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Gautam Vangipuram, Heather Moss; Changes in basement membrane opening displacement within 1 hour following intracranial pressure lowering in subjects with and without idiopathic intracranial hypertension. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):2232.
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© ARVO (1962-2015); The Authors (2016-present)
Changes in basement membrane(BM) contour in the region of the optic nerve head are a promising marker for intracranial pressure(ICP) changes in idiopathic intracranial hypertension(IIH) based on studies showing change following surgical and medical treatment for elevated ICP. Rapid changes in BM configuration associated with ICP lowering have yet to be studied. This study tests the hypothesis that changes in BM opening(BMO) displacement, a surrogate for BM contour, occur rapidly following ICP lowering via lumbar puncture (LP).
Within 1 hour prior to and following LP in seven (27-60 yrs old, 11-24mL CSF drained) prospectively recruited subjects, 20o OCT B-scan images centered on the right optic nerve head along the nasal/temporal axis were acquired. The BM and inner limiting membrane(ILM) were automatically segmented and manually corrected. Optic nerve head maximum nasal, temporal and cup thicknesses were calculated as the distance between the BM and ILM. BMO displacement was calculated at the nasal and temporal margins of the BMO referenced to a straight line between the outer nuclear layer-inner segment junction 3 mm nasally and temporally from the optic nerve head(fig.). Based on LP opening pressure(OP), subjects were grouped as IIH (n=3, OP 28-55cm H2O, all with papilledema) or non-IIH (n=4, OP 10-20cm H2O, none with papilledema).
Across all subjects, BM displaced posteriorly following LP (p=0.018 nasal, 0.063 temporal, Wilcoxan signed ranks(WSR)). Optic nerve thicknesses and cup depth did not change following LP (p=0.15, 0.87, 0.18, WSR). IIH subjects had greater optic nerve thicknesses, shallower cup depth, and a more anterior BMO prior to LP than non-IIH subjects (p=0.034 for all, Mann Whitney Rank Sum). IIH and non-IIH subjects did not differ in the pre-post LP change in BM displacement, optic nerve thickness or cup depth. Groups did not differ by age or amount of CSF drained.
Changes in BMO displacement occur within 1 hour of ICP lowering via LP in subjects with and without IIH. Changes in optic nerve head contour do not occur within 1 hour of ICP lowering in subjects with or without IIH. These observations align with reports of BMO changes preceding optic nerve changes in treated IIH and support the candidacy of BMO displacement as a non-invasive rapid marker of ICP changes.
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