Related Experiment Video
Updated: Jul 13, 2025

A Detailed Protocol for Physiological Parameters Acquisition and Analysis in Neurosurgical Critical Patients
Published on: October 17, 2017
Letter to Our Colleagues Family Practitioners, Geriatricians, and Radiologists to Increase Awareness Regarding
Daniele Rigamonti1, Sevil Yasar2, Tito Vivas-Buitrago3
1Department of Neurosurgery, Johns Hopkins School of Medicine, Baltimore, Maryland, USA; KHDR Consulting, Baltimore, Maryland, USA.
Objective:
Idiopathic normal pressure hydrocephalus (iNPH) affects elderly individuals and is characterized by a progressive deterioration of gait, urinary continence, and cognition. In most cases, it is reversible with treatment. INPH is not uncommonly an unrecognized cause of dementia. We wish to raise awareness of iNPH among primary care providers who are seeing these patients first.
Methods:
We reviewed the current epidemiological data regarding iNPH as well as epidemiological data regarding Alzheimer disease. We searched for the most sensitive radiological screening test for iNPH.
Results:
Alzheimer disease comprises 60%-70% of all dementia cases, in 2023 is affecting 6.7 million Americans, about 10.7% of people 65 and older. Epidemiological data from the Scandinavian countries confirmed that 3.7% of people older than 65 have iNPH. Surgical studies confirmed the presence of early Alzheimer's pathology in about 25% of operated patients with iNPH. Useful radiological findings of iNPH include an Evans Index greater than 0.30, and a disproportionally enlarged subarachnoid space hydrocephalus (DESH). However, the callosal angle is thought to represent the best tool to discriminate iNPH from its mimics.
Conclusions:
According to the available epidemiological data iNPH is underdiagnosed. We strongly encourage the primary care physicians and geriatricians to ask the radiologist to measure the callosal angle on the initial brain computed tomography (or magnetic resonance) image. If the callosal angle is ≤71°, it is appropriate to refer the patient to neurosurgery for further diagnostic work-up.
Related Concept Videos
Glaucoma: Overview
Aneurysm II: Clinical Manifestations and Diagnostic Studies
Hypertension III: Clinical Manifestations and Diagnostic Studies
Errors occurring during blood pressure monitoring
Several factors...
Open Angle Glaucoma: Treatment
Drugs such as carbonic anhydrase inhibitors, α2- and...

