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J Neurol Neurosurg Psychiatry 75:1516-1517 doi:10.1136/jnnp.2004.044578
  • Enlarged Virchow-Robin spaces
  • Editorial commentary

Enlarged Virchow-Robin spaces: do they matter?

  1. F Barkhof
  1. Correspondence to:
 F Barkhof
 Department of Radiology, Image Analysis Centre, and Alzheimer Centre, VU Medical Centre, PO Box 7057, 1007 MB Amsterdam, The Netherlands; f.barkhofvumc.nl

    The clinical significance of widened Virchow-Robin spaces

    With the introduction of magnetic resonance imaging (MRI), we have become increasingly aware of the process of brain maturation and ageing. While there is MRI evidence that the former may continue into the third decade, the latter starts as early as the fourth decade. Early ageing phenomena include the development of subtle loss of brain tissue with widening of the sulci and ventricular system, development of periventricular caps and bands, and dilatation of the perivascular Virchow-Robin spaces (VRS).

    The VRS are extensions of the subarachnoid space that accompany vessels entering the brain parenchyma. Widening of VRS often first occurs around penetrating arteries in the substantia perforata and can be seen on transverse MRI slices around the anterior commisure, even in young subjects. Another typical location of widened VRS is near the vertex of the brain, but with advancing age they can be seen anywhere in the white matter, basal ganglia, and hippocampus, especially when high resolution (using a 512 matrix) images are obtained. Their typical MRI appearance includes sharp demarcation and cerebral spinal fluid (CSF)-like signal on all sequences—depending on location and slice orientation, they can appear as dots or linear structures (fig 1).

    Figure 1

     Heavily T2-weighted MRI obtained with high resolution, showing multiple enlarged VRS, visible as well-demarcated CSF like structures, which, dependent on their orientation and plane of imaging, appear as dots (transverse image on the left) or stripes (coronal image on the right).

    In this issue, MacLullich et al1 (see page 1519) examine the clinical significance of widened VRS in a community-based sample of 79 healthy men. A standard MRI protocol was used with a 1 mm in-plane resolution and a categorical scoring system was devised to try to account for the multiplicity of widened VRS. The lowest score (less than 10 widened VRS) was found in the majority of subjects. Higher VRS scores were associated with decreased performance in terms of non-verbal reasoning and general visuospatial ability. However, when controlling for the coexistence of T2-hyperintense white matter lesions (WML), VRS did not seem to have an independent contribution to (decreased) cognitive performance. VRS were also rated separately in the hippocampal region, and although these were significantly correlated with WML, they were not associated with poorer cognitive performance (including episodic memory).

    It is tempting to speculate on the pathogenesis of widened VRS and their significance in determining white matter integrity. Clearly, these CSF spaces do not represent viable tissue, and thus present (a mild form of) local atrophy, which may occur independent of cortical atrophy and ventricular widening. In my clinical experience, widened VRS in elderly subjects often coincide with WML on MRI, and this corroborates with the current findings of MacLullich et al. Apparently, white matter damage may manifest itself as general atrophy (with ventricular widening), incomplete white matter infarction (with WML on MRI), and by virtue of widened VRS. What is particularly interesting is why some patients may develop extensive WML in the basal ganglia and diffusely widened VRS (so-called état criblé) without significant atrophy (fig 2), while others develop only volume reduction (global atrophy). Perhaps this reflects a different mode of communication of the VRS with the subarachnoid space. This remains a subject of debate.

    Figure 2

     Coexistence of hyperintense white matter lesions (WML), and diffusely widened enlarged hypointense VRS (so-called état criblé) on a CSF-supressed transverse MR image.

    In summary, the findings by MacLullich et al indicate that widened VRS are a common ageing phenomenon that is associated with WML and cognitive function. More work is needed to develop an integrated methods to probe white matter integrity, which should not only address WML, but also the quality of the remaining tissue (e.g. using diffusion tensor MRI), and residual white matter volume by accounting for the degree of widening of the VRS—a measure of focal atrophy.

    The clinical significance of widened Virchow-Robin spaces

    REFERENCE

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