Maybe an ABR would be helpful. If the reflex decay is from hydrocephalus
the fourth ventrical is probably involved (compressing the lower pontine
region where CN VII and crossed AR pathways reside). The ABR is
particularly sensitive to this compression effect and may be used to
monitor changes in function associated with changes in ventricular
pressure. It would be real helpful if you had a pre-eppisode ABR. Maybe
the neurosurgeon got one after the last shunt?