Shunt disconnection is less likely using a surgeon's knot compared with a surgical constrictor knot.

INTRODUCTION: Ventriculo-peritoneal shunt malfunction is a common neurosurgical presentation, which may occur as a result of shunt disconnection at the level of the valve. Previous studies assessing ligatures have suggested that the constrictor knot is stronger in securing a ligature compared to the surgeon's knot. Our study compared the ability of each knot to secure shunt tubing to the valve. METHODS: A medtronic shunt valve was secured to a peritoneal catheter using the surgeon's knot versus constrictor's knot. The weight and subsequent force (N) required to pull off the shunt tubing at the knot site were recorded. RESULTS: The mean pull-off force was 11.7 N for the surgeon knot, and 8.9 N for the constrictor knot. There was significant difference in favour for the surgeon's knot compared to the constrictor knot. CONCLUSIONS: The surgeon's knot is significantly stronger than the constrictor knot for securing a peritoneal catheter to a CSF shunt valve.

CT scan exposure in children with ventriculo-peritoneal shunts: single centre experience and review of the literature.

PURPOSE: A computed tomography (CT) scan in childhood is associated with a greater incidence of brain cancer. CT scans are used in patients with ventriculo-peritoneal (VP) shunts in whom shunt dysfunction is suspected. We wanted to assess the CT scan exposure in a cohort of children with VP shunts and attempt to quantify their radiation exposure. METHODS: A single-centre retrospective analysis was performed recording CT head scans in children younger than 18 years with VP shunts. Hospital coding data was cross-referenced with electronic records and radiology databases both in our neurosurgery unit and in hospitals referring to it. RESULTS: One hundred and fifty-two children with VP shunts were identified. The mean time with shunt in situ was 5.4 years (± 4.61). A mean of 3.33 CT scans (range 0-20) were performed on each child, amounting to 0.65 (± 0.87) CTs per shunt year. Based on 2 msv of radiation per scan, this equates to an average exposure of 1.31 msv per child per shunt year. CONCLUSION: Children who have multiple CT head scans for investigation of possible shunt dysfunction are at a greater risk of developing cancer. We discuss the implications of this increased risk and discuss strategies to limit radiation exposure in children with VP shunts.

Cauda equina syndrome secondary to intradural renal cell carcinoma metastasis haemorrhage.

Intradural renal cell carcinoma (RCC) metastasis is rare. We report a case of an 81-year-old female presenting with acute cauda equina syndrome (CES), secondary to intradural RCC metastasis haemorrhage. To our knowledge this is the first case of CES secondary to acute haemorrhage within an intradural RCC metastasis.