Sleep Disorders Flashcards
Narcolepsy and cataplexy
Narcolepsy is a disorder of unknown etiology that is characterized by excessive
sleepiness that typically is associated with cataplexy and other REM sleep phenomena, such as sleep paralysis and hypnagogic hallucinations.
The excessive sleepiness of narcolepsy is characterized by repeated episodes of naps or lapses into sleep of short duration (usually less than one hour). The narcoleptic patient typically sleeps for 10 to 20 minutes and awakens refreshed but within the next two to three hours begins to feel sleepy again, and the pattern repeats itself.
There may be sudden and irresistible sleep attacks in situations where sleep normally never occurs (e.g. during an examination or while eating). A history of cataplexy is a characteristic and unique feature of narcolepsy. It is
characterized by sudden loss of bilateral muscle tone provoked by strong emotion. Consciousness remains clear, memory is not impaired, and respiration is intact. The duration of cataplexy is usually short, ranging from a few seconds to several minutes, and recovery is immediate and complete. Cataplexy is always precipitated by emotion that usually has a pleasant or exciting component, such as laughter, elation, pride, anger, or surprise.
The use of tricyclic antidepressant medications such as protriptyline hydrochloride or imipramine hydrochloride almost always ameliorates cataplexy.
Sleep paralysis, hypnagogic hallucinations, automatic behaviour, and nocturnal sleep disruption commonly occur in patients with narcolepsy. Both sleep paralysis and hypnagogic hallucinations almost always correspond with sleep-onset REM periods.
Narcolepsy most commonly begins in the second decade, with a peak incidence around 14 years of age.
Periodic limb movement disorder
Periodic limb movement disorder is characterised by periodic episodes of repetitive and highly stereotyped limb movements that occur during sleep. The movements usually occur in the legs and consist of extension of the big toe in combination with partial flexion of the ankle, knee, and sometimes hip. Similar movements can occur in the upper limbs.
The movements are often associated with a partial arousal or awakening, however, the patient is usually unaware of the limb movements or the frequent sleep disruption. Between the episodes, the legs are still. There can be marked nightly variability in the number of movements. There may be a history of frequent nocturnal awakenings and unrefreshing sleep. Patients who are unaware of the sleep interruptions may have symptoms of excessive sleepiness.
Periodic limb movements may be an incidental finding, and medication that reduces the number of limb movements can produce little or no change in sleep duration or sleep efficiency. It is possible that a centrally mediated event can give rise to both the periodic movements and the related sleep disturbance.
Restless legs syndrome
Restless legs syndrome is a disorder characterised by disagreeable leg sensations that usually occur prior to sleep onset and that cause an almost irresistible urge to move the legs.
The most characteristic feature is the partial or complete relief of the sensation with leg motion and the return of the symptoms upon cessation of leg movements. The sensations and associated leg movements usually interfere with sleep onset.
Risk factors of restless legs syndrome
Older age Female sex Pregnancy Iron deficiency and anemia Renal failure Hypothyroidism Diabetes B12 deficiency
Jet lag syndrome
Jet lag syndrome consists of varying degrees of difficulties in initiating or maintaining sleep, excessive sleepiness, decrements in subjective daytime alertness and performance, and somatic symptoms (largely related to gastrointestinal function) following rapid travel across multiple time zones.
The sleep-wake disturbances generally abate after two to three days in the arrival location. Adaptation of the timing of physiologic functions other than sleep and waking may take eight or more days. Symptoms typically last longer following eastward flights.
Shift work sleep disorder
Shift work sleep disorder consists of symptoms of insomnia or excessive sleepiness that occur as transient phenomena in relation to work schedules.
The work is usually scheduled during the habitual hours of sleep (i.e., shift work-rotating or permanent shifts), roster work, or irregular work hours. The sleep complaint typically consists of an inability to maintain a normal sleep duration when the major sleep episode is begun in the morning (6 a.m. to 8 a.m.) after a night shift. The reduction in sleep length usually amounts to one to four hours (mainly affecting REM and stage 2 sleep). Subjectively, the sleep period is perceived as unsatisfactory and unrefreshing.
Non 24 hour sleep wake syndrome
Non 24 hour sleep wake syndrome consists of a chronic steady pattern comprising one to two hour daily delays in sleep onset and wake times in an individual living in society.
Patients with non 24 hour sleep wake syndrome exhibit a sleep-wake pattern
that is reminiscent of that found in normal individuals living without environmental time cues (i.e., sleep-onset and wake times occur at a period of about every
25 hours). At times, one or more noncircadian (longer than 27 hours) sleep-wake cycles may occur in the patient with the non-24-hour syndrome. In the long run, their sleep phase periodically travels in and out of phase with the conventional social hours for sleep. When in phase, the patient may have no sleep complaint, and daytime alertness is normal. As incremental phase delays in sleep occur, the complaint will consist of difficulty initiating sleep at night coupled with oversleeping into the daytime hours or inability to remain awake in the daytime. Therefore, over long periods of time, patients alternate between being symptomatic and asymptomatic, depending on the degree of synchrony between their internal biologic rhythm and the 24-hour world.
Sleepwalking
Sleepwalking consists of a series of complex behaviours that are initiated during slow-wave sleep and result in walking during sleep.
Episodes can range from simple sitting up in bed to walking and even to apparent frantic attempts to escape. The patient may be difficult to awaken but, when awakened, often is mentally confused. The patient is usually amnestic for the episode’s events. Sleepwalking originates from slow-wave sleep and, therefore, is most often evident during the first third of the night or during other times of increased slow-wave sleep, such as after sleep deprivation.
Sleepwalking episodes can occur as soon as a child is able to walk, but reach a peak prevalence between ages four and eight years, and usually disappear spontaneously after adolescence.
The use of lithium can exacerbate or induce sleepwalking.
Sleep terrors
Sleep terrors are characterized by a sudden arousal from slow wave sleep with a piercing scream or cry, accompanied by autonomic and behavioural manifestations of intense fear.
Sleep terrors manifest as a severe autonomic discharge, with tachycardia, tachypnea, flushing of the skin, diaphoresis, mydriasis, decreased skin resistance, and increased muscle tone. The patient usually sits up in bed, is unresponsive to external stimuli, and, if awakened, is confused and disoriented. Amnesia for the episode occurs, although sometimes there are reports of fragments or very brief vivid dream images or hallucinations. The episode may be accompanied by incoherent vocalizations or micturition.
Rhythmic movement disorders
Rhythmic movement disorder comprises a group of stereotyped, repetitive movements involving large muscles, usually of the head and neck. The movements typically occur immediately prior to sleep onset and are sustained into light sleep.
The most commonly recognised variant is head banging, which itself has several forms. The child may lie prone, repeatedly lifting the head or entire upper torso, forcibly banging the head back down into the pillow or mattress. The child may rock on hands and knees, banging the vertex or frontal region of the head into the headboard or wall. Or, the child may sit with the back of the head against the headboard or wall, repeatedly banging the occiput.
The vast majority of affected individuals are otherwise normal infants and children. However, when it persists into older childhood or beyond, rhythmic-movement disorder of sleep may be associated with mental retardation, autism, or other significant psychopathology.
Sleep starts
Sleep starts are sudden, brief contractions of the legs, sometimes also involving the arms and head, that occur at sleep onset. Sleep starts usually consist of a single contraction that often affects the body asymmetrically. The jerks may be either spontaneous or induced by stimuli. Sleep starts are sometimes associated with the subjective impression of falling, a sensory flash, or a visual hypnagogic dream or hallucination. A sharp cry may occur.
Nocturnal leg cramps
Nocturnal leg cramps are painful sensations of muscular tightness or tension, usually in the calf but occasionally in the foot, that occur during the sleep episode.
The symptom may last for a few seconds and remit spontaneously but, in some cases, may remain persistent for up to 30 minutes. The cramp often results in arousal or awakening from sleep. Patients with nocturnal leg cramps will often experience one or two episodes nightly, several times a week. The cramp can usually be relieved by local massage, application of heat, or movement of the affected limb.
Nightmares
Nightmares are frightening dreams that usually awaken the sleeper from REM sleep. The nightmare is almost always a long, complicated dream that becomes increasingly frightening toward the end. The long, dreamlike feature is essential in making the clinical differentiation from sleep terrors. The awakening occurs out of REM sleep.
Sleep paralysis
Sleep paralysis is a common condition characterized by transient paralysis of skeletal muscles which occurs when awakening from sleep or less often while falling asleep. It is thought to be related to the paralysis that occurs as a natural part of REM (rapid eye movement) sleep. Sleep paralysis is recognised in a wide variety of cultures.
Features include paralysis (after waking up or shortly before falling asleep) and hallucinations. If troublesome clonazepam may be used.
