Diffuse Axonal Injury

Diffuse axonal injury (from Latin diffusus — dispersed, widespread and Greek axon — axis, neuron extension) is one of the most severe and prognostically unfavorable forms of traumatic brain injury.

It is characterized by multiple microscopic tears in nerve fibers across extensive areas of the brain’s white matter.

Etiology and pathophysiology

This pathology occurs exclusively with high-energy traumas featuring powerful rotational (spinning) acceleration or sudden deceleration, typical of severe car accidents. In this mechanism, less fixed parts of the brain (such as the cerebral hemispheres) shift relative to the fixed brainstem, leading to the damage of conducting tracts in the region of the cerebral peduncles.

The physical difference in inertia causes a giant “scissor” effect that stretches, twists, and mechanically tears long neuron extensions (axons) and small blood vessels. The process of destruction does not end at the moment of the accident. Over the following day, damaged yet intact axons swell, their internal transport skeleton disintegrates, and they eventually detach from their cells (known as secondary axotomy).

Clinical significance

The classic clinical picture is the immediate development of a deep and prolonged coma right at the scene of the accident. In such cases, the patient does not have large intracranial hematomas or fractures that could explain such a severe condition. In the acute phase, there are severe brainstem symptoms, decerebrate rigidity (forced unnatural extension of the limbs), and breathing rhythm disturbances.

Diagnosis is challenging: initial CT scans may appear nearly normal or have only small pinpoint hemorrhages in the corpus callosum. MRI is the gold standard for confirming the diagnosis. The prognosis is extremely serious: the condition often results in profound disability, progression to a chronic vegetative state, or a fatal outcome.