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Brief, Resolved, Unexplained Event (BRUE)


Christopher P. Raab

, MD, Sidney Kimmel Medical College at Thomas Jefferson University

Reviewed/Revised Feb 2023 | Modified Sep 2023
Topic Resources

BRUE (brief, resolved, unexplained event) is not a specific disorder. Rather it is a term used to describe the sudden occurrence in children under 1 year old of certain alarming symptoms, such as a change in breathing, a change in color, a change in muscle tone, or a change in the level of responsiveness.

  • An event is classified as a BRUE if no cause of the symptoms is found after a thorough medical evaluation.

  • Similar symptoms, may be caused by digestive, nervous system, breathing, infectious, heart, and metabolic disorders as well as by physical trauma.

  • The diagnosis is based on a discussion with caregivers, a physical examination, and sometimes the results of certain laboratory tests.

  • Treatment is aimed at specific causes, if they are identified.

Sometimes infants have episodes of symptoms that raise concern about their health. Terminology to describe these episodes 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).

BRUE is a term that describes only episodes that occur in children under 1 year of age:

  • B = Brief: The event lasts for less than 1 minute.

  • R = Resolved: The event ends and the child returns to a normal state of health.

  • U = Unexplained: No cause can be found after a doctor's evaluation.

  • E = Event: The child has symptoms such as changes in breathing or a period of no breathing (apnea), a change in color, a change in muscle tone, and/or a change in the level of responsiveness.

Such episodes may seem to be related to sudden infant death syndrome Sudden Infant Death Syndrome (SIDS) Sudden infant death syndrome is the sudden, unexpected death, usually during sleep, of a seemingly healthy infant between 1 month and 1 year of age. The cause of sudden infant death syndrome... read more (SIDS), but most infants with SIDS did not have any type of alarming event beforehand. However, infants who have had 2 or more BRUEs appear to be at an increased risk of SIDS.

Symptoms of BRUE

A BRUE is characterized by an unexpected, sudden change in an infant that alarms the parent or caregiver.

Features of a BRUE that may alarm a parent or caregiver include some or all of the following:

  • Breathing that stops for 20 seconds or more (apnea), breathing that is irregular, or no breathing at all

  • Color change, blue or pale

  • Change in muscle tone, too stiff or floppy

  • Change in the level of responsiveness (for example, drowsiness, inactivity, loss of consciousness)

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

Causes of symptoms similar to BRUE

By definition, a BRUE is an episode with no known cause. In some cases, a cause for the symptoms is identified during a medical evaluation.

When a cause exists, the most common possible causes include

Less common possible causes include

Diagnosis of BRUE

  • 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 abnormalities, 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.

Laboratory Tests

Treatment of BRUE

  • Treatment of identified causes

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 do not recommend using at-home breathing monitors as a way to reduce the risk of SIDS. There is no evidence that these monitors reduce the risk of SIDS. They are not substitutes for following recommended safe sleep measures Prevention Sudden infant death syndrome is the sudden, unexpected death, usually during sleep, of a seemingly healthy infant between 1 month and 1 year of age. The cause of sudden infant death syndrome... read more .

Prognosis for BRUE

The prognosis depends on any identified causes. For example, risk of death or disability is higher if the cause is a serious neurologic disorder.

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

More Information

The following English-language resource 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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