Clinical study Failure rate of frontal versus parietal approaches for proximal catheter placement in ventriculoperitoneal shunts: revisited RD Dickerman 1 DO DO PhD PhD, WJ McConathy 2 PhD PhD, J Morgan 3 DO DO, QE Stevens 3 DO DO, JT Jolley 3 RN RN, S Schneider 3 MD MD, MA Mittler 3,4 MD MD 1 North Texas Neurosurgical Associates and Department of Neurosurgery, Medical Center of Plano, Plano, Texas, 2 Department of Internal Medicine, University of North Texas Health Science Center, Fort Worth, Texas, 3 Long Island Jewish Medical Center, Department of Neurosurgery, New Hyde Park, New York, 4 North Shore University Hospital, Department of Pediatric Neurosurgery, New York; USA Summary Early studies on ventriculoperitoneal shunt malfunctions demonstrated that proximal catheter obstruction was the most common cause for shunt malfunction and choroid plexus was the primary culprit for catheter obstruction. Subsequently, several studies were performed using stereotactic and endoscopic guidance systems to assist with optimal placement of proximal shunt catheters. Surgeons collectively agree that optimum placement of the proximal catheter tip is away from choroid plexus in the frontal horn. To achieve this catheter placement, neurosurgeons typically choose a frontal or parietal approach. Two previous studies comparing parietal and frontal shunt failure rates in the pediatric population have different conclusions. Thus, we decided to compare proximal catheter failure rates of frontal versus parietal approaches on 117 patients (ages ranging from 1 month to 80 years) who had undergone ventriculoperitoneal shunt placement at our institution. Statistical analysis demonstrated a significantly higher malfunction rate in the patients less than 3 years of age and a lower overall malfunction rate in patients shunted for normal pressure hydrocephalus. Surprisingly, there was no significant difference between the two surgical approaches. Thus, we concluded after reviewing the literature, that regardless of the initial surgical approach, the most important variable in shunt malfunction appears to be the final destination of the catheter tip in relation to the choroid plexus. ª 2005 Elsevier Ltd. All rights reserved. Keywords: hydrocephalus, obstruction, shunt malfunction, cerebrospinal fluid shunt, technique, ventricle INTRODUCTION Proximal ventriculoperitoneal (VP) shunt malfunction continues to be the most common cause of shunt failure. 1 The primary eti- ology of proximal catheter malfunction is obstruction by the cho- roid plexus. 2 It is well known that the ideal placement of the proximal catheter tip is in the frontal horn away from the choroid plexus. 3 Neurosurgeons typically utilize a frontal or parietal ap- proach for proximal catheter placement. 4 The decision of which approach to utilize is typically neurosurgeon-dependent, based on training, cosmesis and other patient specific variables. To date two studies have performed comparative analysis on the shunt malfunction rates when using the two surgical approaches with different conclusions. 5,6 There are advantages of each approach. The frontal approach has more consistent anatomical landmarks and placement of the proximal catheter anterior to the choroid plexus is easier. 4 The parietal approach is thought to be advanta- geous due to the larger posterior horn and the option of leaving the catheter tip posterior or advancing it into the frontal horn. 4 Based on the current controversy in the medical literature about which approach has the lower failure rate, we decided to revisit this topic with an additional point that was theorized by the fa- mous Greek mathematician, Euclid, who stated that ‘‘the shortest distance between two points is a straight line”. 5–7 Along with the aforementioned benefits of the frontal approach, we add that the shorter distance allows for easier optimal placement by the sur- geon and with reduced passage through brain parenchyma and other tissue, thus lowering the obstruction rate. METHODS A retrospective analysis was performed on 117 patients who had undergone VP shunt revision at our institution within the past four years. Each patient had a complete chart review with multiple variables recorded including: age, date of initial shunt placement, date of revision, number of revisions, approach (frontal versus parietal), cause of hydrocephalus and reason for shunt failure. Se- ven different neurosurgeons were involved in the surgical inser- tion of these shunts. Statistical analysis was performed using an unmatched paired t-test to compare rate of failure for frontal ver- sus parietal placement. Each surgeon was also independently ana- lyzed for failure rates. Statistical significance was set at (p < 0.05). RESULTS The 117 patients included 46 frontal and 71 parietal catheters, with an average age of 19.0 € 23.3 versus 31.3 € 30.6 respectively (p = 0.0240). To assess the association of age and failure rates we compared failure rates for patients <3 years of age and >3 years of age and demonstrated a significantly higher failure rate in the <3 years of age group (p = 0.0317) (Table 1). In analyzing the failure rates for patients with normal pressure hydrocephalus (NPH), we found a significantly lower VP shunt failure rate of 23%, in com- parison to all other categories. When comparing failure rates of each individual surgeon via ANOVA we found no significant dif- ference. Lastly, in comparing the frontal approach versus the pari- etal approach for VP shunt failure rates there was no significant difference in the surgical approaches (p = 0.6934) (Tables 1 and 2). Journal of Clinical Neuroscience (2005) 12(7), 781–783 0967-5868/$ - see front matter ª 2005 Elsevier Ltd. All rights reserved. doi:10.1016/j.jocn.2004.12.005 Received 20 October 2004 Accepted 6 December 2004 Correspondence to: Rob D Dickerman DO PhD, North Texas Neurosurgical Associates Medical Center of Plano, Department of Neurosurgery 3001 Communications Parkway, Suite 1027 Plano, TX 75093, USA. Tel.: +1 972 608 5000; Fax: +1 972 608 5020; E-mail: drrdd@yahoo.com 781