What is the management and treatment approach for a patient with suspected diffuse axonal brain injury?

Management of Diffuse Axonal Injury

For patients with suspected diffuse axonal injury, immediately obtain non-contrast CT as first-line imaging, maintain systolic blood pressure >110 mmHg, control ventilation with end-tidal CO2 monitoring to prevent hypocapnia, and obtain MRI with T2, SWI, and DWI sequences when CT is negative but neurologic findings persist.* 1, 2, 3

Immediate Diagnostic Approach

Non-contrast CT is mandatory as the first-line imaging modality and must be performed immediately upon presentation in all patients with suspected moderate to severe traumatic brain injury, including DAI (Class I recommendation). 4, 1, 2, 3 However, recognize that NCCT has significant limitations—it detects only 10% of DAI cases because most lesions lack macroscopic hemorrhage visible on conventional CT. 2

MRI is indicated when NCCT results are normal but persistent unexplained neurologic findings are present (Class I recommendation). 4, 1, 2, 3 The optimal MRI sequences for DAI detection include:

• T2-weighted gradient-echo (GRE) imaging* for detecting microhemorrhages in acute, early subacute, and chronic stages (Class IIa recommendation) 4, 1, 2
• Susceptibility-weighted imaging (SWI), which is 3-6 times more sensitive than T2* GRE in detecting hemorrhagic axonal injuries 2
• Diffusion-weighted imaging (DWI) to visualize axonal injuries not easily appreciated on other sequences 2

MRI can detect DAI lesions within the first 24 hours after injury, with approximately 27% of mild TBI patients with normal CT showing abnormalities on early MRI that improve prediction of 3-month outcomes. 2

Acute Physiological Management

Management focuses on preventing secondary brain injury, as there is no specific treatment for the primary axonal damage itself. 1, 2 The critical interventions are:

Hemodynamic Management

• Maintain systolic blood pressure >110 mmHg to ensure adequate cerebral perfusion 1, 3
• Avoid hypotension, which compounds secondary brain injury 1

Ventilation Control

• Control ventilation through tracheal intubation and mechanical ventilation with end-tidal CO2 monitoring (Grade 1+ recommendation) 4, 1, 3
• Prevent hypocapnia, which causes cerebral vasoconstriction and increases the risk of brain ischemia 4, 1, 3
• This applies even during the pre-hospital period 4

Intracranial Pressure Management

• ICP monitoring is recommended for patients with severe TBI to detect intracranial hypertension, with intervention threshold typically at ICP >20 mmHg 3
• External ventricular drainage is suggested for treating persisting intracranial hypertension despite sedation and correction of secondary brain insults (Grade 2+ recommendation) 4
• Decompressive craniectomy may be considered for refractory intracranial hypertension in multidisciplinary discussion (Grade 2+ recommendation) 4

Prognostic Assessment

DAI grading correlates strongly with outcomes, with Grade III DAI (dorsolateral brainstem lesions) associated with poor outcomes and highest mortality. 1 Specific prognostic indicators include:

• The presence of both a contusion and >4 foci of hemorrhagic axonal injury on MRI is an independent prognostic predictor 1, 2
• The location and extent of DAI lesions correlate with clinical outcomes 2
• Age is a significant predictor, with older patients (mean age 40) having worse outcomes compared to younger patients (mean age 24) 5

Common pitfall: The number of microhemorrhages, while helpful for accurate diagnosis, is not currently thought to be associated with injury severity or outcomes. 2

Rehabilitation and Long-term Management

Early physical therapy and rehabilitation are essential to prevent joint contractures and muscle atrophy, including proper positioning, frequent repositioning, range of motion exercises, and splinting. 3, 6

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. 4, 1, 3

Observation Period for Perceived Devastating Injury

When severe brain injury is perceived to be devastating, a period of physiological stabilization and observation is recommended to improve the quality of decision making, as prognostication at the acute stage can be inaccurate. 4 During this observation period:

• The therapeutic aim is to provide cardiorespiratory stability to facilitate accurate neurological prognostication 4
• Communication of aims and goals should be consistent from the outset, with families informed that additional time will increase the certainty of prognosis 4
• The duration should be determined by clinical judgment, changes in neurological function, degree of support required, and communication with family 4

Follow-up Imaging

Follow-up imaging is indicated with neurological deterioration rather than on a routine basis. 3 Repeat NCCT is recommended for patients with epidural, subdural, and parenchymal hematomas, but may be less likely to alter clinical management in patients with subarachnoid hemorrhage. 4

Outcome Expectations

Approximately one-third of TBI patients with DAI achieve favorable long-term outcomes (GOSE 6-8). 5 Importantly, outcomes can change between 6 months and ≥1 year follow-up, with approximately half of patients showing either improvement or deterioration during this period. 5 This underscores the importance of continued monitoring and rehabilitation efforts beyond the initial 6-month period.

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