Another technique moving into trauma field is quantitative volumetric assessment of the cortical field. This technique measures the thickness and volume of different cortical and subcortical regions, Dr. Diaz-Arrastia said. “In our patients, we have found that the brain shrinks overall after a severe traumatic injury, but that not all structures shrink at the same rate. Some cortical regions shrink very little, while others, like the hippocampus, appear particularly sensitive to injury.” This finding makes sense given the cognitive and mood issues that TBI patients can experience, he said.
On average, whole brain volume and both grey and white matter volumes decreased by 3%–10% in the first few months after severe TBI. In comparison, Dr. Diaz-Arrastia said, the rate of atrophy for patients with Alzheimer's disease is about 1%–2% a year.
Functional MRIs also provide some clues that the injured brain sustains long-term problems. In the resting state, the blood oxygen level dependent signal typically shows seemingly random fluctuations when the brain is at rest. But recent studies have shown that these fluctuations actually represent the communication between brain regions that work together.
“In our patients, we found a very high indication that the functional connectivity between the hippocampi was greatly reduced,” compared with controls, he said.
Imaging provides objective documentation to help convince insurers to cover rehabilitative services.
Source DR. DIAZ-ARRASTIA