The differential diagnosis of arousal disorders depends on the types of behaviors that occur. For patients with sleep terrors or sleepwalking, diagnostic considerations may include nightmares, REM sleep behavior disorder (RBD), epilepsy, nocturnal delirium, panic disorder, and dissociative states. Timing of episodes, the length of time required to attain full alertness after an episode, and amount of recall are helpful distinguishing features. Sleep terrors and sleepwalking usually begin with an arousal from slow-wave sleep and therefore generally occur in the first third of the night, often within an hour or two of sleep onset; patients are difficult to awaken during an episode and are confused and groggy if they are awakened. Patients usually have little recall of episodes, although some report vague images or fragmentary thoughts or emotions. On the other hand, nightmares and the activity of RBD occur during REM sleep and are therefore more common later in the night; full alertness develops rapidly after an awakening from either. The REM sleep behavior disorder is usually associated with dream-enacting behavior, sometimes violent and accompanied by shouting, and sometimes with dream recall. Unlike sleep terrors, autonomic activation is absent or minimal, even with violent episodes. Some patients, however, have violent dreams during NREM sleep and clinical features that suggest an "overlap" between RBD and sleep terrors (Hurwitz et al., 1991).
As with sleep terrors, sleepwalking often can be diagnosed based on the history. Occurrence in children of complex nonstereotyped behaviors during the first portion of the night with amnesia in the morning is almost always due to an arousal disorder. If the presentation is atypical, however, complex partial seizures should be considered, particularly if stereotyped behaviors, tonic postures, or oral automatisms (such as chewing, swallowing, or salivation), have been observed by others. Other features that increase the likelihood of epilepsy include the occurrence of several brief episodes each night and a poor response to usual treatments for arousal disorders.
Diagnostic considerations for confusional arousals include sleep talking, RBD, and partial complex seizures. The lack of stereotypy and dream-enacting behaviors and the predilection to occur during the first third of the night are usually sufficient for diagnosis.
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