Fact-sheet: Diffuse axonal injury
Updated on 09/17/2021 at 12:16 PM
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Definition
Axonal injury induced by inertial forces.
Acceleration/deceleration and angular rotational forces.
Cerebral structures (e.g., cortex, white matter) then move at different velocities, inducing injury through stretching or even disconnection of axons.
Types of lesions:
-Hemorrhagic lesions (20%):
-Non-hemorrhagic lesions (80%): most often not visible > tip of the iceberg++
.Location:
-Gray-white matter junction - fronto-temporal lobes ++
-Corpus callosum (20%) - splenium +
-Brainstem - pons.
-Less common: basal ganglia, corona radiata, cerebellar peduncles.
.Size and morphology:
-punctate, round, ovoid. Always multiple and bilateral.
-1 to 15 mm
.Epidemiology: associated in 50% of cases with intra-axial post-traumatic lesions.
Clinical features
-Deep loss of consciousness – Coma: highly suggestive++ in a post-traumatic setting.
-Disproportion of symptoms compared to findings on CT performed emergently+++. > The majority of lesions are then missed.
CT
-Initially normal in 50 to 80% of cases > missing++ the lesions
-Spontaneously hyperdense punctate lesions – hemorrhagic petechiae.
-Non-hemorrhagic hypodense punctate lesions – perilesional edema.
MRI
Multiple bilateral punctate lesions with suggestive topography.
Examination for prognostic purposes to be performed within 7 days.
-T1: T1 hyperintensity of hemorrhagic petechial lesions.
-T2: Hemorrhagic petechial lesions of variable signal (hemoglobin degradation). Non-hemorrhagic lesions in T2 hyperintensity
-T2 GRE: hypointensity of hemorrhagic petechial lesions (magnetic susceptibility).
- SWAN/SWI: High-resolution magnetic susceptibility imaging. petechiae +++
-Diffusion (+/- Tractography): Punctate foci of diffusion hyperintensity - ADC restriction.
Management
No specific treatment. Symptomatic management.
Classification
Adams and Gennarelli: grade 1 to 3 according to trauma severity and cerebral locations.
Differential diagnosis
Multifocal non-hemorrhagic lesions:
-Vascular: leukoaraiosis, lacunes – no history of trauma
-Inflammatory: clinical context, periventricular location, ovoid shape, +/- contrast enhancement.
-Marchiafava-Bignami disease: chronic alcohol use, malnutrition, splenium.
-Non-hemorrhagic metastases: primary tumor, enhancement.
Multifocal hemorrhagic lesions:
-Amyloid angiopathy: vascular dementia, sequelae of IP Hematoma, hemosiderosis
-Cavernomatosis: lesions of different ages, family history.
-Hemorrhagic metastases: clinical context, enhancement.