This document summarizes a literature search on surgical treatments for trapped fourth ventricle. The search found one review and 40 case series or case studies totaling 199 patients, mostly from North America before 2000. Surgical techniques included placing shunts from the fourth ventricle to the ventricles or subarachnoid space, endoscopic fenestration or catheterization, and posterior fossa decompression. The evidence was limited to small, heterogeneous case studies with variable outcomes and follow-up. Both shunting and endoscopic techniques appear safe but higher quality evidence is needed to determine the best approach.

1. • 16/2/17
Evidence Based Surgery
• Shinuo Liu

2. AHV6121
• 55 yo man,
original AVM
operation 2014

3. PICO
• P = All patients with trapped fourth ventricle
• I = Best mode of surgical treatment (eg. Posterior fossa
decompression)
• C = Other forms of surgical treatment
• O = Efficacy (progression free survival)
• In all patients with entrapped fourth ventricle, what is the best form
of (surgical) treatment?

4. Search Terms
• Entrapped Fourth Ventricle
• Trapped Fourth Ventricle
• Isolated Fourth Ventricle
• Sequestered Fourth Ventricle
• Surgery
• Therapy
• Shunt

5. Search criteria
• Inclusion
• ?All patients
• Exclusion
• ?adults
• Case reports?
• Related to neural tube defects

6. Scopus – “entrapped fourth ventricle”

8. “trapped fourth ventricle”

9. “isolated fourth ventricle”

10. Medline

11. Embase

12. Results

13. • 1 review
• 40 articles – all case series or case studies
• No higher level evidence
• N = 199 (adult n = 33)
• Mostly North American studies
• Prior to 2000, 4th ventricular catheterisation
• After 2000, endoscopic techniques
• F/U = 2 to 90 months

14. • All small cohorts
• Heterogeneous population
• Unclear aetiology
• Unclear previous treatment
• Unclear outcome, variable F/U
• Vast majority had clinical and radiological success = publication bias?

15. • Techniques:
• 4th ventricle  VP shunt
• 4th ventricle  SAS
• EA ST
• EA IT
• +/- stent
• Posterior fossa decompression, adhesiolysis, duraplasty
• Endoscopic fenestration (ST)
• Endoscopic transtentorial catheterisation
• +/- ETV
• Shunting and endoscopic techniques are probably both safe, although one is
safer.
• Posterior fossa arachnoiditis deserves consideration
• Largest cohort was Garber et al in JNS 2013 with n = 29

17. • Case by case – consider aetiology
• Unclear whether paeds = adults
• Stenting ?