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SLEEP DISORDERS IN CHILDREN WITH CEREBRAL PALSY
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Background: Cerebral palsy (CP) is a common pathology in children, with an incidence of 2-2.5 per 1,000 live births. Sleep is a crucial process for childgrowth and development. For children with CP, sleep is also essential in the recovery process. Th us, sleep disorders (SD), which are common in childrenwith CP (prevalence estimated between 20-42%), have a negative impact on growth, development and recovery.Th is paper is a synthesis of specialized literature with the aim to analyze the correlations between cerebral palsy and sleep disorders in children. A practicalstudy is also expected for the future.
Material and method: An analysis of the latest scientifi c sources was conducted using the search engines PubMed, “HINARI” and Google Academicusing such keywords as: sleep disorders [and] children, cerebral palsy. Th e reference lists of articles have been consulted in search of additional references.
Results: CP is a source of risk factors for SD development: was established 21 factors divided in two groups: intrinsic factors (various CP comorbidities -epilepsy, psychiatric disorders, etc.) and extrinsic factors (socio-familial, medical and pharmacological interventions). Th ese factors trigger in children withCP a broad spectrum of SD which are also infl uenced by CP presentation and comorbidities.In turn, SD in children with CPs signifi cantly aff ects physical development, emotional and cognitive performance, which in result negatively infl uence therecovery process and the patient’s and family’s quality of life.
Conclusion: Correlations between CP and SD are bidirectional and mutual worsening. In the process of evaluating children with cerebral palsy, it isimportant to highlight and then to reduce that factors that can trigger sleep disturbances. At the same time, early diagnosis and correct treatment of sleepdisorders in children with CP decreases morbidity, improves recovery, and increases the quality of life of patients and their families.
Cerebral palsy (CP) is a common pathology in children, with an incidence of 2-2.5 per 1,000 live births . Sleep is a crucial process for child growth and development, learning and general health [2,3].
For children with CP, sleep is also essential for the recovery process. Studies show that sleep duration in children has decreased over the last 20 years, in the same time, the incidence of sleep disorders (SD) is increasing. SD are more common in children with CP (prevalence estimated between 20-42%) [1,4,5,6] and negatively affects not only growth, development, but also the recovery process. It is estimated that up to 85% of children with neurodevelopmental disabilities, including CP, suffer from a clinically significant sleep problem . D.M. Romeo et al.  reported an incidence of SD over 30% in pre-school children with CP. Also, low quality of life of children with CP was associated with insomnia and excessive daytime sleepiness . Sleep problems in these children start at an early age and continue throughout their lives. These disorders are detrimental to the physical and behavioral development, school performance and mental health, the latter also referring to their caregivers [7,10].
MATERIAL AND METHOD
An analysis of the latest scientific sources was conducted using the search engines PubMed, “HINARI” and Google Academic with the help of keywords: sleep disorders [and] children, cerebral palsy. The reference lists of articles have been consulted in search of additional references.
In the literature were described several factors and mechanisms by which the CP generates a wide spectrum of SD, which are also influenced by CP presentation and comorbidities [1,9,10]. These factors were divided into intrinsic (various CP comorbidities - epilepsy, psychiatric disorders, etc.) and extrinsic, also called environmental factors (socio-familial factors, medical and pharmacological interventions) (Table I). Among the intrinsic factors, a common comorbidity in children with CP is epilepsy and nocturnal seizures . Epilepsy is a risk factor for SD onset in children with neurodevelopment disabilities. Physiopathological mechanisms are complex, and add in sleep fragmentation because of seizures, sleep architecture disruption and daytime sleepiness due to anticonvulsant medications. Romeo D. et al. found an incidence of SD in 33% of children with CP and active epilepsy, in 17% of children with controlled epilepsy, and in 7% of children with CP without epilepsy . It has also been observed that there is a link between the type of epilepsy and the sleep disorder. Thus, one study  demonstrated that the type of epilepsy influences sleep architecture, so patients with generalized epilepsy have a total sleep time, sleep efficacy index, and REM sleep duration significantly diminished compared to patients with partial epilepsy.
Another important factor that negatively impacts the quality of sleep in children with epilepsy is an antiepileptic drug therapy. Thus, in children with polytherapy, REM sleep duration and sleep efficacy are significantly diminished compared to untreated patients. As a result, these patients have learning difficulties compared to patients with normal REM sleep duration .
Another intrinsic factor is abnormal secretion of melatonin. Melatonin is the hormone involved in sleep initiation and circadian rhythm regulation. Several studies have determined that children with mental or cognitive disabilities, which frequently coexist with CP, have disturbed melatonin secretion [7,12]. At the same time, the coexistence of primary visual disturbances in patients with CP, represent also a risk factor for SD. Because of lack or alteration of light perception, CP patients with visual disturbances can have disturbed sleep onset and maintenance through the effect of decreased melatonin secretion. According to studies 20 to 50% of children with CP have low light perception . Brain stem dysfunction may also affect circadian rhythm and sleep onset latency .
Mental disabilities and cognitive impairment as well as the presence of comorbidities such as autism or hyperactivity and attention deficit syndrome predispose to decreased sleep duration. It is reported that 30% to 50% of children with CP have mental retardation or cognitive impairment. The negative influence on sleep can be explained by the fact that cognitive impairment and mental disorder are frequently associated with poor sleep hygiene and an inappropriate sleep routine [4,13].
Breathing-Related Sleep Disorder is common, but underestimated in CP children. These disturbances are characterised by obstructive or central sleep apneas and/or alveolar hypoventilation and they develop in CP patients due abnormalities of upper airway structure or tone, poor brain stem control, or because of muscle weakness . Obstructive sleep apnea is common for children with CP. In the general population, sleep apnea has prevalence between 1 and 4%. In the study by Newman and his colleagues, 173 children with CP 14.5% had a pathological score for breathing-related sleep disorders. Obstructive sleep apnea is characterized by obstruction of the upper airways during sleep. In children with CP there are several factors involved in SD pathophysiology: anatomical factors such as the disproportionate face, mandibular changes, muscular dysfunction of the upper respiratory tract (hypotonia, hypertonia or dystonia). Other elements that can contribute are insufficient central control of breathing, obesity, drugs that depress the tone of the upper airway muscles. Obstructive sleep apnea has multiple squeals, adversely affects physical development, cardiorespiratory and neurodegenerative disorders and also increases the risk for sudden death. Appropriate diagnosis and management of obstructive sleep apnea prevents the development of it’s side effects. While diagnosing a patient with suspicion for sleep apnea, it is mandatory to take a detailed history of sleep, noisy breathing, snoring during sleep or wakefulness, breathing pauses during sleep, and daytime sleepiness.
Physical examination may reveal a hypertrophy of adenoid or palatine tonsils. The gold standard for the paraclinic diagnosis of sleep disorders is polysomnography.
However, polysomnography is costly and is not accessible in all medical centers. Another effective method is nocturnal cardiorespiratory polygraphy for the detection of moderate or severe obstructive sleep apnea. Pediatric sleep questionnaire and Brouillette score can serve as screening tools. Flexible endoscopy may be required to demonstrate tonsillar hypertrophy. The treatment is individualized and depends on the etiology of obstructive sleep apnea. Adenozilectomy is the treatment for adenotonsillar hypertrophy. Sometimes children with CP need surgical treatment, such as mandibular advancement. Also, an important part of the management of obstructive sleep apnea in children with cerebral palsy is the identification and appropriate treatment of such comorbidities as gastroesophageal reflux, hypersalivation, and obesity.
Disturbances of muscle ton. For those with spasticity of the whole body, muscle spasms and the need for repositioning at night can result in disrupted sleep [1,14]. A recent study  performed on 35 children with bilateral CP (ex: spastic tetraplegia or diplegia) and severe spasticity showed a decrease in nighttime awakenings and severity of pain 6 months later after an implantation of baclofen intrathecal pump. Another study  conducted on 26 children with tetraplegic CP reported improvement in sleep after treatment of lower limb spasticity with Botulinum toxin type A injection. Pain. Pain interferes with sleep and there is evidence that the relationship is bidirectional, so deprivation of sleep increases the severity of pain, and increased pain leads to SD. Spasticity, abnormal muscle tone, involuntary movements and abnormal postures, scarring, increase the pain in these patients. In a study  in which sleep disorders were analyzed in children with CP based on the presence or absence of pain, the authors determined that sleep problems were more common in the group with untreated pain and included such sleep disorders as: parasomnias, diminishing sleep duration and sleep disturbed breathing.
Extrinsic factors. Another important aspect of the pathophysiology of sleep disorders in children with cerebral palsy is the influence of the environment, the socio-economic situation of the family (socially vulnerable families, single-parent families that cannot provide a sleeping environment), lack of sleep hygiene, etc. Similarly, sleep in children with CP can be adversely affected by the administration of various medications (anticonvulsants, myorelaxants). They can, alone or in combination, modify the degree of sleep maintenance, increase the risk of sleep disturbances and reduce the level of daytime alertness [6,8,15]. The use of medical devices (postural equipment at night, night-time orthotics, etc.) in these children also may disturb sleep.
As a result of the above-mentioned intrinsic/extrinsic factors, children with CP may develop a wide range of sleep disorders: difficulties in initiating and maintaining sleep, frequent awakenings, sleep disturbances, bruxism, nocturnal hyperhidrosis, excessive daytime sleepiness, Insomnia, nightmares, parasomnias (sleepwalking, sleep-waking disorders) [1,7,16]. The most common sleep disorders in children with CP are difficulties in initiating and maintaining sleep, sleep-wake transition disorders . Children with CP also have an increased risk of developing sleep disturbances, especially obstructive sleep apnea due to diminished upper airway muscle tone or because of respiratory center dysfunction [7,17]. Elsayed , studying 100 children with CP, who were divided into preschools and schoolchildren, determined that 46.2% of children from preschool group had sleeponset insomnia and 50% bruxism. In the school age group, 50% of children experienced breathing-related sleep disorder, 50% nightmares, 12.5% sleep talking, and 62.5% experienced excessive daytime sleepiness. Electrophysiological studies reported abnormal patterns of electroencephalogram (lack of rapid eye movements and disruption of the structure and amount of sleep spindles) during sleep in more than 50% of children with CP. These changes can slow the improvements and outcomes of mental, neurological or medical disorders in CP patients.
The consequences of the SD are wide-ranging and affect both the child and his family. It is known that SD has a negative consequence on daytime behaviour, both in children with or without disabilities in neurodevelopment, such as hyperactivity, aggression, impulsivity. Sleep deficiency in children with CP significantly affects the physical development, emotional and cognitive performance of the child, and negatively affects carers who are also deprived of sleep .
Correlations between CP and SD are bidirectional and mutual worsening. In the process of evaluating children with cerebral palsy, it is important to highlight and then to reduce that factors that can trigger sleep disturbances. At the same time, early diagnosis and correct treatment of sleep disorders in children with CP decreases morbidity, improves recovery, and increases the quality of life of patients and their families.