A Clinicopathological Study of Idiopathic Normal Pressure Hydrocephalus

Abstract

Background: Since Hakim and Adams introduced the clinical entity of normal pressure hydrocephalus (NPH) in 1965, postmortem studies of idiopathic NPH have been few in number. Several autopsy cases reported with clinically probable “idiopathic NPH” were diagnosed with Alzheimer's disease (AD) or Binswanger's disease (BD) neuropathologically. Therefore, the neuropathological study of pathologically confirmed idiopathic NPH remains to be completed both quantitatively and qualitatively. Methods: Out of 239 autopsy cases in Fukushimura Hospital, 13 patients had been diagnosed clinically as having NPH. After excluding seven cases diagnosed neuropathologically with other diseases or secondary NPH, we investigated the clinicopathological findings of six patients with idiopathic NPH. Results: Four patients presented with the complete classic triad consisting of progressive dementia, gait disturbance, and urinary incontinence. All cases exhibited progressive ventricular enlargement with periventricular lucency by computed tomography images. We found (1) diffuse marked dilatation of the lateral ventricles of unknown etiology, and (2) the changes of ependymal cells and subependymal tissue around the callosocaudate angle. Furthermore, no complications were suspected neuropathologically in all cases, such as AD, BD, or Lewy body disease. Conclusion: We experienced six autopsy cases with pathologically confirmed idiopathic NPH. They had two pathological features of NPH but no other pathological disorders that might cause NPH. Several “idiopathic NPH” cases reported previously have been diagnosed neuropathologically with other disorders. However, the presented cases could be clearly distinguished from such “idiopathic NPH.” Therefore, our cases should be defined as idiopathic NPH neuropathologically. By accumulating more cases and investigating further we hope to elucidate the pathogenesis and further develop treatment for idiopathic NPH.