Why after lambar puncture procedur the CSF rhinorrhea was stopped?

May be temporary. By removing fluid, the pressure in the CSF compartment decreases, so the leak may stop for a bit.
Decreasing ICP. By lowering intracranial pressure (icp) when performing the lp, you may be lowering the tendency for the CSF to leak from a crib inform plate fracture that is responsible for the rhinorrhea.