A comparative study of three cases of neuronal intranuclear inclusion disease (NIID)

All three patients were men in their 70s. All cases were solitary onset and the chief complaint was gait disturbance. All patients had miosis and limb and trunk ataxia, MMSE score was declined in two patients, and FAB score was declined in all patients. Head MRI showed leukoencephalopathy, cerebellar atrophy, and DWI high intensity signal in corticomedullary junction. However, two of the three patients were not followed up without further examination. Skin biopsies in all cases showed ubiquitin-positive and p62-positive intranuclear inclusions. Genetic testing showed CGG repeat expansion of NOTCH2NLC. The diagnosis of neuronal intranuclear inclusion disease (NIID) was made based on the above findings in all cases. Most patients are diagnosed with NIID due to memory loss, but sometimes they are diagnosed due to gait disturbance with ataxia. It is important to proceed with the diagnosis by skin biopsy and genetic diagnosis based on the characteristic MRI findings of the head.