A case of neuronal intranuclear inclusion disease diagnosed 19 years after onset through clinical re-evaluation

We report a case of a woman diagnosed with neuronal intranuclear inclusion disease (NIID) 19 years after onset. The patient was 54 years old at onset and 73 years old at diagnosis. Various neurological symptoms, including hemianopia, ataxia, aphasia, and hemiparesis, persisted for several hours to several days. The patient continued to have loss of deep tendon reflexes and miosis. Brain MRI showed progressive deterioration of deep white matter lesions and brain atrophy, but diffusion-weighted imaging (DWI) showed no abnormalities. We experienced another patient with NIID with typical linear DWI hyperintensity at the corticomedullary junction, and the similarity of their clinical course (various neurological symptoms, including cortical signs, appearing and remitting within a short period of time) provided clues for the differential diagnosis of NIID. Skin biopsy and genetic testing were performed, and the diagnosis of NIID was confirmed. Some NIID patients lack typical DWI signs. It is important to raise NIID as a differential diagnosis when we see the patients with various neurological symptoms which is difficult to explain on monism.