Reflex Mechanisms Research Articles

Differences in resting sympathetic nervous activity between orthostatic hypertension, conventional hypertension, and healthy individuals

Abstract Introduction Standing places a significant hemodynamic burden on the cardiovascular system. In healthy individuals, neurohumoral reflex mechanisms, particularly the arterial baroreflex, maintain blood pressure during standing. However, in some cases, the counterregulatory response can be excessive, resulting in a condition known as orthostatic hypertension (OHT), which appears to be linked to an increased cardiovascular risk. In recent years, OHT has been recognized as an indicator for assessing the effectiveness of renal denervation. It is suggested that abnormalities in sympathetic nervous system regulation, particularly related to the renal sympathetic nerves, may play a role in influencing RDN outcomes, however, the relationship between OHT and sympathetic nerve activity remains poorly understood. This study aims to assess the differences in sympathetic nerve activity between OHT patients, conventional hypertensive(cHT) patients and healthy individuals using muscle sympathetic nerve activity (MSNA) measurements. Methods We conducted an examination of hypertensive patients undergoing drug treatment at our clinic between April 1, 2023, and June 30, 2023, to identify cases of OHT. OHT was defined as a sustained increase in systolic blood pressure ≥20 mmHg and/or diastolic blood pressure ≥10 mmHg within 3 minutes of standing. We measured MSNA in the cases for which consent was obtained. Results Among the 138 cases, 31 were diagnosed with OHT, and 7 of them consented to MSNA measurement. Of the 11 cases of cHT patients who consented, two groups were well age-matched. And it was also compared with 11 cases of healthy individuals who underwent MSNA measurement during the same period. Both of the MSNA burst frequency and burst incidence in OHT (38.4 +/- 12.2 bursts/min, 61.1 +/- 21.3 bursts/100 heartbeats) was significantly greater (p<0.05) than that in cHT (28.3 +/- 5.7 bursts/min, 44.6 +/- 11.1 bursts/100 heartbeats), and all these were significantly greater (p<0.05) than in healthy individuals (21.8 ± 7.3 bursts/min, 35.8 +/- 11.3 bursts/100 heartbeats) at rest. Conclusions OHT is associated with sympathetic hyperactivity compared to normal hypertensive patients, contributing to an increased cardiovascular risk. These results indicate that therapy for OHT in hypertensive patients would be required to prevent sympathetic augmentation.

Comparative analysis of muscle sympathetic nerve activity in patients afflicted with orthostatic hypertension versus conventional hypertension

Abstract Introduction Standing places a significant hemodynamic burden on the cardiovascular system. In healthy individuals, neurohumoral reflex mechanisms, particularly the arterial baroreflex, maintain blood pressure during standing. However, in some cases, the counterregulatory response can be excessive, resulting in a condition known as orthostatic hypertension (OrthoHT), which appears to be linked to an increased cardiovascular risk. Epidemiologically, orthostatic hypertension has been reported in 5-30% of hypertensive patients. Furthermore, in recent years, it has garnered attention as a responder group in renal denervation therapy. Purpose In hypertensive patients, sympathetic hyperactivity is expected to exacerbate cardiovascular risk. However, the relationship between OrthoHT and sympathetic nerve activity remains poorly understood. This study aims to assess the differences in sympathetic nerve activity between OrthoHT and conventional hypertensive patients using muscle sympathetic nerve activity (MSNA) measurements. Methods We conducted an examination of hypertensive patients undergoing drug treatment at our clinic between April 1, 2023, and June 30, 2023, to identify cases of OrthoHT. Only patients with essential HT were included in the HT group; patients diagnosed with secondary HT were excluded. HT patients with other active CV diseases (i.e., symptomatic cerebral/coronary artery diseases or heart failure) and/or severe renal dysfunction (estimated glomerular filtration rate <30 mL/min/1.73 m2) were also excluded. OrthoHT was defined as a sustained increase in systolic blood pressure ≥20 mmHg and/or diastolic blood pressure ≥10 mmHg within 3 minutes of standing. MSNA was recorded from the left peroneal nerve using a tungsten microelectrode at supine position. We measured MSNA in the cases for which consent was obtained. Statistical analyses were performed using SPSS software. Results Among the 183 cases, 31 were diagnosed with OrthoHT, and 7 of them consented to MSNA measurement. Of the 11 cases of hypertensive patients who consented, two groups were well age-matched. We assessed body mass index, resting systolic blood pressure, diastolic blood pressure, heart rate, blood glucose level, creatinine, cholesterol, brain natriuretic hormone, and ejection fraction measured by echocardiography, but found no significant differences between the two groups. OrthoHT patients exhibited elevated MSNA burst frequency (28.3 +/- 5.7 vs. 38.4 +/- 12.2 bursts/min, P < 0.05) and burst incidence (44.6 +/- 11.1 vs. 61.1 +/- 21.3 bursts/100 heartbeats, P < 0.05) at rest. Conclusions OrthoHT is associated with sympathetic hyperactivity compared to normal hypertensive patients, contributing to an increased cardiovascular risk.

Carotid Sinus Massage in clinical practice: the Six-Step-Method.

Carotid sinus massage (CSM) as integral part of cardiovascular autonomic testing, is indicated in all patients > 40 years with syncope of unknown origin and suspected reflex mechanism. However, large practice variation exists in performing CSM which inevitably affects the positivity rate of the test and may result in an inaccurate diagnosis in patients with unexplained syncope. Even though CSM was introduced into medical practice more than 100 years ago, the method of performing CSM is still largely operator- and centre-dependent, while in many places the test has been entirely abandoned. Here we describe a standardized protocol on how to perform CSM, which basic monitoring equipment is necessary and why CSM is a safe procedure to perform. Our aim is to create an uniform approach to perform CSM. The new proposed algorithm, the Six Step Method includes: 1) Check history for exclusion CSM; 2) Turn head slightly contralaterally and posterior (see also explanatory video and poster provided as supplementary material; 3) Palpation to identify carotid sinus location; 4) Massage for 10 seconds; 5) Monitoring of blood pressure and heart rate to assess of the hemodynamic response type, and 6) Include time intervals between subsequent massages. CSM should be performed on both the left and right and in the supine and upright position. The recommended equipment to perform CSM consists of: 1) a tilt table in order to perform CSM in supine and standing position, 2) a continuous blood pressure monitor or cardiac monitor and 3) at least two persons.

Cardiovascular Reflexes - Vagus as the Key Player.

The cardiac and vascular systems work in coordination by activating various reflex mechanisms based on the body's needs. These may be during physiological variations or pathophysiological changes seen in disease conditions of varying degrees of severity. This article intends to explain various reflexes involved in the homeostasis of the cardiovascular system and the role of vagus as the key component in all these reflexes. The article also explains the components of the reflex arc, the stimulus and response, and the role of reflex in a few diseases. This article describes 22 different cardiovascular reflexes in detail.

Relation between stretch and activation of the medial gastrocnemius muscle during gait in children with cerebral palsy compared to typically developing children

Stretch hyperreflexia is often a target for treatment to improve gait in children with spastic cerebral palsy (CP). However, the presence of stretch hyperreflexia during gait remains debated. Therefore, we assessed the relation between gastrocnemius medialis muscle-tendon stretch and muscle activation during gait in children with CP compared to typically developing (TD) children. 3D gait analysis including electromyography (EMG) and dynamic ultrasound was carried out to assess, respectively gastrocnemius medialis activation and fascicle, belly, and tendon stretch during treadmill walking. Musculotendon-unit stretch was also estimated using OpenSim. Ratios of EMG/peak lengthening velocities and accelerations were compared between CP and TD. Velocity and acceleration peaks prior to EMG peaks were qualitatively assessed. EMG/velocity and EMG/acceleration ratios were up to 500% higher for CP (n = 14) than TD (n = 15) for most structures. Increased late swing muscle activation in CP was often preceded by fascicle and musculotendon-unit peak lengthening velocity, and early stance muscle activation by peaks in multiple structures. Increased muscle activation in CP is associated with muscle-tendon stretch during gait. Concluding, late swing muscle activation in CP appears velocity-dependent, whereas early stance activation can be velocity- and acceleration-dependent. These insights into stretch reflex mechanisms during gait can assist development of targeted interventions.

Improving Spasticity by Using Botulin Toxin: An Overview Focusing on Combined Approaches.

Spasticity is a very common sign in the neurological field. It can be defined as "a motor disorder marked by a velocity-dependent increase in muscle tone or tonic stretch reflexes" associated with hypertonia. It leads to a high risk of limb deformities and pain that prejudices residual motor function, impairing quality of life". The treatment of spasticity depends on its severity and its location and, in general, it is based on rehabilitation, oral therapies (the gamma-aminobutyric acid b agonist baclofen) and injectable medications (i.e., botulin toxins, acting on polysynaptic reflex mechanisms). The botulin toxin type A (BoNT-A) injection has been effectively used to improve different types of spasticity. However, when BoNT-A is not sufficient, a combination of nonpharmacological approaches could be attempted. Therefore, additional intervention, such as conventional physical therapy by itself or further combined with robotic gait training, may be needed. Indeed, it has been shown that combination of BoNT-A and robotics has a positive effect on activity level and upper limb function in patients with stroke, including those in the chronic phase. The aim of this review is to evaluate the efficacy of pharmacological or nonpharmacological treatment in combination with BoNT-A injections on spasticity. The combined therapy of BoNT with conventional or adjunct activities or robot-assisted training, especially with end-effectors, is a valid tool to improve patients' performance and outcomes. The combined strategies might rise the toxin's effect, lowering its dosages of botulinum and reducing side effects and costs.

Nasal resistance and inflammation: mechanisms for obstructive sleep apnea from chronic rhinosinusitis.

We have previously estimated that the prevalence of obstructive sleep apnea (OSA) among World Trade Center rescue and recovery workers is 75% and identified that having symptoms of chronic rhinosinusitis (CRS) is an independent risk factor for OSA in this population. Nasal inflammation and/or elevated awake nasal resistance that carried over into sleep could explain this association. To understand the mechanism(s) for the elevated risk of OSA observed in World Trade Center responders with CRS symptoms we examined if elevated awake supine nasal resistance was associated with OSA, CRS and/or nasal inflammatory biomarkers. A total of 601 individuals (83% male, average age 53 years, body mass index = 29.9 ± 5.5 kg/m2) enrolled in the World Trade Center Health Program and without significant snoring prior to September 11, 2001 underwent 2 nights of home sleep apnea testing, measurements of anterior rhinomanometry in the supine position, and nasal lavage. Awake supine nasal resistance was not associated with OSA; 74.8% and 74.4% of the participants with low and high nasal resistance respectively, had OSA. Patients with CRS had elevated nasal inflammatory markers (interleukin 6, interleukin 8, eosinophilic cationic protein, and neutrophil) but did not have high nasal resistance. Nasal inflammatory markers were not correlated with nasal resistance. As awake nasal resistance did not explain the relationship of CRS to OSA in this large and well characterized dataset, our findings suggest that either "sleep" nasal resistance or other factors such as increased supraglottic inflammation, perhaps through impairing upper airway reflex mechanisms, or systemic inflammation are involved in the pathophysiology of OSA in the World Trade Center population. Ayappa I, Laumbach R, Black K, etal. Nasal resistance and inflammation: mechanisms for obstructive sleep apnea from chronic rhinosinusitis. J Clin Sleep Med. 2024;20(10):1627-1636.

Modelling of impulse activity of afferent fibers of antagonist muscles during transcutaneous electrical stimulation of the spinal cord during walking

The article describes the results of studies on the impulse activity of various groups of afferent fibers and EMG patterns of lower leg antagonist muscles when walking without, during and after transcutaneous electrical stimulation of the dorsal roots of the lower thoracic spinal cord of a person. Using a mathematical model based on the prediction of the triggering of muscle spindles, variability in the manifestation of impulse activity of various afferents tibialis anterior muscle (TA) and gastrocnemius medialis muscle (GM) when walking under different experimental conditions is shown. It was found that walking on a movable treadmill tape in the absence of spinal cord stimulation was accompanied by strong impulse activity of afferents I (Ia and Ib) and II groups GM, increased excitability of its motorneuron pool and weakening of afferent activity and excitability of TA. On the contrary, electrical stimulation of the spinal cord during walking caused strong impulsive activity of group II TA afferents and moderate — GM, while the activity of Ia fibers TA and GM decreased to moderate impulsivity, Ib afferents of the same muscles had the weakest activity, and the excitability of the GM motorneuron pool was greater than TA. During the postactivation period, walking was accompanied by increased impulses of afferent fibers of group Ib and II GM, weakening of afferent flows of Ib TA and Ia afferents GM, but along with this, afferent signals of group Ia and II to the motorneuron nucleus TA decreased to moderate impulses, and excitability of the motorneuron pool GM was higher than TA. The supposed reflex mechanisms of locomotion regulation are discussed on the basis of well-known phenomena associated with the interaction of various afferent inputs to the spinal cord neuronal apparatus in the system of lower leg antagonist muscles.

Laryngopharyngeal reflux disease: Updated examination of mechanisms, pathophysiology, treatment, and association with gastroesophageal reflux disease.

Laryngopharyngeal reflux disease (LPRD) is an inflammatory condition in the laryngopharynx and upper aerodigestive tract mucosa caused by reflux of stomach contents beyond the esophagus. LPRD commonly presents with sym-ptoms such as hoarseness, cough, sore throat, a feeling of throat obstruction, excessive throat mucus. This complex condition is thought to involve both reflux and reflex mechanisms, but a clear understanding of its molecular mechanisms is still lacking. Currently, there is no standardized diagnosis or treatment protocol. Therapeutic strategies for LPRD mainly include lifestyle modifications, proton pump inhibitors and endoscopic surgery. This paper seeks to provide a comprehensive overview of the existing literature regarding the mechanisms, patho-physiology and treatment of LPRD. We also provide an in-depth exploration of the association between LPRD and gastroesophageal reflux disease.

Mechanisms underpinning sympathoexcitation in hypoxia.

Sympathoexcitation is a hallmark of hypoxic exposure, occurring acutely, as well as persisting in acclimatised lowland populations and with generational exposure in highland native populations of the Andean and Tibetan plateaus. The mechanisms mediating altitude sympathoexcitation are multifactorial, involving alterations in both peripheral autonomic reflexes and central neural pathways, and are dependent on the duration of exposure. Initially, hypoxia-induced sympathoexcitation appears to be an adaptive response, primarily mediated by regulatory reflex mechanisms concerned with preserving systemic and cerebral tissue O2 delivery and maintaining arterial blood pressure. However, as exposure continues, sympathoexcitation is further augmented above that observed with acute exposure, despite acclimatisation processes that restore arterial oxygen content ( ). Under these conditions, sympathoexcitation may become maladaptive, giving rise to reduced vascular reactivity and mildly elevated blood pressure. Importantly, current evidence indicates the peripheral chemoreflex does not play a significant role in the augmentation of sympathoexcitation during altitude acclimatisation, although methodological limitations may underestimate its true contribution. Instead, processes that provide no obvious survival benefit in hypoxia appear to contribute, including elevated pulmonary arterial pressure. Nocturnal periodic breathing is also a potential mechanism contributing to altitude sympathoexcitation, although experimental studies are required. Despite recent advancements within the field, several areas remain unexplored, including the mechanisms responsible for the apparent normalisation of muscle sympathetic nerve activity during intermediate hypoxic exposures, the mechanisms accounting for persistent sympathoexcitation following descent from altitude and consideration of whether there are sex-based differences in sympathetic regulation at altitude.

Tongue reflex for speech posture control

Although there is no doubt from an empirical viewpoint that reflex mechanisms can contribute to tongue motor control in humans, there is limited neurophysiological evidence to support this idea. Previous results failing to observe any tonic stretch reflex in the tongue had reduced the likelihood of a reflex contribution in tongue motor control. The current study presents experimental evidence of a human tongue reflex in response to a sudden stretch while holding a posture for speech. The latency was relatively long (50 ms), which is possibly mediated through cortical-arc. The activation peak in a speech task was greater than in a non-speech task while background activation levels were similar in both tasks, and the peak amplitude in a speech task was not modulated by the additional task to react voluntarily to the perturbation. Computer simulations with a simplified linear mass-spring-damper model showed that the recorded muscle activation response is suited for the generation of tongue movement responses that were observed in a previous study with the appropriate timing when taking into account a possible physiological delay between reflex muscle activation and the corresponding force. Our results evidenced clearly that reflex mechanisms contribute to tongue posture stabilization for speech production.

Acute Effects of Countermovement Jumps with Post-activation Potentiation Utilizing Additional Elastic Resistance during Eccentric Stretching Phase

<p>目的：本研究欲探究下蹲階段輔以彈性阻力之反向跳預先活動，對於6分鐘恢復時間後之跳躍表現的活化後增益效應。方法：本研究招募11名國立大學體育相關科系男性學生為受試對象，施以2循環、每循環5次的反向跳預先活動，且於下蹲制動階段介入外加彈性阻力，阻力強度分為0% BW、15% BW、30% BW三種情境，並於預先活動介入前與介入後第6分鐘後進行前測與後測。以兩塊測力板擷取前測與後測之反向跳過程中垂直地面反作用力值與時間，並計算發力率、跳躍高度、修正式反應力量指標以及下肢勁度。以相依樣本 t-test 進行統計檢驗，統計水準訂為 α = .05，比較前測與後測的下肢動態力量特徵之參數是否有差異。結果：本研究結果顯示，三種介入模式皆顯著提升反向跳制動末點力值 (p < .05)。15% BW與30% BW的介入模式顯著提升制動期與推蹬期發力率 (p < .05)。30 % BW的介入模式顯著提升反向跳下肢勁度、修正式反應力量指標，並縮短制動期時間 (p < .05)。結論：本研究之介入應有助於增進牽張反射機制之效益，尤其是在離心制動階段的肌力特徵表現上，因此，建議在進行具備牽張反射機制之動作執行前，可透過反向跳下蹲階段輔以30% BW彈性阻力進行下肢動態肌力活化之預先活動，以助於後續之運動表現。</p> <p> </p><p>Purpose: The current study aimed at exploring the immediate effect of pre-activities of countermovement jumps, with elastic resistance and 6 minutes of recovery time, on post-activation potentiation during squatting phase. Method: Eleven male college students recruited from the Physical Education department at National Dong Hwa University were asked to perform pre-activities of countermovement jumps (2 cycles, 5 repetitions for each cycle), with elastic resistances (0% BW, 15% BW, and 30% BW) during the squatting phase, followed by pre-tests and post-tests before and after six minutes of recovery time. Two AMTI force plates were used to collect data on vertical ground reaction force and time during countermovement jumps for pre- and post-tests. Rate of force development, jump heights, reactive strength index modified, and lower extremity stiffness were calculated accordingly. Dependent sample t-test was conducted (α=.05) to determine if there were significant differences in the parameters related to lower extremity dynamic strength between the pre- and post-tests. Results: Pre-activities with all three interventions significantly increased the ground reaction forces during the breaking phase (p < .05). Pre-activities with elastic resistances of 15% and 30% BW significantly elevated the rates of force development during the breaking and propulsive phases (p < .05). Pre-activities with 30% BW elastic resistance significantly led to increased lower extremity stiffness, reactive strength index modified, and decreased breaking time (p < .05). Conclusion: The added elastic resistance enhanced the benefits of stretch reflex mechanism, especially the muscle strength characteristics during the eccentric breaking phase. Based on our finding, countermovement jumps with pre-activity with elastic resistance of 30% BW is recommended prior to performing movements concerning stretch reflex mechanism.</p> <p> </p>

Sorbus Aucuparia L. Fruit Extract and its Cosmetics – As Promising Agents for Prophylactic and Treatment of Pyodermitis: Phytochemical and Microbiological Research

Background: The problem of acne is relevant. The market mostly represents synthesized substances for prevention and treatment, but medical cosmetics based on plant-origin raw material, especially fruits, can be offered. The fruits of Sorbus aucuparia L. are rich in biologically active substances, which turned out to be unique in solving problems of acne. Objective: The aim of the research was to study the phenolic composition and microbiological activity of the S. aucuparia fruit extract and the proposed medicinal cosmetics to prove the possibility of their use for the treatment of pyodermitis. Methods: The phenolic compounds of the S. aucuparia fruit extract obtained with 70% ethanol solution were studied by HPLC. The microbiological research was carried out by methods of diffusion into agar. Results: In the S. aucuparia extract gallic acid, gallocatechin, epigallocatechin, catechin, epicatechin, epicatechin gallate, ellagic acid, hyperoside, rutin, quercetin-3-D-glucoside, chlorogenic, caffeic, ferulic and р-coumaric acids, umbelliferone were identified and quantified. The antimicrobial activity of the S. aucuparia extract has been established. The synergism of antimicrobial activity of 1/4 and 1/64 minimal suppression concentration erythromycin against all tested Staphylococci strains was manifested by the extract. Biological active substances of S. aucuparia fruits more effectively restore sensitivity to erythromycin in Staphylococci with low macrolide resistance of Staphylococci (MLS-resistance) due to blocking reflex mechanisms. Conclusion: The S. aucuparia fruit extracts are rich in phenolic compounds and show antimicrobial activity against all used test-strains of microorganisms. The results of the study indicate their high antimicrobial activity against the main pathogens of pyodermitis - S. aureus, S. epidermidis, and Propionibacterium acnes.

Neurophysiological Factors Associated with Compression and Reflex Mechanisms of Lower Back Pain

Introduction: Vertebrogenic pain syndromes (PSs) in the lower back (LB) are among the most common neurological disorders in the population. Currently, clinical, neurophysiological and neuroimaging characteristics are used as predictors of the course and effectiveness of the treatment for vertebrogenic PSs in the LB.
 Aim: To identify the neurophysiological factors associated with compression and reflex mechanisms of PSs in the LB for their differentiation in complicated diagnostic cases.
 Materials and methods: The study included 73 patients, 43 of them men and 30 women of the mean age 46.5 years. Based on the results of clinical neurological examination and the magnetic resonance imaging data, reflex vertebrogenic PSs (lumboischialgia) were verified in 40 cases, and radiculopathy of L5 and/or S1 (compression vertebrogenic PSs) in 33 cases. The patients underwent stimulation electroneuromyography with record of motor and sensory responses from the lower limbs, of F- and H-response, and examination of heart rate variability.
 Results: Logit regression analysis was used to create models permitting to divide patients into groups with different mechanisms of PSs based on the neurophysiological parameters. The first model demonstrated high sensitivity in the identification of predominantly compression vertebrogenic disorders with the independent factors being the mean F-wave latency and the sensory response amplitude. The second model was more sensitive in identification of reflex PSs with the main predictors being the F-response amplitude and heart rate variability parameters.
 Conclusion: The identified factors reflect the role of conduction disorders in compression PSs, as well as the involvement of segmental motor neuronal apparatus and autonomic regulatory mechanisms in the reaction in reflex PSs, which are additional sources of information in taking medical decisions in complicated diagnostic cases.

Neural sensory stimulation does not interfere with the H-reflex in individuals with lower limb amputation.

Individuals with lower limb loss experience an increased risk of falls partly due to the lack of sensory feedback from their missing foot. It is possible to restore plantar sensation perceived as originating from the missing foot by directly interfacing with the peripheral nerves remaining in the residual limb, which in turn has shown promise in improving gait and balance. However, it is yet unclear how these electrically elicited plantar sensation are integrated into the body's natural sensorimotor control reflexes. Historically, the H-reflex has been used as a model for investigating sensorimotor control. Within the spinal cord, an array of inputs, including plantar cutaneous sensation, are integrated to produce inhibitory and excitatory effects on the H-reflex. In this study, we characterized the interplay between electrically elicited plantar sensations and this intrinsic reflex mechanism. Participants adopted postures mimicking specific phases of the gait cycle. During each posture, we electrically elicited plantar sensation, and subsequently the H-reflex was evoked both in the presence and absence of these sensations. Our findings indicated that electrically elicited plantar sensations did not significantly alter the H-reflex excitability across any of the adopted postures. This suggests that individuals with lower limb loss can directly benefit from electrically elicited plantar sensation during walking without disrupting the existing sensory signaling pathways that modulate reflex responses.

Effect of digital screen usage on the visual-vestibular system interaction

Background/aimThis research aims to develop an original understanding of the subject by examining how digital screen usage correlates with visual-vestibular system interaction and the vestibuloocular reflex mechanism using vestibular test parameters.Materials and methodsThe study included 59 healthy participants. Participants were divided into two groups according to their screen usage time 3–6 h (Group 1) and over 6 h (Group 2). Participants were asked questions about complaints after screen use. After that, Video Head Impulse, Dynamic Visual Acuity, Videonystagmography test was applied to the participants.ResultsDVA was significantly poor in group 2. In vHIT and Videonystagmography test, a significant difference was not observed between the groups.ConclusionThere is no conclusive evidence that digital screen usage directly affects the peripheral or central vestibular systems. However, the decrease in DVA in individuals who use digital screens for more than 6 h may be related to the effects of digital screen exposure on the visual-vestibular system.

Overweight and dysregulation of the autonomic nervous system in young persons

Background. More than 1 billion people worldwide are obese, and this number is growing. Obesity at an early age is accompanied by impaired carbohydrate tolerance and the development of type 2 diabetes, lipid metabolism pathology, obstructive apnea, hypercoagulability, chronic inflammation and the development of insulin resistance in the future. In modern literature, there is no single point of view regarding the role of the autonomic nervous system in the coordination of hormonal, nervous and metabolic factors in the body.Aim. The article presents the results of studying the functional state of the sympathetic and parasympathetic parts of the autonomic nervous system in overweight persons and presents an assessment of the central hemodynamic parameter depending on the type of autonomic reactivity of the cardiovascular system.Methods. The study involved measuring systolic and diastolic blood pressure, heart rate, and anthropometric measurements for calculating the corresponding indices. An active orthostatic test to determine the functional state of reflex mechanisms for regulating hemodynamics. Statistical methods were used for data analysis.Results. Based on anthropometric indicators and calculated indices, boys and girls with overweight differed from the control group in abdominal and total distribution of fat. However, there were no differences in terms of vegetative tone (sympathicotonic, vagotonic, eutonic). The distribution of eutonic and vagotonic types of the autonomic nervous system and sympathicotonia was similar in both groups. Most overweight individuals had insufficient reactivity of the parasympathetic autonomic nervous system. Paradoxical reactivity in both groups was observed with the same frequency. In the group of people with paradoxical autonomic reactivity among overweight people, a significantly lower increase in heart rate was found than in the control group. In persons with overweight and increased autonomic reactivity, minute blood volume and pulse pressure increased 1.5-fold, there was a tendency to increase stroke volume and inotropic function of the heart. The increase in this characteristic indicated a hyperkinetic type of hemodynamics in overweight persons in the group with normal autonomic reactivity. In groups with paradoxical and increased autonomic reactivity of the cardiovascular system, a normokinetic type of hemodynamics was observed.Conclusions. Signs of altered autonomic reactivity found in most overweight individuals indicate dysfunction of the parasympathetic autonomic nervous system and possible dysfunction of nonspecific regulatory (limbic-reticular) parts of the brain.

Effects of a short period of postural training on postural stability and vestibulospinal reflexes.

The effects of postural training on postural stability and vestibulospinal reflexes (VSRs) were investigated in normal subjects. A period (23 minutes) of repeated episodes (n = 10, 50 seconds) of unipedal stance elicited a progressive reduction of the area covered by centre of pressure (CoP) displacement, of average CoP displacement along the X and Y axes and of CoP velocity observed in this challenging postural task. All these changes were correlated to each other with the only exception of those in X and Y CoP displacement. Moreover, they were larger in the subjects showing higher initial instability in unipedal stance, suggesting that they were triggered by the modulation of sensory afferents signalling body sway. No changes in bipedal stance occurred soon and 1 hour after this period of postural training, while a reduction of CoP displacement was apparent after 24 hours, possibly due to a beneficial effect of overnight sleep on postural learning. The same period of postural training also reduced the CoP displacement elicited by electrical vestibular stimulation (EVS) along the X axis up to 24 hours following the training end. No significant changes in postural parameters of bipedal stance and VSRs could be observed in control experiments where subjects were tested at identical time points without performing the postural training. Therefore, postural training led to a stricter control of CoP displacement, possibly acting through the cerebellum by enhancing feedforward mechanisms of postural stability and by depressing the VSR, the most important reflex mechanism involved in balance maintenance under challenging conditions.

EFFECTIVENESS OF PERINEAL PELVIS REHABILITATION COMBINED WITH BIOFEEDBACK AND RADIOFREQUENCY DIATHERMY (RDF) IN ANORECTAL FUNCTIONAL PAIN SYNDROMES ASSOCIATED WITH PARADOXICAL CONTRACTION OF THE LEVATOR ANI MUSCLES. A PROSPECTIVE STUDY.

•Anorectal functional pain syndrome is a very often disabling disease with a consequent significant negative impact on the patient's quality of life. Chronic proctalgia, in many patients, is secondary to the paradoxical contraction of the pelvic floor and associated with a dissynergy between the thorax-abdomen and the pelvic floor. •The use of radiofrequency diathermy with a system of static electrodes associated with biofeedback represents a valid rehabilitation option for those patients suffering from anorectal functional pain syndrome because it reduces pain and paradoxical contraction of the levator ani and improves quality of life of the patient. Background - Anorectal functional pain syndrome, also called chronic proctalgia, represents a neglected clinical entity and often confused with other syndromes such as vulvodynia or acute proctalgia. It is a very often disabling disease with a consequent significant negative impact on the patient's quality of life. Chronic proctalgia, in many patients, is secondary to the paradoxical contraction of the pelvic floor and associated with a dissynergy between the thorax-abdomen and the pelvic floor. To improve symptoms in functional anorectal pain syndromes, various rehabilitation techniques are used with the aim of promoting relaxation of the pelvic floor; however, to improve defecatory dynamics in patients with levator ani syndrome, only biofeedback has shown efficacy in a randomized study. The aim of this work is to evaluate whether a rehabilitation protocol with manometric biofeedback and radiofrequency diathermy (mt100 Fremslife emotion Tecar) reduces pain and paradoxical contraction of the levator ani and improves the quality of life in patients with anorectal pain syndromes. functional. Methods - This was a prospective study on 30 patients (20 women and 10 men) with anorectal functional pain syndrome and paradoxical contraction of the pelvic floor enrolled at the UOC of General, Minimally Invasive, Oncological and Obesity Surgery of the AOU "Luigi Vanvitelli" of Naples, Italy, from September 2021 to May 2022. All patients were evaluated with a coloproctological specialist visit followed by anorectal manometry and evaluation of altered clinical physiatric parameters (Brusciano Score). The protocol consisted of 10 rehabilitation sessions of the pelvic floor once a week and lasting approximately 45 minutes. During the sessions the patients were subjected to diathermy / radiofrequency treatment (10 minutes) with a static resistive electrode on the diaphragm, during which they were required to breathe diaphragmatically and to become aware of the perineal muscles, under the supervision of a physiotherapist; followed by application of diathermy with static capacitive (5 minutes) and resistive (10 minutes) electrode at the lumbar level. This was followed by the use of manometric biofeedback (15 minutes of tonic / phasic exercises) in order to instruct the patient on the reflex mechanism to obtain a voluntary relaxation of the external anal sphincter. The variables evaluated were Pain (VAS 0-10) and the questionnaire on the impact of colorectal and anal pathologies on the quality of life (CRAIQ-7) at the beginning, after 3 months and at the end of the treatment. Results - After 10 weeks, the rehabilitation treatment combined with diathermy and manometric biofeedback proved effective in the short term with a reduction in the scores of the Vas scale and CRAIQ-7 questionnaire and an increase in the percentage of release of the anal muscles on anorectal manometry. Conclusion - The use of radiofrequency diathermy with a system of static electrodes associated with biofeedback represents a valid rehabilitation option for those patients suffering from anorectal functional pain syndrome because it reduces pain and paradoxical contraction of the levator ani and improves quality of life of the patient.

Cerebral multi-autoregulation model based enhanced external counterpulsation treatment planning for cerebral ischemic stroke.

Enhanced external counterpulsation (EECP) treatment for cerebral ischemic stroke patients with differing severity of stenosis, is subject to uncertainties due to the varying effects of the cerebral autoregulation mechanism on haemodynamics. The current study reports the development of a cerebral multi-autoregulation (MR) mathematical model, based on cerebral arteriole regulation of neurogenic, vascular smooth muscle reflex and shear stress mechanisms which takes into account the severity of stenosis. The model was evaluated by comparison to authentic clinical measurements of cerebral autoregulatory efficiency. Then it was applied to a 0D/3D geometric multi-scale haemodynamic model of a cerebral artery. Haemodynamic indicators were calculated under different pressurization durations of EECP to evaluate the efficacy for different stenosis lesions. Moderate stenosis of 50% to 60% produced excessive time-averaged wall shear stress in the distal area of the stenosis (>7 Pa) during prolonged pressurization and may result in damage to vascular endothelial cells. However, prolonged pressurization did not result in haemodynamic risk for severe stenosis of 70% to 80%, indicating that the duration of pressurization may be extended with increasing severity of stenosis. The current MR model accurately simulated cerebral blood flow and has relevance to the simulation of cerebral haemodynamics in a clinical setting.