Mild traumatic brain injury

Last reviewed: 4 Nov 2023

Last updated: 18 Nov 2022

Mild traumatic brain injury (TBI), previously termed concussion, 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.

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

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 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, medications, and tracheal intubation.[2] Concussion is a subset of mild TBI which is typically classified based on acute injury characteristics at the less severe end of the brain injury spectrum.[3] However, 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

More key diagnostic factors

Other diagnostic factors

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

Other diagnostic factors

Risk factors

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

More risk factors

Diagnostic investigations

1st investigations to order

CT head

More 1st investigations to order

Investigations to consider

MRI head

More investigations to consider

Emerging tests

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

Treatment algorithm

ACUTE

all patients

Contributors

Authors

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.

Differentials
- Moderate/severe traumatic brain injury (TBI)
- Depression
- General trauma or injury to the body not involving the head
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Guidelines
- Critical Issues in the management of adult patients presenting to the emergency department with mild traumatic brain injury
- Concussion/mild traumatic brain injury and persistent symptoms: for adults over 18 years of age
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Mild traumatic brain injury

Summary

Definition

History and exam

Key diagnostic factors

Other diagnostic factors

Risk factors

Diagnostic investigations

1st investigations to order

Investigations to consider

Emerging tests

Treatment algorithm

all patients

Contributors

Authors

Luke C. Henry, PhD

Disclosures

Maria Twichell, MD

Disclosures

Acknowledgements

Disclosures

Peer reviewers

Eirik Helseth, MD, PhD

Disclosures

Margot Putukian, MD

Disclosures

Differentials

Guidelines

Patient leaflets

Log in or subscribe to access all of BMJ Best Practice

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