Traumatic brain injuries (TBI) are common and come with a large cost to both society and the individual. Imaging, particularly CT, plays a key role in accurate diagnosis, classification and follow-up.
They can be broadly divided into closed and penetrating head injuries 4:
closed head injury
- vastly more common
- blunt trauma: motor vehicle collision, assault, sport, industrial/workplace accidents, etc
- blast injuries
- non-accidental injury in children
- penetrating head injury
The remainder of this article focuses on closed head injury.
Traumatic brain injuries are more common in young patients, and men account for the majority (75%) of cases 4. Although sport is a common cause of relatively mild repeated head injury potentially eventually leading to chronic traumatic encephalopathy, more severe injuries are most often due to motor vehicle accidents and assault.
Patients typically present with a combination of reduced Glasgow Coma Scale (GCS), nausea/vomiting and/or amnesia 3. The severity of the injury can be assessed with GCS 4:
- mild TBI: GCS 14-15
- moderate TBI: GCS 9-13
- severe TBI: GCS 3-8
This scale has limitations as there are other causes for reduced GCS in trauma (alcohol, drugs, seizure, etc).
In the acute setting patients can present with primary brain damage 4:
- traumatic subarachnoid haemorrhage (tSAH)
- subdural haematoma (SDH)
- extradural haematoma (EDH)
- intraventricular haemorrhage
- cerebral haemorrhagic contusion
- diffuse axonal injury (DAI)
Secondary brain damage can also occur and manifests as 4:
- generalised cerebral oedema
- hypoxic-ischaemic brain injury
- ischaemic stroke from traumatic arterial dissection
Long-term sequelae of head trauma include:
- chronic subdural haematomas / CSF hygromas
- chronic traumatic encephalopathy
- depression, anxiety and alcohol abuse 5
- increased risk of schizophrenia, bipolar disorder and organic mental disorders 6
Severe mass effect can result in:
- midline shift: associated with worse prognosis
- cerebral herniation: often requires urgent treatment
- hydrocephalus: can also be a chronic non-mass effect related complication
Other traumatic injuries are common:
- cervical spine injury: patients with GCS <8 are most at risk 7
- skull fracture
- facial fracture
- extracranial injuries in 35% 4
CT is the workhorse of imaging in TBI, especially in the acute setting, and is able to identify the majority of injuries at the time of presentation. It is common for multiple injuries to be present simultaneously, such as the combination of cerebral contusions and traumatic subarachnoid, subdural and extradural haemorrhage as well as skull fractures and facial fractures – these are discussed separately.
MRI has a supplementary role, especially in the evaluation of patients whose clinical condition do not match the CT findings (this can often occur in DAI) 1,2. Please see the relevant articles for imaging findings.
Treatment and prognosis
Large haematomas with significant mass effect require urgent neurosurgical evacuation. Hydrocephalus can develop and urgent ventricular drainage may be required. Intracranial pressure (ICP) monitor insertion is a common procedure used to help in the assessment of severe TBI.
Ongoing follow-up with CT is often required. In patients with diffuse injuries ~15% will develop new lesions, and ~35% (range 25-45%) of cerebral contusions will increase in size with progression thought to typically occur 6-9 hours after injury 4.
- 1. Provenzale JM. Imaging of traumatic brain injury: a review of the recent medical literature. AJR Am J Roentgenol. 2010;194 (1): 16-9. doi:10.2214/AJR.09.3687 - Pubmed citation
- 2. Davis PC. Head trauma. AJNR Am J Neuroradiol. 2007;28 (8): 1619-21. AJNR Am J Neuroradiol (full text) - Pubmed citation
- 3. Lee B, Newberg A. Neuroimaging in traumatic brain imaging. NeuroRx. 2005;2 (2): 372-83. doi:10.1602/neurorx.2.2.372 - Free text at pubmed - Pubmed citation
- 4. Maas A, Stocchetti N, Bullock R. The Lancet Neurology. 2008;7 (8): . doi:10.1016/S1474-4422(08)70164-9
- 5. Fann JR, Hart T, Schomer KG. J Neurotrauma. Treatment for Depression after Traumatic Brain Injury: A Systematic Review, 2009 Dec; 26(12): 2383–2402, available at https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2864457/
- 6. Oriovska S et. al Head injury as risk factor for psychiatric disorders: a nationwide register-based follow-up study of 113,906 persons with head injury. Am J Psychiatry 2014 Apr;171(4):463-9. doi: 10.1176/appi.ajp.2013.13020190. Abstract available at https://www.ncbi.nlm.nih.gov/pubmed/24322397
- 7. Holly LT, Kelly DF, Counelis GJ et-al. Cervical spine trauma associated with moderate and severe head injury: incidence, risk factors, and injury characteristics. J. Neurosurg. 2002;96 (3 Suppl): 285-91. Pubmed citation