I never CT for isolsated syncope with return to normal mental status. If there was head trauma, persisting AMS, if I can't do a neuro exam, or if the syncope was really a seizure then I'll do the CT. In order to loose consciousness from a CNS etiology one must loose function of both cerebral hemispheres or the entire reticular activating system. In both cases that ptient will not return to a normal mental status.
But as I type the above dogma I find myself wondering why I feel compelled to do a complete neuro exam on each syncope patient. Is it just chart dressing?