Pediatric Subpial Hemorrhage

• Etiology:
  — Subpial space is potential space bordered externally by pia mater and internally by glia limitans (external glial limiting membrane)
  — Subpial space is distinct from fluid-filled subarachnoid space through which cerebrospinal fluid flows
  — Subpial space contains collagen fiber bundles that contribute to basement membranes related to both pia mater and glia limitans and segments of vessels (arterioles and small veins) and occasionally inflammatory cells
• Imaging:
  — Heterogenous blood collections along outer cortical margin
  — Ellipsoid or semiellipitical or spherical
  — Long axis tangential to brain
  — Abut and displace underlying cortical ribbon
  — Sufficiently contained to produce local mass effect on cortex
  — Frequently multiple and multifocal
  — More common in temporal and parietal lobes
  — As it evolves a layer of additional simple fluid is often seen along its deep aspect interposed between subpial hemorrhage and cortex creating an imaging sign that resembles a cleft and the cleft is more evident on follow-up studies reflecting degradation of blood products starting from parenchymal interface
• DDX:
• Complications:
  — Variable functional prognosis
  — May result in acquired focal cortical dysplasia and local vascular disorganization
  — Recurrence not typically seen in absence of risk factors like bleeding diatheses
• Treatment:
• Clinical: Estimated incidence as much as 15% of perinatal intracranial hemorhage

Radiology Cases of Subpial Hemorrhage