Diffuse axonal injury Diffuse axonal injury DAI is

• Diffuse axonal injury (DAI) is a brain injury in which damage in

Prevalence • Probably present even in concussion • Present in 72% of TBI survivors

Mechanism • Severe acceleration of brain in skull • Differing density of grey &

Pathophysiology • Axonal shearing • Stretching of axons – primary brain injury • Swelling

Radiology • Poorly seen on initial CT – better later • Better seen on

Management • Initial resuscitation to normal parameters • Keep everything normal • Maintain venous

Prognosis • Death • Disability – unpredictable nature & severity • Brainstem involvement –

Diffuse axonal injury • Suspect from mechanism • Resuscitate to normal parameters • Expect

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Diffuse axonal injury

• Diffuse axonal injury (DAI) is a brain injury in which damage in the form of extensive lesions in white matter tracts occurs over a widespread area. DAI is one of the most common and devastating types of traumatic brain injury, and is a major cause of unconsciousness and persistent vegetative state after severe head trauma.

Prevalence • Probably present even in concussion • Present in 72% of TBI survivors with GCS 3 -13 (moderate-severe TBI) • Combined with haematomas/contusions in 50%

Mechanism • Severe acceleration of brain in skull • Differing density of grey & white matter causes shearing of axons • Lateral & rotational impacts especially • No absorption of force by facial or skull fractures

Pathophysiology • Axonal shearing • Stretching of axons – primary brain injury • Swelling & rupture of axons • Biochemical changes & release of mediators • Cerebral oedema causing raised ICP & restriction of diffusion • Secondary brain injury from hypoxia & relative hypotension (↓CPP)

Radiology • Poorly seen on initial CT – better later • Better seen on MRI • Graded according to increasing severity: • 1: only lobar white matter – grey/white • 2: lesions of corpus callosum • 3: dorsolateral brainstem – negative prognostic sign

Management • Initial resuscitation to normal parameters • Keep everything normal • Maintain venous drainage • Adequate sedation • Avoid hyperventilation acutely • Expect cerebral oedema to develop • ICP monitor – maintain CPP

Prognosis • Death • Disability – unpredictable nature & severity • Brainstem involvement – worse • Young – better (but not children) • Better connectivity – better outcome • Poor initial GCS – worse outcome • Complicated by hydrocephalus/infection – worse • Can recover to very good quality of life

Diffuse axonal injury • Suspect from mechanism • Resuscitate to normal parameters • Expect to swell – ICP bolt • Avoid hyperventilation unless ICP raised • Diagnose on repeat CT or MRI • Aggressive TBI management of ICP • All outcomes possible