MINNEAPOLIS — Structural imaging markers hold promise for developing accurate, noninvasive, and accessible solutions to differentiate Parkinson’s disease (PD) and Alzheimer’s dementia (AD) reversible conditions and those caused by traumatic brain injury (TBI).
“Normal Pressure Hydrocephalus (NPH) is a prominent type of reversible dementia that may be treated with shunt surgery, and it is crucial to differentiate it from irreversible degeneration caused by its symptomatic mimics like Alzheimer’s dementia (AD) and Parkinson’s disease (PD),” wrote researchers from the University of Minnesota and the Minneapolis VA Healthcare System. “Similarly, it is important to distinguish between (normal pressure) hydrocephalus and irreversible atrophy/degeneration which are among the chronic effects of traumatic brain injury (cTBI), as the former may be reversed through shunt placement.”
In a report published in Frontiers in Neurology, the study team described how it searched the PubMed database for keywords related to NPH, AD, PD and cTBI and then reviewed studies that examined the (1) distinct neuroanatomical markers of degeneration in NPH versus AD and PD, and atrophy versus hydrocephalus in cTBI and (2) computational methods for their (semi) automatic assessment on Computed Tomography (CT) and Magnetic Resonance Imaging (MRI) scans.
The review determined that structural markers of NPH and those that can distinguish it from AD have been studied frequently, but only a few of those have explored its structural distinction between PD. “The structural implications of cTBI over time have been studied,” the researchers explained. “But neuroanatomical markers that can predict shunt response in patients with either symptomatic idiopathic NPH or post-traumatic hydrocephalus have not been reliably established. MRI-based markers dominate this field of investigation as compared to CT, which is also reflected in the disproportionate number of MRI-based computational methods for their automatic assessment.”
The articles not only provided an up-to-date literature review on the structural neurodegeneration due to NPH vs. AD/PD, and hydrocephalus vs. atrophy in cTBI but also elucidated “the potential of structural imaging markers as (differential) diagnostic aids for the timely recognition of patients with reversible (normal pressure) hydrocephalus, and opportunities to develop computational tools for their objective assessment.”
Background information in the article pointed out that NPH is a prominent type of dementia that is often reversible via ventricular shunt surgery, with earlier intervention leading to better outcomes, explaining, “A notable discrepancy between the incidence (of patients who had surgical intervention) and prevalence rates suggests its under-recognition. This is substantiated by an estimate from the Hydrocephalus Association that 80% of patients with NPH remain unrecognized with most frequent misdiagnoses being Alzheimer’s Dementia (AD) or Parkinson’s Disease (PD), which themselves significantly contribute to the global burden of neurological disorders.”
About half of NPH cases are considered to be idiopathic, with the other half deemed to be secondary to TBI, tumor, meningitis or infections. “Adding complexity to its recognition may be the fact that in the secondary NPH group, while tumors or infection linked to the disease can be detected definitively, a TBI-related origin may not be accurately identified due to incomplete medical history,” the authors pointed out. “Therefore, the accurate detection and treatment of NPH may inevitably depend on discerning it from irreversible atrophic pathologies like AD, PD, and post-traumatic degeneration.”
The researchers advised that, in terms of structural neurodegeneration, hydrocephalic ventriculomegaly is the key marker of NPH. They added that “the structural degeneration in AD and PD is also characterized by atrophy. Both atrophy and hydrocephalus can give an appearance of ventricular enlargement, which may set a precedent for misdiagnosis if not examined carefully.”
- Kadaba Sridhar S, Dysterheft Robb J, Gupta R, Cheong S, Kuang R, Samadani U. Structural neuroimaging markers of normal pressure hydrocephalus vs. Alzheimer’s dementia and Parkinson’s disease and hydrocephalus vs. atrophy in chronic TBI-a narrative review. Front Neurol. 2024 Mar 21;15:1347200. doi: 10.3389/fneur.2024.1347200. PMID: 38576534; PMCID: PMC10991762.
