Imaging demonstrates recovery from traumatic head injury
Victims of traumatic
brain injury may progress through comatose, vegetative and minimally conscious states,
at the end of which they only intermittently show behavioral evidence of communication
or awareness of self or their environment. When a patient unexpectedly emerged from
a minimally conscious state after 19 years, Henning U. Voss of the Citigroup Biomedical
Imaging Center, Dr. Nicholas D. Schiff and their colleagues at Weill Medical College
of Cornell University in New York performed two studies on the patient’s brain
in an attempt to understand the recovery process.
As reported in the July issue of The Journal
of Clinical Investigation, the researchers applied magnetic resonance diffusion
tensor imaging, using a 3T MRI Signa Excite scanner from GE Healthcare of Waukesha,
Wis., to map changes in white matter across several brain structures over 18 months.
They also used a GE Healthcare PET-CT LS Discovery scanner to measure the local
metabolic rates of brain tissue during each study.
Anisotropy maps of the patient (a) and control subject (b) illustrate
the predominant white matter fiber directions. Red, blue and green indicate left
to right, superior to inferior, and anterior to posterior, respectively. Courtesy
of Weill Cornell Citigroup Biomedical Imaging Center/Henning U. Voss.
Structural changes and increased metabolism
found in the brain correlated with improvement in the patient’s motor functions.
These findings suggest that undamaged areas of the brain sprouted new white matter
connections over time, which might play a role in functional recovery.
While these studies were performed
after the patient’s recovery, the team studied another patient who remains
in a minimally conscious state six years after injury. Although the patient has
not exhibited significant functional changes, the imaging techniques revealed features
that are suggestive of changes in white matter connectivity.
Imaging may help to evaluate recovery
if physical changes are unobservable. The researchers believe that functional recovery
is a slow, ongoing process, and that tracking changes in the brain beginning shortly
after injury will allow better understanding of the entire process.
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