What are the outcomes of Diffuse Axonal Injury (DAI)?

From the Guidelines

Diffuse Axonal Injury (DAI) is associated with poor outcomes, including long-term neurocognitive sequelae and increased risk of chronic traumatic encephalopathy.

Outcomes of DAI

• The presence of DAI on subacute MRI is associated with poor outcomes, particularly in patients with lower GCS scores 1.
• DAI Stage 3 (dorsolateral brain stem lesions) is associated with poor outcomes, while DAI Stage 1 (lobar white matter lesions only) and DAI Stage 2 (callosal lesions) have similar outcomes 1.
• The depth and stage of DAI lesions can help predict recovery or non-recovery at 1 year 1.
• Traumatic microhemorrhages in DAI are associated with the presenting GCS, but the number of microhemorrhages is not currently thought to be associated with injury severity or outcomes 1.

Imaging and Diagnosis

• MRI is more sensitive than CT for detecting subtle findings adjacent to the calvarium or skull base, including small cortical contusions and subdural hematomas 1.
• MRI is also more sensitive for small white matter lesions in traumatic or diffuse axonal injury (DAI) 1.
• Susceptibility-weighted imaging is a high-resolution 3-D T2*-weighted sequence that uses both magnitude and phase information to increase sensitivity for paramagnetic blood products, such as microbleeds 1.

Prognostication and Long-term Outcomes

• Abnormalities on early subacute MRI, such as small cortical contusions or hemorrhagic axonal injury, are clinically relevant in improving prediction of 3-month outcomes in patients with mild TBI 1.
• The presence of frontal-temporal-parietal microbleeds on early MRI susceptibility-weighted imaging is correlated with the presence or absence of depressive symptoms at 1 year after injury 1.
• Chronic traumatic encephalopathy, a condition characterized by brain atrophy and dementia, is thought to be related to repeated head injury and is associated with aggregation of hyperphosphorylated tau and neurofibrillary tangles, along with diffuse axonal disruption and loss 1.

From the Research

Outcomes of Diffuse Axonal Injury (DAI)

The outcomes of Diffuse Axonal Injury (DAI) can be severe and varied. Some of the key outcomes include:

• Functional outcome and quality of life are difficult to predict in patients with DAI after traumatic brain injury (TBI) 2
• More than half of patients with DAI had a favorable functional outcome and a good health-related quality of life (HRQL) at long-term follow-up 2
• Independent prognostic factors for functional outcome were age, pupillary reaction, Hb, DAI grading, and return of consciousness ≤7 days 2
• Age was an independent prognostic factor for HRQL 2

Mortality and Poor Outcome

Some of the factors associated with higher mortality and poor outcome in DAI include:

• Dysautonomia, hyperglycemia, and subdural hematoma 3
• DAI count ≥6 3
• Absence of consciousness recovery 3
• Transfusion need 3
• Higher age and lesions in substantia nigra and mesencephalic tegmentum indicate poor long-term outcome in DAI 4

Comparison of Outcomes between Adults and Children

• Pediatric patients with DAI have improved outcomes and fewer associated injuries than adult counterparts 5
• Adults had higher Injury Severity Score, increased mortality, longer hospitalizations, and higher rehabilitation need rates compared to pediatric patients 5

Importance of Coexisting DAI

• Coexisting DAI is an important factor in determining outcomes in severe head injury 6
• DAI of varying severity is the common subjacent lesion in fatal patients 6