Simple Identification of Cerebrospinal Fluid Turbulent Motion Using a Dynamic Improved Motion-sensitized Driven-equilibrium Steady-state Free Precession Method Applied to Various Types of Cerebrospinal Fluid Motion Disturbance

An Alzheimer's Disease Mechanism Based on Early Pathology, Anatomy, Vascular-Induced Flow, and Migration of Maximum Flow Stress Energy Location with Increasing Vascular Disease

This paper suggests a chemical mechanism for the earliest stages of Alzheimer's disease (AD). Cerebrospinal fluid (CSF) flow stresses provide the energy needed to induce molecular conformation changes leading to AD by initiating amyloid-β (Aβ) and tau aggregation. Shear and extensional flow stresses initiate aggregation in the laboratory and in natural biophysical processes. Energy-rich CSF flow regions are mainly found in lower brain regions. MRI studies reveal flow stress "hot spots" in basal cisterns and brain ventricles that have chaotic flow properties that can distort molecules such as Aβ and tau trapped in these regions into unusual conformations. Such fluid disturbance is surrounded by tissue deformation. There is strong mapping overlap between the locations of these hot spots and of early-stage AD pathology. Our mechanism creates pure and mixed protein dimers, followed by tissue surface adsorption, and long-term tissue agitation ultimately inducing chemical reactions forming more stable, toxic oligomer seeds that initiate AD. It is proposed that different flow stress energies and flow types in different basal brain regions produce different neurotoxic aggregates. Proliferating artery hardening is responsible for enhanced heart systolic pulses that drive energetic CSF pulses, whose critical maximum systolic pulse energy location migrates further from the heart with increasing vascular disease. Two glymphatic systems, carotid and basilar, are suggested to contain the earliest Aβ and tau AD disease pathologies. A key to the proposed AD mechanism is a comparison of early chronic traumatic encephalopathy and AD pathologies. Experiments that test the proposed mechanism are needed.

Intrathecal Drug Delivery: Advances and Applications in the Management of Chronic Pain Patient

Advances in our understanding of the biology of spinal systems in organizing and defining the content of exteroceptive information upon which higher centers define the state of the organism and its role in the regulation of somatic and automatic output, defining the motor response of the organism, along with the unique biology and spatial organization of this space, have resulted in an increased focus on therapeutics targeted at this extracranial neuraxial space. Intrathecal (IT) drug delivery systems (IDDS) are well-established as an effective therapeutic approach to patients with chronic non-malignant or malignant pain and as a tool for management of patients with severe spasticity and to deliver therapeutics that address a myriad of spinal pathologies. The risk to benefit ratio of IDD makes it a useful interventional approach. While not without risks, this approach has a significant therapeutic safety margin when employed using drugs with a validated safety profile and by skilled practioners. The present review addresses current advances in our understanding of the biology and dynamics of the intrathecal space, therapeutic platforms, novel therapeutics, delivery technology, issues of safety and rational implementation of its therapy, with a particular emphasis upon the management of pain.

Evaluation of Cardiac- and Respiratory-driven Cerebrospinal Fluid Motions by Applying the S-transform to Steady-state Free Precession Phase Contrast Imaging

PURPOSE

To extract the status of hydrocephalus and other cerebrospinal fluid (CSF)-related diseases, a technique to characterize the cardiac- and respiratory-driven CSF motions separately under free breathing was developed. This technique is based on steady-state free precession phase contrast (SSFP-PC) imaging in combination with a Stockwell transform (S-transform).

METHODS

2D SSFP-PC at 3 T was applied to measure the CSF velocity in the caudal-cranial direction within a sagittal slice at the midline (N = 3) under 6-, 10-, and 16-s respiratory cycles and free breathing. The frequency-dependent window width of the S-transform was controlled by a particular scaling factor, which then converted the CSF velocity waveform into a spectrogram. Based on the frequency bands of the cardiac pulsation and respiration, as determined by the electrocardiogram (ECG) and respirator pressure sensors, Gaussian bandpass filters were applied to the CSF spectrogram to extract the time-domain cardiac- and respiratory-driven waveforms.

RESULTS

The cardiac-driven CSF velocity component appeared in the spectrogram clearly under all respiratory conditions. The respiratory-driven velocity under the controlled respiratory cycles was observed as constant frequency signals, compared to a time-varying frequency signal under free breathing. When the widow width was optimized using the scale factor, the temporal change in the respiratory-driven CSF component was even more apparent under free breathing.

CONCLUSION

Velocity amplitude variations and transient frequency changes of both cardiac- and respiratory-driven components were successfully characterized. These findings indicated that the proposed technique is useful for evaluating CSF motions driven by different cyclic forces.

Respiratory-driven Cyclic Cerebrospinal Fluid Motion in the Intracranial Cavity on Magnetic Resonance Imaging: Insights into the Pathophysiology of Neurofluid Dysfunction

Neurofluids, a recently developed term that refers to interstitial fluids in the parenchyma and cerebrospinal fluid (CSF) in the ventricle and subarachnoid space, play a role in draining waste products from the brain. Neurofluids have been implicated in pathological conditions such as Alzheimer’s disease and normal pressure hydrocephalus. Given that CSF moves faster in the CSF cavity than in the brain parenchyma, CSF motion can be detected by magnetic resonance imaging. CSF motion is synchronized to the heartbeat and respiratory cycle, but respiratory cycle-induced CSF motion has yet to be investigated in detail. Therefore, we analyzed CSF motion using dynamic improved motion-sensitized driven-equilibrium steady-state free precession-based analysis. We analyzed CSF motion linked to the respiratory cycle in four women and six men volunteers aged 23 to 38 years. We identified differences between free respiration and tasked respiratory cycle-associated CSF motion in the ventricles and subarachnoid space. Our results indicate that semi-quantitative analysis can be performed using the cranial site at which CSF motion is most prominent as a standard. Our findings may serve as a reference for elucidating the pathophysiology of diseases caused by abnormalities in neurofluids.

Styloidogenic-cervical spondylotic internal jugular venous compression, a vascular disease related to several clinical neurological manifestations: diagnosis and treatment-a comprehensive literature review

Internal jugular vein (IJV) stenosis is associated with several central nervous system disorders such as Ménière or Alzheimer’s disease. The extrinsic compression between the styloid process and the C1 transverse process, is an emerging biomarker related to several clinical manifestations. However, nowadays a limited number of cases are reported, and few information are available about treatment, outcome and complications. Our aim is to collect and identify clinical-radiological characteristics, diagnosis and treatment of the styloidogenic internal jugular venous compression. We performed a comprehensive literature review. Studies reporting patients suffering from extracranial jugular stenosis were searched. For every patient we collected: demography, clinical and radiological characteristics and outcome, type of treatment, complications. Thirteen articles reporting 149 patients were included. Clinical presentation was non-specific. Most frequent symptoms were headache (46.3%), tinnitus (43.6%), insomnia (39.6%). The stenosis was monolateral in 51 patients (45.9%) and bilateral in 60 (54.1%). Anticoagulants were the most common prescribed drug (57.4%). Endovascular treatment was performed in 50 patients (33.6%), surgery in 55 (36.9%), combined in 28 (18.8%). Improvement of general conditions was reported in 58/80 patients (72.5%). Complications were reported in 23% of cases. Jugular stenosis is a complex and often underestimated disease. Conservative medical treatment usually fails while surgical, endovascular or a combined treatment improves general conditions in more than 70% of patients.

Shear-Induced Amyloid Aggregation in the Brain: V. Are Alzheimer's and Other Amyloid Diseases Initiated in the Lower Brain and Brainstem by Cerebrospinal Fluid Flow Stresses?

Amyloid-β (Aβ) and tau oligomers have been identified as neurotoxic agents responsible for causing Alzheimer's disease (AD). Clinical trials using Aβ and tau as targets have failed, giving rise to calls for new research approaches to combat AD. This paper provides such an approach. Most basic AD research has involved quiescent Aβ and tau solutions. However, studies involving laminar and extensional flow of proteins have demonstrated that mechanical agitation of proteins induces or accelerates protein aggregation. Recent MRI brain studies have revealed high energy, chaotic motion of cerebrospinal fluid (CSF) in lower brain and brainstem regions. These and studies showing CSF flow within the brain have shown that there are two energetic hot spots. These are within the third and fourth brain ventricles and in the neighborhood of the circle of Willis blood vessel region. These two regions are also the same locations as those of the earliest Aβ and tau AD pathology. In this paper, it is proposed that cardiac systolic pulse waves that emanate from the major brain arteries in the lower brain and brainstem regions and whose pulse waves drive CSF flows within the brain are responsible for initiating AD and possibly other amyloid diseases. It is further proposed that the triggering of these diseases comes about because of the strengthening of systolic pulses due to major artery hardening that generates intense CSF extensional flow stress. Such stress provides the activation energy needed to induce conformational changes of both Aβ and tau within the lower brain and brainstem region, producing unique neurotoxic oligomer molecule conformations that induce AD.

A Combination of Magnetic Resonance Imaging Techniques to Localize the Dural Defect in a Case of Superficial Siderosis-A Case Report

Background: Superficial siderosis is a progressively disabling disease caused by recurrent subarachnoid hemorrhage with accumulation of hemosiderin in the surface of the central nervous system. Although a wide variety of conditions may cause superficial siderosis, approximately half of the cases are reported to be associated with a defect in the ventral spinal dura mater, in which case treatment entails surgical repair of the defect. Here, we report a case of superficial siderosis and report on our method to pinpoint the dural defect using a combination of magnetic resonance imaging (MRI) techniques. Methods and Results: A 74-year-old female presented suffering from hearing loss and progressive ataxia over a duration of seven years. A T2-weighted MRI study revealed hypointensity in the superficial areas of the central nervous system, leading to the diagnosis of superficial siderosis, and the presence of a fluid-filled collection in the anterior spinal canal of C7 to T10 suggested that a dural defect was the cause of the repeated hemorrhage. A balanced turbo field echo (BTFE) MRI sequence revealed possible dural defects at T1–T2 and T5–T6, and a dynamic improved motion-sensitized driven-equilibrium steady-state free precession (dynamic iMSDE SSFP) sequence revealed an irregular flow of cerebrospinal fluid through the dura at the T5–T6 level. The dural defect was confirmed and sutured through a minimal T5–T6 laminectomy without neurological consequences, and the patient reported mild improvement in gait one year after surgery. Conclusions: A combination of MRI sequences provided the necessary information to confidently perform minimal surgery to repair the dural defect. We recommend coupling a balanced steady-state free precession (SSFP) sequence to provide high resolution, high contrast images of anatomical structures and a dynamic iMSDE SSFP sequence to confirm cerebrospinal fluid motion through the defect.