Review Question - QID 216402

This patient who presents with episodes of walking around at night that he does not remember is most likely sleepwalking. Sleepwalking is a parasomnia most strongly associated with delta waves on electroencephalography (EEG) during stage N3 of non-rapid-eye-movement (NREM) sleep.

Sleepwalking (somnambulism) occurs in up to 15% of children between the ages of 5 and 10. It can present from mild episodes such as walking and standing quietly by a parent’s bed to agitatedly running about the house. This condition is benign and does not interfere with sleep quality, but it can be a source of significant concern for parents. Sleepwalking most commonly occurs during stage N3 sleep, the deepest phase of NREM sleep (formerly known as slow-wave sleep). EEG, which measures electrical activity in the brain, demonstrates the rhythmic activity of neurons firing in synchrony divided into bands of frequency termed delta (<4 Hz), theta (4-7 Hz), alpha (8-15 Hz), and beta (16-31 Hz). Stage N3 sleep and sleepwalking are most strongly associated with delta waves, which show the greatest synchrony (lowest frequency and highest amplitude) among all biologically relevant EEG waveforms. In otherwise healthy children presenting with episodes of sleepwalking that results in the child leaving the bed, environmental safety measures should be discussed with parent(s).

Kotagal reviews the clinical presentation and differential diagnoses for common parasomnias of childhood including sleepwalking, sleep terrors, and confusional arousals. Of note, Table 2 compares arousal parasomnias such as sleepwalking with nocturnal seizures. The author recommends performing polysomnography with EEG in patients with frequent episodes of parasomnia to rule out nocturnal seizures.

Incorrect Answers:
Answer 1: Alpha waves are characteristic of wakefulness with eyes closed. Alpha waves disappear in sleep and are not seen during parasomnias.

Answer 2: Beta waves are characteristic of wakefulness with eyes open and rapid-eye-movement (REM) sleep. REM sleep is associated with dreaming and nightmares, but not with sleepwalking.

Answer 4: Sleep spindles and K complexes are characteristic of stage N2 of NREM sleep. This stage of sleep is associated with bruxism. Sleepwalking often occurs during the transition from stage N3 sleep into other stages of sleep but is generally categorized as happening during stage N3 sleep, which is more strongly associated with delta waves.

Answer 5: Theta waves are characteristic of stage N1 of NREM sleep, which is the lightest sleep stage. Nocturnal seizures most often occur during stage N1 sleep and can mimic sleepwalking, but are generally shorter in duration (<5 minutes), happen multiple times in a single night, and are associated with familial seizure disorders. While some evidence suggests stage N3 sleep with rhythmic theta waves may also be associated with sleepwalking, delta waves are more strongly associated with stage N3 sleep and sleepwalking.

Bullet Summary:
Sleepwalking happens in stage N3 sleep and is associated with rhythmic delta wave activity on electroencephalography.