CT of hydrocephalus
Author:
Mikael Häggström [notes 1]
Evaluation
Diagnosis
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):
- Normal pressure hydrocephalus versus atrophy.jpg
Head CT in normal pressure hydrocephalus (left image) and head MRI (right image), in the coronal plane at the level of the posterior commissure. In the left image, the CSF spaces over the convexity near the vertex are narrowed ("tight convexity", red circle), as are the medial cisterns (red circle) - these are typical findings of NPH. On the right image, however, the CSF spaces over the convexity near the vertex (red arrow) and the medial cisterns (green arrow) are widened, a finding consistent with brain atrophy.
The blue lines in both images indicate the callosal angle: an acute angle is typical of NPH (left image), while an obtuse angle is typical of brain atrophy (right image).
The blue arrows indicate leucoaraiosis (periventricular signal alterations). In the left image these may well represent transependymal CSF diapedesis due to NPH. The unilateral occurrence of these alterations in right image suggests they are probably due to vascular encephalopathy.[2]
Notes
- ↑ 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
- ↑ 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:. ISSN 2042-0080.
- ↑ Damasceno, Benito Pereira (2015). "Neuroimaging in normal pressure hydrocephalus ". Dementia & Neuropsychologia 9 (4): 350–355. doi:. ISSN 1980-5764.
