  Approximating light charged point-like particles in terms of (nonextremal)
dilatonic black holes is shown to lead to certain pathologies in Planckian
scattering in the eikonal approximation, which are traced to the presence of a
(naked) curvature singularity in the metric of these black holes. The existence
of such pathologies is confirmed by analyzing the problem in an `external
metric' formulation where an ultrarelativistic point particle scatters off a
dilatonic black hole geometry at large impact parameters. The maladies
disappear almost trivially upon imposing the extremal limit. Attempts to derive
an effective three dimensional `boundary' field theory in the eikonal limit are
stymied by four dimensional (bulk) terms proportional to the light-cone
derivatives of the dilaton field, leading to nontrivial mixing of
electromagnetic and gravitational effects, in contrast to the case of general
relativity. An eikonal scattering amplitude, showing decoupling of these
effects, is shown to be derivable by resummation of graviton, dilaton and
photon exchange ladder diagrams in a linearized version of the theory, for an
asymptotic value of the dilaton field which makes the string coupling constant
non-perturbative.
