Night Terrors

Etiology

Because there is no clear transition between the primary sleep states and stages, there are multiple time periods in a single duration of sleep in which a person can be in a combination of both wakefulness and sleep. Herein lies the most accepted theory of parasomnia etiology.

Furthermore, there are theories that there is a genetic component; however, this has never been proven and remains antidotal. The exact etiology is unknown; however, there are strong correlations with fever and illness, excessive physical activity, excessive caffeine or alcohol intake, lack of sleep and exhaustion, and emotional stress.

Epidemiology

Night terrors are most often seen between the ages 3 to 7 years of age, and they often subside by 10 years of age. There appears to be an equal prevalence between boys and girls, with a prevalence of approximately 30% in children.

Night terrors can occur in adults; however, it is rare. This may indicate underlying neurologic disorders requiring more workup and investigation.

Pathophysiology

No consistent reason to explain night terror is available. No biochemical or structural abnormality is found in the brain. It has been suggested that levels of serotonin or its precursor may be linked. Thus, SSRIs are often prescribed for night terrors. There is a strong association between sleepwalking and night terrors; in addition, there is a high familial risk.

DSM 5 Criteria

1. Recurrent episodes
2. Sudden arousal from sleep
3. Maybe unresponsive during the attack
4. Often, there is no recall of the nightmare
5. When fully awake, there is complete amnesia of the terror
6. Causes significant distress in interpersonal life, academics, work, and social interaction
7. Individuals may scream or be distressed during the attack
8. Autonomic symptoms are common (tachycardia, diaphoresis)
9. Symptoms are not explained by any other condition

History and Physical

Episodes of night terrors most often occur in the first third of the night during slow non-rapid eye movement sleep when the child is in the transitional state of being wakeful and sleeping. This particular period is referred to as the arousal state.

Episodes can appear to be very dramatic in presentation, with the child screaming and thrashing without realizing their surroundings. Children may show signs of excessive autonomic activity, such as tachycardia, tachypnea, mydriasis, and excessive sweating. In some cases, enuresis can also occur.

Unfortunately, children often do not respond to verbal cues, being comforted, or attempts to awaken. It is extremely difficult to wake these children in the middle of an episode. These spells can last approximately 10 to 20 minutes, and then the child will abruptly return to sleep. Most do not recall the episodes.

Evaluation

No specific test must be done in an emergent clinical setting to make the diagnosis. A night terror is a clinical diagnosis that can be determined by taking a careful history, especially detailing the actual episode from families and witnesses. The only lab work or imaging that needs to be done is to rule out other differential diagnoses listed below.[7][8][9]

In some children, EEG studies or polysomnography may be required to rule out seizures. Patients with nocturnal frontal lobe epilepsy can present in a similar fashion.

Treatment / Management

There is no specific treatment for night terrors other than comforting the child. Reassurance and education for the parents or guardians are strongly encouraged, especially to ensure the safety of the child during a night terror.

If there is excessive stress or conflict in the child’s life, a combination of therapy and coping techniques can be recommended to help decrease the frequency of episodes. Medication administration is strongly discouraged and not indicated.

Rarely is a sleep study ever indicated since the prognosis of night terrors is good and self-limiting; however, there is developing research involving scheduled awakenings through the night with a vibration machine to help improve quality of life.

Differential Diagnosis

The differential diagnosis for night terrors can include but is not limited to the following:

• Seizures: An abnormal, excessive synchronous discharge of neurons originating from the cerebral cortex causing a physical disturbance
• Somnambulism (also known as sleepwalking): A benign, self-limited arousal parasomnia disorder that is characterized by either excessive bed movement or walking during sleep
• Nightmares: A disorder that occurs during the REM stage of sleep that is characterized by extreme fear, horror, distress, or anxiety
• Narcolepsy: An adolescent age chronic sleep disorder consisting of excessive daytime drowsiness
• Sleep Apnea Hypersomnia: A sleep disorder in which the feeling of constant, recurrent episodes of extreme sleepiness and sleep deprivation are intertwined with interruptions of breathing. 
• Breath-holding spells: These occur most often between the ages of six to eighteen months, in which some irritating stimuli trigger a voluntary episode of apnea or alteration in consciousness. It is not uncommon for these children to become cyanotic during the episodes.
• Syncope: A brief, sudden loss of consciousness and muscle tone that may be caused by a variety of reasons. 
• Benign myoclonus: A self-limited episode of sudden jerking of the extremities in the early stages of sleep
• Shuddering attacks: A whole body attacks that resembles an essential tremor
• Tics: These are repetitive movements such as twitching, blinking, head shaking or other subtle movements that are done unconsciously by the patient.
• Gastroesophageal reflux: An arching or dystonic posturing (Sandifer's positioning) due to regurgitated gastric contents or acid into the esophagus
• Psychogenic Nonepileptic Seizures (PNES): formerly known as "Pseudoseizures," this is a movement disorder that appears to be seizures; however, there is no abnormal brain activity, and underlying etiology is often psychiatrically associated.

Prognosis

The prognosis for night terror is good with most children outgrowing these episodes by 10 years of age. In contrast, excessive movements may become a disturbance that alters a family’s or child’s quality of life during an exacerbation. There are developing therapies to encourage scheduled awakenings to prevent further episodes.