Opsoclonus is a rare but distinctive disorder of ocular motility, characterised by irregular, continual, and conjugated chaotic saccades of the eyes. It is increased with eye closure and with fixation, and it persists during sleep. When accompanied by other symptoms of CNS involvement, such as head and appendicular myoclonus and truncal ataxia, it constitutes a striking clinical picture, known as opsoclonus-myoclonus syndrome. Opsoclonus is relatively frequent in children, but it is rare in adults. In adults, the most common aetiology is idiopathic, accounting for about 50% of cases; usually these patients are younger than 40 and have a good prognosis. The second most common cause is paraneoplastic, responsible for 20% of cases. All paraneoplastic cases reported in the literature occurred in patients over 40. The most common tumours, which give rise to 70% of described cases, are breast and lung cancers (small cell lung cancer and adenocarcinoma). Because of the nature of the underlying lesion, the great majority of these patients die in a few months.1 Whereas successful treatment of the malignancy results in a significant improvement …