What is best treatment to prevent cauda equina syndrome in patient who has sciatica ?

None: That's like asking, "One of the rooms in my house is uncomfortably warm. How can I prevent my house from burning down?" Aside from the fact that a house fire produces heat, the two things are unrelated. CAS is RARE. Sciatica and CAS can be produced by some of the same pathologies, but sciatica is just a pain. CAS is serious. My advice: Find something else to worry about.