{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,7]],"date-time":"2026-08-07T18:00:35Z","timestamp":1786125635871,"version":"build-2736575974"},"reference-count":20,"publisher":"Ovid Technologies (Wolters Kluwer Health)","issue":"3","license":[{"start":{"date-parts":[[2021,6,15]],"date-time":"2021-06-15T00:00:00Z","timestamp":1623715200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/academic.oup.com\/journals\/pages\/open_access\/funder_policies\/chorus\/standard_publication_model"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Neurosurg.","NEUROS"],"published-print":{"date-parts":[[2021,9]]},"abstract":"Abstract<\/jats:title>\n \n BACKGROUND<\/jats:title>\n Normal pressure hydrocephalus (NPH) is frequently treated with ventriculoperitoneal shunt (VPS) surgery. However, VPS implantation can lead to overdrainage and complications such as headaches, hygroma, and subdural hematoma due to a siphon effect in an upright position. Gravitational valves prevent overdrainage through position-dependent adjustment of valve resistance. Flow-regulated valves that increase resistance in presence of high cerebrospinal fluid flow may provide similar protection against overdrainage and present an alternative to gravitational valves.<\/jats:p>\n <\/jats:sec>\n \n OBJECTIVE<\/jats:title>\n To compare gravitational and flow-regulated shunt valves in patients with symptomatic NPH.<\/jats:p>\n <\/jats:sec>\n \n METHODS<\/jats:title>\n We performed a retrospective analysis of 97 patients suffering from NPH who underwent VPS implantation with a gravitational or a flow-regulated valve. The primary endpoint was the occurrence of hygroma or subdural hematoma. Secondary endpoints were neurological outcome (Kiefer score, Stein and Langfitt score, and NPH recovery rate), frequency of valve adjustments, and reoperations.<\/jats:p>\n <\/jats:sec>\n \n RESULTS<\/jats:title>\n \n No significant differences in the occurrence of hygroma and subdural hematoma (11.4% for flow-regulated valves vs 5.7% for gravitational valves,\n P<\/jats:italic>\n \u00a0=\u00a0.462) or response to treatment (77.3%\u00a0vs 81.1%,\n P<\/jats:italic>\n \u00a0=\u00a0.802) were found. Patients with flow-regulated valves required fewer valve adjustments (1.12\u00a0vs 2.02,\n P<\/jats:italic>\n \u00a0<\u00a0.001) to reach their optimal neurological outcome and underwent fewer surgical revisions (11.4%\u00a0vs 28.3%,\n P<\/jats:italic>\n \u00a0=\u00a0.047).\n <\/jats:p>\n <\/jats:sec>\n \n CONCLUSION<\/jats:title>\n Our data suggest that shunt therapy in NPH patients with a flow-regulated instead of a gravitational valve is safe and effective with a comparable clinical outcome and risk of overdrainage complications. Moreover, patients with flow-regulated valves may need fewer valve adjustments and reoperations.<\/jats:p>\n <\/jats:sec>","DOI":"10.1093\/neuros\/nyab176","type":"journal-article","created":{"date-parts":[[2021,6,8]],"date-time":"2021-06-08T15:48:39Z","timestamp":1623167319000},"page":"413-419","source":"Crossref","is-referenced-by-count":9,"title":["Comparison Between Flow-Regulated and Gravitational Shunt Valves in the Treatment of Normal Pressure Hydrocephalus: Flow-Grav Study"],"prefix":"10.1227","volume":"89","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-6596-456X","authenticated-orcid":false,"given":"Pierre","family":"Scheffler","sequence":"first","affiliation":[{"name":"Department of Neurosurgery, University Hospital Zurich, University of Zurich, Zurich, Switzerland"},{"name":"Clinical Neuroscience Center, University Hospital Zurich, University of Zurich, Zurich, Switzerland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5121-5376","authenticated-orcid":false,"given":"Markus Florian","family":"Oertel","sequence":"additional","affiliation":[{"name":"Department of Neurosurgery, University Hospital Zurich, University of Zurich, Zurich, Switzerland"},{"name":"Clinical Neuroscience Center, University Hospital Zurich, University of Zurich, Zurich, Switzerland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3744-5105","authenticated-orcid":false,"given":"Lennart Henning","family":"Stieglitz","sequence":"additional","affiliation":[{"name":"Department of Neurosurgery, University Hospital Zurich, University of Zurich, Zurich, Switzerland"},{"name":"Clinical Neuroscience Center, University Hospital Zurich, University of Zurich, Zurich, 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