High accuracy of external ventricular drainage placement using anatomical landmarks

The conventional approach for external ventricular drainage (EVD) application is the freehand method. Technical devices can improve the accuracy of placement, but they have not yet replaced anatomical landmarks owing to the cost and effort that they entail. There is disagreement as to whether freehand EVD application is safe enough to be accepted as a standard technique. Many authors have investigated the final catheter position in retrospect. They describe variable rates of malpositioning. However, few studies have assessed in how far cranial surface anatomy has really been respected during burr-hole drilling and catheter insertion. The aim of this study was to investigate parameters that might play a part in determining the final intracranial catheter position.

In all, 100 pre- and postprocedural thin-layer computed-tomography (CT) scans of EVD patients were analysed with the help of JiveX® and OsiriX Lite® software. A series of anatomical and catheter-related parameters, including inter alia intraventricular blood, midline shift, burr-hole location and catheter entrance angle, were correlated with the final catheter position.

A majority of EVDs show an optimal or nearly optimal position. Only the deviation of catheter entrance angle has a significant influence on catheter malpositioning. The burr-hole location can vary within an area of several centimetres around the coronary suture.

The freehand application of EVD is safe as long as the intracranial anatomy is not disfigured to a large extent, the surface measurements are carried out precisely and the puncturing is done perpendicularly to the skull.