Pathophysiology of neurally-mediated syncope

Malamud-Kessler, Caroline; Bruno, Erik; Chiquete, Erwin; Sentíes-Madrid, Horacio; Campos-Sánchez, Miguel

doi:10.1016/j.nrleng.2014.04.015

Cited by 5 publications

(10 citation statements)

References 47 publications

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“…It is thus obvious that VVS is indeed an enigma as suggested by Dikshit (1) and its mode of occurrence remains far from being explained suitably. In apparently healthy elderly population (6th to 8th decades of life) a 6% to 11% incidence of unexplained syncope has been reported (6). Incidence in children may be as high as 10%-44% (12).…”

Section: Definition and Types Of Syncopementioning

confidence: 99%

“…Recovery is full and rapid. It is more a symptom complex than a disease, but to maintain postural tone that was not compatible with a seizure disorder, vertigo, coma, shock, and other states of altered consciousness" (3); "A sudden and brief loss of consciousness and postural tone from which recovery is spontaneous (4), or more recently as "A temporary loss of consciousness and postural tone" (5) or as "A sudden and transient loss of consciousness with spontaneous recovery" (6). It is obvious that basic concept of what defines syncope has remained unchanged over a period of about six decades, and is unlikely to do so in the future.…”

Section: Introductionmentioning

confidence: 99%

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Current Concepts of Pathophysiology of Vasovagal Syncope and its Evaluation and Management: A Review

Dikshit

Jaju

2020

ANAMS

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Vasovagal syncope (VVS) with a sudden, temporary loss of consciousness (LoC) is a common phenomenon in the young and the elderly. Though generally described as innocuous, it may lead to serious consequences in special category of people (pilots), or in the elderly in whom LoC may lead to a fall and serious injury. The topic has been copiously researched upon and discussed in medical literature over the last few decades, but the exact mechanisms which lead to the disability have yet to be fully agreed upon. Changes in cardiovascular baroreceptor sensitivity, aberrations in the complex interaction amongst the nucleus of the tractus solitarius and the nuclei around it, inability of the peripheral circulation to respond to autonomic vasoconstrictors, or excess production of vasodilators such as nitric oxide produced locally have been considered in its pathophysiology. Various extraneous situations like dehydration, exposure to heat stress, medications, psychological factors may adversely stress regulatory physiological responses and promote occasional episodes of VVS. More complex dysautonomia could be a reason for the recurrent VVS. Differences between brain structure of VVS sufferers and normal subjects have been proposed. Head-up tilt table (HUT) test is the most widely applied investigation for evaluating VVS episodes. Lower body negative pressure (LBNP) has also been used. Enhancement of the orthostatic stress may be done by simultaneous use of both, or with peripheral vasodilators. As to whether such an enhancement is necessary is debatable. Management with increased salt and fluid intake, corticosteroids, beta adrenergic receptor blockers, alpha adrenergic receptor stimulants, selective serotonin reuptake inhibitors, and nitric oxide synthase inhibitors have been tried with variable success.

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Section: Definition and Types Of Syncopementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Current Concepts of Pathophysiology of Vasovagal Syncope and its Evaluation and Management: A Review

Dikshit

Jaju

2020

ANAMS

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“…Diagnosis of NMS is based on clinical history and physical examination, including blood pressure measurement during orthostatic change. There are two methods for evaluating the response to postural changes: active standing and the head-up tilt test [6]. The orthostatic test has a specificity of about 90% and a sensitivity ranging from 32% to 82% [7].…”

Section: Introductionmentioning

confidence: 99%

Heart rate variability in patients presenting with neurally mediated syncope in an emergency department

Akizuki

Hashiguchi

2020

The American Journal of Emergency Medicine

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a b s t r a c tBackground: Neurally mediated syncope (NMS) is a disorder of autonomic nervous system (ANS) regulation. Orthostatic stress is one of the most common causative factors seen in clinical practice. Analysis of heart rate variability (HRV) is a non-invasive method that is used to assess ANS regulation. In this study, we investigated the pathophysiology of NMS using HRV in our emergency department. Methods: The subjects were 19 patients (age 25.8 ± 6.2 years old) who presented with NMS and 20 healthy individuals (age 26.6 ± 2.7 years old) who served as controls. HRV was measured in supine, sitting and standing positions. Heart rate (HR), low frequency (LF 0.04-0.15 Hz), high frequency (HF N 0.15 Hz), and coefficient of variation of the R-R interval (CVRR) were determined. Results: LF and HF in the supine position were significantly lower in the patients with NMS (p b 0.05). HR was higher in all positions in patients with NMS than in healthy individuals (p b 0.05). CVRR in the supine position was lower in the patients with NMS (p b 0.001), and it was significantly lower in patients who were positive in an orthostatic test (p = 0.0017). Area under the curve was calculated to be 0.824, and at the cutoff value of 4.997 of CVRR in supine, the sensitivity and the specificity were 78.9% and 85.0%. Conclusion: The sympathetic and parasympathetic nervous systems were both suppressed in patients with NMS. In post-syncope, parasympathetic withdrawal, rather than sympathetic reactivation, was responsible for the increased HR after syncope. CVRR may serve as a new clinical biomarker in the emergency department.

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“…Types of reflex syncope include vasovagal syncope, situational syncope, carotid sinus syncope, and some cases without apparent triggers (Shen et al., ). Although the pathophysiologic mechanisms of reflex syncope are not fully understood, alterations in autonomic activation have been put forth as the most likely cause (Alboni & Alboni, ; Malamud‐Kessler, Bruno, Chiquete, Senties‐Madrid, & Campos‐Sanchez, ). Intermittent and sudden disruptions in the activity of the autonomic nervous system can occur, causing a sudden drop in blood pressure, heart rate, and brain perfusion (Malamud‐Kessler et al., ).…”

Section: Introductionmentioning

confidence: 99%

“…Although the pathophysiologic mechanisms of reflex syncope are not fully understood, alterations in autonomic activation have been put forth as the most likely cause (Alboni & Alboni, ; Malamud‐Kessler, Bruno, Chiquete, Senties‐Madrid, & Campos‐Sanchez, ). Intermittent and sudden disruptions in the activity of the autonomic nervous system can occur, causing a sudden drop in blood pressure, heart rate, and brain perfusion (Malamud‐Kessler et al., ). Some evidence suggests that brain abnormalities are associated with reflex syncope, highlighting the fact that specific brain regions modulate the cardiovascular autonomic nervous system (Beacher, Gray, Mathias, & Critchley, ; Kim, Suh, Seo, Koh, & Kim, ; Shin et al., ).…”

Section: Introductionmentioning

confidence: 99%

Alterations of brain network hubs in reflex syncope: Evidence from a graph theoretical analysis based on DTI

et al. 2018

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ObjectiveWe evaluated global topology and organization of regional hubs in the brain networks and microstructural abnormalities in the white matter of patients with reflex syncope.MethodsTwenty patients with reflex syncope and thirty healthy subjects were recruited, and they underwent diffusion tensor imaging (DTI) scans. Graph theory was applied to obtain network measures based on extracted DTI data, using DSI Studio. We then investigated differences in the network measures between the patients with reflex syncope and the healthy subjects. We also analyzed microstructural abnormalities of white matter using tract‐based spatial statistics analysis (TBSS).ResultsMeasures of global topology were not different between patients with reflex syncope and healthy subjects. However, in reflex syncope patients, the strength measures of the right angular, left inferior frontal, left middle orbitofrontal, left superior medial frontal, and left middle temporal gyrus were lower than in healthy subjects. The betweenness centrality measures of the left middle orbitofrontal, left fusiform, and left lingual gyrus in patients were lower than those in healthy subjects. The PageRank centrality measures of the right angular, left middle orbitofrontal, and left superior medial frontal gyrus in patients were lower than those in healthy subjects. Regarding the analysis of the white matter microstructure, there were no differences in the fractional anisotropy and mean diffusivity values between the two groups.ConclusionsWe have identified a reorganization of network hubs in the brain network of patients with reflex syncope. These alterations in brain network may play a role in the pathophysiologic mechanism underlying reflex syncope.

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Pathophysiology of neurally-mediated syncope

Cited by 5 publications

References 47 publications

Current Concepts of Pathophysiology of Vasovagal Syncope and its Evaluation and Management: A Review

Current Concepts of Pathophysiology of Vasovagal Syncope and its Evaluation and Management: A Review

Heart rate variability in patients presenting with neurally mediated syncope in an emergency department

Alterations of brain network hubs in reflex syncope: Evidence from a graph theoretical analysis based on DTI

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