Familial normal pressure hydrocephalus (NPH) with an autosomal-dominant inheritance: a novel subgroup of NPH.

Normal pressure hydrocephalus (NPH) has two clinical forms: secondary NPH and idiopathic NPH (iNPH). Most patients with NPH occur sporadically: until now, only two families have been reported to have sibling cases of NPH. We here report a large family with 4 patients with elderly-onset NPH in three generations. All of them had cognitive impairment, gait disturbance, and urinary problems, along with normal pressure of cerebrospinal fluid. Their brain MRI showed enlargement of the ventricles and a disproportional narrowing of the subarachnoid space and cortical sulci at the high convexity of the cerebrum, which are the features of iNPH on MRI. The family interview also disclosed additional 4 patients who were suspected as having NPH. The disease seems to be inherited in an autosomal-dominant fashion. No known causes of secondary NPH were found in any of the patients. This is the first report to show a large family with NPH patients in three generations, who had clinical and MRI features indistinguishable from iNPH. This seems to represent a novel subgroup of NPH, familial NPH.