[Case Report] Unintended advancement of ventricular catheter during external ventricular drainage placed via the occipital route: report of two cases

[ABSTRACT] Displacement of the tip of an implanted tube is a serious complication in medical practice. Herein, we report two cases of unintended advancement of a drainage catheter during external ventricular drainage (EVD). Fortuitously, the patient did not present with any associated symptoms. The similarities between the two patients included the technique used, such that the EVD catheter was inserted through the occipital area, as well as the patient’s postoperative tendency to be restless and rub the back of his/her head against a pillow. In other words, the same phenomenon occurred in the postoperative period of two surgeries performed at different times over an interval of two years by different surgical teams. Therefore, it is considered appropriate to investigate the constitutive causes from the viewpoint of medical safety. Our detailed material science and mathematical considerations, especially topological considerations, proved that the outer diameter of the catheter decreases with tension and twisting. Therefore, strategies to prevent catheter migration include the following. 1) EVD should be tunneled subcutaneously to an appropriate length, and the EVD exit site should be adequately far from the main incision site. 2) The distal end of the ligature thread on the distal drainage catheter might be sutured to the skin instead of being cut. 3) A purse-string suture at the catheter exit site and modified Roman sandal tie could be created. 4) Frequent rubbing against the pillow or bed at the exit site of the EVD catheter should be avoided.