A 67-year-old woman presented with a 2-year history of forgetfulness and unsteadiness. She scored 17 on the Montreal Cognitive Assessment. She had tremor of head and upper limbs (video 1) since early adulthood, which was diagnosed as essential tremor. Brain MRI showed leukoencephalopathy and high signal intensity along the corticomedullary junction on diffusion-weighted images (figure 1). The diagnosis of adult-onset neuronal intranuclear inclusion disease (NIID) was confirmed by skin biopsy showing eosinophilic intranuclear inclusions (figure 2).1 NIID is a clinically heterogeneous rare neurodegenerative disease.2 Its characteristic MRI pattern should prompt confirmation of the diagnosis by skin biopsy.