Early Stage Longitudinal Subcortical Volumetric Changes following Mild Traumatic Brain Injury.
Jiachen Zhuo, Li Jiang, Chandler Sours Rhodes and 6 others
PMID 33822686WHAT IT FOUND
Patients with persistent post-concussive symptoms showed early volume loss in the thalamus and hippocampus within one month of mild traumatic brain injury.
This thalamic shrinkage persisted at six months and correlated with worse self-reported symptoms and lower quality of life, unlike objective cognitive test scores which recovered.
Key findings
01Thalamic and hippocampal volumes significantly decreased by one month post-injury, with only thalamic volume remaining significantly lower at six months.
02Volume loss in the thalamus at six months correlated with higher self-reported symptom ratings and poorer global outcomes, but not with objective cognitive test scores.
03These structural changes and symptom correlations were observed only in patients classified as having persistent post-concussive symptoms (PCS); those without PCS showed no longitudinal volume changes.
STILL TO COME
How it was doneWhat they foundWhat it means for PTsWhat it means for OTsWhat it means for SLPs
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What it does not show
Sample size was small (53 patients), which limits statistical power for subgroup analyses. Controls had only one visit, so their data cannot account for practice effects or natural variability over time. The study did not account for medical comorbidities like hypertension or diabetes, which can affect brain volume. Imaging protocol changed mid-study (anisotropic to isotropic voxels), requiring statistical adjustments that may not fully remove bias. The 6-month follow-up is still considered early; volume changes and symptom trajectories may differ in the chronic phase (>1 year).
Declared interests
The authors declare no conflicts of interest. The study was supported by NIH grants.
The easy way to misread this
Do not conclude that these brain volume changes cause the symptoms. The study shows an association, not causation. Furthermore, do not assume that a patient with normal objective cognitive test scores has no underlying brain injury; this study found that structural changes correlated with self-reported symptoms even when cognitive test scores had recovered.