[Adult-Onset Neuronal Intranuclear Inclusion Disease in Two Female Siblings]

Neuronal intranuclear inclusion disease (NIID) in two adult siblings (both women, aged 76 and 68 years) is reported on here. The elder sister had a resting tremor and bradykinesia at age 66 years, and treatment with L-DOPA was initiated(L-3, 4-dihydroxyphenylalanine). Three years later, she showed a frozen gait that was associated with the medication wearing off. The clinical manifestations did not improve with the administration of antiparkinson drugs. Six years later, she showed impaired cognitive functions, which had occured gradually, and she began to take donepezil. At age 76, she was diagnosed with NIID based on a skin biopsy. The younger sister exhibited peculiar behaviors at age 62 years, and showed impaired cognitive function 4 years later. At age 68 years, she died because of an accident in the bath tub. In both cases, diffusion-weighted magnetic resonance imaging (DWI) showed high-intensity signals in the U fiber area of the corticomedullary junction. These signals began in the frontal lobe at the initial stages of the disease, and extended to the parietal and temporal lobes at later stages. High-intensity signal areas were detected in the deep white matter in T2-weighted and fluid-attenuated inversion recovery (FLAIR) images in the elder sister. The histological examination via a skin biopsy was useful in diagnosing NIID. (Received August 18, 2016; Accepted December 8, 2016; Published March 1, 2017).