Fig. 1

Dura Mater schematic illustrating morphological features for orientation. Collagen fiber is more uniformly oriented towards the skull and less uniform towards the arachnoid membrane (A). In addition, cellular density is low towards the skull with only a few fibroblasts present while the number of cells increases towards the arachnoid membrane. Bottom panels are representative images showing cellular density and collagen fiber orientation throughout the dura mater stained with cresyl violet (B) or through IHC (C). The dura biopsy was obtained from the site of shunt catheter insertion in all iNPH patients. (D) The trepanation (arrow) was placed in the right frontal region, about 12 cm posterior to glabella, and average 1.6 cm lateral to the superior sagittal sinus. (E) The dura (marked by red rectangle) was incised circumferential (diameter about 5 mm) in its entire thickness (about 1 mm) and removed in one piece. Illustration in E: Øystein Horgmo, University of Oslo