Opsoclonus: brainstem or cerebellum?

Abstract

Dear Sir, Recently, Celebisoy and colleagues' reported four adult cases of opsoclonus. Although the authors rightly point out that the localisation of the abnormality is debatable, they clearly favoured the hypothesis that brainstem premotor units, particularly pause units (PUs), were responsible for opsoclonus. The authors, as have previous authors, cited Zee and Robinson² as showing this. Since PU excitation blocks saccades, it is indeed very likely that the back-to-back saccades of opsoclonus could occur only if PUs were silent. However, this does not mean that there is disease of the PUs, and Zee and Robinson did not show, or claim to show, PU disease.