Long-term evolution of EEG in Unverricht-Lundborg disease

Unverricht-Lundborg disease (ULD) is a progressive myoclonus epilepsy characterized by myoclonus, epilepsy, and ataxia, without major cognitive decline. There is no systematic study on the long-term evolution of EEG in this condition.

Twenty-five patients with ULD who came to our observation before 1995 and periodically followed in our Epilepsy Centres were included. All waking EEG traces were visually reviewed for the characterization background activity, with particular regard to the frequency of the posterior dominant rhythm (PR), and for the occurrence of spontaneous generalized spike or polyspike and wave discharges (GSWD) and photoparoxysmal response (PPR). Sleep recordings were analyzed with particular regard to the preservation of the physiological sleep patterns and the occurrence of GSWD and other epileptic abnormalities.

PR was normal in 68% of patients at the beginning of the disease and kept stable over the years. GSWD were present in 92% of patients at the onset of the disease and gradually disappeared during the follow-up with a significant difference (p<0.001) after the 15th year of disease. PPR was present in 88% of patients at the disease onset and gradually disappeared with a significant difference (p<0.001) after the 10th year of disease. A gradual reduction of GSWD and a progressive disappearance of physiological sleep patterns were observed in sleep EEGs.

In patients with ULD followed for an extended period of time, EEG shows no relevant deterioration of BA while a gradual reduction of GSWD and PPR is observed over time, well correlating with the good seizure outcome in this condition.