What are the next steps for a patient with a right frontal approach ventriculostomy (cerebrospinal fluid drainage catheter) catheter terminating near the foramen of Monro, showing slit-like ventricles concerning for over-shunting?

Management of Slit Ventricles with Ventriculostomy Catheter Terminating Near Foramen of Monro

For a patient with slit-like ventricles and a ventriculostomy catheter terminating near the foramen of Monro suggesting over-shunting, the most appropriate next step is to consider shunt system revision with incorporation of an anti-siphon device or programmable valve set to a higher pressure to reduce overdrainage. 1

Assessment of Over-Shunting

• Slit ventricles on imaging with a ventriculostomy catheter terminating near the foramen of Monro strongly suggests over-shunting, which can lead to significant complications including shunt malfunction, headaches, and potentially slit ventricle syndrome 1
• Confirm the diagnosis with clinical correlation - patients with over-shunting may present with positional headaches, nausea, vomiting, lethargy, and decreased cognitive skills 2
• Consider measuring intracranial pressure (ICP) via a sedated lumbar puncture, as some patients with slit ventricles paradoxically have high ICP despite over-drained ventricles 2, 3

Management Options

1. Valve Adjustment/Replacement

• For patients with programmable valves, increasing the valve setting to a higher pressure is the first-line intervention 1
• If using a non-programmable valve, consider replacing with a higher pressure valve or adding an anti-siphon device 4
• Evidence shows that anti-siphon devices can reduce complications and proximal catheter obstructions in patients with over-drainage 1

2. Anti-Siphon Device Addition

• Adding an anti-siphon device to the shunt system can prevent further overdrainage of CSF 4
• In a retrospective review, patients with secondary placement of an anti-siphon device showed fewer complications and proximal catheter obstructions 1
• Anti-siphon devices provide progressive resistance to flow to counteract the siphoning that occurs with vertical positioning 1

3. Consider Alternative Shunt Systems

• For refractory cases, consider conversion to a different valve type 1
• The Orbis-Sigma valve has been associated with a lower incidence of slit-like ventricles (3.6%) compared to differential pressure valves (10.8%) and Delta valves (10.5%) (p = 0.007) 1
• This suggests that valves providing slower reduction in ventricle size and controlled flow may lead to more appropriate ventricular dimensions after shunt placement 1

4. Advanced Imaging Guidance for Revision

• If shunt revision is necessary, consider using ultrasound-guided or electromagnetic image-guided catheter placement 1
• Electromagnetic navigation has shown promise in difficult cases including those with small and slit ventricles, with one study demonstrating a 9% proximal revision rate compared to historical rates of 35% 1

5. Alternative Approaches for Refractory Cases

• For patients with persistent symptoms despite ventriculoperitoneal shunt revisions, consider lumboperitoneal shunting 2, 5
• Lumboperitoneal shunts have shown effectiveness in patients with slit ventricle syndrome who remain symptomatic from increased ICP despite functional ventriculoperitoneal shunts 2
• In severe cases with persistent symptoms, bilateral shunting of the ventricular system may be necessary 3

Monitoring After Intervention

• Close clinical and radiological follow-up is essential after any intervention 1
• Be aware that patients may experience temporary overdrainage symptoms after adjustment that typically resolve over several weeks 2
• Monitor for signs of underdrainage after adjustment (worsening headache, nausea, vomiting, altered mental status) which may indicate need for further adjustment 3

Pitfalls and Caveats

• Slit ventricles can be associated with either low or extremely high ICP, making clinical assessment crucial 3
• Fundoscopic examination may not always reveal signs of raised ICP in these patients 3
• Radiographic appearance of slit-like ventricles should not be the sole determinant for management decisions; clinical symptoms and possibly direct ICP measurement should guide treatment 2, 3
• In cases with competing collaterals or complex flow dynamics, addressing only the valve pressure may be insufficient 1