Cerebrospinal fluid and blood flow in mild cognitive impairment and Alzheimer's disease: a differential diagnosis from idiopathic normal pressure hydrocephalus

Abstract

BackgroundPhase-contrast magnetic resonance imaging (PC-MRI) enables quantification of cerebrospinal fluid (CSF) flow and total cerebral blood (tCBF) flow and may be of value for the etiological diagnosis of neurodegenerative diseases. This investigation aimed to study CSF flow and intracerebral vascular flow in patients with Alzheimer's disease (AD) and patients with amnesic mild cognitive impairment (a-MCI) and to compare the results with patients with idiopathic normal pressure hydrocephalus (NPH) and with healthy elderly volunteers (HEV).MethodsTen a-MCI and 9 mild AD patients were identified in a comprehensive neurological and neuropsychological assessment. They underwent brain MRI; PC-MRI pulse sequence was performed with the following parameters: two views per segment; flip angle: 25° for vascular flow and 20° for CSF flow; field-of-view (FOV): 14 × 14 mm²; matrix: 256 × 128; slice thickness: 5 mm; with one excitation for exams on the 3 T machine, and 2 excitations for the 1.5 T machine exams. Velocity (encoding) sensitization was set to 80 cm/s for the vessels at the cervical level, 10 or 20 cm/s for the aqueduct and 5 cm/s for the cervical subarachnoid space (SAS). Dynamic flow images were analyzed with in-house processing software. The patients' results were compared with those obtained for HEVs (n = 12), and for NPH patients (n = 13), using multivariate analysis.ResultsArterial tCBF and the calculated pulsatility index were significantly greater in a-MCI patients than in HEVs. In contrast, vascular parameters were lower in NPH patients. Cervical CSF flow analysis yielded similar values for all four populations. Aqueductal CSF stroke volumes (in μl per cardiac cycle) were similar in HEVs (34 ± 17) and AD patients (39 ± 18). In contrast, the aqueductal CSF was hyperdynamic in a-MCI patients (73 ± 33) and even more so in NPH patients (167 ± 89).ConclusionOur preliminary data show that a-MCI patients present with high systolic arterial peak flows, which are associated with higher mean total cerebral arterial flows. Aqueductal CSF oscillations are within normal range in AD and higher than normal in NPH. This study provides an original dynamic vision of cerebral neurodegenerative diseases, consistent with the vascular theory for AD, and supporting primary flow disturbances different from those observed in NPH.

Differential Diagnosis of Normal Pressure Hydrocephalus by MRI Mean Diffusivity Histogram Analysis

“…9 A number of quantitative imaging biomarkers have also been proposed as aids to NPH diagnosis, such as phase-contrast aqueductal flow measurements, 10 aqueductal stroke volume measurements, 11 the ratios of ventricular volume to cortical thickness, 7 increased DTI fractional anisotropy of periventricular white matter and the basal ganglia, 12 CSF and blood flow, 13 and temporal changes in the apparent diffusion coefficient during the cardiac cycle. 14 The use of these techniques has largely been confined to research studies in specialty centers, and none have been proved to improve the diagnosis of NPH in routine clinical practice.…”

Arterial hypertension impact on cerebral blood flow in patients with Alzheimer’s disease

“…They found increased cerebral blood flow in patients with amnestic MCI and decreased blood flow (even standardization) in Alzheimer patients. 3 Unfortunately, we note an imbalance of genders in the groups (aHT+ : 9 females and 1 male and aHT-: 3 females and 6 males), which could influence the results.…”

“…This might be associated with vascular adaptation (deterioration) in hypertension, which was deactivated due to hypertension-induced vascular changes. 3 This phenomenon would lead to a failure of self-regulatory system of the brain.…”

“…24 A previous study showed both an increased average blood flow in the cerebral arteries and high arterial systolic peak in patients with amnestic mild cognitive impairment (MCI). 3 Similarly, in 2009, Dai showed that average blood flow in cerebral arteries, average blood flow in cerebral veins and the oscillations of the cervical cerebrospinal fluid (CSF) were highest in patients with amnestic mild cognitive impairment. 4 These results had come as a surprise as several authors have demonstrated a local decrease in blood flow in patients with amnestic mild cognitive impairment.…”

Numerical Modeling of the Intracranial Pressure using Windkessel Models

“…Non-communicating hydrocephalus is the most viewable by imaging techniques and well known of these pathologies: it is characterized by a large increase of the cerebral ventricles [15] and can also induce significant redistribution of CSF pulsations within the SAS to the ventricular system [3,24]. First studies on the global cerebrospinal system were carried out mainly to understand the behavior of these obstructive pathologies.…”