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.
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.
Authors: Adam M Staffaroni; Fanny M Elahi; Dana McDermott; Kacey Marton; Elissaios Karageorgiou; Simone Sacco; Matteo Paoletti; Eduardo Caverzasi; Christopher P Hess; Howard J Rosen; Michael D Geschwind Journal: Semin Neurol Date: 2017-12-05 Impact factor: 3.420
Authors: J Neikter; S Agerskov; P Hellström; M Tullberg; G Starck; D Ziegelitz; D Farahmand Journal: AJNR Am J Neuroradiol Date: 2020-06-11 Impact factor: 3.825
Authors: Nityanand Miskin; Hersh Patel; Ana M Franceschi; Benjamin Ades-Aron; Alexander Le; Brianna E Damadian; Christian Stanton; Yafell Serulle; James Golomb; Oded Gonen; Henry Rusinek; Ajax E George Journal: Radiology Date: 2017-05-10 Impact factor: 11.105
Authors: Ivan Jovanović; Jakob Nemir; Danilo Gardijan; Milan Milošević; Zdravka Poljaković; Marijan Klarica; David Ozretić; Marko Radoš Journal: Neuroradiology Date: 2021-06-15 Impact factor: 2.804
Authors: Yafell Serulle; Henry Rusinek; Ivan I Kirov; Hannah Milch; Els Fieremans; Alexander B Baxter; John McMenamy; Rajan Jain; Jeffrey Wisoff; James Golomb; Oded Gonen; Ajax E George Journal: J Neurol Date: 2014-08-01 Impact factor: 4.849