A 60-year-old man is brought to the emergency department after he was found unresponsive at the bottom of a stairwell. Upon arrival, the patient is hemodynamically stable but has a Glasgow coma score of 7. There are no other obvious injuries. CT scan of the head reveals no skull fractures or large hematoma. The patient is intubated for airway protection. His mentation does not improve over the next several hours, and diffuse axonal injury is suspected. Which of the following neuroimaging findings is most suggestive of this patient's diagnosis?

Question

A 60-year-old man is brought to the emergency department after he was found unresponsive at the bottom of a stairwell.  Upon arrival, the patient is hemodynamically stable but has a Glasgow coma score of 7.  There are no other obvious injuries.  CT scan of the head reveals no skull fractures or large hematoma.  The patient is intubated for airway protection.  His mentation does not improve over the next several hours, and diffuse axonal injury is suspected.  Which of the following neuroimaging findings is most suggestive of this patient's diagnosis?

Quizplus · Accepted Answer

11ec25c8_d588_c5bb_bc81_f773410d0710_MD0003_00 This patient who likely fell down a stairwell has poor neurologic status (eg, Glasgow coma score of 7), which is concerning for severe traumatic brain injury. Given that his initial head CT scan was unremarkable (eg, no large hematoma), this presentation is most consistent with diffuse axonal injury (DAI). Glasgow coma score Sudden acceleration-deceleration or rotational forces during blunt head trauma can cause shearing of the long, white matter tracts (ie, axons) of the brain. This particularly affects junctions between brain tissues of different densities (eg, gray-white matter junction), which experience mismatched changes in velocity in response to the external forces. Axonal injury occurs when the shearing forces break the axonal cytoskeleton, leading to impairment of axonal transport, swelling, and potential degeneration of the axon. Because these injuries occur on a microscopic level, DAI may not be apparent on initial head CT, which is typically performed without contrast to detect macroscopic bleeding or skull fractures. However, MRI is more sensitive than CT for DAI and can often reveal numerous minute punctate hemorrhages in the white matter (ie, axons) and blurring of the gray-white interface (due to edema). (Choices A and D) Blunt head trauma can cause rapid hematoma formation capable of compressing and displacing brain tissue (ie, brain herniation). When severe, this can result in tonsillar herniation (ie, downward displacement of the cerebellar tonsils through the foramen magnum) or subfalcine herniation (ie, lateral shift in midline structures inferior to the falx cerebri) accompanied by unconsciousness. In contrast to patients with brain herniation, patients with DAI typically experience unconsciousness in the absence of major neuroimaging findings (eg, hematoma, herniation). brain herniation (Choice B) A generalized decrease in cerebral volume (ie, cerebral atrophy) is often a long-term consequence of traumatic brain injury and can contribute to progressive cognitive and functional decline. However, this occurs over months to years after the trauma. (Choice C) Hyperdense blood in the basal cisterns, which typically appears immediately on noncontrast CT as white, hyperdense regions in the brain parenchyma, is more characteristically associated with subarachnoid hemorrhage. Subarachnoid hemorrhage can occur due to head trauma and, if severe, result in a decreased level of consciousness. However, because DAI occurs due to microscopic damage to axons rather than bleeding into the subarachnoid space, it may not be seen on initial CT scan of the head. Educational objective: Diffuse axonal injury (DAI) often causes severe neurologic impairment in the absence of major CT scan findings. MRI is more sensitive for DAI and may reveal minute punctate hemorrhages in the white matter and blurring of the gray-white interface.

A 60-Year-Old Man Is Brought to the Emergency Department After