Rhythmic pupillary oscillation in Creutzfeldt-Jakob disease associated with the Glu/Lys mutation of prion protein codon 200.

We report two Creutzfeldt-Jakob disease (CJD) patients with rhythmic pupillary and palpebral oscillation who had a mutation of prion protein codon 200 that resulted in the substitution of lysine for glutamate (Glu/Lys). Alternating dilation and constriction of the pupils combined with elevation and descent of the eyelids occurred in correspondence with periodic sharp wave complexes (PSWCs) on the electroencephalogram and with myoclonus of the head, face, and extremities. The onset of pupillary dilation and palpebral elevation coincided with the PSWCs. Initiation of these rhythmic pupillary and palpebral movements may depend on sympathetic activity, but the site of the generator is unclear. Such rhythmic pupillary and palpebral oscillation may be a feature of rapidly progressive CJD with predominant right hemispheric involvement.