Diagnostic performance of light reflex pupillometry in Alzheimer's disease.

Easily applied diagnostic tools such as digital biomarkers for Alzheimer's disease (AD) are urgently needed due to the recent approval of disease-modifying therapies. We aimed to determine the diagnostic performance of hand-held, quantitative light reflex pupillometry (qLRP) in patients with AD in a proof-of-concept, cross-sectional study. Participants underwent qLRP at a university memory clinic from August 2022 to October 2023. We fitted multivariable logistic regression models with qLRP, sex, and age as predictors evaluated with area under the receiver operating characteristics curve (AUROC). In total, 107 patients with AD, 44 patients with mixed AD and vascular cognitive dysfunction (VCD), 53 patients with dementia with Lewy bodies (DLB), and 50 healthy controls (HCs) were included. Our diagnostic models showed similar discriminatory ability (AUROC range 0.74-0.81) when distinguishing patients with AD from HCs and other dementias. The qLRP seems promising as a bedside digital biomarker to aid in diagnosing AD. Highlights: We demonstrated the diagnostic performance of qLRP in Alzheimer's disease.The diagnostic models were robust in sensitivity analyses.qLRP may assist in the bedside diagnostic evaluation of Alzheimer's disease.

Persistence and activity levels of primitive reflexes in young high-level football players.

Introduction: Primitive reflexes (PR) induce involuntary automatic movements in response to specific stimuli. This study aimed to determine the prevalence of active PR in young high-level football players. Methodology: Sixty-nine national-level football players from a French academy were tested (17.0 ± 1.4 years; 69.6 ± 8.0 kg; 178.9 ± 6.9 cm) to evaluate the persistence of PR, following the methodology of the Institute for Neuro-Physiological Psychology (INPP) and the classification by a global score (GS). Based on the sum of seven tests, each was rated between 0 = null and 4 = max. The GS is classified into five categories from no activity to maximal (0-1 = no activity, 2-7 = low, 8-13 = medium, 14-21 = high, and 22-28 = maximal). Result: Around two-thirds (68.1%) of players presented active PR at different activity levels. Among them, a small proportion (7.2%) had medium GS, while 60.9% had a low GS. The GS was not dependent on field position or the age of the players (p > 0.05). However, playing football in an age category higher than their own was associated with significantly more active primitive reflexes (PR) compared to being in their age category (p < 0.01). The results showed that 72.7% of "upgraded" football players had low GS and 18.2% had medium GS, compared to 55.3% and 2.1% in the non-upgraded group. Discussion: The findings of the current study demonstrate that PR could still be active in a healthy population of high-level football players. Practicing a single sport for years and upgrading players could create a negative environment that can ultimately lead to the activation of otherwise integrated PR.

Transcranial alternating current stimulation can modulate the blink reflex excitability. Effects of a 10- and 20-Hz tACS session on the blink reflex recovery cycle in healthy subjects.

BACKGROUND: The blink reflex excitability, assessed through paired electrical stimuli responses, has been modulated using traditional non-invasive neurostimulation techniques. Recently, transcranial Alternating Current Stimulation (tACS) emerged as a tool to modulate brain oscillations implicated in various motor, perceptual, and cognitive functions. This study aims to investigate the influence of 20-Hz and 10-Hz tACS sessions on the primary motor cortex and their impact on blink reflex excitability. MATERIALS AND METHODS: Fifteen healthy volunteers underwent 10-min tACS sessions (intensity 1 mA) with active/reference electrodes placed over C4/Pz, delivering 20-Hz, 10-Hz, and sham stimulation. The blink reflex recovery cycle (BRrc) was assessed using the R2 amplitude ratio at various interstimulus intervals (ISIs) before (T0), immediately after (T1), and 30 min post-tACS (T2). RESULTS: Both 10-Hz and 20-Hz tACS sessions significantly increased R2 ratio at T1 (10-Hz: p = 0.02; 20-Hz: p < 0.001) and T2 (10-Hz: p = 0.01; 20-Hz: p < 0.001) compared to baseline (T0). Notably, 20-Hz tACS induced a significantly greater increase in blink reflex excitability compared to sham at both T1 (p = 0.04) and T2 (p < 0.001). CONCLUSION: This study demonstrates the modulatory effect of tACS on trigemino-facial reflex circuits, with a lasting impact on BRrc. Beta-band frequency tACS exhibited a more pronounced effect than alpha-band frequency, highlighting the influential role of beta-band oscillations in the motor cortex on blink reflex excitability modulation.

Nursing insights on the effectiveness of automated pupillometry in two distinct pediatric intensive care units.

PURPOSE: Automated pupillometry (AP) facilitates objective pupillary assessment. In this study, we aimed at assessing nursing perspective about the utility of AP in neurocritically ill children to understand acceptance and usage barriers to guide development of a standardized use protocol. METHODS: We conducted a web-based, cross-sectional, anonymous, Google™ survey of nurses at two independent pediatric ICUs which have been using AP over last four years. The survey included questions related to user-friendliness, barriers, acceptance, frequency of use, and method of documenting AP findings. RESULTS: A total of 31 nurses responded to the survey. A total of 25 nurses (80.6%) used the automated pupillometer and 19 (61.3%) nurses preferred to use the automated pupillometer on critically ill intubated patients. Respondents rated the pupillometer a median [IQR] frequency of use of 7/10 [4-9] and a mean user-friendliness of 8/10 [7-10]. Barriers to pupillometer use included pupillometer unavailability, technical issues, lack of perceived clinical significance, and infection control. CONCLUSION: Nurses have widely adopted the use of automated pupillometer in the PICU especially for critically ill intubated patients and rate it favorably for user-friendliness. Barriers against its use include limited resources, infection concerns, technical issues, and a lack of perceived clinical significance and training. Implementation of standardized PICU protocol for AP usage in critically ill children, may enhance the acceptance, increase usage and aid in objective assessments. PRACTICE IMPLICATIONS: These findings can be used to create a standardized protocol on implementing automated pupillometry in the PICU for critically ill children.

Establishing reflex test rules for platelet fluorescent counting method using machine learning models on Sysmex XN-series hematology analyzer.

INTRODUCTION: The platelet fluorescent counting (PLT-F) method is utilized as a reflex test method following the initial test of the platelet impedance counting (PLT-I) method in clinical practice on the Sysmex XN-series automated hematology analyzer. Our aim is to establish reflex test rules for the PLT-F method by combining multiple parameters provided by the "CBC + DIFF" mode of the Sysmex XN-series automated hematology analyzer. METHODS: We tested 120 samples to evaluate the baseline bias between the PLT-F and PLT-I methods. Then, we selected 1256 samples to establish and test reflex test rules using seven machine learning models (decision Tree, random forest, neural network, logistic regression, k-nearest neighbor, support vector machine, and Naive Bayes). The training set and test set were divided at a ratio of 7:3. We evaluated the performance of machine learning models on the test set using various metrics to select the most valuable model. RESULTS: The PLT-F method exhibited a high degree of correlation with the PLT-I method (r = 0.998). The random forest model emerged as the most valuable, boasting an accuracy of 0.893, an area under the curve of 0.954, an F1 score of 0.771, a recall of 0.719, a precision of 0.831, and a specificity of 0.950. The most important variable in the random forest model was mean cell volume, weighted at 15.09%. CONCLUSION: The random forest model, which demonstrated high efficiency in our study, can be used to establish PLT reflex test rules based on the PLT-F method for the Sysmex XN-series automated hematology analyzer.

Functional involvement of the sternohyoid muscle during breathing and swallowing in rats.

The sternohyoid muscle depresses the hyoid bone, but it is unclear whether the muscle contributes to respiratory and swallowing mechanisms. This study aimed to clarify whether the sternohyoid muscle participates in the respiration and swallowing reflex and how the activity is modulated in two conditions: with airway stenosis and with a fixed sternohyoid muscle length. Electromyographic activity in the sternohyoid, digastric, thyrohyoid, and diaphragm muscles was recorded in anesthetized rats. The sternohyoid muscle activity was observed in the inspiratory phase and during swallowing, and was well coordinated with digastric and thyrohyoid muscle activity. With airway stenosis, the respiratory activity per respiratory cycle was facilitated in all assessed muscles but the facilitation of activity per second occurred only in the digastric, thyrohyoid, and sternohyoid muscles. With airway stenosis, the swallowing activity was facilitated only in the digastric muscle but not in the thyrohyoid and sternohyoid muscles. Swallowing activity was not observed in the sternohyoid muscle in the condition with the sternohyoid muscle length fixed, although increased inspiratory activity remained. The current results suggest that (1) the sternohyoid muscle is slightly activated in the inspiratory phase, (2) the effect of airway stenosis on respiratory function may differ between the upper airway muscles and diaphragm, and (3) swallowing activity in the sternohyoid muscle is not dominantly controlled by the swallowing central pattern generator but instead occurs as a myotatic reflex.

Evaluation of the Effects of Optokinetic Stimuli and Dual-Task Performance on Vestibulo-Ocular Reflex Function in Children With Attention Deficit and Hyperactivity Disorder.

OBJECTIVES: This study investigated the effects of optokinetic stimuli and dual-task performance on vestibulo-ocular reflex (VOR) function. The study primarily focused on understanding the effects of attention deficit and hyperactivity disorder (ADHD) and its subtypes. STUDY DESIGN: A case-control study. SETTING: Tertiary medical centre. METHODS: Thirty-eight children diagnosed with ADHD and 40 typically developing (TD) children aged 8-18 were included in the study. According to their diagnostic reports, children diagnosed with ADHD were also examined in three subtypes: predominantly inattentive (ADHD-PI), predominantly hyperactive-impulsive (ADHD-HI) and the combined type. Functional head impulse test (fHIT) was applied to all participants in three conditions-with no additional stimulus, optokinetic stimulation and dual-task. Correct responses (CR) were determined for each group, and the conditions were compared. For the dual-task test performance, children were given a counting task. RESULTS: The findings of the study are significant. The CR values obtained from the fHIT tests applied under three different conditions were lower in the ADHD group compared to the control group. CR values for all fHIT conditions and all semicircular canals were lower in the ADHD-PI subtype and higher in the ADHD-HI subtype compared to other subgroups. CONCLUSION: This study has significant practical implications underscoring its relevance. fHIT, when applied with different protocols, can provide valuable information about the vestibular and cognitive states of children with ADHD. These results are particularly significant as the diagnosis of ADHD often relies on subjective interpretations, and fHIT offers a more objective and reliable method of evaluation.

Investigating acoustic startle habituation and prepulse inhibition with silent functional MRI and electromyography in young, healthy adults.

Introduction: Startle habituation and prepulse inhibition (PPI) are distinct measures of different sensory information processes, yet both result in the attenuation of the startle reflex. Identifying startle habituation and PPI neural mechanisms in humans has mostly evolved from acoustic-focused rodent models. Human functional magnetic resonance imaging (fMRI) studies have used tactile startle paradigms to avoid the confounding effects of gradient-related acoustic noise on auditory paradigms and blood-oxygen-level-dependent (BOLD) measures. This study aimed to examine the neurofunctional basis of acoustic startle habituation and PPI in humans with silent fMRI. Methods: Using silent fMRI and simultaneous electromyography (EMG) to measure startle, the neural correlates of acoustic short-term startle habituation and PPI [stimulus onset asynchronies (SOA) of 60 ms and 120 ms] were investigated in 42 healthy adults (28 females). To derive stronger inferences about brain-behaviour correlations at the group-level, models included EMG-assessed measures of startle habituation (regression slope) or PPI (percentage) as a covariate. A linear temporal modulator was modelled at the individual-level to characterise functional changes in neural activity during startle habituation. Results: Over time, participants showed a decrease in startle response (habituation), accompanied by decreasing thalamic, striatal, insula, and brainstem activity. Startle habituation was associated with the linear temporal modulation of BOLD response amplitude in several regions, with thalamus, insula, and parietal lobe activity decreasing over time, and frontal lobe, dorsal striatum, and posterior cingulate activity increasing over time. The paradigm yielded a small amount of PPI (9-13%). No significant neural activity for PPI was detected. Discussion: Startle habituation was associated with the thalamus, putamen, insula, and brainstem, and with linear BOLD response modulation in thalamic, striatal, insula, parietal, frontal, and posterior cingulate regions. These findings provide insight into the mediation and functional basis of the acoustic primary startle circuit. Instead, whilst reduced compared to conventional MRI, scanner noise may have disrupted prepulse detection and processing, resulting in low PPI and impacting our ability to map its neural signatures. Our findings encourage optimisation of the MRI environment for acoustic PPI-based investigations in humans. Combining EMG and functional neuroimaging methods shows promise for mapping short-term startle habituation in healthy and clinical populations.

Acute effects of local vibration inducing tonic vibration reflex or illusion of movement on maximal wrist force production.

Local vibration (LV) mainly stimulates primary afferents (Ia) and can induce a tonic vibration reflex (TVR) and an illusion of movement. This study aimed to evaluate the effect of these two phenomena on maximal voluntary isometric contraction (MVIC) capacity. LV (80 Hz) was applied to the wrist flexor muscles in two randomized experiments for 6 minutes. LV conditions were adjusted to promote either TVR (visual focus on the vibrated wrist) or ILLUSION (hand hidden, visual focus on electromyographic activity of the flexor carpi radialis muscle (FCR)). Mechanical and electromyographic (EMG) responses of the FCR and extensor carpi radialis muscles were recorded during MVIC in flexion and extension and during electrically evoked contractions at supramaximal intensity. Measurements were performed before (10 minutes and just before) and after (0 and 30 minutes) LV protocol. An increase in FCR EMG was observed during LV in the TVR condition (+340%) compared to the illusion condition (P=0.003). In contrast, the movement illusion was greater in the ILLUSION condition (assessed through subjective scales) (P=0.004). MVIC was reduced in flexion only after the TVR condition (≈ -7%, all P<0.034). Moreover, the decrease in force was correlated with the amount of TVR recorded on the FCR muscle (r=-0.64, P=0.005). Although potentiated doublets of each muscle did not evolve differently between conditions, a decrease was observed between the first and the last measure. In conclusion, when conducting research to assess maximal strength, it is necessary to have better control and reporting of the phenomena induced during LV.

Prevalence and clinical predictors of vasodepressor syncope during head up tilt test.

INTRODUCTION: The aim of our study was to evaluate the prevalence and clinical predictors of vasodepressor (VD) response during head-up tilt test (HUTT) in patients with history of syncope admitted to a tertiary referral syncope unit. MATERIAL AND METHODS: We retrospectively evaluated all consecutive patients who underwent HUTT for suspected or established reflex syncope at our institution from March 1st, 2017, to June 1st, 2023. VD response was defined when syncope occurred during hypotension along with no or slight (< 10% bpm) decrease of heart rate. Univariate and multivariate analyses were performed to test the association of VD response to HUTT with a set of clinical covariates. RESULTS: 1780 patients (40 ± 19.9 years; 49.3% male) were included; among them, 1132 (63 %) showed a positive response to HUTT and 124 (7.0%) had a VD response. The prevalence of VD response showed a peak after 69 years (11.52% vs 6.18%; P = 0.0016), mainly driven by male patients (13.7% vs 4.9%; P < 0.0001). At multivariate analysis, age (OR: 1.15; P = 0.0026) was independently associated to HUTT-induced VD syncope; in contrast, smoking (OR: 0.33: P = 0.0009) and non-classical presentation of syncope (OR: 0.55; P = 0.0029) inversely correlated with VD syncope. CONCLUSIONS: VD response represents the less frequent responses among those induced by HUTT, accounting up to 7% of overall responses. A gender and age-related distribution has been shown. Advanced age was the only independent predictor of VD syncope; conversely, smoking and non-classical presentation of syncope reduced the probability of VD response to HUTT.

Effects of cerebellar transcranial direct current stimulation on the excitability of spinal motor neurons and vestibulospinal tract in healthy individuals.

Cerebellar transcranial direct current stimulation (ctDCS) modulates cerebellar cortical excitability in a polarity-dependent manner and affects inhibitory pathways from the cerebellum. The cerebellum modulates spinal reflex excitability via the vestibulospinal tract and other pathways projecting to the spinal motor neurons; however, the effects of ctDCS on the excitability of spinal motor neurons and vestibulospinal tract remain unclear. The experiment involved 13 healthy individuals. ctDCS (sham-ctDCS, anodal-ctDCS, and cathodal-ctDCS) was applied to the cerebellar vermis at 2 mA with an interval of at least 3 days between each condition. We measured the maximal M-wave (Mmax) and maximal H-reflex (Hmax) in the right soleus muscle to assess the excitability of spinal motor neurons. We applied galvanic vestibular stimulation (GVS) for 200 ms at 100 ms before tibial nerve stimulation to measure Hmax conditioned by GVS (GVS-Hmax) and calculated the change rate of Hmax by GVS as the excitability of vestibulospinal tract. We measured the Mmax, Hmax, and GVS-Hmax before, during, and after ctDCS in the sitting posture. No main effects of tDCS condition, main effects of time, or interaction effects were observed in Hmax/Mmax or the change rate of Hmax by GVS. It has been suggested that ctDCS does not affect the excitability of spinal motor neurons and vestibulospinal tract, as measured by neurophysiological methods, such as the H-reflex, in healthy individuals in a sitting posture. Effect of ctDCS on other descending pathways to spinal motor neurons, the neurological mechanism of tDCS and the cerebellar activity during the experiment may have contributed to these results. Therefore, we need to investigate the involvement of the cerebellum in Hmax/Mmax and the change rate of Hmax by GVS under different neuromodulation techniques and postural conditions.

Association between pain threshold and manifested pain assessed using a PD-specific pain scale in Parkinson's disease.

Background: The neurodegenerative process in Parkinson's disease (PD) affects both dopaminergic and non-dopaminergic structures, which determine the wide range of motor and non-motor symptoms (NMS), including different types of pain. Diverse mechanisms contribute to pain in PD. Abnormal nociceptive processing is considered a distinctive feature of the disease. Objective: In the present study, we used a validated PD-specific pain assessment tool to investigate self-reported pain in PD patients and to analyze the association with the objective pain threshold. Methods: The RIII component of the nociceptive flexor reflex was assessed in 35 patients with PD and was compared to 40 healthy controls. Self-reported pain was measured using the Bulgarian version of the King's Parkinson's Disease Pain Scale (KPPS-BG). A correlation analysis was used to investigate the relationship between the objective nociceptive threshold and PD pain as assessed by KPPS-BG. Results: PD patients had a significantly lower RIII threshold than control individuals (the mean SD value was 6.24 ± 1.39 vs. 10.33 ± 1.64) when assessed in the "off" state. A statistically significant (p < 0.05) fairly negative Spearman's correlation was observed between the decreased spinal nociceptive threshold and fluctuation-related pain (-0.31). Domain 4, "nocturnal pain" (-0.21), and the KPPS-BG total score (-0.21) showed a weak negative correlation. An insignificant positive correlation was found between domain 6-"discoloration, edema/swelling"-and the RIII threshold. A higher Movement Disorders Society Unified Parkinson's Disease Rating Scale (MDS-UPDRS) part III score and modified Hoehn and Yahr (H&Y) scale are associated with a decreased nociceptive flexor reflex threshold. Conclusion: The results of the present study demonstrate the important role of increased spinal nociception in the occurrence of pain, which is associated with fluctuations and, to a lesser extent, nocturnal pain.

Importance of Preoperative Pupillary Reflex in Traumatic Optic Neuropathy.

Objective: Traumatic optic neuropathy (TON) refers to a pathological condition caused by direct or indirect injury to the optic nerves. In the case of patients with traumatic brain injury, adequate vision evaluation is difficult in many cases due to altered mentality. In order to address this problem, we investigated preoperative pupillary light reflex in TON patients as a predictive factor of surgical outcomes after optic nerve decompression. Methods: From April 2020 to September 2022, we enrolled patients who were diagnosed with TON and underwent endoscopic optic nerve decompression at our institution. Vision and pupil reflex tests were performed by an ophthalmologist before and after surgery. Results: Seven patients were enrolled. Their ages ranged from 9 to 78 years and all were male. Among the 7 patients, the patient whose pupillary light reflex was 6mm with sluggish and 7mm with fixated pupil before surgery showed no improvement in vision. Patients with some response to direct reflex or contralateral indirect reflex testing preoperative showed vision improvement postoperative. Conclusion: Direct and indirect pupillary reflexes can be important factors determining treatment for TON. In unconscious patients with a fracture involving the optic canal, timely surgical intervention based on pupillary reflex can prevent permanent loss of vision.

An intense electrical stimulus can elicit a StartReact effect but with decreased incidence and later onset of the startle reflex.

Planned actions can be triggered involuntarily by a startling acoustic stimulus (SAS), resulting in very short reaction times (RT). This phenomenon, known as the StartReact effect, is thought to result from the startle-related activation of reticular structures. However, other sensory modalities also can elicit a reflexive startle response. Here, we assessed the effectiveness of an intense startling electric stimulus (SES) in eliciting the StartReact effect as compared to a SAS. We tested SES intensities at 15 and 25 times the perceptual threshold of each participant, as well as SAS intensities of 114 dB and 120 dB. The electrical stimulation electrodes were placed over short head of the biceps brachii on the arm not involved in the task. Intense electric and acoustic stimuli were presented on 20% of the trials in a simple RT paradigm requiring a targeted ballistic wrist extension movement. The proportion of trials showing short latency (≤ 120 ms) startle reflex-related activation in sternocleidomastoid was significantly lower on intense electrical stimulus trials compared to intense acoustic trials, and the startle response onset occurred significantly later on SES trials compared to SAS. However, when a startle reflex was observed, RTs related to the prepared movement were facilitated to a similar extent for both SES and SAS conditions, suggesting that the accelerated response latency associated with the StartReact effect is independent of stimulus type.

Intracerebroventricular insulin injection acutely normalizes the augmented exercise pressor reflex in male rats with type 2 diabetes mellitus.

The exercise pressor reflex (EPR) is exaggerated in type 2 diabetes mellitus (T2DM), but the underlying central nervous system aberrations have not been fully delineated. Stimulation of muscle afferents within working skeletal muscle activates the EPR, by sending information to neurons in the brainstem, where it is integrated and results in reflexively increased mean arterial pressure (MAP) and sympathetic nerve activity. Brain insulin is known to regulate neural activity within the brainstem. We hypothesize that brain insulin injection in T2DM rats attenuates the augmented EPR, and that T2DM is associated with decreased brain insulin. Using male Sprague-Dawley rats, T2DM and control rats were generated via an induction protocol with two low doses of streptozotocin (35 and 25 mg/kg, i.p.) in combination with a 14-23-week high-fat diet or saline injections and a low-fat diet, respectively. After decerebration, MAP and renal sympathetic nerve activity (RSNA) were evaluated during EPR stimulation, evoked by electrically induced muscle contraction via ventral root stimulation, before and after (1 and 2 h post) intracerebroventricular (i.c.v.) insulin microinjections (500 mU, 50 nl). i.c.v. insulin decreased peak MAP (ΔMAP Pre (36 ± 14 mmHg) vs. 1 h (21 ± 14 mmHg) vs. 2 h (11 ± 6 mmHg), P < 0.05) and RSNA (ΔRSNA Pre (107.5 ± 40%), vs. 1 h (75.4 ± 46%) vs. 2 h (51 ± 35%), P < 0.05) responses in T2DM, but not controls. In T2DM rats, cerebrospinal fluid insulin was decreased (0.41 ± 0.19 vs. 0.11 ± 0.05 ng/ml, control (n = 14) vs. T2DM (n = 4), P < 0.01). The results demonstrated that insulin injections into the brain normalized the augmented EPR in brain hypoinsulinaemic T2DM rats, indicating that the EPR can be regulated by brain insulin. KEY POINTS: The reflexive increase in blood pressure and sympathetic nerve activity mediated by the autonomic nervous system during muscle contractions is also known as the exercise pressor reflex. The exercise pressor reflex is dangerously augmented in type 2 diabetes, in both rats and humans. In type 2 diabetic rats both cerebrospinal fluid insulin and phosphoinositide 3-kinase signalling within cardiovascular brainstem neurons decrease in parallel. Brain insulin injections decrease the magnitude of the reflexive pressor and sympathetic responses to hindlimb muscle contraction in type 2 diabetic rats. Partial correction of low insulin within the central nervous system in type 2 diabetes may treat aberrant exercise pressor reflex function.

Takotsubo Syndrome Associated with Neurally Mediated Reflex Syncope: A Meta-summary of Case Reports and Literature Review.

Background: Neurally mediated reflex syncope (NMRS) has been recently described as a possible trigger of Takotsubo syndrome (TTS). There are few data in the literature about this association. Methods: In the present meta-summary, 6 case reports describing patients who experienced TTS following an NMRS episode were included. Patient characteristics, triggers and type of syncope were collected. Results: A total of 7 patients with a median age of 63.4 years (interquartile range, IQR: 47.5-76) were evaluated; 71.4% were females, mainly in the menopausal state (80%). The TTS triggers were: vasovagal syncope in 6 patients (85.7%) and situational syncope in 1 patient (14.3%). 2 patients underwent a comprehensive clinical evaluation which showed a cardioinhibitory response. Conclusions: NMRS due to sudden orthostatism and emotional stress, mainly with a cardioinhibitory response, has been associated with the onset of TTS, in particular among female patients in a menopausal state.

Pupil light reflex in young elite athletes: autonomic nervous system activity and viscoelastic properties.

Introduction: The pupil light reflex (photomotor reflex) has a duration of 3.5 s and is a highly reproducible measurement. Conventionally, the autonomic nervous system (ANS) activity evaluated by this reflex does not consider the viscoelasticity of the iris muscles. This study aims to detect differences in reflex autonomic activity in a supine position with parameters derived from the Kelvin-Voigt viscoelastic model in two distinct groups of elite athletes. Method: Groups formed using a dendrogram analysis based on basal autonomic activity assessed with heart rate variability. Heart rate variability was measured, and the photomotor reflex was modeled. Results: The model showed a high degree of adjustment to the photomotor reflex (r2 = 0.99 ± 0.01). The impulse 3, an indicator of reflex sympathetic activity, revealed a significantly higher activity (ρ ≤ 0.05) in the [sympa/para]+ group compared to the [sympa/para]⁻ group. This result was further supported by a greater relative total redilation amplitude (ρ ≤ 0.05) and a shorter duration of 75% redilation (ρ ≤ 0.01). Finally, the relative total redilation amplitude exhibited a significant correlation with the linear stiffness constant (ρ ≤ 0.001) and the maximum redilation speed with restoring force (ρ ≤ 0.001). Discussion: These results indicate that (i) the photomotor reflex can detect an alteration of the reflex autonomic activity specific to each of the two branches of the ANS (ii) the viscoelastic properties of the iris muscles play a significant role in the energy storage-restitution mechanisms during the photomotor reflex. This approach could allow athletes to benefit from reduced time spent in the analysis of ANS activity, potentially making it an almost daily and automated process.

Neurally-mediated syncope Associated with Neck Sarcoma.

A 60-year-old male presented with recurrent syncopes and a right-sided neck mass, due to squamous cell carcinoma. His syncopes were caused by bradycardias and hypotension, requiring transvenous pacing and vasopressors. Surgical resection and radiotherapy relieved the hemodynamic symptoms. This case report of an unusual response to presumed carotid sinus compression highlights the need for a multidisciplinary approach in addressing the etiology of reflex syncope in patients with oncological conditions.