PURPOSE OF REVIEW: Since it was first described in 1965, normal pressure hydrocephalus (NPH) has been a controversial subject. New studies have shed light on its epidemiology and pathogenesis and provided objective ways to measure outcome in patients with NPH. Neuroimaging has improved and allows better recognition of both NPH and the presence of overlapping diseases

RECENT FINDINGS: Several recent epidemiologic studies confirm that NPH is a rare disease, but the presence of large ventricles is a common finding with aging. NPH may be multifactorial, including congenital causes, vascular disease, and impaired CSF absorption. MRI features of NPH include enlarged ventricular size and CSF fluid collection outside the ventricles not due to atrophy. The term disproportionately enlarged subarachnoid space hydrocephalus (DESH) has been used to describe prognostic MRI features in NPH, including a “tight high convexity” and enlargement of CSF spaces in the sylvian fissure. DESH has been included in the Japanese guideline for the diagnosis and treatment of NPH. A new NPH scale has been published that provides an objective framework for evaluating patients with NPH before and after shunt placement. Programmable shunts can noninvasively manage overdrainage complications. Surgical outcome has been improving over time. Recent studies have led to improved recognition of overlapping diseases such as Alzheimer pathology, which co-occurs in about 30% of NPH cases. Fludeoxyglucose positron emission tomography (FDG-PET) is a promising imaging modality for diagnosing NPH and detecting concomitant degenerative disease.

SUMMARY: A systematic approach to patients with possible NPH allows recognition of the subset of patients who will respond to shunt surgery and identification of those with alternative diagnoses.

Address correspondence to Dr Neill R. Graff-Radford, Department of Neurology, Mayo Clinic Jacksonville, 4500 San Pablo Rd, Jacksonville, FL 32224, Graff-radford.neill@mayo.edu.

RELATIONSHIP DISCLOSURE: Dr Graff-Radford serves on the editorial board of Alzheimer’s Research & Therapy and receives research/grant support from Abbvie Inc; Axovant Sciences, Inc; Biogen; Eli Lilly and Company; the National Institutes of Health (P50AG16574, 1R01AG045390-01A1, R56AG057195, UF1AG032438, U54NS092089, U01AG24904, U01NS100620); Novartis AG; and the US Department of Defense (WEI1872). Dr Jones receives research/grant support from the Minnesota Partnership for Biotechnology and Medical Genomics (P006598701) and the National Institutes of Health (U01EB 24450-1, R01DC14942-1, U01AG52943, U01AG45390, U19AG24904).

UNLABELED USE OF PRODUCTS/INVESTIGATIONAL USE DISCLOSURE: Drs Graff-Radford and Jones report no disclosures.