Normal-pressure hydrocephalus with misleading features of irreversible dementias: a case report.

An 85-year-old man presented with the clinical triad (gait instability, dementia, and bladder and bowel incontinence), the ventriculomegaly, and the normal CSF pressure that characterize normal-pressure hydrocephalus (NPH). Diagnostic uncertainty was raised by an unusually rapid onset and a lack of initial response to CSF tap tests. Additionally, periodic sharp waves on EEG suggested the possibility of Creutzfeldt-Jakob disease, and positron emission tomography (PET) demonstrated a pattern of cerebral hypometabolism typical of Alzheimer's disease. Nevertheless, the diagnosis of NPH was supported by delayed improvement following CSF tap tests, and it was confirmed by a dramatic clinical recovery after CSF shunting, resolution of the EEG and PET abnormalities, and a normal brain biopsy. NPH remains one of the few reversible causes of dementia, and the presence of its core features, regardless of rate of onset or ancillary test results, warrants careful consideration of therapeutic intervention.