Benign enlargement of subarachnoid spaces (BESS) is not associated to bridging vein rupture/thrombosis.

BACKGROUND

There is some controversy as to whether benign enlargement of the subarachnoid spaces (BESS) in infants predisposes to bridging vein rupture/thrombosis and subdural hematomas following minor trauma.

OBJECTIVE

To evaluate the prevalence of subdural collections and bridging vein rupture/thrombosis in infants with BESS undergoing brain MRI for macrocephaly more or less rapid increase in head circumference.

METHODS

In a single-center retrospective observational study, infants younger than one year who underwent brain MRI for macrocephaly (head circumference > 2 SD) more or less rapid head circumference increase, between January 2017 and August 2023, were included. Early preterm infants and those with incomplete MRI protocols were excluded. MRI was reviewed for subarachnoid space enlargement, subdural collections and bridging vein abnormalities. BESS was defined by a craniocortical distance above 5 mm.

RESULTS

Of 92 infants, 78 were diagnosed with BESS. Six infants with BESS (7.7%) had unilateral or bilateral non-compressive subdural collections: fluid-like signal intensity (n = 4), intermediate signal intensity (n = 1) or a hemorrhagic component with a hypointense rim (n = 1) without bridging vein abnormalities or vertex clots. In this last case, the child had no reported previous trauma and no acute clinical symptoms but had hypotonia. No history of trauma or acute clinical symptoms was reported and no direct or indirect MRI signs of bridging vein rupture or thrombosis were identified in any infant, including those with subdural collection.

CONCLUSIONS

Non-traumatic BESS may be associated with non-compressive subdural fluid collections but not with imaging evidence of direct or indirect signs of bridging vein rupture.