Unpublished data from the assessment demonstrated that NS is a seizure disorder, and that the nodding episodes are due to atonic seizures resulting in loss of tone associated with changes on electroencephalography (EEG) including multiple other clinical and subclinical seizure types. The surveillance data showed that the prevalence of NS in parts of Kitgum region is many-fold higher than what would be expected for comparable forms of epilepsy, based upon data from North America and Europe.