I'm lazy, so I just copy paste my comments in an older thread with a similar topic
Had two discs ruptured (C4/C6) in 2008. First weeks after the accident I thought I'd never be able to ride (horse or board) again. Had no feeling in left fingers for months and electrical buzzes in the arm whenever I reclined the head for years. Was very afraid of backwards falls the first seasons. Besides of trying to get stronger neck muscles, it helped me to ride with a neck stabilizing collar. First year a thick one, next season a thiner one, actually designed from a horse riding outfitter but it was helpful for snowboarding too.
Out of the USG catalog:
It won't absorb all energy of a backwards fall but it would prevent fast/extreme reclining.