Callosal angle

The callosal angle has been proposed as a useful marker of patients with idiopathic normal pressure hydrocephalus (iNPH), helpful in distinguishing these patients from those with ex-vacuo ventriculomegaly (see hydrocephalus versus atrophy). 


Ideally the angle should be measured on a coronal image perpendicular to the anterior commissure - posterior commissure (AC-PC) plane at the level of  the posterior commissure 1,2.


In general patients with iNPH have smaller angles than those with ventriculomegaly from atrophy or normal controls. 

A normal value is typically between 100-120°. In patients with iNPH that value is lower, between 50-80° 2.  

In one study, symptomatic iNPH patients who responded to shunting had a significantly smaller mean preoperative callosal angle (59° (95% CI 56°-63°)) compared with those who did not respond (68° (95% CI 61°-75°)) 1

Share article

Article information

rID: 37405
Section: Signs
Synonyms or Alternate Spellings:

Support Radiopaedia and see fewer ads

Cases and figures

  • Case 1
    Drag here to reorder.
  • Case 2
    Drag here to reorder.
  • Case 3
    Drag here to reorder.
  • Case 4
    Drag here to reorder.
  • Case 5
    Drag here to reorder.
  • Updating… Please wait.

     Unable to process the form. Check for errors and try again.

     Thank you for updating your details.