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Related Experiment Video

Updated: Feb 15, 2026

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Increase in callosal angle and decrease in ventricular volume after shunt surgery in patients with idiopathic normal

Johan Virhammar1, Katarina Laurell2, Kristina Giuliana Cesarini3

  • 11Neurology and.

Journal of Neurosurgery
|February 3, 2018
PubMed
Summary

Shunt surgery for idiopathic normal pressure hydrocephalus (iNPH) increased the callosal angle (CA) and decreased ventricle size. The callosal angle is a promising, noninvasive marker for shunt function in iNPH patients.

Keywords:
AC-PC = anterior commissure–posterior commissureCA = callosal angleEvans indexICC = intraclass correlation coefficientIQR = interquartile rangeMMSE = Mini-Mental State ExaminationNPHQRAPMASTER = quantification of relaxation times and proton density by multiecho acquisition of saturation-recovery with turbo spin-echo readoutcallosal angleiNPH = idiopathic normal pressure hydrocephalusnormal pressure hydrocephaluspostoperative radiologyquantitative MRIshunt dysfunction

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Area of Science:

  • Neurosurgery
  • Radiology
  • Neurology

Background:

  • Postoperative ventricle size changes in idiopathic normal pressure hydrocephalus (iNPH) are often subtle.
  • Traditional measurements like the Evans index may not reliably detect these changes.

Purpose of the Study:

  • To assess if the callosal angle (CA) increases and ventricular volume decreases after shunt surgery in iNPH patients.
  • To evaluate the CA as a potential indirect marker for shunt function.

Main Methods:

  • Brain MRI was performed before and 3 months after shunt surgery in 18 iNPH patients.
  • Measurements included the callosal angle (CA), Evans index, and quantitative ventricular volume.
  • Correlation between CA changes and ventricular volume changes was analyzed.

Main Results:

  • The callosal angle (CA) significantly increased postoperatively (p < 0.001).
  • Lateral ventricle volume contralateral to the shunt significantly decreased postoperatively (p < 0.001).
  • The Evans index showed a smaller, though significant, postoperative decrease (p < 0.05).

Conclusions:

  • Shunt surgery in iNPH patients leads to increased callosal angle and decreased ventricular volume.
  • The callosal angle demonstrated a more pronounced relative change than the Evans index.
  • The callosal angle is a potential, accessible, noninvasive radiological marker for evaluating shunt function in iNPH.