Case report: Neuronal intranuclear inclusion disease with recurrent nausea and vomiting

Neuronal intranuclear inclusion disease (NIID) is a rare neurodegenerative disease involving multiple systems and is characterized by the widespread presence of eosinophilic intranuclear inclusions in neurons and systemic visceral cells. We report a case of sporadic adult-onset NIID in a 72-year-old female who presented with recurrent nausea and vomiting as her initial symptoms. Head MRI revealed a subcortical lace sign in the corticomedullary junction and hyperintense signals in the middle cerebellar peduncle (MCP sign). Notably, her GGC repeat size in the 5′ region of the human-specific NOTCH2NLC gene tested positive for NIID. The skin biopsy revealed diagnostically positive intranuclear inclusions in the cells of the sweat glands, fibroblasts, and adipocytes due to positive anti-p62 antibodies. NIID patients may present symptoms of other systems before neurological involvement, leading to frequent misdiagnosis or underdiagnosis. The diagnostic process for NIID currently involves either NOTCH2NLC genetic analysis or a skin biopsy of the patient on the basis of a suspicious head MRI to confirm the diagnosis. This article covers a case of NIID with unusual symptoms to help clinicians deepen their understanding of the clinical spectrum of NIID.