What is the role of imaging studies in the workup of normal pressure hydrocephalus (NPH)?

Updated: Oct 19, 2018
  • Author: Michael J Schneck, MD, MBA; Chief Editor: Selim R Benbadis, MD  more...
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Answer

In most cases of new onset neurologic symptoms, a CT scan of the brain is initially obtained. Although MRI is more specific than CT in NPH, a normal CT scan can exclude the diagnosis. CT and MRI findings in NPH include the following:

  • Ventricular enlargement out of proportion to sulcal atrophy, as shown in the image below

  • Prominent periventricular hyperintensity consistent with transependymal flow of CSF, also shown below

    T2-weighted MRI showing dilatation of ventricles o T2-weighted MRI showing dilatation of ventricles out of proportion to sulcal atrophy in a patient with normal pressure hydrocephalus. The arrow points to transependymal flow.
  • Prominent flow void in the aqueduct and third ventricle, the so-called jet sign, (presents as a dark aqueduct and third ventricle on a T2-weighted image where remainder of CSF is bright)

  • Thinning and elevation of corpus callosum on sagittal images

  • Rounding of frontal horns, shown below

    CT head scan of a patient with normal pressure hyd CT head scan of a patient with normal pressure hydrocephalus showing dilated ventricles. The arrow points to a rounded frontal horn.
  • A narrow CSF space at the high convexity/midline areas relative to Sylvian fissure size was recently shown to correlate with a diagnosis of probable or definite iNPH. [11]


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