Why do i need to lie down for 24 hours after hydrocephalus shunt surgery?

Surgeon preference: Your surgeon must have a preference for you laying down. Every neurosurgeon's practice is different and yours definitely has his reasons. I would not second guess his protocol. In our facility, our shunt patients are usually up and walking the evening of surgery and home the next day- but trust your surgeon.

Adjustment to flow: Shunt surgery is performed to divert spinal fluid from the brain compartment to the abdominal or lung cavity, to increase the body's ability to absorb excess spinal fluid. Staying flat for 24 hours will minimize excessive drainage immediately after surgery, and hopefully will prevent severe post-op headaches.