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Brief, Resolved, Unexplained Event (BRUE) and ALTE


Christopher P. Raab

, MD, Sidney Kimmel Medical College at Thomas Jefferson University

Full review/revision Aug 2021 | Modified Sep 2022
Topic Resources

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. Currently, 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.


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


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


  • A doctor's evaluation

  • Other testing based on the results of the evaluation

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

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.

Laboratory Tests


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 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

The following is an English-language resource that may be useful. Please note that THE MANUAL is not responsible for the content of this resource.

  • Safe to Sleep®: Information for parents and caregivers about safe sleep practices for infants

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