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Introduction
Sleep is essential for:
Restorative processes.
Maintaining cognitive performance and work productivity.
Physical, psychological, and emotional well-being.
The brain requires sleep to function and control movements and thoughts. edited me
Normal Sleep Physiology
Assessed by polysomnography (PSG).
Sleep staging using electroencephalography (EEG).
Multi-channel recording of video, snoring, nasal airflow, and thoracic and abdominal respiratory effort.
Produces an apnea-hypopnea index (AHI).
Sensors to detect body position and leg movement.
EEG and video are often omitted in assessments of subjects likely to have sleep-related breathing disorders.
Facilitates portable (ambulatory) or home monitoring as cardio-respiratory polygraphy.
During normal sleep, PSG shows cycling through periods:
Light sleep (stages 1 and 2).
Deep sleep (N3, comprising former stages 3 + 4). 丟垃圾
Brain is resting and becomes refreshed.
Rapid eye movement (REM) sleep. 長知識
Brain is active in consolidating thoughts, learning, and memory.
As the night progresses, periods of deep sleep become shorter, while REM periods become longer.
In REM sleep:
Pathognomonic rolling eye movements are noted.
Generalized inhibition of skeletal muscles, including intercostal, accessory, and pharyngeal dilators. → 剩下 diaphragm largely supports ventilation，因此 respiratory rate 增加
Ventilatory failure more likely, particularly in subjects with respiratory or neuromuscular disorders.
【看不懂在寫三小啊～～～】Sleep onset leads to hypoventilation with reduced metabolic rate.
Loss of voluntary and emotional control of breathing.
Loss of wakefulness drive and decrease in reticular activating system (RAS) activity rate. → Leads to dependence on brainstem reflex activity.
Reduced ventilation leads to a rise in partial pressure of carbon dioxide (PaCO2), and consequent fall in partial pressure oxygen (PaO2).
Small rise in PaCO2 is necessary to exceed the apneic threshold and maintain ventilation.
Reduced medullary phasic electrical activity.
Reduced chemo-sensitivity to partial pressures of arterial carbon dioxide (PaCO2) and oxygen (PaO2), together with increased airway resistance.
Respiratory system is less able to adapt to changes in sleep, including hypoxemia.
Endogenous circadian rhythm exists in pulmonary function, respiratory control, and basal metabolism.
Appears independent of daily changes in behavior (including sleep) and environment.
During the night:
Diurnal falls in cortisol levels and body temperature occur.
Increased cholinergic tone may lead to increased airflow limitation in patients with chronic obstructive pulmonary disease (COPD).
Sleep Deprivation
Acute sleep deprivation leads to:
Impaired cognitive, psychomotor, and executive function.
Increased cortisol.
Impaired glucose tolerance.
Androgen deficiency.
Increased appetite due to a reduced blood leptin/ghrelin ratio.
leptin：瘦素，抑制食慾、降低脂肪儲存、增加脂肪燃燒
ghrelin：飢餓素，增加食慾
Longer-term sleep deprivation may lead to:
Deranged metabolism with obesity.
Increased insulin resistance and risk of diabetes mellitus.
Hyperlipidemia.
Cardiovascular disease, coronary events, and increased all-cause mortality.
Sleep deprivation has been shown to affect pulmonary function.
Significant decline in minute ventilation and inspiratory muscle endurance after 24 hours.
May lead to 5–6% fall in forced expiratory volume in one second (FEV1) and forced vital capacity (FVC) in COPD.
Sleep restriction and fragmentation may occur due to:
Emotional stress.
Environmental factors such as shift work.
Acute and chronic medical conditions, including obesity.
Specific sleep disorders.
Excessive Daytime Sleepiness
Subjective marker of many sleep disorders.
Can affect up to 12% of the normal population.
More common in subjects with snoring, obesity, diabetes mellitus, and renal failure.
Difficult to quantify consistently or objectively.
The Epworth Sleepiness Scale (ESS) score is commonly used as a validated simple self-administered assessment tool.
A score of more than 10 is considered significant, but lower scores may not exclude sleepiness, possibly due to misinterpretation of the test. ← 共8題，每題3分
The multiple sleep latency test (MSLT) uses EEG to assess how quickly a subject falls asleep during 5 attempted naps over the course of a day.
A shortened mean sleep latency of less than 8 minutes is considered consistent with pathological excessive sleepiness.
Sleep diaries (logs) may help to confirm adequate sleep opportunity.
The maintenance of wakefulness test (MWT) conversely assesses how long a subject can remain awake and may indicate reduced alertness if mean sleep latency is less than 20 minutes.
Correlation between subjective and objective measurements may be poor.
Psycho-motor vigilance can be measured using the Oxford Sleep Resistance (Osler) test, and in driving simulators.
Classification of Sleep Disorders
The International Classification of Sleep Disorders describes a range of respiratory and non-respiratory conditions.
May be associated with insomnia or excessive daytime sleepiness while awake, or behavioral abnormalities in sleep
Insomnia
Criteria include a report of subjective difficulty with sleep initiation or maintenance, including waking up earlier than desired, resistance to going to bed on appropriate schedule, or difficulty sleeping without parent or caregiver intervention.
Must be associated with adequate opportunity and circumstances to sleep.
Requires a report of daytime consequences, including:
Fatigue or malaise.
Impairment of attention, concentration, or memory.
Impaired social, family, occupational, or academic performance.
Mood disturbance or irritability.
Daytime sleepiness.
Behavioral problems (e.g., hyperactivity, impulsivity, aggression).
Reduced motivation, energy, or initiative.
Proneness for errors or accidents.
Concerns about, or dissatisfaction with, sleep.
Occasional insomnia common (50%), with 6–10% describing chronic insomnia.
Common in a range of medical and psychiatric disorders.
Short-term insomnia often associated with an identifiable cause or trigger, commonly particular daytime stressors.
Chronic insomnia disorder is defined by symptoms at least three times per week for a duration of 3 months.
Usually only made when the insomnia is especially prominent or unexpectedly prolonged, and under assessment or treatment.
Combines a number of categories previously defined as psychophysiological insomnia, idiopathic insomnia, sleep-state misperception, and inadequate sleep hygiene.
Diagnosis relies on a medical, sleep, and psychiatric history and is aided by keeping a sleep log.
Predisposing, potentiating, and precipitating factors may be identified.
Management involves dealing with identified underlying causes and considering behavioral and drug therapies.
Sleep hygiene advice includes restriction of caffeine and alcohol, especially during the evening.
Cognitive behavioral therapy for insomnia (CBTI) also includes relaxation, stimulus control, and sleep restriction techniques.
CBTI is preferred but can be combined with pharmacological treatments including benzodiazepines, non-benzodiazepines, and low-dose antidepressants.
Hypnotics should be used for a maximum of 2–3 per week to avoid dependence.
Sleep-Related Breathing Disorders
Include a spectrum of problems with similar pathophysiology:
Obstructive sleep apnea hypopnea (OSA).
Sleep-related hypoventilation.
Less common condition of central sleep apnea (CSA).
Children and adults with tonsillar hypertrophy, craniofacial syndromes, and neuromuscular disorders have an increased risk.
Although patients may be asymptomatic, ventilatory failure during sleep and consequent sleep fragmentation usually lead to presentation with one or more associated problems:
Snoring.
Subjective sleep disturbance.
Excessive daytime sleepiness.
Witnessed pauses in breathing.
Right heart failure (cor pulmonale).
Cardio-metabolic comorbidities.
Children may present with:
Insomnia.
Enuresis (尿床).
Behavioral problems.
Hyperactivity.
Reduced attention span, memory, and learning ability.
Impaired growth due to lack of deep sleep necessary to produce growth hormone.
Snoring is generated by the vibration of anatomical structures of the nasopharynx during sleep.
Prevalence of habitual snoring ranges from 24% to 50% in men and from 14% to 30% in women and increases with age, obesity, alcohol ingestion, and nasal obstruction.
Isolated snoring, although asymptomatic, results in social disability and relationship disharmony.
General population surveys have found a strong correlation between snoring and daytime sleepiness.
Snoring with sleepiness as features of obstructive sleep apnea has been associated with hypertension, ischemic heart disease, diabetes mellitus, and cerebrovascular accident, as well as increased morbidity and mortality from road traffic and work-related accidents.
Obstructive Sleep Apnea (OSA)
Common condition comprising intermittent complete collapse of the pharyngeal airway, followed by brief arousals or awakenings which then enable return of breathing.
The term obstructive sleep apnea-hypopnea (OSAH) is used to include episodes of breathing with reduced amplitude.
The condition may be asymptomatic but often presents with witnessed snoring, pauses in breathing or choking during sleep, or with symptoms due to sleep fragmentation including excessive sleepiness, impaired alertness, loss of concentration or memory, comprising the OSAH syndrome (OSAHS).
Upper airway resistance syndrome (UARS) is classified as a variant of OSA, characterized by increased airway resistance to breathing during sleep, without cessation of breathing.
The primary symptoms are similar to those in OSAS, although snoring may not be noted.
Sleepiness and excessive fatigue develop due to arousals in sleep with changes in pulse transit time associated with respiratory flow limitation, and increased negative intra-thoracic pressure.
The pathophysiology of OSA includes intermittent hypoxia and possibly sympathetic activation which drive insulin resistance and disordered lipid metabolism, as well as a systemic inflammatory cascade with free-radical production, inflammatory cytokine release, and oxidative stress.
Interaction of hemodynamic and inflammatory changes promote vascular endothelial growth factor, endothelial dysfunction, and vascular remodeling, which may combine to promote the development of atherosclerosis and cardiovascular disease, including heart failure and arrhythmias.
Organ, tissue, or functional impairment is related to the severity of nocturnal hypoxia.
OSA may play a causative role in the development of hypertension, insulin resistance and hyperlipidemia in the cardio-metabolic syndrome, as well as in heart failure, pulmonary hypertension, coronary artery disease, arrhythmias, and cerebrovascular accidents.
Patients with heart failure may have less subjective daytime sleepiness despite significantly reduced sleep time, such that the absence of subjective sleepiness is not a reliable means of ruling out OSA.
OSA is a risk factor for stroke independently of sex, body mass index (BMI), diabetes, and hypertension, at least in men.
Hypothyroidism, acromegaly, and chronic renal failure may also be associated with OSA.
Studies have reported impaired glucose metabolism in OSA patients, independent of obesity, although possibly related to visceral obesity, and with prevalence 9 times more in subjects with OSA than controls matched for BMI.
Insulin resistance may develop due to the effect of intermittent hypoxia and increased sympathetic activity.
Cross-sectional studies show a strong association of diabetes mellitus with OSA, but in longitudinal studies, the incidence of diabetes was not related to the initial severity of OSA.
These cardiovascular and metabolic associations may, in addition to road traffic and work-related accidents, contribute to the increased morbidity and mortality associated with OSA, and the reduction in mortality seen in uncontrolled treatment studies using continuous positive airway pressure (CPAP).
Central Sleep Apnea (CSA)
CSA comprises recurrent episodes of apnea during sleep despite a patent airway.
CSA may be associated with periodic breathing in left ventricular cardiac failure with Cheyne-Stokes respiration (CSR) in which there is temporary loss of ventilatory effort or unstable ventilatory control (CSR-CSA).
This may have an adverse effect on cardiac prognosis and mortality as it is associated with sympathetic activation, ventricular ectopy, and atrial fibrillation.
Central sleep apnea, right ventricular dysfunction, and low diastolic BP are predictors of mortality in systolic heart failure.
CSA may develop in subjects at high altitude and those with neurological disorders, autonomic dysfunction, or narcotic opiate drug toxicity even at therapeutic dosage.
CSA may also occur with OSA in patients with nasal obstruction or after treatment with continuous positive airways pressure (CPAP) which reduces PaCO2.
Management involves treatment of the underlying condition, and continuous positive airway pressure (CPAP) and oxygen may be used.
Sleep-Related Hypoventilation Disorders
Obesity hypoventilation syndrome (OHS) is the combination of obesity (BMI > 30 kg/m2), with hypoxia during sleep, and hypercapnia during the day, due to hypoventilation.
About one third of all people with morbid obesity (a BMI exceeding 40 kg/m2) have elevated carbon dioxide levels in the blood.
Typical clinical features include obesity, excessive daytime sleepiness, a plethoric complexion, cyanosis, and evidence of right heart failure including peripheral edema.
Patients may not complain of dyspnea despite obvious hypoxemia.
Almost all subjects with OHS will also have OSAS as an overlap syndrome.
Alternative explanations for hypoventilation must be excluded, including use of narcotics, severe obstructive or interstitial lung disease, kyphoscoliosis, severe hypothyroidism, neuromuscular disease, and congenital central hypoventilation syndrome.
Overlap Syndromes
OSA commonly coincides with Chronic Obstructive Pulmonary Disease (COPD) and OHS, and those with COPD may have more severe nocturnal oxygen desaturation, and considerably greater risk of death.
Features of cor pulmonale and pulmonary hypertension may be prominent.
OSA may also coincide with narcolepsy and may be a trigger for non-respiratory sleep disorders including sleepwalking and parasomnias.
Assessment of Sleep Breathing Disorders
A structured assessment and screening of patients with associated comorbidities will identify people with a high probability for sleep breathing disorders.
Reporting of apnea by the bed partner has been more predictive of sleep apnea than snoring alone.
Validated screening questionnaires for OSAS include the Epworth Sleepiness Scale (ESS) score and the STOP-BANG questionnaire which has proved useful in pre-operative anesthetic risk assessment.
Examination may reveal obesity (in 70% of patients with obstructive sleep apnea), with BMI >30, often with increased neck circumference (often > 40cm) and waist circumference (men > 94cm; women > 80cm).
Some patients may have nasal airway obstruction (deviated nasal septum, rhinitis, or polyps) or enlarged soft palate, tonsils, or uvula.
Signs of cor pulmonale may occasionally be present, including ankle swelling.
Physiological Investigation of Sleep-Related Breathing Disorders
Cardio-respiratory polygraphy (multi-channel portable or ambulatory monitoring) allows diagnosis of sleep apnea, classification, and assessment of severity in most patients with typical OSA in a home or inpatient setting.
OSA is detected as an absence of nasal airflow with the persistence of chest and abdominal respiratory effort using nasal airflow, chest, and abdominal sensors, to measure respiration, producing an apnea-hypopnea index (AHI).
Oximetry in OSA typically shows a normal baseline oxygen saturation with intermittent dips and a 4% oxygen desaturation index (ODI) (blood oxygen level drops by a certain degree from baseline，所以是僅根據SpO2而獲得的結果) of more than 10 per hour, together with heart rate variability.
Overnight oximetry alone is relatively specific but insensitive for OSA such that absence or relative paucity (匱乏) of oximetry dips does not exclude sleep apnea.
Periods of low baseline oxygen saturation suggest other causes of respiratory failure, including sleep hypoventilation syndromes and COPD which may be concurrent with OSA as overlap syndromes.
Oxygen desaturation may occur due to other respiratory and cardiac disorders, and expert interpretation is essential.
In UARS, apneas and hypopneas are absent or low in number, but a diagnosis may be made using a nasal cannula and pressure transducer to measure inspiratory airflow limitation and detect a pattern known to be associated with respiratory related arousals (RERA) on EEG.
Full PSG may be required in complex sleep disorders including cases of possible OSA which may overlap with comorbidities including cardiac failure, COPD, upper airway resistance, obesity hypoventilation syndrome, or non-respiratory sleep disorders including periodic limb movement and narcolepsy.
Full PSG adds an electroencephalogram (EEG) for sleep staging and video recording and may help to differentiate OSA from nocturnal epilepsy or demonstrate OSA as a trigger for sleepwalking or other sleep behavioral disorders (parasomnias).
In UARS, multiple RERAs may be seen on EEG in association with nasal flow limitations, and if an esophageal probe is used, progressive elevation of esophageal pressure fluctuations (Pes) terminating in arousals.
Management of Sleep Breathing Disorders
General measures include behavioral modification and lifestyle advice comprising weight control, elevation of the bed head, and avoidance of supine posture, alcohol, tobacco, sedatives, and narcotics (毒品).
Significant weight loss has been associated with a ‘cure’ rate of 10–20% in OSAHS.
Treatment of nasal congestion using nasal steroids may be helpful, especially if there is nasal obstruction or upper airway resistance due to rhinitis.
Driving should be avoided if excessively sleepy, and subjects with OSAS must inform the relevant driving licensing authority of the diagnosis.
Driving may be allowed if symptoms are controlled on treatment, with confirmation by medical opinion.
A range of interventions may be employed in the treatment of sleep breathing disorders, including weight management, nasal continuous positive airway pressure (CPAP), oral appliance therapy, and surgical intervention in OSAHS, as well as non-invasive bi-level ventilation in sleep hypoventilation syndromes.
Central Disorders of Hypersomnolence
Narcolepsy and Cataplexy
Narcolepsy is a condition in which subjects develop severe, often unavoidable chronic sleepiness, with fragmented sleep and frequent awakenings at night, often beginning in early adolescence or adult life.
Its prevalence is 1 in 2500, but most are undiagnosed.
Consequent problems include avoidance of social or emotional situations, exam failures, few work opportunities, marital difficulties, low self-esteem, and depression.
Narcolepsy may be associated with other sleep disorders including restless legs syndrome (RLS) and periodic limb movement syndrome (PLMS), parasomnias, snoring, OSA, and disorders of appetite and mood.
Sleepiness is usually severe, with ESS score often above 15.
Subjects often develop hypnagogic (sleep onset) or hypnopompic (sleep offset) hallucinations and sleep onset/offset paralysis due to REM intrusion into wakefulness while falling asleep or on waking.
These are, however, non-specific features of sleep deprivation, and they may occur in other conditions of significant sleep loss including shift work or sleep apnea.
Cataplexy (猝倒症) develops in 60% of subjects.
During wakefulness, REM intrusions cause sudden episodes of bilateral muscle weakness leading to partial or complete collapse and often triggered by strong emotions such as laughter, anger, or excitement.
Episodes last 1–2 minutes and are not associated with impairment of consciousness at onset.
Narcolepsy is usually sporadic and possibly autoimmune or related to brain injury, but genetic factors play an important role with a 40-fold risk in first-degree relatives.
Most narcoleptics (50–90%) have HLA DR2 or DQB1*0602 antibody subtypes.
The pathophysiology of classical narcolepsy involves a deficiency of the hypothalamic excitatory neuropeptide hypocretin 下視丘泌素 (= orexin 食慾素).
This is required to stabilize the hypothalamic sleep/wake switch between sleep promotion (ventro-lateral pre-optic nucleus) and wake promotion (tubero-mamillary nucleus).
CSF examination reveals the absence of hypocretin (orexin) in 90% of subjects.
PSG may show a short REM latency 5–10 mins (in 50%).
Frequent intrusions of REM cause fragmentation of deeper sleep, although total sleep time and time in REM are normal.
A daytime MSLT may show sleep-onset REM (SOREM) episodes.
A diagnosis of classical narcolepsy (Type 1) requires either cerebrospinal fluid hypocretin-1 deficiency (<110 pg/mL or less than one-third of the normative values with the same standardized assay) or a mean latency of <8 min with evidence of two SOREMPs on MSLT (or one SOREMP on PSG and one or more on MSLT) and clear cataplexy.
Narcolepsy Type 2 maintains the same MSLT requirements, but cataplexy must be absent, and cerebrospinal fluid hypocretin-1 levels, if measured, must not meet the narcolepsy Type 1 criterion.
The differential diagnosis of narcolepsy includes OSA, depression, REM deprivation, and drug toxicity, while the differential diagnosis of cataplexy includes epilepsy (especially gelastic and atonic), vertebro-basilar insufficiency, cardiac dysrhythmias, drop attacks, myasthenia gravis, periodic paralysis, faints, gelastic syncope, and hysteria.
Management of narcolepsy includes planned napping, sleep hygiene, and psychosocial support.
Sleepiness may respond to stimulants including modafinil, dexamphetamine, or methylphenidate.
Cataplexy may respond to REM sleep-suppressing medications including tricyclic and SSRI antidepressants.
Sodium oxybate or pitolisant may control cataplexy as well as sleep fragmentation and excessive daytime sleepiness.
Hypersomnia may also be idiopathic or due to medical or psychiatric disorders including Kleine-Levin Syndrome.
Behaviorally induced insufficient sleep can be excluded by actigraphy or sleep logs to record wake and sleep using body movements over periods of days.
Circadian Rhythm Sleep-Wake Disorders
Circadian rhythm problems include jetlag, shift work sleep disorder, and advanced or delayed sleep phase syndromes.
Delayed sleep phase is not uncommon in younger subjects who may be genetically predisposed to be ‘night-owls’ with difficulty in rising and excessive morning sleepiness.
Symptoms may be incorrectly attributed to insomnia or depression, although these may be true comorbidities.
Assessments are made using sleep diaries and actigraphy to record wake and sleep using body movements over periods of days.
Treatment involves advancing sleep onset by use of evening melatonin and morning bright light therapy.
Parasomnias
The term parasomnia encompasses sleep-related behaviors, emotions, perceptions, dreaming, and autonomic nervous system events during entry into sleep, within sleep, or during arousals from sleep.
Parasomnias may occur in non-REM and REM sleep.
Non-REM Parasomnias
Include sleepwalking, sleep talking, confusional arousals, sleep terrors, sleep-related nocturnal eating disorder, and catathrenia (夜間呻吟 groaning).
Instinctual behaviors, including violence and sexual activity, may be released inappropriately.
Arousals in sleep leave the individual in a state of incomplete awakening, with inappropriate responsiveness.
Higher cognitive functions and social inhibitions may be absent or impaired, and primitive behaviors may appear unexpectedly with partial or complete amnesia.
Predisposition to non-REM parasomnias may be based on genetic susceptibility with a familial pattern.
A priming factor may trigger an episode, for example, sleep deprivation, situational stress, medications, fever, alcohol, sleep-disordered breathing (e.g., OSA), PLMS, noise, and touch.
Assessment requires a full medical and sleep history, neuropsychiatric and psychometric examination, and EEG.
PSG may reveal precipitating and modulating factors including OSA or PLMS.
Treatment comprises reassurance and explanation of the mechanisms and potentiating factors, and treatment of confirmed priming or trigger factors.
Counseling and psychological intervention with cognitive behavioral therapy may have a role.
Drug therapy is usually avoided in the absence of behavior that causes violence to the subject or others.
In that event, clonazepam or other sedatives are usually advised until the parasomnia resolves in the hope that a normal sleep pattern will return without prolonged drug therapy.
Subjects with non-REM parasomnia (e.g., sleepwalking) may expect occasional relapse if under particular emotional stress, physically ill with fever or other physical stress, or under the influence of alcohol, drugs, or other toxins.
REM-Related Parasomnias
Include REM sleep behavior disorder (RBD), nightmares, and recurrent isolated sleep paralysis.
RBD involves vocalization or dream enactment during REM sleep, without the normal loss of muscle tone.
The dream-enacting behaviors are usually non-directed and may include punching, kicking, leaping, or jumping from bed while asleep.
Subjects may recall the dream that corresponds to the physical activity, sometimes vividly or as nightmares.
Abnormal sleep movements may lead to injuries including bruising, lacerations, fractures, and subdural hematomas.
Subjects are often middle-aged or older at the time of presentation, and RBD may be a precursor of degenerative brain disease or Parkinson’s disease.
Acute RBD may follow withdrawal of alcohol or drugs including pentazocine, nitrazepam, tricyclic antidepressants, or caffeine.
Chronic RBD may follow toxicity from tricyclic or SSRI antidepressants, selegiline, or anticholinergics.
Chronic RBD may also be associated with neurodegenerative conditions, synucleinopathies (Parkinson’s disease, multiple system atrophy, and dementia with Lewy bodies), and other neurological disorders including multiple sclerosis, Guillaine-Barre syndrome, Shy-Drager syndrome, Arnold-Chiari malformation, Alzheimer’s dementia, ischemic strokes, and narcolepsy.
RBD may reflect dysfunction in the brainstem circuitry and the dorsolateral pontine tegmentum mechanisms responsible for the normal suppression of muscle tone and paralysis in REM sleep.
PSG may show persistence of EMG tone in REM sleep, absence of seizure activity, and gross complex body movements that correspond to dream mentation.
Management of REM-related parasomnias comprises the removal of potential drug or other triggers.
Drug therapies including clonazepam or other benzodiazepines, and melatonin may be helpful, avoiding the potential risks of opiate sedation.
Epilepsy may co-exist with, or mimic, sleep disorders.
Sleep deprivation can increase the risk of seizure activity, and seizures can affect the sleep-wake cycle.
Nocturnal frontal lobe epilepsy may occur only during sleep and can present with bizarre movements such that differentiation from parasomnia may be difficult, and expert assessment is required.
Sleep-Related Movement Disorders
Include restless legs syndrome (RLS), periodic limb movement disorder (PLMD), and sleep-related bruxism (teeth grinding).
RLS is a clinical diagnosis, characterized by symptoms including unpleasant, creeping, or crawling sensations deep within the lower legs, but sometimes in the upper limbs.
It occurs only after rest and is diurnal, becoming most severe in the late evening.
There is an almost irresistible urge to move the legs, with relief on movement such as walking. Test save
The prevalence of RLS is 5–10%, and it is slightly more common in women.
It occurs at any age, but commonest onset is in those aged in the 5th and 6th decades.
60–80% of cases are familial with autosomal dominance and variable penetrance.
More than 80% of RLS patients have PLM in sleep (PLMS), although not all PLMS patients have RLS.
PLMS comprises involuntary rhythmic muscular jerks, with extension of the great toe and dorsiflexion of ankles or other joints.
PSG demonstrates a series of 4 or more consecutive movements lasting 0.5–20 seconds with an interval of 4–90 seconds.
PLMS at a rate of more than 5 per hour, associated with arousals, can present as insomnia, excessive sleepiness, or movements that wake the patient or bed-partner.
PLMD may be diagnosed when, in the absence of RLS, the frequency of PLMs is >15 per hour accompanied by clinical sleep disturbance or other functional impairment.
Predisposing factors for RLS/PLMS include some genetic variants, positive family history, and female sex.
Precipitating factors include iron deficiency, often related to pregnancy, menorrhagia, chronic renal failure, or rheumatoid arthritis.
RLS/PLMS may be precipitated or worsened by prolonged immobility, caffeine, nicotine, and alcohol, and also by anti-depressants and dopamine antagonists including anti-psychotic and anti-emetics.
PSG can reveal periodic limb movement and associated arousals.
Physiological changes include microarousals with fragmentation of normal sleep architecture, reduced time asleep, and frequent wakening.
The pathology in PLMS may involve defective dopaminergic neurotransmission and abnormal iron uptake and storage in the substantia nigra where it is a dopamine substrate.
Management is by avoidance of caffeine, tobacco, and alcohol stimulants, as well as regular daily exercise, good sleep hygiene, and avoidance of medicines that trigger symptoms.
Prolonged iron therapy is indicated if serum ferritin is low or low normal (<50ng/ml) even if hemoglobin is normal.
Treatment options include gabapentin, pregabalin, or dopaminergic agonists (rotigotine, ropinirole, pramipexole, L-dopa).
Benzodiazepines, opiates, and anticonvulsants can also be effective.
Summary
Sleep disorders are common causes of morbidity and mortality, affecting the population beyond those with the condition.
The presentation of sleep disorders is myriad due to complex pathophysiological mechanisms, such that important treatable conditions are often unrecognized.
Greater awareness and screening of those at risk, including those with associated comorbidities, and those undergoing anesthetic assessment and surgery, will lead to improved diagnosis and management outcomes.
Key points
Excessive daytime sleepiness that is severe or unavoidable is suggestive of narcolepsy (sleep attacks), especially if associated with cataplexy.
Excessive sleepiness may be due to multiple sleep disorders (e.g., narcolepsy and sleep apnea, both often associated with excessive weight).
Sleep Maintenance insomnia associated with excessive daytime sleepiness suggests an underlying primary sleep disorder as a cause of arousals (e.g., sleep apnea or periodic limb movement).
Sleep initiation insomnia without excessive daytime sleepiness suggests adequate sleep but a possible psychological cause or misperception of actual sleep.
RLS is a clinical diagnosis based on symptoms, whereas diagnosis of periodic limb movement requires PSG.
Sleepwalking (non-REM parasomnia) is common, and often associated with a family or previous childhood history and complex stereotypical movement (e.g., talking).
Parasomnias need careful differentiation from seizure disorders and degenerative brain disease, especially if movements are bizarre.
Consider obstructive sleep apnea in subjects with snoring, witnessed apneas, nocturnal choking or snorting, and excessive daytime sleepiness.
Sleep maintenance insomnia with wakings and arousals associated with excessive daytime sleepiness suggests a possible underlying sleep disorder, e.g., sleep apnea or periodic limb movement. Test being edited
Consider nocturnal hypoventilation in subjects with morning headache, otherwise unexplained ankle swelling (reflecting cor pulmonale and pulmonary hypertension).
Screen for obstructive sleep apnea prior to anesthesia and surgery in subjects at high risk including those with retrognathia, craniofacial abnormalities, obesity, hypertension, diabetes mellitus Type 2, cardiovascular disease, and cerebrovascular disease (e.g., stroke).