Clinical tips in diagnosing idiopathic normal pressure hydrocephalus: a new concept beyond the cerebrospinal fluid tap test.

Accurate diagnosis of idiopathic normal pressure hydrocephalus is important to manage patients with idiopathic normal pressure hydrocephalus more appropriately. Based on the clinical features and brain magnetic resonance imaging findings, the idiopathic normal pressure hydrocephalus diagnosis is made up. However, most clinicians do not recommend the shunt operation to their patients with presumed idiopathic normal pressure hydrocephalus unless any patients with idiopathic normal pressure hydrocephalus show a considerable improvement through the cerebrospinal fluid tap test. The cerebrospinal fluid tap test is an invasive method and has some limitations to diagnose idiopathic normal pressure hydrocephalus. Therefore, we suppose that a new diagnostic approach of idiopathic normal pressure hydrocephalus is necessary. Various magnetic resonance imaging findings suggesting idiopathic normal pressure hydrocephalus have been applied to diagnose idiopathic normal pressure hydrocephalus. Besides, advances in neuroimaging techniques, including dopamine transporter imaging, and amyloid imaging may allow clinicians to exclude the potential misdiagnosis including Parkinsonian disorders and Alzheimer's disease in patients with presumed idiopathic normal pressure hydrocephalus. Herein, we suggest a neuroimaging-supportive algorithm for the diagnosis of idiopathic normal pressure hydrocephalus. We suspect that this is the time to change the classical approach of diagnosing idiopathic normal pressure hydrocephalus.