What is the operative technique for Ventriculoperitoneal (VP) shunting at Kocher's point?

Operative Technique for VP Shunting at Kocher's Point

The standard VP shunt placement at Kocher's point involves creating a burr hole 10-11 cm posterior and 2-3 cm lateral to the nasion (approximately 2-3 cm from midline and 1 cm anterior to the coronal suture), followed by ventricular catheter insertion perpendicular to the skull surface targeting the frontal horn of the lateral ventricle, with the distal catheter tunneled subcutaneously to the abdomen for peritoneal placement.

Ventricular Access at Kocher's Point

Patient Positioning and Preparation

• Position the patient supine with the head elevated 15-30 degrees to reduce venous pressure and facilitate CSF drainage
• Shave and prepare the scalp from the frontal region extending posteriorly to allow for subcutaneous tunneling
• Mark Kocher's point: approximately 10-11 cm posterior to the nasion and 2-3 cm lateral to midline (or 1 cm anterior to the coronal suture and 2-3 cm from midline)

Cranial Incision and Burr Hole

• Make a 3-4 cm linear or curved incision centered over Kocher's point
• Perform subperiosteal dissection to expose the skull
• Create a burr hole using a twist drill or cranial perforator
• Coagulate the dura and make a cruciate dural incision

Ventricular Catheter Placement

• Insert the ventricular catheter perpendicular to the skull surface, aiming toward the ipsilateral medial canthus and external auditory meatus
• Advance the catheter 5-6 cm in adults (depth varies with age and ventricular size) until CSF flow is obtained
• Confirm adequate CSF drainage before securing the catheter
• Connect the ventricular catheter to the valve system at a postauricular or frontal location

Distal Catheter Placement Techniques

Traditional Open Peritoneal Placement

• Make a small upper abdominal incision (typically right upper quadrant)
• Create a subcutaneous tunnel from the cranial incision to the abdominal incision using a tunneling device
• Open the peritoneum under direct visualization
• Insert 15-20 cm of distal catheter into the peritoneal cavity, directing it toward the pelvis or paracolic gutter
• Close the peritoneum, fascia, and skin in layers

Laparoscopic-Assisted Techniques (When Available)

• Falciform Ligament Technique: Create a window through the falciform ligament and place the distal catheter in the right subdiaphragmatic space, which significantly reduces distal obstruction rates (0% in one series versus traditional placement) 1
• Use an infraumbilical trocar with Hasson technique to establish pneumoperitoneum 2
• Insert the catheter through a 10-12 Fr metallic puncture cannula under direct laparoscopic visualization 2
• Position the catheter tip in the hepatic flexure to allow drainage into the right paracolic gutter 1
• This approach reduces distal catheter migration and obstruction, particularly beneficial in patients with obesity, peritoneal adhesions, or requiring shunt revisions 3

Hardware Selection and Assembly

Valve System Considerations

• Incorporate adjustable valve systems with antigravity or antisiphon devices to reduce low-pressure headache complications 4
• Select programmable valves that allow non-invasive post-operative pressure adjustments based on clinical response 4
• Common systems include Hakim-Cordis valve systems or equivalent modern programmable valves

Catheter Specifications

• Use standard ventricular catheters (typically 1.5-2.0 mm internal diameter)
• Ensure adequate distal catheter length (typically 60-80 cm total) to accommodate growth in pediatric patients
• Verify all connections are secure before final placement

Perioperative Management

Infection Prevention

• Administer perioperative antibiotics according to institutional protocols
• Consider longer antibiotic courses in patients with multiple prior revisions due to increased infection risk 4
• Minimize operative time and tissue handling

Intraoperative Verification

• Confirm CSF flow through the entire system before closure
• Test valve function by pumping mechanism
• Ensure no kinking or compression of the catheter along its subcutaneous course

Post-Operative Monitoring

Immediate Assessment

• Monitor for signs of increased intracranial pressure (headache, nausea, vomiting, visual changes) or low-pressure symptoms (positional headache relieved when supine) 4
• Assess surgical sites for CSF leakage or infection 4
• Document neurological status including pupillary examination 4

Common Complications to Anticipate

• Proximal catheter obstruction occurs in approximately 5% of cases 1
• Distal catheter migration can lead to rare complications including gastric perforation, though this is uncommon 5
• Shunt infection risk necessitates vigilance for fever, wound erythema, or neurological deterioration 6

Critical Technical Pitfalls

Ventricular Catheter Malposition

• Avoid angling the catheter too medially (risk of crossing midline) or too laterally (risk of parenchymal placement)
• Use neuronavigation when available to ensure accurate placement and minimize malposition risk 4
• Inadequate depth results in catheter tip in parenchyma rather than ventricle

Distal Catheter Issues

• Insufficient intraperitoneal length leads to catheter retraction and malfunction
• Placement in adhesion-prone areas increases obstruction risk
• The falciform ligament technique addresses these concerns by securing the catheter in the subdiaphragmatic space 1, 3