Approach
The diagnosis of a parasomnia is based on a thorough history, usually from the bed partner. The diagnosis will help to guide the subsequent careful selection of tests.
Presence of risk factors
In general, parasomnias are more common in children than in adults, especially nonrapid eye movement (NREM) parasomnias.[1] Rapid eye movement sleep behavior disorder (RBD) and sleep-related cramps are more common at an older age. RBD is more common in men, while nightmare disorder is more common in women.[13][32] Parasomnias are frequently reported to occur after a forced awakening from sleep.
It is important to inquire about a family history of sleep disorder, as this is a very common finding in sleepwalking, and also occurs with confusional arousals and sleep terrors.[1] The presence of the human leukocyte antigen gene DQB1 is strongly associated with sleepwalking.[21]
Other primary sleep disorders, such as obstructive sleep apnea, sleep deprivation, and periodic limb movement disorders should be screened for, as these typically cause parasomnias.
Nightmare disorder is strongly associated with chronic or acute stress and psychiatric disorders, particularly posttraumatic stress disorder, but also anxiety, bipolar disorder, and depression.[18][46]
Certain medications and pharmacologic agents are strongly associated with particular disorders: venlafaxine and mirtazapine with RBD; norepinephrine, serotonin, and dopamine with nightmares and other sleep disturbances.[18][40][43][44][47] Neurodegenerative disorders such as Parkinson disease are strongly associated with RBD, as is narcolepsy, and sleep-related eating disorders have been reported to occur more frequently in people receiving treatment for a known eating disorder.[39] People with sleep-related eating disorders are also more likely to have a history of sleepwalking, sleeptalking, and periodic limb movements of sleep.[45]
History
The history is usually obtained from the bed partner when available. Patients with parasomnias may be reported to arouse from sleep and exhibit disturbed cognition, behavior, or both. Mental slowing, disorientation, and memory problems, as well as speech disturbances, are noted in confusional arousals.
Vigorous or even violent behavior may be present in confusional arousals, sleepwalking, sleep terrors, and RBD.[1][5] The sensation of a sudden loud noise in the head in exploding head syndrome may be virtually diagnostic.[48][49]
There are some features that can help distinguish NREM parasomnia and RBD. With NREM parasomnia, the events are typically in the first 1-2 hours of sleep onset, the eyes are often open during the event, and there is little to no dream recall. In contrast, RBD behaviors can happen throughout the sleep period but are typically after the first hour and most often late in the sleep period, when rapid eye movement sleep predominates. The eyes are closed, and there are often vivid dreams associated with the more vigorous events.
Witnesses of a person experiencing sleep terrors or nightmares may describe how frightened the patient appears to be. This is manifested in signs of autonomic hyperactivity such as tachycardia, tachypnea, and pupillary dilation.
In recurrent isolated sleep paralysis, episodes of inability to move and chest heaviness are described. Careful questioning for symptoms of narcolepsy such as cataplexy and hypnagogic and hypnopompic hallucinations is warranted before a diagnosis of recurrent isolated sleep paralysis is made.
Other important behavior data in parasomnias include the eating behavior noted in sleep-related eating disorder. The patient may recall eating behavior during the night, or the parasomnia may be described by a spouse, bed partner, or other household member.
In community-based surveys with RBD screening questionnaires, the chance of probable RBD was higher in those with lower educational level and lower socioeconomic status, as well as in those who had more risk factors for cardiovascular disease.[50]
Physical exam
In most parasomnias, the examination in the office is normal. However, there may be evidence of external injuries pointing toward a violent parasomnia such as RBD. People with RBD often develop neurodegenerative disorders that are usually synucleinopathies, such as Parkinson disease.[37][51] Therefore, people with RBD may have manifestations of these disorders, including the following:
Slowness of thought
Memory difficulties
Decreased facial expression
Extraocular movement abnormalities
Resting tremor
Bradykinesia
Rigidity of the extremities, possibly with cogwheeling
Gait abnormalities such as shuffling and instability
Chorea
Overnight polysomnography (PSG)
If any investigations are required to confirm the diagnosis of a particular type of parasomnia, the first step would most frequently be overnight PSG with extended electroencephalographic (EEG) montage to rule out atypical presentation of seizures. PSGs for NREM parasomnias are higher yield if leg electrodes are included as well as psychotropic medications stopped.[52] Expanded EEG electrodes during the PSG are useful to evaluate for sleep-related hypermotor epilepsy. In some parasomnias, the diagnosis is not obvious from the history alone, and many would suggest that if the behavior is bothersome enough to treat, then PSG evaluation is indicated. PSG is also indicated if there is a suspicion of a primary sleep disorder such as obstructive sleep apnea or periodic limb movement disorder. PSG should be requested when a complaint of leg kicking is voiced by the patient's bed partner. PSG is essential if RBD is suspected.[53] In RBD, PSG shows evidence of increased electromyography tone during episodes of rapid eye movement sleep and evident abnormal behavior documented on video monitoring during an episode. This may include shouting and swearing, kicking, punching, and even jumping out of bed. PSG is not required for the diagnosis of confusional arousals, sleepwalking, sleep terrors, or sleep-related eating disorder, but can help. It is not required for nightmare disorder, sleep-related hallucinations, or exploding head syndrome.[2][54]
PSG can aid diagnosis in unusual cases and may reveal comorbid conditions that increase the likelihood of parasomnia events. Although PSG is not necessarily required for the diagnosis of confusional arousals, sleepwalking, sleep terrors, or sleep-related eating disorder, it can have a very high diagnostic yield.[55]
In recurrent isolated sleep paralysis, no tests are necessary unless narcolepsy is suspected. In enuresis, a PSG is required if obstructive sleep apnea is suspected.
Further investigations
PSG with expanded EEG can be used to determine the presence of epilepsy.[1] However, if the test is not diagnostic, a prolonged EEG for 24-48 hours should be considered if nocturnal seizures are suspected in the differential diagnosis of confusional arousals, sleepwalking, sleep terrors, and RBD.[56] Epileptiform spikes may be noted. In some cases, clinical seizure activity during EEG monitoring may be accompanied by an electrographic seizure. EEG may also be required in enuresis to rule out nocturnal seizures. The frontal lobe epilepsy and parasomnia scale, a validated questionnaire for the diagnosis of nocturnal events, can aid diagnostic confidence between NREM parasomnia and sleep-related hypermotor epilepsy, but it cannot distinguish either of these from RBD.[56]
A urine drug screen is also indicated if drug misuse is suspected.
In sleepwalking episodes, EEG shows increased slow-wave activity and slow oscillation density.[57]
Use of this content is subject to our disclaimer