Adult onset Niemann-Pick disease type C presenting with dementia and absent organomegaly

A 39-year-old female presented to the Bryan Memory Disorders Clinic at Duke University with a 7-year history of an atypical progressive dementia, mildly impaired vertical gaze, dysarthria and mild ataxia. There was no evidence of organomegaly by clinical examination or by radionucleide liver/spleen scan. Brain biopsy disclosed a neuronal storage disorder characterized by ballooned neurons filled with oligolamellar cytosomes and lipid droplets. Cultured skin fibroblasts had diminished sphingomyelinase activity and impaired cholesterol esterification, although peripheral leukocyte sphingomyelinase activity was normal. Two years after biopsy, follow-up examination revealed marked progression of vertical gaze paralysis and ataxia. This case expands the clinical spectrum of Niemann-Pick disease type C by presenting in adulthood with subtle neurologic abnormalities; no visceromegaly and profound dementia.