  We show that that the non-equilibrium spin polarization of one dimensional
helical edge states at the boundary of a two dimensional topological insulator
can dynamically induce a polarization of nuclei via the hyperfine interaction.
When combined with a spatially inhomogeneous Rashba coupling, the steady state
polarization of the nuclei produces backscattering between the topologically
protected edge states leading to a reduction in the conductance which persists
to zero temperature. We study these effects in both short and long edges,
uncovering deviations from Ohmic transport at finite temperature and a current
noise spectrum which may hold the fingerprints for experimental verification of
the backscattering mechanism.
