Keyhole Surgery for the Positioning of the Distal Catheter in Ventricular Peritoneal Shunt Placement

Overview

Ventriculoperitoneal shunting (VPS) was first described at the beginning of the 20th century as a diversionary procedure in patients with a hydrocephalus. After the introduction of silastic catheters in the 1970's this method became the treatment of choice for children and adults with communicating hydrocephalus. The average patient necessitating VPS will undergo at least two shunt revisions every three years, with some patients requiring more than twenty revisions within the first year. Therefore, any technical improvement with a positive impact on the revision rate not only benefits the patient through a reduction of the surgical burden but may also have economic advantages. Distal shunt failures - either due to improper placement or secondary dislocation of the distal catheter out of the peritoneal cavity - have been reported in 10-30% of cases. Catheter placement in obese patients and in patients with adhesions owing to previous abdominal surgery remains challenging. Most neurosurgeons will carry out a mini-laparotomy to allow for the placement of the distal catheter end within the peritoneal cavity, which rarely requires the help of a general or visceral surgeon. An alternative to laparotomy is the laparoscopic placement of the peritoneal catheter in VPS. Retrospective series have since shown the safety of this procedure and suggested an advantage of laparoscopic VPS in terms of operation duration, length of hospital stay and the rate of distal (and thus potentially overall) shunt dysfunction. The evidence concerning the effect of laparoscopic surgery for VPS placement is so far based on non-randomized studies, in which a selection bias may have influenced the outcomes.

Background Ventriculoperitoneal shunting (VPS) as diversionary procedure in patients with hydrocephalus was first described in 1908. After the introduction of silastic catheters during the 1970s this method has become the treatment of choice for children and adults with communicating hydrocephalus. However, the average patient having had VPS will undergo 2.1 shunt revisions every 3 years of life, with a wide range from no revisions during the first decade to up to 21 revisions within the first year. For this reason technical improvements impacting positively on the revision rate and on the surgical burden are strongly needed. In the standard VPS procedure the proximal part of the shunt is first placed in one of the lateral ventricles. The distal part of the shunt is then tunneled subcutaneously from the head to the abdomen, where 20-25 cm of the distal catheter and the tip are introduced in the peritoneal cavity through a paraumbilical mini-laparotomy. The intraperitoneal placement of the distal catheter is performed blindly, whereby the tip of the catheter is directed caudally in direction of the pelvis in order to avoid kinking and potential strangulation of the catheter. In this setting the functionality of the system can be estimated by feeling the resistance to out- and inflow while manually pumping the reservoir near the valve at the cranial level. Distal shunt failure has been reported to occur in 10-30% of cases. Secondary dislocation of the peritoneal catheter in the subcutaneous tissue or its improper placement in the peritoneal cavity during the procedure both contribute to this high shunt failure rate. Furthermore, blind catheter placement in obese patients and in patients with adhesions from previous abdominal surgery can be a challenge and may lead to injuries of the intra-abdominal organs. In 1993, Bassauri et al reported on the laparoscopic placement of the peritoneal catheter in VPS. Since then several, small retrospective series have shown good results in laparoscopic VPS, both in terms of efficacy and safety, in adults and in children. Two larger series were published recently. Schubert et al. reported a prospective study on 50 adult patients using the laparoscopically assisted peritoneal shunt insertion. A retrospective cohort of 50 matched patients served as a control. They reported no intraoperative complications, a longer operation time in the laparoscopic group (59 versus 49 minutes), 2 malfunctions (4%) and 1 infection in the laparoscopic group (2%) and 6 malfunctions (12%) and 6 infections (12%) in the historic cohort, the difference being statistically significant in favour of the laparoscopic group. In the most recent and largest series published to date, Bani et al. report on their experience with 151 patients, where the peritoneal catheter was implanted using a laparoscopic technique. They also used a retrospective cohort of 50 non-laparoscopy patients as a control. The operation time was slightly longer using the laparoscopic technique (35-130 versus 30-120 minutes), the infection rate was 2% in both groups. They describe no dislocation of the distal catheter in the abdominal wall and no malpositioning of the distal catheter in the laparoscopic group and 4 such cases in the non-laparoscopy group (8%). In summary, these non-randomized trials suggest the safety of the procedure. The laparoscopic technique offers at least theoretically some significant advantages over the standard technique. The laparoscopic introduction of the peritoneal catheter allows for intra-abdominal inspection, lyses of adhesions whenever necessary, confirmation of the catheter position, and the visual assessment of cerebrospinal fluid (CSF) flow through the catheter tip during the procedure. Due to the minimal trauma to the abdominal wall the laparoscopic access also has the potential of reducing postoperative adhesions, wound complications and the overall postoperative morbidity. Despite these theoretical advantages, however, comparative, randomized data are lacking and ventriculoperitoneal shunting is still performed through a minilaparotomy in the vast majority of neurosurgical centres. The absence of scientific evidence favouring the laparoscopic technique, the lack of training of neurosurgeons in laparoscopic techniques and the potential prolongation of the operating time (and potentially a higher risk of infection) are probably the main reasons to explain why the shift to the laparoscopic technique has not yet taken place. Also, theoretically, the inflation of the peritoneal cavity for laparoscopy could potentially generate an acute hydrocephalus (e.g. during a distal revision) due to the elimination of the pressure gradient necessary to obtain flow of CSF into the peritoneal cavity. These potential limitations warrant, in our view, a prospective, randomized, controlled trial comparing the standard (minilaparotomy) technique. The demonstration of the superiority of the laparoscopic technique in a prospective, randomized study has the potential of changing the standard of care for patients with hydrocephalus needing shunting. Methods 120 patients scheduled for VPS surgery were randomised for laparoscopic or open insertion of the peritoneal catheter. The primary endpoint was the rate of overall shunt complication/failure after 12 months. Secondary endpoints were distal shunt failure rate at 6 weeks, 6 months and 12 months, overall complication/failure at 6 weeks and 6 months, duration of surgery and hospitalisation, and morbidity.