Seven patients, after seemingly uncomplicated surgery for ascending aorta aneurysm or dissection, with or without aortic valve replacement, developed an unusual and fairly stereotyped biphasic neurologic disorder without imaging evidence of related cerebral ischemia or infarct. The initial phase was mild, nonprogressive, or receding. The latent and progressive phase closely resembled a progressive supranuclear palsy phenotype. The disorder may prove to be self-limiting but leaves the patients with considerable neurologic deficits.