MRI After Mild Brain Injury Shows Evidence of Vascular Injury

MRI soon after mild traumatic brain injury may be able to identify linear hemorrhagic lesions in the brain that may be a marker of vascular injury, according to a study presented at the recent American Academy of Neurology annual meeting. If further validated, these linear lesions may provide a target for acute therapy after mild traumatic brain injury.

Previous studies of brain tissue once a person has died have shown that different types of lesions are associated with more severe traumatic brain injury. With their recent research, Gunjan Parikh, MD, with the National Institute of Neurological Disorders and Stroke and the University of Maryland R Adams Cowley Shock Trauma Center, Baltimore, Md., and colleagues believe that linear hemorrhagic lesions seen on MRI after mild traumatic brain injury may be the imaging equivalent of vascular injury that is typically only seen in histopathology after severe traumatic brain injury.

They conducted a prospective study of 256 people with a mean age of 50 years who were admitted to the emergency department at Suburban Hospital in Bethesda, Md., and Washington Hospital Center, Washington, DC, after mild head injuries. After undergoing MRI, 104 (41 percent) of patients had evidence of hemorrhage and underwent additional advanced MRI.

Parikh and colleagues classified the lesions as either punctate lesions or linear lesions, and then compared the evidence for ischemia or edema in the adjacent brain tissue. Twenty percent of the patients had punctate lesions and 33 percent had linear lesions.

“When you classified these two different types of lesions by location, you saw that the microhemorrhages, which typically occur in particular areas in the grey-white junction or the brainstem, were seen profusely,” Parikh said in an interview. “Linear bleeds though were seen in front of the brain or the anterior corona radiate.”

Sixty-eight percent of the linear lesions were graded as severe, and linear lesions were associated with ischemia on DWI or edema on FLAIR (P=.001).

“In our study we were seeing linear lesions in milder patients,” said Parikh. “This means that radiologists or clinicians should not look at holes on MRI and say they are evidence of diffuse axonal injury when, in fact, these more linear shaped lesions may be direct evidence of vascular injury.”

Current criteria for clinical evaluation of head injuries in the emergency department require a head CT, with no requirement for MRI as part of the standard clinical pathway for evaluation, Parikh said.

“The more we accumulate evidence that there are MRI findings in this hyper-acute setting,” he said, “it would be important to incorporate it for monitoring purposes for clinical targeted therapy, and for following these patients through rehabilitation and recovery.”