Mild traumatic brain injury

Overview 
Theory 
Diagnosis 
Management 
Follow up 
Resources 

Last reviewed: 4 Jun 2025

Last updated: 03 Jul 2025

Mild traumatic brain injury (TBI) is a closed head injury due to a direct blow to the head or deceleration of the head from an impulsive force, resulting in a transient change in mental status.

The most common causes are motor vehicle accidents, sports, assaults, and falls.

Diagnosing mild TBI is difficult based on acute injury characteristics and presenting signs and symptoms.

Headache, mental slowing and fogginess, and memory difficulties are typical symptoms. Symptoms may fluctuate, but typically subside after 1 week to 1 month. Loss of consciousness is not necessary for a positive diagnosis.

Computed tomography scan and magnetic resonance imaging are typically normal in mild TBI.

For uncomplicated cases, physical and cognitive rest is usually sufficient.

Definition

TBI is a closed head injury due to a direct blow to the head or deceleration of the head from an impulsive force that results in a change in mental status.[1] The Glasgow Coma Scale (GCS) remains the main instrument for classifying the severity of TBI as mild (GCS 13–15), moderate (GCS 9–12), or severe (GCS ≤8).[2] However, the GCS is confounded by several factors, including drug and alcohol use, prescription or nonprescription drugs, and tracheal intubation.[2] Concussion and mild TBI are overlapping but distinct terms; concussion can be considered a subset of mild TBI, which comprises a range of injury types at the less severe end of the brain injury spectrum (which includes concussion with other features).[3][4] Currently there are no distinct symptom profiles, diagnostic criteria, or objective biomarkers that distinguish concussion from mild TBI.[4] Centers for Disease Control and Prevention: HEADSUP Opens in new window

History and exam

Key diagnostic factors

direct blow to the head or deceleration of the head from an impulsive force
previous brain trauma, substance use, or alcohol misuse

Full details

Other diagnostic factors

headache
feeling foggy/slow
dizziness/balance problems
memory difficulties
vomiting/nausea
neck pain
normal physical neurologic exam
abnormalities on neuropsychological testing

Full details

Risk factors

head injury
previous brain trauma
alcohol and drug misuse
poor neck strength

Full details

Diagnostic tests

1st tests to order

clinical diagnosis

Full details

Tests to consider

CT head
MRI head

Full details

Emerging tests

PET, single-photon emission CT (SPECT) of head
multimodal MRI technologies

Full details

Treatment algorithm

ACUTE

confirmed mild traumatic brain injury

Contributors

Expert advisers

Luke C. Henry, PhD

Assistant Professor

Department of Neurological Surgery

Senior Clinical Neuropsychologist

University of Pittsburgh

Pittsburgh

Disclosures

LCH declares that he has no competing interests.

Maria Twichell, MD

Assistant Clinical Professor

Director

General Rehabilitation Unit

UPMC Physical Medicine and Rehabilitation

University of Pittsburgh Medical Center

Pittsburgh

Disclosures

MT declares that she has no competing interests.

Acknowledgements

Dr Luke C. Henry and Dr Maria Twichell would like to gratefully acknowledge Dr Jeffrey Bazarian and Dr Maryse Lassonde, previous contributors to this topic.

Disclosures

JB has been reimbursed by Roche, the manufacturer of an automated assay for serum S-100B, to attend a conference, and has been reimbursed by Banyan Biomarkers and Neuren Pharmaceuticals to help develop their research protocols. JB is also an author of a reference cited in this topic. ML is an author of several references cited in this topic.

Peer reviewers

Eirik Helseth, MD, PhD

Professor and Consultant

Department of Neurosurgery

Ulleval University Hospital

Oslo

Norway

Disclosures

EH declares that he has no competing interests.

Margot Putukian, MD

Director of Athletic Medicine

Princeton University

Princeton

Disclosures

MP is an author of a reference cited in this topic.

References

Our in-house evidence and editorial teams collaborate with international expert contributors and peer reviewers to ensure that we provide access to the most clinically relevant information possible.

Key articles

Maas AIR, Menon DK, Manley GT, et al. Traumatic brain injury: progress and challenges in prevention, clinical care, and research. Lancet Neurol. 2022 Nov;21(11):1004-60.Full text Abstract

Harmon KG, Clugston JR, Dec K, et al. American Medical Society for Sports Medicine position statement on concussion in sport. Br J Sports Med. 2019 Feb;53(4):213-25.Full text Abstract

Patricios JS, Schneider KJ, Dvorak J, et al. Consensus statement on concussion in sport: the 6th International Conference on concussion in sport-Amsterdam, October 2022. Br J Sports Med. 2023 Jun;57(11):695-711.Full text Abstract

American College of Emergency Physicians Clinical Policies Subcommittee (Writing Committee) on Mild Traumatic Brain Injury; Valente JH, Anderson JD, Paolo WF, et al. Clinical policy: critical issues in the management of adult patients presenting to the emergency department with mild traumatic brain injury - approved by ACEP Board of Directors, February 1, 2023, clinical policy endorsed by the Emergency Nurses Association (April 5, 2023). Ann Emerg Med. 2023 May;81(5):e63-105.Full text Abstract

Reference articles

A full list of sources referenced in this topic is available to users with access to all of BMJ Best Practice.

Differentials
- Moderate/severe traumatic brain injury (TBI)
- Depression
- General trauma or injury to the body not involving the head
More Differentials
Guidelines
- Living guideline for pediatric concussion
- Living concussion guidelines: guideline for concussion and prolonged symptoms for adults 18 years of age or older
More Guidelines
Calculators
Glasgow Coma Scale
Canadian Head CT Rule for Minor Head Injury
More Calculators
Patient information
Concussion (mild traumatic brain injury)
More Patient information
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Mild traumatic brain injury

Summary

Definition

History and exam

Key diagnostic factors

Other diagnostic factors

Risk factors

Diagnostic tests

1st tests to order

Tests to consider

Emerging tests

Treatment algorithm

confirmed mild traumatic brain injury

Contributors

Expert advisers

Luke C. Henry, PhD

Disclosures

Maria Twichell, MD

Disclosures

Acknowledgements

Disclosures

Peer reviewers

Eirik Helseth, MD, PhD

Disclosures

Margot Putukian, MD

Disclosures

References

Key articles

Reference articles

A full list of sources referenced in this topic is available to users with access to all of BMJ Best Practice.

Differentials

Guidelines

Calculators

Patient information

Log in or subscribe to access all of BMJ Best Practice

Log in or subscribe to access all of BMJ Best Practice

Log in to access all of BMJ Best Practice