Temporal Changes in Brain Magnetic Resonance Imaging Findings over 16 Years in a Patient with Neuronal Intranuclear Inclusion Disease: A Case Report.

Leukoencephalopathy with high-intensity signals in the corticomedullary junction on diffusion-weighted imaging (DWI) is a diagnostic hallmark for neuronal intranuclear inclusion disease (NIID). We herein report a 65-year-old man who developed dementia and was diagnosed with NIID 2 years later. Of note, he had coincidentally undergone brain magnetic resonance imaging 14 and 10 years before the onset of dementia. No abnormalities were discerned on DWI on either of these occasions, but high-intensity signals in the corticomedullary junction on DWI were revealed two years before the clinical onset. The early recognition of this pathognomonic white matter change may facilitate the presymptomatic diagnosis of NIID.