A prospective diffusion tensor imaging study in mild traumatic brain injury.
OBJECTIVE
Only a handful of studies have investigated the nature, functional significance, and course of white matter abnormalities associated with mild traumatic brain injury (mTBI) during the semi-acute stage of injury. The present study used diffusion tensor imaging (DTI) to investigate white matter integrity and compared the accuracy of traditional anatomic scans, neuropsychological testing, and DTI for objectively classifying mTBI patients from controls.


METHODS
Twenty-two patients with semi-acute mTBI (mean = 12 days postinjury), 21 matched healthy controls, and a larger sample (n = 32) of healthy controls were studied with an extensive imaging and clinical battery. A subset of participants was examined longitudinally 3-5 months after their initial visit.


RESULTS
mTBI patients did not differ from controls on clinical imaging scans or neuropsychological performance, although effect sizes were consistent with literature values. In contrast, mTBI patients demonstrated significantly greater fractional anisotropy as a result of reduced radial diffusivity in the corpus callosum and several left hemisphere tracts. DTI measures were more accurate than traditional clinical measures in classifying patients from controls. Longitudinal data provided preliminary evidence of partial normalization of DTI values in several white matter tracts.


CONCLUSIONS
Current findings of white matter abnormalities suggest that cytotoxic edema may be present during the semi-acute phase of mild traumatic brain injury (mTBI). Initial mechanical damage to axons disrupts ionic homeostasis and the ratio of intracellular and extracellular water, primarily affecting diffusion perpendicular to axons. Diffusion tensor imaging measurement may have utility for objectively classifying mTBI, and may serve as a potential biomarker of recovery.
Mayer
A R
AR
The Mind Research Network, Pete & Nancy Domenici Hall, 1101 Yale Blvd. NE, Albuquerque, NM 87106, USA. amayer@mrn.org
Ling
J
J
Mannell
M V
MV
Gasparovic
C
C
Phillips
J P
JP
Doezema
D
D
Reichard
R
R
Yeo
R A
RA
D000328:Adult; D000704:Analysis of Variance; D016880:Anisotropy; D001288:Attention / Q000502:physiology; D001921:Brain / Q000473:pathology / Q000503:physiopathology*; D001930:Brain Injuries / Q000175:diagnosis* / Q000473:pathology / Q000503:physiopathology; D001931:Brain Mapping; D016022:Case-Control Studies; D056324:Diffusion Tensor Imaging / Q000379:methods*; D056344:Executive Function / Q000502:physiology; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D008568:Memory / Q000502:physiology; D008875:Middle Aged; D015999:Multivariate Analysis; D009413:Nerve Fibers, Myelinated / Q000473:pathology; D009483:Neuropsychological Tests; D011446:Prospective Studies