  We present an exact solution to the problem of the spin edge states in the
presence of equal Bychkov-Rashba and Dresselhaus spin-orbit fields in a
two-dimensional electron system, restricted by a hard-wall confining potential
and exposed to a perpendicular magnetic field. We find that the spectrum of the
spin edge states depends critically on the orientation of the sample edges with
respect to the crystallographic axes. Such a strikingly different spectral
behavior generates new modes of the persistent spin helix-spin edge helices
with novel properties, which can be tuned by the applied electric and magnetic
fields.
