Adult‐onset neuronal intranuclear inclusion disease presenting with typical MRI changes

Background This study aims to analyze the clinical, imaging, electrophysiological, and dermatopathological features of a patient with adult‐onset neuronal intranuclear inclusion disease (NIID) and to explore the diagnostic methods of adult‐onset NIID. Case presentation We here report a 63‐year‐old male with recurrent acute encephalopathy syndrome and autonomic nervous system damage syndrome characterized by sexual dysfunction and urinary and fecal dysfunction. Cranial diffusion‐weighted magnetic resonance imaging (DWI) demonstrated symmetrically distributed strip‐shaped high‐intensity signal in bilateral fronto‐occipital‐parietal cortical‐medullary junction. Electrophysiological test revealed that the main site of injury was myelin sheath in both motor and sensory nerves. Skin biopsy revealed eosinophilic spherical inclusion bodies in the nucleus of sweat gland epithelial cells. Conclusion This case suggests that adult NIID is a chronic neurodegenerative disease with high clinical heterogeneity. Subcortical strip‐shaped high‐intensity signal on DWI has high diagnostic significance. Eosinophilic intranuclear inclusion bodies detected by skin biopsy contribute to diagnosis. Adult‐onset neuronal intranuclear inclusion disease (NIID) has a low incidence, diverse clinical manifestations, and difficulty in early diagnosis. NIID has typical clinical manifestations and suggestive MRI features. The use of skin biopsy with minimal trauma can promptly diagnose NIID and improve the awareness of the clinicians.