Infundibular Recess Angle Reduction After Endoscopic Third Ventriculostomy: Does It Reflect Clinical Success?

Although the ventricular size is significantly reduced after endoscopic third ventriculostomy (ETV) in most successfully treated patients, ventricular size reduction is not always seen after a successful ETV. Practical and reliable radiologic parameters are still needed to assess the clinical success of an ETV.

We retrieved the clinical and radiologic data of patients who underwent an ETV. Patients with the following criteria were included: (1) preoperative magnetic resonance imaging studies available, (2) postoperative magnetic resonance imaging studies done within the first 2 postoperative weeks, and (3) the infundibular recess clearly visible on preoperative and postoperative sagittal magnetic resonance imaging. Preoperative and postoperative measurements of the angle of the infundibular recess of the third ventricle were performed on midsagittal T1-weighted, T2-weighted, fast imaging employing steady-state acquisition, or constructive interference in steady state images.

The extent of reduction of the infundibular recess angle predicted the clinical outcome of ETV during the early postoperative period with a high degree of accuracy. The average reduction was about 48% in successful procedures versus only 15% in failed procedures.

The degree of reduction of the angle of the infundibular recess of the third ventricle correlated with the amount of third ventricular decompression after ETV. Most importantly, such a reduction was noted to occur during the early postoperative period when radiologic changes are less pronounced. Assessment of change in infundibular recess angle measurement is easy to perform and may prove helpful in cases with no clear-cut clinical evidence of success of ETV.