A Case of Neuronal Intranuclear Inclusion Disease with Isolated Bladder Dysfunction

Neuronal intranuclear inclusion disease (NIID) is a progressive neurodegenerative disease caused by GGC repeat expansion in the NOTCH2NLC gene. The clinical manifestations are highly heterogeneous, ranging from chronic symptoms such as cognitive impairment and autonomic dysfunction to acute symptoms like encephalitis-like episodes or seizures. This report describes a case of adult-onset NIID with a disease course of 10 years, presenting solely with urinary retention and bladder dysfunction. The patient's head MRI demonstrated characteristic subcortical "band-like" high signals on DWI, and genetic testing confirmed the diagnosis. This case highlights the need for clinicians to consider the possibility of NIID when encountering unexplained urinary symptoms and to use imaging and genetic testing for definitive diagnosis.