Last reviewed: 3 Jun 2022
Last updated: 11 May 2021



History and exam

Key diagnostic factors

  • direct blow to the head or deceleration of the head from an impulsive force
  • previous brain trauma or alcohol misuse
More key diagnostic factors

Other diagnostic factors

  • headache
  • feeling foggy/slow
  • dizziness/balance problems
  • memory difficulties
  • vomiting/nausea
  • normal physical neurologic exam
  • abnormalities on neuropsychological testing
Other diagnostic factors

Risk factors

  • 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
  • functional MRI (fMRI)
More investigations to consider

Emerging tests

  • PET, single-photon emission CT (SPECT) of head
  • alternative imaging techniques
  • anatomic brain imaging techniques

Treatment algorithm


all patients



Luke C. Henry, PhD
Luke C. Henry

Assistant Professor

Department of Neurological Surgery

Senior Clinical Neuropsychologist

University of Pittsburgh




LCH declares that he has no competing interests.

Maria Twichell, MD

Assistant Clinical Professor


General Rehabilitation Unit

UPMC Physical Medicine and Rehabilitation

University of Pittsburgh Medical Center




MT declares that she has no competing interests.


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. 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




EH declares that he has no competing interests.

Margot Putukian, MD

Director of Athletic Medicine

Princeton University




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

  • Concussion images
  • Differentials

    • Moderate/severe traumatic brain injury
    • Depression
    • General trauma or injury to the body not involving the head
    More Differentials
  • Guidelines

    • American Medical Society for Sports Medicine position statement on concussion in sport
    • Living guideline for diagnosing and managing pediatric concussion
    More Guidelines
  • Patient leaflets

    Alzheimer disease and other kinds of dementia

    Alzheimer disease and other types of dementia: what treatments work?

    More Patient leaflets
  • padlock-lockedLog in or subscribe to access all of BMJ Best Practice

Use of this content is subject to our disclaimer