"Acute changes in the corpus callosum visible on magnetic resonance diffusion tensor imaging (DTI) up to six days after mild traumatic brain injury are related to postconcussion symptoms, results of a small study indicate.
Despite normal head CT imaging and neurologic functioning, many individuals report postconcussion symptoms following mild traumatic brain injury, note Dr. Elisabeth A. Wilde from the department of physical medicine and rehabilitation, Baylor College of Medicine, Houston and colleagues in the March 1st issue of
Neurology. "This dissociation has been enigmatic for clinicians and investigators."
Dr. Wilde's team studied changes in white matter integrity using DTI of the corpus callosum, in relation to neurobehavioral findings, in 10 adolescents aged 14 to 19 years with mild traumatic brain injury. All of them were one to six days post injury, had a Glasgow Coma Scale score of 15, and negative CT findings. Ten age- and gender-matched uninjured controls also underwent DTI.
A DTI pattern of increased fractional anisotropy and decreased diffusivity was present in 8 of 10 adolescents with mild traumatic brain injury relative to their matched normal control subjects, the investigators report.
This pattern is suggestive of subtle cytotoxic edema associated with "compressed intracellular space between corpus callosum fibers, thus restricting diffusion in a more uniform direction," Dr. Wilde and colleagues note.
Increased fractional anisotropy and decreased diffusivity correlated with the severity of postconcussion symptoms in the adolescents with mild traumatic brain injury.
"DTI," Dr. Wilde and colleagues conclude, "may prove more sensitive than conventional imaging methods in detecting subtle, but clinically meaningful, changes following mild traumatic brain injury and may be critical in refining diagnosis, therapeutic intervention, and management of mild traumatic brain injury."
Neurology 2008;70:948-955"
