Eyelid myoclonus in Subacute Sclerosing Panencephalitis – A newly recognised slow myoclonic pattern?

We describe three cases of SSPE with eyelid myoclonus, a newly recognized slow myoclonic pattern.The first case is that of a 20-year-old woman (Jabbour Stage III) who developed rapidly progressive cognitive decline and periodic myoclonic jerks involving the limbs, eyelids, forehead, jaw, and neck over a period of eight months.She had several periodic, brisk eyelid openings, associated with frontalis contraction, leading to eyebrow elevation, followed by slow eyelid closure due to delayed relaxation of the levator palpebrae superioris (Video 1).There were several of these periodic myoclonic jerks, time-locked to the triphasic long-interval periodic discharges (Radermecker complexes) on the electroencephalography (EEG) (Figure 1).Several normal blinks with brisk eyelid closure followed by opening are also seen, which are clearly different from the slow eyelid closure following the synchronous jerks.The myoclonic jerks in this patient involved synchronous opening of the eyelids, elevation of the eyebrows, and jaw opening, involving multiple cranial nerves with motor nuclei in the brainstem.