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Brief, Resolved, Unexplained Event (BRUE) and ALTE


Christopher P. Raab

, MD, Sidney Kimmel Medical College at Thomas Jefferson University

Last full review/revision Oct 2019| Content last modified Oct 2019

BRUE (brief, resolved, unexplained event) and ALTE (apparent life-threatening event) are not specific disorders but are terms referring to the sudden occurrence of certain alarming symptoms such as periods of no breathing (apnea), change in color or muscle tone, coughing, and gagging in children under 1 year of age.

  • An event is classified as a BRUE if no cause is found after a thorough history and physical examination and sometimes testing are done.
  • Known causes, when identified, include digestive, nervous system, breathing, infectious, heart, metabolic, and traumatic disorders.
  • The diagnosis is based on a discussion with caregivers, a physical examination, and sometimes the results of certain laboratory tests.
  • The prognosis depends on any identified cause of the event.
  • Treatment is aimed at specific causes when they can be identified.

Terminology has changed recently. Previously, doctors used the term "ALTE" (apparent life-threatening event) to classify all events where infants suddenly developed alarming symptoms regardless of whether an underlying cause was ultimately found. Now, if there is no underlying cause, doctors refer to the event as a BRUE (brief, resolved, unexplained event). Some doctors still use the term "ALTE" at first while they are looking for a cause and later if a cause is found.

Although they may seem to be related to sudden infant death syndrome (SIDS), there is no clear relationship between SIDS and BRUE or ALTE.

Causes of BRUE and ALTE

A cause for the alarming symptoms cannot be determined in more than half of cases. These cases are referred to as BRUEs.

When a cause exists, the most common causes include

Less common causes include

  • Heart disorders
  • Metabolic disorders
  • Narrowing or complete blockage of the airways (obstructive apnea)
  • Other disorders (such as drug-related disorders, child abuse, or an anaphylactic reaction)

Symptoms of BRUE and ALTE

A BRUE (or ALTE) usually is characterized by an unexpected, sudden change in an infant’s breathing that alarms the parent or caretaker. Features of an event include some or all of the following:

  • Not breathing for 20 seconds or more
  • Color change, usually blue or pale, but sometimes red
  • Change in muscle tone, usually floppy
  • Choking or gagging

Diagnosis of BRUE and ALTE

  • A doctor's evaluation
  • Other testing based on the results of the evaluation

When a BRUE occurs, the doctor asks several key questions:

  • What was observed by the caregiver who witnessed the event (including a description of changes in breathing, color, muscle tone, and eyes, noises made, length of the episode, and symptoms that occurred before the event)?
  • What interventions were taken (such as gentle stimulation, mouth-to-mouth breathing, or cardiopulmonary resuscitation [CPR])?
  • Did the mother use drugs while pregnant? Do members of the family currently use drugs, tobacco, and alcohol?
  • What was the child's gestational age (length of time spent in the uterus after the egg was fertilized)? Were there any complications at birth? Did the infant remain hospitalized after birth for apnea?
  • While feeding, does the child gag, cough, or vomit? Has poor weight gain been an issue?
  • Has the child reached all age-appropriate developmental milestones?
  • Has the child had a BRUE before or had a recent injury?
  • Have there been any other similar events in the family or early death?

The doctor does a physical examination to check for obvious defects, particularly nervous system abnormalities, such as being too stiff (posturing) or being too floppy (poor muscle tone), and signs of infection, injury, or suspected abuse.

Based on the discussion with the caregivers and the physical examination, the doctor may have enough information to ensure the child does not have a serious medical condition. However, if unsure, the doctor may do laboratory tests (blood [including liver tests], stool, urine, and spinal fluid studies), imaging tests (such as a chest x-ray or computed tomography [CT] of the head), electrocardiography, or a combination of tests based on the infant's examination findings. Other tests to check for possible seizure activity (such as electroencephalography) also may be done.

Prognosis of BRUE and ALTE

The prognosis depends on any identified causes. For example, risk of death or disability is higher if the cause is a serious neurologic disorder. A BRUE or an ALTE itself does not seem to have any long-term effects on the child's development.

Although the relationship between a BRUE or an ALTE and SIDS is unclear, children who have had 2 or more events have a higher risk of SIDS.

Treatment of BRUE and ALTE

  • Treatment of identified causes
  • Sometimes monitoring devices at home

The cause, if identified, is treated. Infants who needed CPR, have had any abnormalities identified during the examination or initial laboratory testing, or whose history is concerning to the doctor are hospitalized for monitoring and further evaluation.

Parents and caregivers should be trained in CPR for infants and in general safe infant care (such as putting infants to sleep on their back and eliminating exposure to tobacco smoke). Doctors sometimes recommend home apnea monitoring devices for a limited period of time. Monitors that can record the infants’ breathing pattern and heart rate are preferred to those that simply sound an alarm. Recording monitors may help doctors distinguish false alarms from real events.

More Information about BRUE and ALTE

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