William E. Whitehead, Jay Riva-Cambrin, Abhaya V. Kulkarni, John C. Wellons III, Curtis J. Rozzelle, Mandeep S. Tamber, David D. Limbrick Jr., Samuel R. Browd, Robert P. Naftel, Chevis N. Shannon, Tamara D. Simon, Richard Holubkov, Anna Illner, D. Douglas Cochrane, James M. Drake, Thomas G. Luerssen, W. Jerry Oakes and John R. W. Kestle
Accurate placement of ventricular catheters may result in prolonged shunt survival, but the best target for the hole-bearing segment of the catheter has not been rigorously defined. The goal of the study was to define a target within the ventricle with the lowest risk of shunt failure.
Five catheter placement variables (ventricular catheter tip location, ventricular catheter tip environment, relationship to choroid plexus, catheter tip holes within ventricle, and crosses midline) were defined, assessed for interobserver agreement, and evaluated for their effect on shunt survival in univariate and multivariate analyses. De-identified subjects from the Shunt Design Trial, the Endoscopic Shunt Insertion Trial, and a Hydrocephalus Clinical Research Network study on ultrasound-guided catheter placement were combined (n = 858 subjects, all first-time shunt insertions, all patients < 18 years old). The first postoperative brain imaging study was used to determine ventricular catheter placement for each of the catheter placement variables.
Ventricular catheter tip location, environment, catheter tip holes within the ventricle, and crosses midline all achieved sufficient interobserver agreement (κ > 0.60). In the univariate survival analysis, however, only ventricular catheter tip location was useful in distinguishing a target within the ventricle with a survival advantage (frontal horn; log-rank, p = 0.0015). None of the other catheter placement variables yielded a significant survival advantage unless they were compared with catheter tips completely not in the ventricle. Cox regression analysis was performed, examining ventricular catheter tip location with age, etiology, surgeon, decade of surgery, and catheter entry site (anterior vs posterior). Only age (p < 0.001) and entry site (p = 0.005) were associated with shunt survival; ventricular catheter tip location was not (p = 0.37). Anterior entry site lowered the risk of shunt failure compared with posterior entry site by approximately one-third (HR 0.65, 95% CI 0.51–0.83).
This analysis failed to identify an ideal target within the ventricle for the ventricular catheter tip. Unexpectedly, the choice of an anterior versus posterior catheter entry site was more important in determining shunt survival than the location of the ventricular catheter tip within the ventricle. Entry site may represent a modifiable risk factor for shunt failure, but, due to inherent limitations in study design and previous clinical research on entry site, a randomized controlled trial is necessary before treatment recommendations can be made.
William E. Whitehead, Jay Riva-Cambrin, John C. Wellons III, Abhaya V. Kulkarni, Richard Holubkov, Anna Illner, W. Jerry Oakes, Thomas G. Luerssen, Marion L. Walker, James M. Drake and John R. W. Kestle
Cerebrospinal fluid shunt ventricular catheters inserted into the frontal horn or trigone are associated with prolonged shunt survival. Developing surgical techniques for accurate catheter insertion could, therefore, be beneficial to patients. This study was conducted to determine if the rate of accurate catheter location with intraoperative ultrasound guidance could exceed 80%.
The authors conducted a prospective, multicenter study of children (< 18 years) requiring first-time treatment for hydrocephalus with a ventriculoperitoneal shunt. Using intraoperative ultrasound, surgeons were required to target the frontal horn or trigone for catheter tip placement. An intraoperative ultrasound image was obtained at the time of catheter insertion. Ventricular catheter location, the primary outcome measure, was determined from the first postoperative image. A control group of patients treated by nonultrasound surgeons (conventional surgeons) were enrolled using the same study criteria. Conventional shunt surgeons also agreed to target the frontal horn or trigone for all catheter insertions. Patients were triaged to participating surgeons based on call schedules at each center. A pediatric neuroradiologist blinded to method of insertion, center, and surgeon determined ventricular catheter tip location.
Eleven surgeons enrolled as ultrasound surgeons and 6 as conventional surgeons. Between February 2009 and February 2010, 121 patients were enrolled at 4 Hydrocephalus Clinical Research Network centers. Experienced ultrasound surgeons (> 15 cases prior to study) operated on 67 patients; conventional surgeons operated on 52 patients. Experienced ultrasound surgeons achieved accurate catheter location in 39 (59%) of 66 patients, 95% CI (46%–71%). Intraoperative ultrasound images were compared with postoperative scans. In 32.7% of cases, the catheter tip moved from an accurate location on the intraoperative ultrasound image to an inaccurate location on the postoperative study. This was the most significant factor affecting accuracy. In comparison, conventional surgeons achieved accurate location in 24 (49.0%) of 49 cases (95% CI [34%–64%]). The shunt survival rate at 1 year was 70.8% in the experienced ultrasound group and 66.9% in the conventional group (p = 0.66). Ultrasound surgeons had more catheters surrounded by CSF (30.8% vs 6.1%, p = 0.0012) and away from the choroid plexus (72.3% vs 58.3%, p = 0.12), and fewer catheters in the brain (3% vs 22.4%, p = 0.0011) and crossing the midline (4.5% vs 34.7%, p < 0.001), but they had a higher proportion of postoperative pseudomeningocele (10.1% vs 3.8%, p = 0.30), wound dehiscence (5.8% vs 0%, p = 0.13), CSF leak (10.1% vs 1.9%, p = 0.14), and shunt infection (11.6% vs 5.8%, p = 0.35).
Ultrasound-guided shunt insertion as performed in this study was unable to consistently place catheters into the frontal horn or trigone. The technique is safe and achieves outcomes similar to other conventional shunt insertion techniques. Further efforts to improve accurate catheter location should focus on prevention of catheter migration that occurs between intraoperative placement and postoperative imaging. Clinical trial registration no.: NCT01007786 (ClinicalTrials.gov).