Posted by: Indonesian Children | September 13, 2009

Pathophysiology of Sleep Disorders

Dyssomnias

Primary hypersomnia: Youths with primary hypersomnia have normal sleep efficiency, sleep/wake cycles, and sleep architecture. Patients with primary hypersomnia present with a normal variant sleep pattern except for longer sleep needs. It may be a lifelong pattern. No other identifiable cause exists for the excessive somnolence that continues for at least 4 weeks.

Primary or idiopathic insomnia: The pathogenesis of primary hypersomnia is poorly defined. Patients with primary or idiopathic insomnia may have a lifelong inability to initiate and maintain sleep with associated sequelae.

Sleep-state misperception: Youths with sleep-state misperception may have normal polysomnography. The pathology of sleep-state misperception is associated with an underestimate or misperception of the child’s sleep duration, which results in the patient’s mistaken belief of having experienced inadequate sleep.

Psycho-physiological insomnia: This disorder is related to psychological stressors that interfere with sleep onset or maintenance.

Narcolepsy: Rapid eye movement (REM) sleep mechanisms are dysregulated in youths with narcolepsy, but evidence also exists of nonrapid eye movement (NREM) and circadian sleep-wake cycle abnormalities. REM-associated sleep phenomena intrude into the awakened state. Sleep attacks (sleep), cataplexy (abrupt atonia precipitated by strong emotions), hypnagogic and hypnopompic hallucinations (experienced as dreamlike events immediately before sleep onset or upon awakening) are characteristic of narcolepsy. Excessive daytime somnolence leading to irresistible/involuntary sleep (sleep attacks) may occur. The role of the neuropeptide hypocretin (Orexin) and human leukocyte antigen (HLA)–DR2/DBQ1 as a genetic-neuroimmune interaction is being considered in current research on this issue. Narcolepsy is consistent with the polygenic model of development in most human cases.

Obstructive sleep apnea syndrome (OSAS): The pathophysiology of OSAS is poorly understood. Alterations exist in alveolar ventilation and oxygenation. OSAS is associated with adenotonsillar hypertrophy; however, most youths with adenotonsillar hypertrophy do not experience OSAS. Upper airway neuromotor dysfunction is possible in the initiation of OSAS.

Periodic limb movements in sleep (PLMS): PLMS is more prominent in NREM stage 1 and 2 sleep. PLMS is strongly associated with ADHD and restless legs syndrome (RLS) in the pediatric population. The response to dopaminergic agents and the association with ADHD suggest that PLSM may be a dopaminergic dysfunction. Characteristic movements may aid in further understanding of the pathology of PLMS. Repetitive flexion of lower extremities (more common) or upper extremities occurs in youths with PLMS with a 0.5- to 5-second duration occurring 5-90 seconds apart. Repetitive jerks are associated with frequent awakenings and daytime somnolence or insomnia. The pediatric population with PLMS often experiences inattention, overactivity, and mood lability due to associated sleep disruption/fragmentation. PLMS can occur without RLS.

RLS: The response to dopaminergic agents and the association to ADHD implicate that RLS is a dopaminergic dysfunction. Leg discomfort in patients with RLS is associated with a strong urge to move legs, and the relief with movement may ultimately reveal a pathophysiology similar to that of akathisia. Most patients with RLS have PLMS. The pediatric population with RLS often experiences inattention, overactivity, and mood lability due to associated sleep disruption/fragmentation.

Limit-setting sleep disorder: This is a parent-child transactional model with potentially numerous biopsychosocial variables that influence interactions. It is not simply a failure to set limits but has a more complex pathogenesis and ultimately pathophysiology. Children with limit-setting sleep disorder resist or refuse to go to bed at an appropriate time. Limit-setting sleep disorder may be related to underlying pathophysiology as observed in ADHD and other neurodevelopmental disorders or may be a combined medical-behavioral issue.

Insufficient sleep syndrome: This is a condition of chronic sleep deprivation without an underlying disease process. Youths with insufficient sleep syndrome may experience an increased need for sleep during puberty and adolescence. Insufficient sleep syndrome may represent a poor compensatory ability for sleep loss and includes failure to adequately synchronize sleep-wake behaviors and adapt to environmental demands, such as school. The patient with insufficient sleep syndrome attempts to decrease sleep debt incurred during the week by sleeping later on the weekends. They are unable to obtain sufficient sleep because of school, extracurricular, occupational, and other societal demands.

Circadian sleep disorders: A circadian clock/oscillator located in the suprachiasmatic nuclei of the anterior hypothalamus influences the wakefulness or alertness phase. A circadian clock potentiates alternate or diurnal phases of the sleep-wake cycle. A free-running human sleep-wake cycle is 25 hours; however, the cycle entrained by the environment results in a 24-hour cycle. Sleep and associated processes are at opposite phases or periods in patients with circadian sleep disorders. Circadian sleep disorders may represent a poor compensatory ability for sleep loss and includes failure to adequately synchronize sleep-wake behaviors and adapt to environmental demands, such as school. This disorder is frequently observed in adolescents with delayed sleep phase.

Parasomnias

Parasomnias are sleep-related phenomena disrupting normal sleep. Events can take place during sleep-wake transitions, arousal, or REM sleep. Sleep stages and other variables are related to pathogenesis.

Sleepwalking: Sleepwalking is described as partial arousal from sleep during slow-wave stages 3 and 4. It is most common during the initial third stage of the sleep period.

Bruxism (persistent grinding of the teeth): Bruxism is considered as a stereotyped movement disorder or rhythmic disorder. It is more frequent during the early part of sleep and may be related to stress and/or anxiety or dentition abnormalities. Bruxism is not limited to sleep but may also occur while the child is awake. Basal ganglia dysfunction has been hypothesized.

Nightmares: Nightmares appear to be related to the same etiology as other anxiety-related experiences. They occur during REM sleep.

Sleep terrors: Sleep terrors are associated with autonomic arousal and screaming. They transpire during the first third of sleep in the slow-wave sleep cycle.

Primary nocturnal enuresis: Bladder instability, which is an uninhibited or reduced threshold for detrusor contraction during bladder filling, and urethral instability, which is a failure of urethral sphincter to adequately relax with bladder filling, are characteristic of youths with primary nocturnal enuresis. Youths with primary nocturnal enuresis may have a relative resistance to an antidiuretic hormone at night. Genetic factors contribute significantly in primary nocturnal enuresis with linkage studies positive on chromosome 8. No correlation exists with sleep stage.

Rhythmic movement disorders: These disorders are related to the developmental age of the child. Head banging and body rocking are the most common presentations of this disorder. Rhythmic movement disorder occurs during sleep onset and stages 1 and 2 sleep (light sleep).

Confusional arousals: In a confusional arousal, the child may awaken from stage 1 and 2 sleep frightened and crying. Only minimal autonomic arousal occurs opposed to the high degree observed in sleep terrors. The patient usually fully awakens before returning to sleep. Confusional arousals are associated with higher rates of delayed sleep onset, night awakening, decreased sleep duration, and bedtime resistance.

 

 

 

Supported  by

CHILDREN SLEEP CLINIC

Yudhasmara Foundation

Office ; JL Taman Bendungan Asahan 5 Jakarta Indonesia 10210

phone : 62(021) 70081995 – 5703646

email : judarwanto@gmail.com,

https://sleepclinic.wordpress.com/

 

 

 

Clinic and Editor in Chief :

Widodo Judarwanto, pediatrician

email : judarwanto@gmail.com

curriculum vitae

 

 

Copyright © 2009, Children Sleep Clinic  Information Education Network. All rights reserved


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