Medizinische Universität Graz Austria/Österreich - Forschungsportal - Medical University of Graz
Gewählte Publikation:
SHR Neuro Krebs Kardio Lipid Stoffw Microb
Toma, AK; Holl, E; Kitchen, ND; Watkins, LD.
Evans' index revisited: the need for an alternative in normal pressure hydrocephalus.
Neurosurgery. 2011; 68(4):939-944
Doi: 10.1227/NEU.0b013e318208f5e0
Web of Science
PubMed
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- Co-Autor*innen der Med Uni Graz
- Holl Etienne
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- Abstract:
- BACKGROUND: The international guidelines for the diagnosis of normal pressure hydrocephalus (NPH) define ventricular enlargement as Evans' index greater than 0.3. OBJECTIVE: To establish whether there is a correlation between Evans' index and ventricular volume (VV) in NPH and whether choosing different planes for the measurements could produce significantly different results. METHODS: Pre-shunt insertion, thin-section CT scans of the brains of 10 patients with shunt-responsive NPH were reviewed retrospectively, measuring Evans' index, frontal horn index, VV, and total intracranial volume (ICV). The ventricular/intracranial volume index (VV/ICV) was calculated. Correlation between each of the linear indices and VV and VV/ICV was done. RESULTS: Significant differences were found in the index values calculated at different planes. The frontal horn index at a plane 16 mm parallel to the anterior commissure-posterior commissure (AC-PC) plane showed best correlation with VV and VV/ICV (r: 0.658 and 0.587, respectively). Evans' index, also obtained at a plane 16 mm parallel to the AC-PC plane, showed best correlation with VV and VV/ICV (r: 0.619 and 0.498, respectively). CONCLUSION: Evans' index value can vary significantly in a patient with NPH, depending on the level of the brain CT scan image at which the frontal horns and maximal inner skull diameters are measured. Evans' index is not an ideal method for estimating the VV in NPH patients. Volumetric measurements represent the logical accurate estimate of true ventricular size as well as the size of the other intracranial compartments.
- Find related publications in this database (using NLM MeSH Indexing)
- Brain - radiography
- Humans -
- Hydrocephalus, Normal Pressure - radiography
- Organ Size -
- Retrospective Studies -
- Severity of Illness Index -
- Tomography, X-Ray Computed - methods
- Find related publications in this database (Keywords)
- Evans' index
- Normal pressure hydrocephalus
- Ventriculomegaly