Historical Context & Current Trends

The VP shunt became the gold standard due to its direct access to cerebral ventricles and perceived technical reliability. As recently as 1999, VP shunts accounted for 98% of pediatric and over 80% of adult shunt procedures (Aschoff, 1999). However, a 2018 meta-analysis of over 2,400 iNPH patients revealed a shift: VP shunts still lead at 74%, but LP shunts now represent 8.5% — a significant increase from prior decades (Giordan et al., 2018).

Notably, in Japan, LP shunts have surpassed VP shunts in iNPH cases since 2011, reflecting growing global confidence in their utility (Kazui et al., 2015). This trend is supported by literature growth: a 2015 bibliometric analysis showed a steady rise in publications on LP shunts since the 1970s (Jusue-Torres et al., 2015).

Indications: When to Choose LP Over VP

Ideal Candidates for LP Shunt:

• Communicating hydrocephalus only — CSF pathways must be patent. LP shunts are contraindicated in obstructive (non-communicating) hydrocephalus due to risk of tonsillar herniation.
• Narrow or slit ventricles — Common in idiopathic intracranial hypertension (IIH). Up to 32% of IIH patients receive LP shunts (Azad et al., 2020).
• Patients avoiding cranial surgery — LP shunts eliminate the need for burr holes or brain penetration, reducing risk of hemorrhage or parenchymal injury.
• Local anesthesia candidates — Especially beneficial for high-risk surgical patients.

Advantages of LP Shunt

• Less invasive: No cranial penetration required.
• Reduced brain-related complications: Avoids risks like intraventricular hemorrhage or catheter misplacement in small ventricles.
• Comparable outcomes: Meta-analyses show equivalent symptom improvement and complication rates vs. VP shunts (Giordan et al., 2018; Ho et al., 2023).
• Growing clinical validation: Especially in Asia and for iNPH/IIH populations.

Key Complications: LP vs. VP

While infection, occlusion, and overdrainage affect both shunt types, LP shunts carry unique risks:

Hydrodynamics: Debunking the “No Siphon Effect” Myth

A common misconception suggests that because lumbar and peritoneal sites are level in upright posture, LP shunts are immune to siphoning. This is misleading.

In VP shunts, gravity pulls CSF downward, creating suction below the valve. In LP shunts, hydrostatic pressure above the valve increases with height — effectively “pushing” CSF through the system. The net differential pressure on the valve is similar.

“Lumboperitoneal shunts may produce similar posture-related problems. The difference is that the hydrostatic pressure does not produce pulling but rather pushing force in the vertical body position.” — Mirone et al. (2019)

Solutions for Overdrainage in LP Shunts:

• Gravitational valves: Adjust resistance based on body position (e.g., MIETHKE DUAL SWITCH, Integra H-V Lumbar Valve).
• Flow restrictors: Narrow-lumen catheters (0.8mm ID) reduce flow regardless of posture.
• SiphonGuard: Reduces — but doesn’t eliminate — upright flow.
• Avoid membrane-type ASDs: Devices like Delta® Chamber may malfunction due to implantation height sensitivity (Miyake, 2016).

Valve Selection & Mechanical Considerations

Any differential pressure valve can technically be used in an LP shunt. However, lumbar dynamics demand:

• Secure subcutaneous fixation: Suture eyelets prevent migration.
• Resistance to bending/torsion: Lumbar region undergoes frequent movement.
• Stable gravitational alignment: Valves must remain oriented with the body axis.
• Shallow implantation depth: For magnetic adjustability (in programmable valves).
• Support structures: Fascia, rib cage, or silicone “valve boards” prevent sinking during adjustment.

Valve Compatibility (per Miyake, 2016):

• ✅ Suitable: Integra H-V, MIETHKE DUAL SWITCH
• ⚠️ Limited (pre-2023): MIETHKE proGAV®/proSA® (now compatible with silicone valve board)

Conclusion: Equivalence with Nuance

Current evidence supports the clinical equivalence of LP and VP shunts in treating communicating hydrocephalus and iNPH — provided patient selection is precise and technical considerations are addressed.

LP Shunt: Best For

• Adults with communicating hydrocephalus or IIH
• Patients with narrow ventricles
• Those seeking to avoid cranial surgery
• Cases where local anesthesia is preferred

LP Shunt: Avoid In

• Children (risk of spinal deformity)
• Non-communicating hydrocephalus
• Patients with unstable spinal anatomy

The decision ultimately rests with the treating physician — weighing patient anatomy, comorbidities, surgical risk, and long-term mechanical durability.

References (Selected)

1. Giordan E, et al. J Neurosurg. 2018. doi:10.3171/2018.5.JNS1875
2. Ho YJ, et al. CNS Neurosci Ther. 2023. doi:10.1111/cns.14086
3. Miyake H. Neurol Med Chir (Tokyo). 2016. doi:10.2176/nmc.ra.2015-0282
4. Mirone G, et al. Pediatric Hydrocephalus. Springer, 2019.
5. Jusue-Torres I, et al. Complications of CSF Shunting. Springer, 2015.
6. Azad TD, et al. Neurosurgery. 2020. doi:10.1093/neuros/nyz080
7. Nakajima M, et al. Oper Neurosurg. 2018. doi:10.1093/ons/opy044