Neurology

Diffuse axonal injury (DAI) is one of the most common and devastating types of traumatic brain injury , meaning that damage occurs over a more widespread area than in focal brain injury. DAI , which refers to extensive lesions in white matter tracts, is one of the major causes of unconsciousness and persistent vegetative state after head trauma. It occurs in about half of all cases of severe head trauma and also occurs in moderate and mild brain injury.

Unlike brain trauma that occurs due to direct impact and deformation of the brain, DAI is the result of traumatic shearing forces that occur when the head is rapidly accelerated or decelerated, as may occur in auto accidents, falls, and assaults. It usually results from rotational forces or severe deceleration.Vehicle accidents are the most frequent cause of DAI ; it can also occur as the result of child abuse such as in shaken baby syndrome. The major cause of damage in DAI is the disruption of axons, the neural processes that allow one neuron to communicate with another

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Lesions typically exist in the white matter of brains injured by DAI; these lesions vary in size from about 1–15 mm and are distributed in a characteristic way. DAI most commonly affects white matter in areas including the brain stem, the corpus callosum, and the cerebral hemispheres. The lobes of the brain most likely to be injured are the frontal and temporal lobes.Other common locations for DAI include the white matter in the cerebral cortex, the corpus callosum, the superior cerebral peduncles,basal ganglia, thalamus, and deep hemispheric nuclei.

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