Frontiers in neurology
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Frontiers in neurology · Jan 2021
Decreased Functional Connectivity of the Primary Visual Cortex and the Correlation With Clinical Features in Patients With Intermittent Exotropia.
The purpose of this study is to investigate characteristic alterations of functional connectivity (FC) patterns in the primary visual area (V1) in patients with intermittent exotropia (IXT) using resting-state functional magnetic resonance imaging (rs-fMRI) and how they relate to clinical features. Twenty-six IXT patients and 21 age-, sex-, handedness-, and education-matched healthy controls (HCs) underwent rs-fMRI. We performed FC analyses between bilateral V1 and other brain areas and compared FC strength between two groups. ⋯ The Newcastle Control Test score was positively correlated with mean FC values between the left inferior parietal lobule and bilateral V1, and between the left supramarginal gyrus and left V1. The duration of IXT was positively correlated with mean FC values between the right inferior occipital gyrus and right V1. Reduced FC between the V1 and various brain regions involved in vision and eye movement processes may be associated with the underlying neural mechanisms of impaired visual function in patients with IXT.
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Background: Persistent postural-perceptual dizziness (PPPD) is a persistent chronic vestibular syndrome exacerbated by upright posture/walking, active or passive motion, and exposure to moving or complex visual stimuli. PPPD has four precursors: phobic postural vertigo, space-motion discomfort, visual vertigo, and chronic subjective dizziness. These four diseases share clinical features that form the basis of the diagnostic criteria for PPPD. ⋯ Conclusions: The most common main exacerbating factor of PPPD was the visual factor. PPPD may be categorized into three subtypes. Conventional vestibular tests failed to point the characteristics of each subtype.
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Frontiers in neurology · Jan 2021
Wavelet Autoregulation Monitoring Identifies Blood Pressures Associated With Brain Injury in Neonatal Hypoxic-Ischemic Encephalopathy.
Dysfunctional cerebrovascular autoregulation may contribute to neurologic injury in neonatal hypoxic-ischemic encephalopathy (HIE). Identifying the optimal mean arterial blood pressure (MAPopt) that best supports autoregulation could help identify hemodynamic goals that support neurologic recovery. In neonates who received therapeutic hypothermia for HIE, we hypothesized that the wavelet hemoglobin volume index (wHVx) would identify MAPopt and that blood pressures closer to MAPopt would be associated with less brain injury on MRI. ⋯ We conclude that applying wavelet methodology to short autoregulation monitoring periods may improve the identification of MAPopt values that are associated with brain injury. Having blood pressure above MAPopt with an upper MAP of ~50-60 mmHg may reduce the risk of brain injury during therapeutic hypothermia. Though a cause-and-effect relationship cannot be inferred, the data support the need for randomized studies of autoregulation and brain injury in neonates with HIE.
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Frontiers in neurology · Jan 2021
Stimulation-Induced Side Effects of Deep Brain Stimulation in the Ventralis Intermedius and Posterior Subthalamic Area for Essential Tremor.
Deep brain stimulation (DBS) targeting the ventralis intermedius (VIM) nucleus of the thalamus and the posterior subthalamic area (PSA) has been shown to be an effective treatment for essential tremor (ET). The aim of this study was to compare the stimulation-induced side effects of DBS targeting the VIM and PSA using a single electrode. Patients with medication-refractory ET who underwent DBS electrode implantation between July 2011 and October 2020 using a surgical technique that simultaneously targets the VIM and PSA with a single electrode were enrolled in this study. ⋯ In the present study, the most common stimulation-induced side effect associated with VIM DBS was dysarthria, while that associated with PSA DBS was gait disturbance. Significantly, more side effects were associated with bilateral DBS than with unilateral DBS. Therefore, changing active DBS contacts to simultaneous targeting of the VIM and PSA may be especially helpful for ameliorating stimulation-induced side effects.
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Frontiers in neurology · Jan 2021
Localizing Clinical Patterns of Blast Traumatic Brain Injury Through Computational Modeling and Simulation.
Blast traumatic brain injury is ubiquitous in modern military conflict with significant morbidity and mortality. Yet the mechanism by which blast overpressure waves cause specific intracranial injury in humans remains unclear. Reviewing of both the clinical experience of neurointensivists and neurosurgeons who treated service members exposed to blast have revealed a pattern of injury to cerebral blood vessels, manifested as subarachnoid hemorrhage, pseudoaneurysm, and early diffuse cerebral edema. ⋯ Larger overpressure simulations (250 and 500kPa) demonstrated intraventricular cavitation-also associated with adjacent high periventricular strain rates. Additionally, models of embedded intraparenchymal vascular structures-with diameters as small as 0.6 mm-predicted intravascular cavitation with adjacent high perivascular strain rates. The co-location of local maxima of strain rates near several of the regions that appear to be preferentially damaged in blast TBI (vascular structures, subpial glial plate, perivascular regions, and periventricular regions) suggest that intracranial interface dynamics may be important in understanding how blast overpressures leads to intracranial injury.