also include sucking the thumb or arm flapping or hand washing movements characteristic of Rett’s syndrome. Older children and young adults have behaviors such as nail biting, foot tapping, and hair twirling [45].
Sleep-related rhythmic movement disorders can be classified as primary or secondary. Primary sleep-related rhythmic movements occur in children who are developing normally and do not have behavioral or neurologic disorders. Secondary sleep-related rhythmic movements occur in the presence of signs or symptoms of behavioral or neurological diseases and commonly occur in children with degenerative disorders affecting the brain, pervasive developmental disorders such as autism spectrum disorders and Rett’s syndrome. Secondary sleep-related rhythmic movements can be present in children who have Tourette’s syndrome. Secondary sleep-related rhythmic movements may be associated with structural defects, autoimmune disorders, or an adverse drug reaction [46].
The etiology of sleep-related rhythmic movements is unknown. There are several theories. One popular hypothesis is that the movements are self-soothing behaviors. Sleep-related rhythmic movements appear to be related to the A phases of the cyclic alternating pattern (CAP cycle) [47].
Kohyama et al. studied the polysomnograms of two children with sleep-related rhythmic movements and retrospectively studied 31 additional children with sleep-related rhythmic movements who had been evaluated by polysomnography. Kohyama et al. found that the movements associated with head banging and head rolling rarely resulted in wakefulness. Both head banging and head rolling occurred in clusters. The frequency was increased during N1 and REM sleep. Kohyama et al. found that head banging was not limited to periods of sleep transitions. Head banging occurred during wakefulness but was not recorded during N3 and REM sleep [48].
In comparison, Mayer et al. found head rolling occurred during the transition to sleep and when transitioning to wakefulness. Mayer et al. also noted sleep-related rhythmic movements occurred during wakefulness, in all stages of sleep and was associated with arousals [42].
Treatment is not necessary unless SRMD is associated with sleep disturbance, bodily harm or could result in injury if not controlled. However, the main preventive measure is to make sure that the parent keeps the child in a safe sleeping environment to prevent injury. For violent forms of SRMD, protective measures such as wearing helmets are indicated. Behavioral therapy has been reported to decrease SRMD. Treatment with benzodiazepines, citalopram, and imipramine may be helpful [49].
See Fig. 11.2 for examples of rhythmic movement disorder.
Fig. 11.2
Two examples of rhythmic movement disorder are provided. (a) In the first example of head banging in a 10-year-old male, artifact can be seen in the EEG and EOG. Here the patient is in a prone position putting his elbows on the bed. He forces his face on the pillow so the movement is of the entire head on the pillow. Although not in this case but in similar cases, movement can sometimes be seen on the chin EMG. (b) In the example of body rolling in an 18-year-old male, the patient is on the left side and there is rolling of the trunk from side to side. The artifact is prominent in the EEG and EOG, and there is some activation of the right tibialis anterior muscle as well
Sleep-Related Bruxism
Sleep-related bruxism involves contraction of masticatory muscles characterized by arousal from sleep associated with teeth grinding or clenching of the teeth. Diagnosis requires regular auditory tooth grinding during sleep in association with abnormal wear on the teeth and/or morning jaw muscle pain, jaw locking, or jaw muscle fatigue and/or temporal headache [1].
When sleep-related bruxism involves rhythmic activity of the masseter and temporalis muscles, the condition is called rhythmic masticatory muscle activity (RMMA). RMMA occurs in a cyclic pattern at 1Hz frequency. RMMA is thought to be the intensification of normal orofacial activity and is associated with phase A of the cyclic alternating pattern (CAP). RMMA occurs most often during NREM sleep with increased occurrence during N1 and N2 sleep and is associated with arousals and transitioning to wakefulness. Less common, sleep bruxism (SB) has been reported to occur during REM sleep.
There are three types of sleep-related bruxism. An episode of phasic RMMA is defined as a minimum of three EMG bursts with a duration of ≥0.2 s and <2 s. When the EMG burst is continuous for more than 2 s, the bruxism is considered tonic sleep-related bruxism which is characterized as teeth clenching. Mixed sleep-related bruxism is a combination of phasic and tonic activity. Severity of sleep-related bruxism is described by frequency of EMG burst. One event per hour is normal [50]. When a single episode comprised of three or more individual EMG bursts occur and is followed by more than 3 s of EMG silence, one starts counting new EMG bursts as part of a separate episode. There must be at least two episodes of audible grinding on video with audio as part of the overnight sleep study to meet polysomnographic criteria for a diagnosis of sleep-related bruxism [51].
In the general population, the prevalence of bruxism ranges from 6 to 20 % [52]. Sleep-related bruxism can start at any age. But onset of SRB most often occurs during childhood and decreases with increasing age [53]. Between the ages of 18 and 29, the prevalence of bruxism is 13 %. Among patients over 60 years of age, the prevalence of bruxism decreases to 3 %. Although SRB may resolve spontaneously, nearly 66 % of children with bruxism continue to have teeth grinding in adulthood [1].
The etiology of sleep-related bruxism is unknown. It is no longer accepted that bruxism is secondary to misalignment of teeth. Genetic factors may be involved. Among people with SRB, 20–50 % have a biological relative with a history of teeth grinding, and genetics may be a factor. A serotonin gene has been described in patients with bruxism [1]. One hypothesis is that sleep-related bruxism is secondary to an imbalance of neurochemicals and neurotransmitters such as dopamine and serotonin. Other possible explanations for sleep-related bruxism include sleep arousal mechanisms, sympathetic nervous system activation, and psychosocial factors.
Comorbidities associated with sleep-related bruxism include parasomnias, obstructive sleep apnea, periodic limb movements, epilepsy, Tourette’s syndrome, allergies, Parkinson’s disease, mental health disorders, and stress. Antipsychotics, neuroleptics, and antidepressants can trigger sleep-related bruxism. However, in the case of some of these disorders, the bruxism will be prominent in the day also. Bruxism must be differentiated from nocturnal facio-mandibular myoclonus which is characterized by rapid jerks of the jaw muscles or rapid tooth tapping. Facio-mandibular myoclonus, however, not infrequently accompanies sleep-related bruxism.
Evaluation requires a comprehensive medical history inclusive of symptoms suggestive of comorbid conditions or triggers. A detailed family medical history is necessary because a diagnosis of sleep-related bruxism in biological relatives suggests a genetic component. Twenty to 50 % of children with sleep-related bruxism have a family member with a history of tooth grinding or bruxism. Medications should be reviewed for side effects such as onset of bruxism.
A polysomnogram is not required for the diagnosis of sleep-related bruxism but helps to quantify the frequency. If bruxism occurs at a low frequency, bruxism may not be recorded on the polysomnogram due to night to night variability. The polysomnogram should include at least one channel over the masseter muscle and audiovisual recording.
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