Evaluation of external ventricular drain complications and the use of a procedure-targeted image-guidance system

Access to the cerebral ventricle (e.g. ventriculostomy) is required to manage multiple life-threatening ailments. It can be done either in the operating room or at the bedside to relieve increased intracranial pressure or deliver medication. At the bedside, the procedure is normally performed freehand, with the occasional use of a Ghajar guide for guidance support. In the operating room, ventriculostomy may be performed with an image-guidance system, whether optical or electromagnetic. The most common complications of ventriculostomy are hemorrhage and infection. It is unclear whether catheter placement accuracy and the number of passes of the catheter for each placement are correlated with ventriculostomy complications. Our goals are 1) to evaluate the current state of practice, including complications of ventriculostomy, and 2) to evaluate a targeted image guidance system for use with ventriculostomy the Smart Stylet. To address these goals, an Institutional Review Board-approved retrospective cross-sectional study was conducted at the Brigham and Women's Hospital (BWH) to characterize the practice of external ventricular drain placements using data from the patient electronic medical record. Post-procedure catheter location was measured on post-procedure CT and MRI imaging studies. Most cases were performed in the operating room and the operative reports provided all procedure-related information. Microbiology reports were collected within a four-week interval following catheter placements to evaluate presence of invading pathogens. All imaging studies, microbiology reports, and operative reports were reviewed manually. The rest of the medical records were not reviewed and, therefore, cerebrospinal fluid leak and shunt malfunction were not evaluated. Catheter placement accuracy and the numbers of passes for each placement were assessed. We evaluated whether these metrics were associated with the occurrence of procedure complications. A procedure-targeted image guidance system in development stage, the Smart Stylet, was implemented for use on a ventricular phantom model with a right-sided midline shift. Smart Stylet consists of an electromagnetic tracking system and ventriculostomy catheter connected to a PC and display. The operator of the Smart Stylet can interface with the system via a custom designed module in BWH's 3DSlicer software system. The system was tested for accuracy by calculating targeting error and reporting the precision of catheter placement. Precision was measured using pair-wise distances among experimental groups. The system was reviewed and commented on by three novices and two neurosurgical residents from the Massachusetts General Hospital by using the NASA-TLX grading scale questionnaire and a targeted survey. The phantom model was designed to gauge whether further tests in animals and cadavers are warranted using Smart Stylet. Patients with trauma were more likely to have catheters misplaced (OR = 9.13±2.31; p<0.05). It seems there is an opportunity to improve patient care if catheter placement is made more accurate and reliable. Use of the Smart Stylet system in a phantom study provided improvements in mean pair-wise distance and accuracy for catheter placement at the sub-centimeter level. A blinded operator achieved statistically significant improvement in targeting error using the right frontal approach (p<0.0 5). The operator also significantly improved mean pairwise distances using left and right frontal approaches (p<0.05). Novice operators and neurosurgical residents both showed improvements in targeting accuracy for catheter placement when using the system for the first time. However, the improvements were not statistically significant. Novices' pair-wise distances were significantly better with Smart Stylet guidance using the left frontal approach (p<0.05). Improved guidance techniques, such as the Smart Stylet approach, can potentially decrease ventriculostomy complications if they can be easily integrated into clinical use at low cost. Thesis Supervisor: Ronilda Lacson MD PhD Title: Instructor of Radiology Thesis Supervisor: Kirby Vosburgh PhD Title: Assistant Professor of Radiology