Walking Behavior Change Detector for a “Smart” Walker

AbstractThis study investigates the design of a novel real-time system to detect walking behavior changes using an accelerometer on a rollator. No sensor is required on the user. We propose a new non-invasive approach to detect walking behavior based on the motion transfer by the user on the walker. Our method has two main steps; the first is to extract a gait feature vector by analyzing the three-axis accelerometer data in terms of magnitude, gait cycle and frequency. The second is to classify gait with the use of a decision tree of multilayer perceptrons. To assess the performance of our technique, we evaluated different sampling window lengths of 1, 3 an 5seconds and four different Neural Network architectures. The results revealed that the algorithm can distinguish walking behavior such as normal, slow and fast with an accuracy of about 86%. This research study is part of a project aiming at providing a simple and non-invasive walking behavior detector for elderly who use rollators

Timing of syncope in ictal asystole as a guide when considering pacemaker implantation

Introduction In patients with ictal asystole (IA) both cardioinhibition and vasodepression may contribute to syncopal loss of consciousness. We investigated the temporal relationship between onset of asystole and development of syncope in IA, to estimate the frequency with which pacemaker therapy, by preventing severe bradycardia, may diminish syncope risk. Methods In this retrospective cohort study, we searched video-EEG databases for individuals with focal seizures and IA (asystole >= 3 s preceded by heart rate deceleration) and assessed the durations of asystole and syncope and their temporal relationship. Syncope was evaluated using both video observations (loss of muscle tone) and EEG (generalized slowing/flattening). We assumed that asystole starting 3 s. Thus, in only two instances was vasodepression rather than cardioinhibition the dominant presumptive syncope triggering mechanism. Conclusions In IA, cardioinhibition played an important role in most seizure-induced syncopal events, thereby favoring the potential utility of pacemaker implantation in patients with difficult to suppress IA.Paroxysmal Cerebral Disorder

Management of syncope in adults: An update

10.4065/83.11.1280Mayo Clinic Proceedings83111280-1293MACP

Ictal Asystole Life-Threatening Vagal Storm or a Benign Seizure Self-Termination Mechanism?

Paroxysmal Cerebral Disorder

Video-EEG during tilt-table testing is an invaluable aid for understanding syncope

Paroxysmal Cerebral Disorder

Neurohormones in the pathophysiology of vasovagal syncope in adults

Vasovagal syncope (VVS) is the most common cause of syncope across all age groups. Nonetheless, despite its clinical importance and considerable research effort over many years, the pathophysiology of VVS remains incompletely understood. In this regard, numerous studies have been undertaken in an attempt to improve insight into the evolution of VVS episodes and many of these studies have examined neurohormonal changes that occur during the progression of VVS events primarily using the head-up tilt table testing model. In this regard, the most consistent finding is a marked increase in epinephrine (Epi) spillover into the circulation beginning at an early stage as VVS evolves. Reported alterations of circulating norepinephrine (NE), on the other hand, have been more variable. Plasma concentrations of other vasoactive agents have been reported to exhibit more variable changes during a VVS event, and for the most part change somewhat later, but in some instances the changes are quite marked. The neurohormones that have drawn the most attention include arginine vasopressin [AVP], adrenomedullin, to a lesser extent brain and atrial natriuretic peptides (BNP, ANP), opioids, endothelin-1 (ET-1) and serotonin. However, whether some or all of these diverse agents contribute directly to VVS pathophysiology or are principally a compensatory response to an evolving hemodynamic crisis is as yet uncertain. The goal of this communication is to summarize key reported neurohumoral findings in VVS, and endeavor to ascertain how they may contribute to observed hemodynamic alterations during VVS

A higher proportion of men than of women fainted in the phase without nitroglycerin in tilt-induced vasovagal syncope

Purpose Vasovagal syncope (VVS) affects more women than men. We determined whether this sex ratio affects tilt table test (TTT) results. Methods We retrospectively studied TTT outcomes in suspected VVS. TTT consisted of supine rest, a maximum 20 min of head-up tilt without and, if nitroglycerin was needed, a further maximum 20 min after nitroglycerin administration. TTT was terminated if VVS occurred. We used binary logistic regression for the entire TTT and for each phase, with VVS as outcome and age and sex as predictors. Results TTT provoked vasovagal (pre)syncope in 494 out of 766 tests (64%). The proportion of men and women who fainted during the entire TTT did not differ significantly between the sexes (p = 0.13, corrected for age). A lower proportion of women than men had VVS in the phase without nitroglycerin (odds ratio 0.54; 95% confidence interval 0.37-0.79;p = 0.002, corrected for age), whereas a higher proportion of women than men fainted after nitroglycerin (odds ratio 1.58; 95% confidence interval 1.13-2.21;p = 0.008, corrected for age). These sex differences remained significant after correction for a history of orthostatic versus emotional triggers. The effect of sex on TTT outcome was closely associated with differences of blood pressure change upon tilt-up (lower in men in both TTT phases: without nitroglycerinp = 0.003; with nitroglycerinp = 0.05), but not with heart rate changes. Conclusion Men were more susceptible to induction of VVS without nitroglycerin and women after it. The unexpected findings may be due to sex-specific pathophysiological differences

The semiology of tilt-induced reflex syncope in relation to electroencephalographic changes

Paroxysmal Cerebral Disorder