Neuronal intranuclear inclusion disease: two case report and literature review

Neuronal intranuclear inclusion disease (NIID) is a rare and slowly progressing neurodegenerative disease characterized by the presence of eosinophilic intranuclear inclusions in the nervous system and multiple visceral organs. Sporadic NIID case was more frequently encountered than familial. In our study, we reported two adult-onset NIID patients from a family and described their clinical, imaging, and pathological features. The first patient was a 61-year-old man who only presented with non-specific headache and dizziness; however, Brain MRI with diffusion-weighted images (DWI) sequence showed high-intensity signal involving a small regional portion of corticomedullary junction in the frontal and parietal lobe. The older sister of former, a 64-year-old female, who developed sudden onset of weakness of the right limb was admitted to our neurology department. Compared with the first patient, similar DWI high-intensity signal but more extensive area in the corticomedullary junction was found in her brain MRI examination, also prominent leukoencephalopathy in T2-weighted image. Significantly, skin pathology of the first patient showed that typical inclusions with strongly positive P62 and ubiquitin antibody could be seen in the nuclei of sweat gland cells, adipocytes, and fibroblasts. FMR1 gene was negative. Although rare, adult-onset NIID should be considered when the characteristic radiology changes of high intensity signal involving the corticomedullary junction in the brain DWI sequence was found. In addition, the pathological result of skin biopsy combined with negative genetic testing FMR1 or NOTCH2NLC can contribute to the accurate diagnosis of the disease. This article aims to improve the radiologists' knowledge of NIID by our cases presentation and reviewing literature.