Dilated perivascular spaces: hallmarks of mild traumatic brain injury

Abstract

Background and purpose: Recent animal and human studies have shown an increased frequency of enlarged, high-convexity Virchow-Robin spaces (VRS) in several neurologic diseases, suggesting their role as neuroradiologic markers of inflammatory changes. The aim of this study was to determine the prevalence of high-convexity dilated VRS in mild traumatic brain injury (TBI).

Methods: T2-weighted, T1-weighted, fluid-attenuated inversion recovery, and T2*-weighted gradient-echo brain MR images were acquired in 24 patients with TBI (10 women, 14 men; mean age, 33.6; range, 18.1-50.8 years) and 17 age- and sex-matched healthy control subjects (nine women, eight men; mean age, 32.8; range, 18.4-47.8 years). The mean interval after TBI was 3.6 days (range, 1-9 days) in 15 patients and 3.7 years (range, 0.6-13.4 years) in nine patients. Axial T2-weighted images were used to identify dilated VRS and to measure CSF volume; T1-weighted images were used to measure brain volume. Dilated VRS were identified as punctuate areas with CSF-like signal intensity in the high-convexity white matter.

Results: Mean (+/- standard deviation) number of VRS was significantly higher in patients (7.1 +/- 4.6) than in controls (3.0 +/- 3.0, P = 0.002) [corrected] In controls, VRS were associated with age (R = 0.69, P < .001) whereas in patients, they neither correlated with brain and CSF volumes nor with age and the elapsed time from injury.

Conclusion: Our results suggest that the increased number of dilated VRS is a radiologic marker of mild head injury that is readily detectable on T2-weighted images. Because their number does not vary with time from injury, VRS probably reflect early and permanent brain changes.

Fig 1.

Axial high-convexity T2-weighted images (TE/TR = 119/7900) from younger (A–C) and older (D–F) subjects. Note numerous enlarged VRS in B–F and their absence in A. A, 28-year-old control subject. B, 20-year-old patient imaged 7 days after trauma. C, 27-year-old patient imaged 1.5 years after trauma. D, 40-year-old control subject. E, 42-year-old patient imaged 7 days after trauma. F, 47-year-old patient imaged 1.7 years after trauma.

Fig 2.

Graph showing the correlation between the number of VRS and the age, expressed in years, in patients (squares) and control subjects (circles). VRS are associated with age (R = 0.69, P < .001) only in controls. Least-squares regression line indicates a significant linear relationship: no. of VRS = −4.9 + 0.250 (age in years). That is, the average increment is one VRS per 4-year increment of age.