Neuronal intranuclear inclusion disease cases with leukoencephalopathy diagnosed via skin biopsy

Neuronal intranuclear inclusion disease (NIID) is a progressive neurodegenerative disease characterised by eosinophilic hyaline intranuclear inclusions which are widely observed in neuronal and somatic cells.1 ,2 NIID has been considered to be a heterogeneous disease with highly variable clinical manifestations such as neuropathy, cerebellar ataxia and dementia, which may occur concomitantly in certain cases.1–5 Sporadic and familial cases have been reported, and the onset of disease varies from the infantile stages to late middle age. These factors made the antemortem diagnosis of NIID difficult. However, in 2011, we reported that skin biopsy is a useful antemortem diagnostic tool for familial neuronal intranuclear inclusion disease because it detects intranuclear inclusions in the dermal cells.3 Recently, some autopsies of NIID patients with leukoencephalopathy have been reported.4 In this study, we identified intranuclear inclusions in skin biopsy samples from three sporadic NIID patients who presented with cognitive dysfunction along with notable brain MRIs findings of leukoencephalopathy. A patient aged in the late sixties with neither significant past medical history nor family history of neurological disease was referred to our hospital with gait disturbance and dementia with symptoms including frequent disorientation over 3 years. A neurological examination revealed no ataxia, sensory disturbances or urinary incontinence. The patient's Mini-Mental State Examination (MMSE) Score was 29. A brain MRI showed moderate cerebral and cerebellar atrophy and high-intensity areas in the cerebral white matter in the T2-weighted and fluid-attenuated inversion recovery (FLAIR) images (figure 1A). The MRI diffusion-weighted imaging (DWI) revealed a high-intensity signal in the corticomedullary junction, and these areas showed isointensity and low intensity on the ADC map (figure 1A). A cerebrospinal fluid (CSF) examination showed no pleocytosis or protein elevation and a normal glucose level. The nerve conduction studies …