Pasquale Gallina1, Alfonso Savastano2, Eleonora Becattini1, Simone Orlandini1, Antonio Scollato3, Stanislao Rizzo2, Giulia Carreras4, Nicola Di Lorenzo1, Berardino Porfirio5. 1. 1Department of Surgery and Translational Medicine, Neurosurgery Unit, Tuscany School of Neurosurgery, University of Florence. 2. 2Department of Surgery and Translational Medicine, Ophthalmic Unit, University of Florence. 3. 3Neurosurgery Unit, University Hospital "Ospedali Riuniti" of Trieste, Cattinara. 4. 4Occupational & Environmental Epidemiology Section, Cancer Prevention and Research Institute (ISPO), Florence; and. 5. 5Department of Clinical and Experimental Biomedical Sciences "Mario Serio," University of Florence, Italy.
Abstract
OBJECTIVE: Changes in the pressure gradient between intraocular and intracranial compartments at the lamina cribrosa level are a possible explanation of normal tension glaucoma (NTG). Shunt-treated normal pressure hydrocephalus (NPH) is a model for testing whether the increase (time from disease onset to CSF shunt placement, i.e., "protection period") and decrease (time from shunt placement to observation, i.e., "exposure period") in intracranial pressure (ICP) are glaucoma protective or risk factors, respectively. The authors estimated the prevalence of NTG in patients with shunt-treated NPH and calculated the extent of optic nerve exposure to changes in the trans-lamina cribrosa gradient. METHODS: Data obtained in patients with NPH who had undergone ventriculoperitoneal (VP) shunt placement were analyzed. Patients with more than 6 months' follow-up, no pathologies associated with ICP changes or CSF dynamics disturbances, and no surgical or valve-related complications were scheduled for ophthalmic evaluation. RESULTS: Nine of 22 patients had NTG, which is about a 40-fold increase in rate compared with the rate in the general elderly population without hydrocephalus (p < 0.001). The median protection period was 12.0 months in patients with NTG and 18.0 months in those without NTG (p = 0.033). The median ICP decrease multiplied by duration of exposure in months was 76.0 mm Hg × months in the NTG group and 24.1 mm Hg × months in the no-NTG group (p = 0.048). The patients' median adjusted age (adjusted for "protection" and "exposure" times) was 85.1 years in the NTG group and 78.8 years in the no-NTG group (p = 0.001). CONCLUSIONS: A crucial risk factor for development of NTG in patients with shunt-treated NPH is the duration of optic nerve exposure to the lowering of ICP. Patients with NPH who are candidates for CSF shunting should be informed of the risk of incurring glaucoma. Longitudinal studies could provide estimates of tolerated times for a given ICP decrease.
OBJECTIVE: Changes in the pressure gradient between intraocular and intracranial compartments at the lamina cribrosa level are a possible explanation of normal tension glaucoma (NTG). Shunt-treated normal pressure hydrocephalus (NPH) is a model for testing whether the increase (time from disease onset to CSF shunt placement, i.e., "protection period") and decrease (time from shunt placement to observation, i.e., "exposure period") in intracranial pressure (ICP) are glaucoma protective or risk factors, respectively. The authors estimated the prevalence of NTG in patients with shunt-treated NPH and calculated the extent of optic nerve exposure to changes in the trans-lamina cribrosa gradient. METHODS: Data obtained in patients with NPH who had undergone ventriculoperitoneal (VP) shunt placement were analyzed. Patients with more than 6 months' follow-up, no pathologies associated with ICP changes or CSF dynamics disturbances, and no surgical or valve-related complications were scheduled for ophthalmic evaluation. RESULTS: Nine of 22 patients had NTG, which is about a 40-fold increase in rate compared with the rate in the general elderly population without hydrocephalus (p < 0.001). The median protection period was 12.0 months in patients with NTG and 18.0 months in those without NTG (p = 0.033). The median ICP decrease multiplied by duration of exposure in months was 76.0 mm Hg × months in the NTG group and 24.1 mm Hg × months in the no-NTG group (p = 0.048). The patients' median adjusted age (adjusted for "protection" and "exposure" times) was 85.1 years in the NTG group and 78.8 years in the no-NTG group (p = 0.001). CONCLUSIONS: A crucial risk factor for development of NTG in patients with shunt-treated NPH is the duration of optic nerve exposure to the lowering of ICP. Patients with NPH who are candidates for CSF shunting should be informed of the risk of incurring glaucoma. Longitudinal studies could provide estimates of tolerated times for a given ICP decrease.
Entities:
Keywords:
CSF diversion; ICP = intracranial pressure; IOP = intraocular pressure; NPH = normal pressure hydrocephalus; NTG = normal tension glaucoma; VP = ventriculoperitoneal; intracranial hypotension; normal pressure hydrocephalus; normal tension glaucoma; trans–lamina cribrosa gradient
Authors: Alon Harris; Giovanna Guidoboni; Brent Siesky; Sunu Mathew; Alice C Verticchio Vercellin; Lucas Rowe; Julia Arciero Journal: Prog Retin Eye Res Date: 2020-01-24 Impact factor: 21.198