Diffuse Axonal Injury: Management and Prognosis
Immediate Diagnostic Approach
Non-contrast CT (NCCT) is mandatory as the first-line imaging modality in all patients with suspected moderate to severe traumatic brain injury, including DAI, and should be performed immediately upon presentation. 1, 2, 3
Initial Imaging Strategy
NCCT predicts mortality and unfavorable outcomes but has significant limitations in detecting DAI, as microhemorrhages associated with axonal injury are frequently not visible on conventional CT 1, 2, 4
MRI is indicated when NCCT results are normal but persistent unexplained neurologic findings are present (class I recommendation) 1, 2, 3
Optimal MRI sequences for DAI detection include:
- T2*-weighted gradient-echo (GRE) imaging, which is very sensitive to microhemorrhages in acute, early subacute, and chronic stages of DAI 1, 2, 3
- Susceptibility-weighted imaging (SWI), which is 3-6 times more sensitive than T2* GRE in detecting hemorrhagic axonal injuries 2, 3, 4
- Diffusion-weighted imaging (DWI) for visualization of non-hemorrhagic axonal injuries 1, 2, 3
Gadolinium-based contrast agents are not necessary for conventional MRI in TBI (class IIb recommendation) 2
Acute Management Priorities
Management focuses on preventing secondary brain injury, as there is no specific treatment for the primary axonal damage itself. 2
Critical Physiological Parameters
Maintain systolic blood pressure >110 mmHg to ensure adequate cerebral perfusion 3
Control ventilation through tracheal intubation and mechanical ventilation with end-tidal CO2 monitoring; prevent hypocapnia, which causes cerebral vasoconstriction and increases the risk of brain ischemia 3
ICP monitoring is recommended for patients with severe TBI to detect intracranial hypertension, with a threshold for intervention typically at ICP >20 mmHg 3, 4
Monitor and correct glycemia, peripheral oxygen saturation, and blood pressure, as these are critical prognostic factors 5
Prognostic Assessment
Imaging-Based Prognostic Factors
The presence of both a contusion and >4 foci of hemorrhagic axonal injury on MRI is an independent prognostic predictor. 1, 2
DAI grading correlates strongly with outcomes:
DAI rarely occurs in isolation; traumatic subarachnoid hemorrhage, skull fractures, intraparenchymal hemorrhage, and acute subdural hematoma frequently co-occur 1, 4
Clinical Prognostic Factors
Early Glasgow Coma Scale (GCS) score is a critical predictor: patients with moderate TBI (GCS 9-12) have better outcomes than those with severe TBI (GCS ≤8) 6, 5
Age is a significant independent predictor: younger patients (mean age 24) have favorable outcomes compared to older patients (mean age 40, p<0.001) 7
Time to recover consciousness is an important prognostic indicator 5
72-Hour Assessment Window
For elderly patients (>65 years) with severe brain injury, failure to improve in GCS within 72 hours from the start of treatment is a negative prognostic factor associated with poor functional outcome or death. 1
However, neurological status at 72 hours is a good prognostic factor for in-hospital death but is NOT a valid tool to predict long-term outcomes for survivors 1
This 72-hour window represents the minimum time to assess the chances of survival and effectiveness of initial interventions 1
Common Pitfalls and Critical Caveats
The number of microhemorrhages, while helpful for accurate diagnosis of DAI, is NOT currently thought to be associated with injury severity or outcomes (evidence level II) 1, 2
Do not rely solely on NCCT to rule out DAI, as it misses the majority of axonal injuries 2, 4
Age alone should NOT be used as a reason to limit treatments or withdraw active care; frailty is a superior predictor of poor outcome 1
Approximately one-third of patients achieve favorable long-term outcomes, and outcomes can change in half of patients between 6 months and ≥1 year follow-up 7
Long-Term Management and Rehabilitation
Early physical therapy and rehabilitation are essential to prevent joint contractures and muscle atrophy. 3
Rehabilitation Components
- Proper positioning and frequent repositioning 3
- Range of motion exercises 3
- Splinting as needed 3
- Regular neurological assessments to detect clinical deterioration 3
Follow-up Imaging Strategy
Follow-up imaging is indicated with neurological deterioration rather than on a routine basis 3
MRI at intervals after trauma is useful for evaluating post-traumatic sequelae, including gliosis and volume loss 1
Multidisciplinary Approach and End-of-Life Considerations
Regular multidisciplinary case reviews are recommended for patients with severe DAI, and early communication with regional neuroscience centers is essential for patients with perceived devastating brain injury. 2, 3
Palliative Care Integration
For elderly patients with severe injuries unlikely to be fully recoverable, early insertion of palliative medicine consultation in the decision-making process improves outcomes, reduces in-hospital mortality and length of stay, and improves communication with family. 1
Establish patient values and preferences early to guide end-of-life care planning if needed 3
Honest and realistic discussions of the most likely outcome should occur at admission 3
Palliative care focuses on pain and symptom management, emotional and psychological support, and preserving patient dignity and quality of life 1
Expected Outcomes
Mortality rate at 3 months is approximately 25.6% 6
Satisfactory outcome (GOSE 6-8) is observed in approximately 48.1% of patients at 3 months, increasing to 40% at ≥1 year 6, 7
Survivors require long-term hospitalization (average 9 days acutely) and prolonged rehabilitation to improve their chances of recovery 6
The overall disability rate can be as high as 50% in affected individuals 5