Parasomnias

Parasomnias are unwanted events or experiences that occur during sleep, during the transition from wake to sleep, or during arousals from sleep. Parasomnias may result from a mixed or unstable state of consciousness where certain areas of the brain are awake and others are asleep. There are two types of parasomnias: those that occur during the rapid eye movement (REM) stage of sleep and those in non–rapid eye movement (NREM) stages of sleep ( Table 80.1 ).

A.

REM-sleep behavior disorder (RBD) is a type of REM parasomnia. A cardinal feature is the loss of REM atonia, resulting in dream enactment during REM sleep. The presenting symptom is most often injury to the patient and/or bed partner. Patients should be asked if they can recall their dreams and actions, and are often able to recall violent dream content. Movements may be complex and involve shouting, reaching out, kicking, punching, running, or even dancing. However, walking is not common, and leaving the room is rare. Eyes typically remain closed during the event. A prodrome can exist of sleep talking, limb twitching, or jerking during sleep. Autonomic changes are uncommon, in contrast with disorders of arousal from NREM sleep such as sleep terrors. Three-quarters of patients have concurrent periodic limb movements during NREM sleep. RBD usually affects those over 50 years of age; men are affected more than women. Over 80% of patients with RBD will be diagnosed with a synucleinopathy (Parkinson’s disease, dementia with Lewy bodies, multiple system atrophy) within 10 years. Patients should be asked if they have anosmia, constipation, or orthostasis; follow-up cognitive testing and neurologic exams are indicated to monitor for signs of neurodegeneration. RBD can also be associated with stroke, head injury, posttraumatic stress disorder, and depression. Medications associated with RBD include venlafaxine, serotonin selective reuptake inhibitors, mirtazapine, tricyclic antidepressants, selegiline, and rarely beta blockers and acetylcholinesterase inhibitors. Polysomnography (PSG) is required for diagnosis, and shows evidence of increased REM sleep muscle tone (REM sleep without atonia). Management of RBD involves modifying the sleep environment, including placing the mattress on the floor, having the patient and their bed partner sleep in a separate bed or room, and removing dangerous objects from the vicinity. Melatonin (6–18 mg qhs.) is a common first-line treatment with few side effects. Clonazepam is also frequently used (0.5–2.0 mg qhs.), but caution should be exercised in patients with dementia, gait dysfunction, or obstructive sleep apnea. If synucleinopathy is present, acetylcholine receptor inhibitors (e.g., donepezil, rivastigmine) may be helpful. Pramipexole may be used in RBD with periodic limb movements.
B.

Pseudo-RBD is an NREM parasomnia that mimics features of RBD. This should be considered in patients younger than age 50, and in whom the dream content is not very violent. There also may be a strong suspicion for obstructive sleep apnea (OSA) based on a history of snoring and witnessed apneas. PSG is indicated for diagnosis (demonstrating normal REM-sleep atonia) and to assess for OSA. Treating OSA is typically effective at treating the abnormal sleep behaviors.
C.

Other NREM parasomnias include sleepwalking, sleep terrors, confusional arousals, sleep eating disorder, and sexomnia. These are more prevalent in younger adults, and may be normal in children. During sleepwalking, the patient has blunted responses to questions. They may engage in inappropriate complex activity such as climbing out of a window. There is amnesia of the event, and the patient is confused during the episode. Sleep terrors are heralded by a scream with intense fear and signs of autonomic arousal. Bolting from bed can occur. These are similar to but not the same as nightmares, which may also involve complex dream imagery followed by an arousal, but do not involve dream enactment. Sleep-related abnormal sexual behaviors can occur, as can sleep driving, smoking, or eating. Electroencephalogram (EEG) may not correlate well to the event; in sleep eating, the EEG pattern is predominantly awake, but the patient has an altered level of consciousness. In sleepwalking, there is a classic EEG pattern of high-voltage delta with mixes of delta, theta, and alpha. NREM parasomnias also are diagnosed with PSG—some patients have significant arousals out of slow wave sleep. These can be precipitated by lack of sleep, use of sedative/hypnotics, and other sleep disorders.
D.

Nocturnal seizures can be complex, and patients may have multiple different behaviors, making them difficult to differentiate from parasomnias, especially the nocturnal frontal lobe epilepsies. Seizures are usually stereotyped and repetitive, can be associated with tachycardia and hypertension, and are followed by a postictal confusional state. Patients are amnestic to the events. A PSG with a full 10–20 EEG montage is needed to look for evidence of epileptiform activity.