Management of Diffuse Axonal Injury
The management of diffuse axonal injury (DAI) focuses on preventing secondary brain injury through maintaining adequate cerebral perfusion, controlling ventilation, and providing supportive care, as there is no specific treatment for the primary axonal damage. 1, 2
Diagnostic Approach
- Non-contrast CT (NCCT) is the first-line imaging modality in acute moderate to severe traumatic brain injury (TBI) and can predict mortality and unfavorable outcomes (class I recommendation) 3
- NCCT has significant limitations in detecting DAI, as microhemorrhages associated with axonal injury may not be visible on conventional CT 3, 1
- MRI is indicated when NCCT results are normal but persistent unexplained neurologic findings are present (class I recommendation) 3
- Specific MRI sequences for optimal DAI detection include:
- T2*-weighted gradient-echo (GRE) imaging, which is very sensitive to microhemorrhages in acute, early subacute, and chronic stages of DAI (evidence level II) 3, 1
- Susceptibility-weighted imaging (SWI), which is 3-6 times more sensitive than T2* GRE in detecting hemorrhagic axonal injuries 1
- Diffusion-weighted imaging (DWI) for visualization of non-hemorrhagic axonal injuries 1, 2
Acute Management
- Maintain systolic blood pressure >110 mmHg to ensure adequate cerebral perfusion 2
- Control ventilation through tracheal intubation and mechanical ventilation with end-tidal CO2 monitoring when necessary 2
- Prevent hypocapnia which can cause cerebral vasoconstriction and increase risk of brain ischemia 2
- Rapidly correct arterial hypotension using vasopressors such as phenylephrine and norepinephrine when needed 2
- Consider intracranial pressure monitoring for patients with severe traumatic brain injury 2
- External ventricular drainage may be necessary for persistent intracranial hypertension despite sedation and correction of secondary brain insults 2
- Decompressive craniectomy may be considered for refractory intracranial hypertension 2
Management of Neurostorming
- Neurostorming (paroxysmal sympathetic hyperactivity) is characterized by episodes of tachycardia, hypertension, tachypnea, hyperthermia, diaphoresis, and posturing 4
- Episodes can be triggered by external stimuli such as repositioning, suctioning, or other care activities 4
- Management focuses on symptom control regardless of underlying etiology 4
- Medications commonly used include:
Rehabilitation and Long-term Management
- Early physical therapy and rehabilitation to prevent joint contractures and muscle atrophy 2
- Proper positioning and frequent repositioning to prevent pressure sores and contractures 2
- Range of motion exercises should be initiated as soon as the patient is stabilized 2
- Splinting may be necessary to maintain proper joint alignment and prevent contracture formation 2
- Regular neurological assessments to detect clinical deterioration 2
- Follow-up imaging is indicated with neurological deterioration rather than on a routine basis 3, 2
Prognostic Considerations
- The location and extent of DAI lesions correlate with clinical outcomes, with DAI Stage 3 (dorsolateral brain stem lesions) associated with poor outcomes 1
- The presence of both a contusion and >4 foci of hemorrhagic axonal injury on MRI is an independent prognostic predictor 3, 1
- Early subacute MRI findings (small cortical contusions or hemorrhagic axonal injury) improve prediction of 3-month outcomes 3, 1
Common Pitfalls and 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) 3, 1
- DAI is often underdiagnosed with conventional CT imaging 2, 5
- DAI may be delayed in presentation, with neurological symptoms developing hours after the initial trauma 6
- Regular multidisciplinary case reviews are recommended for patients with severe DAI 1, 2