A computed tomography-based localizer to determine the entry site of the ventricular end of a parietal...

One of the major principles of shunt insertion into the brain involves choosing an entry site that avoids eloquent cortex.

We describe a novel tool to accurately locate the burr hole for insertion of the ventricular end of a catheter during parietal ventriculoperitoneal shunt surgery.

Computed tomography (CT)-based measurements in 2 dimensions were used to mark the entry point with the help of an indigenously designed Vellore burr hole localizer (VL). Patients underwent surgery with either the conventional method to localize the burr hole (Keen point; group A; n = 28) or the VL (group B; n = 28). An independent observer determined the accuracy of shunt placement on postoperative CT scans. The VL is designed with a fixed horizontal arm that can be aligned with the CT or magnetic resonance reference plane and a vertical arm with a flexible sliding horizontal arm that is attached to it with an adjustable screw. By manipulating the flexible arm along the contour of the skull and using the scale provided on both the vertical and horizontal arms, we can mark the burr hole site for placement of a parietal ventriculoperitoneal shunt.

Overall accuracy in group A was 32.1%, whereas in group B, an accuracy of 82.1% could be achieved (P < .01).

Placement of a burr hole guided by the VL increases the accuracy of the desired entry point of the ventricular catheter.