Neuronal intranuclear inclusion disease with initial manifestation of intractable nausea and vomiting responsive to corticosteroids: a case report.

Neuronal intranuclear inclusion disease (NIID) can initially present with gastrointestinal symptoms as the sole or primary manifestation for decades before neurological signs emerge. We report the case of a 61-year-old woman with a 22-year history of drug-refractory, recurrent nausea and vomiting. Previous extensive gastrointestinal evaluations were unremarkable, and conventional therapies proved ineffective. The diagnosis of NIID was established on the basis of the following key findings: diffusion-weighted imaging revealed a characteristic "crown-like" hyperintensity at the corticomedullary junction; genetic analysis revealed a GGC repeat expansion in the NOTCH2NLC gene, with no abnormalities detected in FMR1; and skin biopsy demonstrated p62-positive intranuclear inclusions within sweat gland cells. The patient's symptoms improved markedly with corticosteroid therapy but recurred upon repeated withdrawal. Subsequent initiation of a maintenance corticosteroid regimen resulted in sustained clinical stability, with only occasional mild symptom fluctuations over a six-month follow-up period. This case highlights that vomiting can be a prominent and early clinical feature of NIID. The condition should be considered in the differential diagnosis of patients with unexplained, refractory nausea and vomiting, for whom long-term corticosteroid therapy may represent a viable treatment strategy.