CT of hydrocephalus

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Author: Mikael Häggström [notes 1]

Evaluation

Diagnosis

Evan's index

Evan's index is the ratio of maximum width of the frontal horns to the maximum width of the inner table of the cranium. An Evan's index more than 0.31 indicates hydrocephalus.[1]

Causes

Attempt to indicate either of the main causes: Normal pressure hydrocephalus (NPH) versus cerebral atrophy (as part of CT in dementia):

Typical imaging findings in normal pressure hydrocephalus versus brain atrophy.[2]
Normal pressure hydrocephalus Brain atrophy
Preferable projection Coronal plane at the level of the posterior commissure of the brain.
Modality in this example CT MRI
CSF spaces over the convexity near the vertex (red ellipse Red ellipse.png) Narrowed convexity ("tight convexity") as well as medial cisterns Widened vertex (red arrow) and medial cisterns (green arrow)
Callosal angle (blue V) Acute angle Obtuse angle is typical of brain atrophy
Most likely cause of leucoaraiosis (periventricular signal alterations, blue arrows Flecha tesela.svg) Transependymal cerebrospinal fluid diapedesis Vascular encephalopathy, in this case suggested by unilateral occurrence

Notes

  1. For a full list of contributors, see article history. Creators of images are attributed at the image description pages, seen by clicking on the images. See Radlines:Authorship for details.

References

  1. Ishii, Mitsuaki; Kawamata, Toshio; Akiguchi, Ichiro; Yagi, Hideo; Watanabe, Yuko; Watanabe, Toshiyuki; Mashimo, Hideaki (2010). "Parkinsonian Symptomatology May Correlate with CT Findings before and after Shunting in Idiopathic Normal Pressure Hydrocephalus ". Parkinson's Disease 2010: 1–7. doi:10.4061/2010/201089. ISSN 2042-0080. 
  2. Damasceno, Benito Pereira (2015). "Neuroimaging in normal pressure hydrocephalus ". Dementia & Neuropsychologia 9 (4): 350–355. doi:10.1590/1980-57642015DN94000350. ISSN 1980-5764.