Reflex Parameters Research Articles

Cafeteria diet during the gestation period programs developmental and behavioral courses in the offspring

The objective of this study was to investigate the effect of exposure to maternal consumption of a hyperenergetic, highly palatable diet, known as the cafeteria diet, during the gestation period on the development and behavior of offspring. For this, we used pregnant female mice that were fed a normal or a cafeteria diet during the gestation period. The evaluation of maternal behavior in lactating dams was performed from the second to the eighth day postpartum (PND 2-8). Weight gain, feed intake, and energy intake were recorded during the gestation period. In the offspring, reflex parameters and physical development were evaluated during the lactation period and when they reached adolescence. Behavioral performance was evaluated in light-dark, open-field, and play behavior tests. In addition, biochemical parameters of the dams and the adolescent offspring were evaluated. The cafeteria diet during gestation altered maternal behavior and the onset of physical and neurodevelopmental landmarks and had an impact on emotional and play behavior in adolescent offspring. In conclusion, our results demonstrate that exposure to maternal consumption of a cafeteria diet during the gestation period can program developmental and behavioral courses in the offspring.

The cold pressor test in interictal migraine patients \u2013 different parasympathetic pupillary response indicates dysbalance of the cranial autonomic nervous system

BackgroundData on autonomic nervous system (ANS) activations in migraine patients are quite controversial, with previous studies reporting over- and underactivation of the sympathetic as well as parasympathetic nervous system. In the present study, we explicitly aimed to assess the cranial ANS in migraine patients compared to healthy controls by applying the cold pressor test to a cohort of migraine patients in the interictal phase and measuring the pupillary response.MethodsIn this prospective observational study, a strong sympathetic stimulus was applied to 20 patients with episodic migraine in the interictal phase and 20 matched controls without migraine, whereby each participant dipped the left hand into ice-cold (4 °C) water for a maximum of 5 min (cold pressor test). At baseline, 2, and 5 min during the cold pressor test, infrared monocular pupillometry was applied to quantify pupil diameter and light reflex parameters. Simultaneously, heart rate and blood pressure were measured by the external brachial RR-method at distinct time intervals to look for at least clinically relevant changes of the cardiovascular ANS.ResultsThere were no significant differences between the migraine patients and controls at baseline and after 2 min of sympathetic stimulation in all the measured pupillary and cardio-vascular parameters. However, at 5 min, pupillary light reflex (PLR) constriction velocity was significantly higher in migraineurs than in controls (5.59 ± 0.73 mm/s vs. 5.16 ± 0.53 mm/s; unpaired t-test p < 0.05), while both cardiovascular parameters and PLR dilatation velocity were similar in both groups at this time point.ConclusionsOur findings of an increased PLR constriction velocity after sustained sympathetic stimulation in interictal migraine patients suggest an exaggerated parasympathetic response of the cranial ANS. This indicates that brainstem parasympathetic dysregulation might play a significant role in migraine pathophysiology. More dedicated examination of the ANS in migraine patients might be of value for a deeper understanding of its pathophysiology.

The Dizziness Handicap Inventory does not correlate with vestibular function tests: a prospective study

The Dizziness Handicap Inventory (DHI) is believed to quantitate the handicap related to the presence or severity of underlying vestibular dysfunction. However, patients with chronic vestibular diseases may manifest various degrees of behavioural and physiological adaptation resulting in variances of the DHI. Our primary study objective is to evaluate the correlation between the DHI and measurable vestibular parameters. Secondarily, we compared DHI among different vestibular disorders (central, peripheral and functional), and different types of anatomic deficits (semicircular canal vs otolithic). We also correlated the DHI and posturography. We prospectively evaluated 799 patients with precise vestibular diagnoses using video head impulse testing (vHIT), caloric irrigation, and cervical/ocular vestibular-evoked myogenic potentials (c/oVEMP). Posturography was done for 84 patients. All participants completed the DHI. No significant correlation was found between DHI and (1) vestibulo-ocular reflex parameters: unilateral weakness r = - 0.018, total calorics r = 0.055, vHIT right r = 0.007, vHIT left r = - 0.091, vHIT asymmetry r = 0.013; (2) otolith parameters: cVEMP amplitude right r = - 0.034, amplitude left r = - 0.004, asymmetry r = 0.016; oVEMP amplitude right r = 0.044, amplitude left r = - 0.007, asymmetry r = - 0.008. Patients with central vestibular disorders had higher DHI than those with peripheral (z = - 4.743, p = 0.001) or functional disorders (z = - 2.902, p = 0.004). DHI of patients with deficits of canal or otolith function did not differ significantly from those with no deficits (z = 2.153, p = 0.541). There was no significant correlation between DHI and postural sway on posturography. Therefore, the DHI does not correlate with vestibular tests, and neither reflects the presence nor severity of peripheral vestibular deficits.

Modified motor unit number index (MUNIX) algorithm for assessing excitability of alpha motor neuron in spasticity

ObjectiveThe understanding of the spasticity mechanism is still a problem in the literature, as its definition can be made on the basis of more than one parameter. Therefore, we studied alpha motor neuron excitability, dynamic changes based on force production, and patellar tendon (T) reflex in spasticity and healthy control groups. MethodsAlpha motor neuron excitability, force production, and patellar T reflex were evaluated through three different test protocols. Motor Unit Number Index (MUNIX) measurement was applied for understanding motor neuron pool properties in the first protocol. Voluntary force production and patellar T reflex parameters were evaluated by voluntary force production and triggering patellar T reflex. Twenty spasticity and 20 healthy volunteers participated in the study. ResultsIn the spasticity group, both MUNIX numbers and Motor Unit Size Index (MUSIX) numbers were lower than those in the control group. The results for the Ideal Case Motor Unit Count (ICMUC) parameter show that there is no significant difference between spasticity and healthy individuals for low-level contractions, whereas there is a significant difference for high-level contractions (p < 0.05). In the spasticity group, an increase was observed in the ratio of maximal voluntary force to the T reflex triggered force production (Tf/Vf). ConclusionSpasticity and healthy subjects can be distinguished easily and clearly by evaluating the changes in both kinesiological and electrophysiological findings and the decreasing threshold in the alpha motor neuron pool. SignificanceThis study shows that such combined methods, which allow the evaluation of the alpha motor neuron pool, as well as kinesiological and electrophysiological parameters, are tools that cannot be overlooked in understanding spasticity.

Blink reflex parameters in baseline, active, and head-impact Division I athletes

AbstractThe Centers for Disease Control and Prevention estimates 1.6–3.8 million concussions occur each year. Research cites that 21% of traumatic brain injury in children/youth results from partic...

Sensor-Motor Maps for Describing Linear Reflex Composition in Hopping.

In human and animal motor control several sensory organs contribute to a network of sensory pathways modulating the motion depending on the task and the phase of execution to generate daily motor tasks such as locomotion. To better understand the individual and joint contribution of reflex pathways in locomotor tasks, we developed a neuromuscular model that describes hopping movements. In this model, we consider the influence of proprioceptive length (LFB), velocity (VFB) and force feedback (FFB) pathways of a leg extensor muscle on hopping stability, performance and efficiency (metabolic effort). Therefore, we explore the space describing the blending of the monosynaptic reflex pathway gains. We call this reflex parameter space a sensor-motor map. The sensor-motor maps are used to visualize the functional contribution of sensory pathways in multisensory integration. We further evaluate the robustness of these sensor-motor maps to changes in tendon elasticity, body mass, segment length and ground compliance. The model predicted that different reflex pathway compositions selectively optimize specific hopping characteristics (e.g., performance and efficiency). Both FFB and LFB were pathways that enable hopping. FFB resulted in the largest hopping heights, LFB enhanced hopping efficiency and VFB had the ability to disable hopping. For the tested case, the topology of the sensor-motor maps as well as the location of functionally optimal compositions were invariant to changes in system designs (tendon elasticity, body mass, segment length) or environmental parameters (ground compliance). Our results indicate that different feedback pathway compositions may serve different functional roles. The topology of the sensor-motor map was predicted to be robust against changes in the mechanical system design indicating that the reflex system can use different morphological designs, which does not apply for most robotic systems (for which the control often follows a specific design). Consequently, variations in body mechanics are permitted with consistent compositions of sensory feedback pathways. Given the variability in human body morphology, such variations are highly relevant for human motor control.

P238 Homonymous Ib inhibition during remote muscle contraction

Objective Conflicting theoretical models exist regarding the mechanism related to the ability of the Jendrassek maneuvre to reinforce reflex parameters. Our objective was to investigate if eventually inhibition of the spinal Ib motoneurone during remote muscle contraction would contribute to H-reflex enhancement. Method Soleus H-reflex from 26 healthy subjects was evoked on both sides by stimulating the tibial nerve at rest and during bilateral vigorous hadgrip. This procedure was repeated using paired stimulation at interstimulus intervals ranging from 2 ms to 15 ms. Mean conditioned H-wave amplitude expressed as a percentage of its unconditioned value (H-ratio) evoked during handgrip was compared with the H-ratio obtained at the same interstimulus interval at rest. Results The size of H-reflex evoked during handgrip was significantly higher then of that evoked at rest. The H-ratio value plotted against the interstimulus interval showed both at rest and during handgrip a similar decrease that was maximal at 5 ms and lasted less than 10 ms. Discussion The size of the conditioned H-reflex is determined by the balance between test Ia excitation and Ib inhibition elicited by the conditioning stimulus. According to our results the interneurones intercalated in pathways from Ib afferents retain their inhibitory effect on the alpha motoneurone during remote muscle contraction. Conclusion H-reflex enhancement during Jendrassek maneuvre is not due to inhibition of Ib interneurones. Significance Further studies are needed in order to test the role of other spinal circuits or descending drives that produce subthreshold excitation of alpha motoneurones by remote muscle contraction.

Orthodontic treatment-induced temporal alteration of jaw-opening reflex excitability.

The impairment of orofacial motor function during orthodontic treatment needs to be addressed, because most orthodontic patients experience pain and motor excitability would be affected by pain. In the present study, the temporal alteration of the jaw-opening reflex excitability was investigated to determine if orthodontic treatment affects orofacial motor function. The excitability of jaw-opening reflex evoked by electrical stimulation on the gingiva and recorded bilaterally in the anterior digastric muscles was evaluated at 1 (D1), 3 (D3), and 7 days (D7) after orthodontic force application to the teeth of right side; morphological features (e.g., osteoclast genesis and tooth movement) were also evaluated. To clarify the underlying mechanism of orthodontic treatment-induced alteration of orofacial motor excitability, analgesics were administrated for 1 day. At D1 and D3, orthodontic treatment significantly decreased the threshold for inducing the jaw-opening reflex but significantly increased the threshold at D7. Other parameters of the jaw-opening reflex were also evaluated (e.g., latency, duration and area under the curve of anterior digastric muscles activity), and only the latency of the D1 group was significantly different from that of the other groups. Temporal alteration of the jaw-opening reflex excitability was significantly correlated with changes in morphological features. Aspirin (300 mg·kg-1·day-1) significantly increased the threshold for inducing the jaw-opening reflex, whereas a lower dose (75-150 mg·kg-1·day-1) of aspirin or acetaminophen (300 mg·kg-1·day-1) failed to alter the jaw-opening reflex excitability. These results suggest that an increase of the jaw-opening reflex excitability can be induced acutely by orthodontic treatment, possibly through the cyclooxygenase activation.NEW & NOTEWORTHY It is well known that motor function is affected by pain, but the effect of orthodontic treatment-related pain on the trigeminal motor excitability has not been fully understood. We found that, during orthodontic treatment, trigeminal motor excitability is acutely increased and then decreased in a week. Because alteration of trigeminal motor function can be evaluated quantitatively by jaw-opening reflex excitability, the present animal model may be useful to search for alternative approaches to attenuate orthodontic pain.

Effects of confinement on physiological and psychological responses and expression of interleukin 6 and brain derived neurotrophic factor mRNA in primiparous and multiparous weaning sows.

ObjectiveThe present study aimed to investigate whether the long-lasting, recurrent restricting of sows leads to the physiological and psychological reaction of discomfort.MethodsSows (Large White) that had experienced restricting for about 0.5 or 3 years and age-matched sows kept in a group housing system (loose sows) were compared. Pupillary light reflex parameters were measured at the weaning stage. Immediately after slaughter, blood samples were taken to measure serum cortisol levels, and the brain was dissected, gene expression in the hippocampus, frontal cortex and hypothalamus was analyzed.ResultsThe serum cortisol levels were higher in the confined sows than in the loose sows. The full maturity, but not the young adolescent, confined sows had longer latency time in the onset of pupil constriction than their loose counterparts. Real-time polymerase chain reaction analyses revealed an increased expression of interleukin 6 mRNA in the hippocampus and decreased expression of brain derived neurotrophic factor mRNA in hippocampus and hypothalamus and to a lesser extent in the frontal cortex of the full maturity confined sows, compared with the full maturity loose sows.ConclusionTaken together, these data indicated that recurrent restricting stress in full maturity sows leads to the physiological and psychological reaction of discomfort.

Development of a Chromatic Pupillography Protocol for the First Gene Therapy Trial in Patients With CNGA3-Linked Achromatopsia.

To establish a feasible and sensitive pupillographic protocol to assess outer and inner retinal function for the first gene therapy trial in achromatopsia patients (ACHM) with mutations in CNGA3. Twenty-seven CNGA3-ACHM patients and 22 age-matched control subjects were tested using chromatic pupillography. Three different protocols were established to assess the pupillary light reflex parameters and to create the final protocol. In the individual protocols, various stimulus parameters (i.e., intensity, duration, wavelength, adaptation states) were applied to evaluate the impact of these stimuli on the pupillary response in untreated ACHM patients. In the light-adapted conditions, CNGA3-ACHM patients showed significantly reduced maximal amplitudes compared with the control group when using a 1-second high intensity (28-lux corneal illumination) blue or red stimulus (P < 0.005). In the dark-adapted conditions, CNGA3-ACHM patients unexpectedly revealed significantly increased maximal amplitudes when stimulating with red (1 second) or blue (4 ms and 1 second) stimuli of low intensity (0.01-lux corneal illumination; P < 0.05). Pupil responses of CNGA3-ACHM patients after high intensity (28 lux) red and blue 1-second stimuli were within the normal range. Chromatic pupillography demonstrated significant reduced pupil responses to stimuli addressing primarily cone function, an increased sensitivity to rod-favoring stimuli and evidence for disinhibition of intrinsically photosensitive retinal ganglion cells in CNGA3-ACHM patients. A final protocol was established based on these findings. These conclusions may be useful for the objective assessment of efficacy gained by gene therapy or other innovative interventions in this hereditary retinal disorder.

Maternal dipyrone treatment during lactation in mice reduces maternal behavior and increases anxiety-like behavior in offspring

Dipyrone (metamizole), a powerful drug, is widely used as an analgesic and antipyretic; however, the safety of its use during lactation and the potential impact on the offspring are not well established. This study aimed to determine the effect of maternal dipyrone treatment during lactation on offspring development and emotional behavior and on the dam’s maternal behavior. Hence, on postnatal day (PND) 2, drinking water only or drinking water containing dipyrone at doses of 100, 300, and 500mg/kg/day, were offered to lactating mothers up to PND9. Thereafter, all mice were provided regular drinking water. On PND2, all litters were culled to 8 pups (4 males and 4 females). Maternal behavior was evaluated at PND3, 6, 9, and 12, and at PND7 we evaluated locomotor activity in the open field. Reflex parameters and physical development of offspring were evaluated during lactation. At PND7, analysis of ultrasonic vocalization (USV) was performed. When the animals reached adolescence, we evaluated their performance in the open field, elevated plus maze (EPM), and marble burying. Our data demonstrated that maternal dipyrone treatment during lactation not only altered maternal behavior and the onset of physical and neurodevelopmental landmarks but also had an impact on anxiety-like behavior in offspring.

Pupillary responses driven by ipRGCs and classical photoreceptors are impaired in glaucoma.

The aim was to investigate the involvement of intrinsically photosensitive retinal ganglion cells (ipRGCs) in patients with manifest glaucoma and ocular hypertension (OH) using specific parameters of the pupil light reflex to chromatic stimuli. Twenty-five patients with manifest glaucoma, 16 patients with OH and 16 healthy control subjects were stimulated with 28lx red (605nm) or blue (420nm) light with a duration of either 1s or 4s. The consensual pupil light reaction was recorded by means of infrared pupillometry. The maximal relative amplitude (MRA), the post-illumination pupil response PIPRblue-red, and the slope of the response during exposure to the 4s red stimulus (SORRS) were calculated and compared using ANOVA and Tukey-Kramer post-hoc tests. Correlations between pupil parameters and visual field defects were analyzed using Pearson correlation coefficient r. PIPRblue-red was reduced in glaucoma patients compared to normals (p < 0.001) and OH (p < 0.01). There was no significant difference between OH and normals. Glaucoma patients showed additionally reduced MRA for red and blue light (p < 0.05) and a pupillary escape during exposure to red light (increased SORRS, p < 0.0005). This pupillary escape could also be seen in single subjects with OH. Significant correlations between pupil parameters and visual field defects were detected. The reduced PIPRblue-red indicates a characteristic impairment of the melanopsin-driven pathway of ipRGCs in glaucoma patients, whereas the reduced MRA and increased SORRS suggest a disturbed synaptic function and altered interaction between outer photoreceptors, RGCs, and ipRGCs.

Parasympathetic Nervous System Dysfunction, as Identified by Pupil Light Reflex, and Its Possible Connection to Hearing Impairment.

ContextAlthough the pupil light reflex has been widely used as a clinical diagnostic tool for autonomic nervous system dysfunction, there is no systematic review available to summarize the evidence that the pupil light reflex is a sensitive method to detect parasympathetic dysfunction. Meanwhile, the relationship between parasympathetic functioning and hearing impairment is relatively unknown.ObjectivesTo 1) review the evidence for the pupil light reflex being a sensitive method to evaluate parasympathetic dysfunction, 2) review the evidence relating hearing impairment and parasympathetic activity and 3) seek evidence of possible connections between hearing impairment and the pupil light reflex.MethodsLiterature searches were performed in five electronic databases. All selected articles were categorized into three sections: pupil light reflex and parasympathetic dysfunction, hearing impairment and parasympathetic activity, pupil light reflex and hearing impairment.ResultsThirty-eight articles were included in this review. Among them, 36 articles addressed the pupil light reflex and parasympathetic dysfunction. We summarized the information in these data according to different types of parasympathetic-related diseases. Most of the studies showed a difference on at least one pupil light reflex parameter between patients and healthy controls. Two articles discussed the relationship between hearing impairment and parasympathetic activity. Both studies reported a reduced parasympathetic activity in the hearing impaired groups. The searches identified no results for pupil light reflex and hearing impairment.Discussion and ConclusionsAs the first systematic review of the evidence, our findings suggest that the pupil light reflex is a sensitive tool to assess the presence of parasympathetic dysfunction. Maximum constriction velocity and relative constriction amplitude appear to be the most sensitive parameters. There are only two studies investigating the relationship between parasympathetic activity and hearing impairment, hence further research is needed. The pupil light reflex could be a candidate measurement tool to achieve this goal.

High-flow oxygen therapy in cluster headache patients has no significant effect on nociception specific blink reflex parameters: a pilot study.

BackgroundThe exact pathophysiology of cluster headache is unclear. We examined the influence of interneurons on the trigemino-facial reflex arch and the effect of oxygen, by using the nociception specific blink reflex parameters.FindingsThere is no significant effect of oxygen, immediately and over time, on the nociception specific blink reflex parameters in ten male patients during the active phase of cluster headache, outside attacks. Also, there is no significant difference between the symptomatic and asymptomatic side. None of the subjects experienced a cluster headache attack during study participation. We therefore present the collected data as reference values of nociception specific trigeminal stimulation and the effect of oxygen on nociception specific blink reflex parameters.ConclusionThe nociception specific blink reflex seems not a suitable instrument for exploring the pathophysiology of cluster headache.

Diverse autonomic regulation of pupillary function and the cardiovascular system during alcohol withdrawal

BackgroundPrevious research indicated the complexity of autonomic dysfunction during acute alcohol withdrawal. This study aimed to investigate the pupillary light reflex as an indicator of midbrain and brainstem regulatory systems in relation to cardiovascular autonomic function. MethodsThirty male patients were included in the study. They were investigated during acute alcohol withdrawal syndrome and 24h later during clomethiazole treatment and compared to healthy controls. Parameters of pupillary light reflex of both eyes as well as heart rate variability, blood pressure variability and baroreflex sensitivity (BRS) were studied. ResultsWe observed significantly reduced sympathetic (small diameter, e.g., left eye: 5.00 in patients vs. 5.91mm in controls) and vagal modulation (e.g., prolonged latencies, left eye: 0.28 vs. 0.26ms) regarding both pupils during acute alcohol withdrawal syndrome. Cardiovascular parameters showed reduced vagal modulation (e.g., b-slope of BRS: 7. 57 vs. 13.59ms/mm Hg) and mixed results for sympathetic influence. After 24h, autonomic dysfunction improved significantly, both for the pupils (e.g., left diameter: 5.38mm) and the heart (e.g., b-slope of BRS: 9.34ms/mm Hg). While parameters obtained from the pupil correlated with cardiac autonomic function (e.g, BRS and left diameter: r=0.564) in healthy controls, no such pattern was observed in patients. ConclusionResults obtained from the pupil during acute alcohol withdrawal do not simply mirror autonomic dysfunction regarding the heart. Pupillary and cardiovascular changes after 24h indicate state dependencies of the results. The findings are discussed with respect to autonomic mechanisms and potentially involved brain regions.

The features of sensorimotor integration in patients with levodopa-induced dyskinesia in Parkinson’s disease

Introduction. Parkinson’s disease (PD) is characterized not only by motor but also by a number of nonmotor symptoms, such as sensory, vegetative, and psycho-emotional disorders. Objective. To study the states of the somatosensory system and the sensorimotor integration in patients with levodopa-induced dyskinesia (LID). Materials and methods. Fifty-two patients with LID associated with PD (Hoehn and Yahr stage III–IV) and 29 patients free of dyskinesia were examined. The somatosensory evoked potentials (SSEPs) and blink reflex (BR) were studied. Results. LID in PD were observed significantly more often among females than among males. No differences in disease duration and duration of levodopa administration were observed among patients free of dyskinesia and patients with LID. In the group of patients with LID, MRI examination showed increased brainstem reflex excitability. The acceleration of signal passing from the medulla oblongata to the cortex revealed according to the SSEP data in this group of patients is indicative of the increased reflex excitability at the spinal cord and brainstem, thalamic, and cortical levels. Significant differences in passage of sensory information were found between the two patient groups. Hence, in patients with LID, the latency N20 was 20 (19.6; 21.3) ms; P18, 16.0 (15.1; 16.6) ms; and N13, 13.7 (13.1; 14.8) and was reliably shorter than in the group of patients free of LID, where the latency N20 was 20.9 (20; 21.4) ms; Р18, 16.9 (16.2; 17.6); and N13, 14.2 (13.5; 15.2) ms. Conclusions. The revealed alterations in parameters of blink reflex and SSEPs are hypothetically genetically determined in patients with LID. Objectification of these disorders at the earliest stages of the disease can help in assessing their role as predictor factors for development of LID. Allowance for these factors will make it possible to choose an appropriate treatment strategy and reduce the risk of complications associated with drug therapy.

Pupil function as an indicator of being under the influence of central nervous system-acting substances from a traffic-medicine perspective - Part II.

In order to evaluate driving abilities of each traffic participant, standardised and objective measurement methods are needed. The applicability and value of infrared pupillography as an objective measurement method to indicate possible influence of central nervous acting substances has been demonstrated in former publications. Healthy test subjects (n = 41), as well as persons who were under the influence of drugs and/or medication (n = 105), were exposed to different light stimuli using infrared technology in order to demonstrate the relevance of specific parameters of the pupillary light reflex (PLR) in the field of traffic medicine. Based on former reported results, the statistical examination was extended to further parameters of the PLR, which again confirmed the high value of infrared pupillography as a reliable indicator of previous consumption of drugs and/or medication.

Estimation of operators' fatigue using optical methods for determination of pupil activity.

The purpose of this study was to develop and initially validate an objective, yet quick, method for assessment of human fatigue. This aim can be achieved by the use of an optical, non-contact method of analysis of pupil activity. The study involved 2 phenomena typical for the behavior of the human pupil: pupillary reflex and pupillary movements. The 1st phenomenon is related to the pupillary light reflex (PLR), which presents the results of physiological adaptation mechanisms of the human eye. The pupillary unrest index (PUI) is an additional parameter referring to the tendency for instability of the pupil. Indicators of these 2 mechanisms were assessed under the same experimental laboratory conditions. Assessment was conducted on a group of volunteers (N = 10) during 4 controlled series of measurements performed at night. Pupillary reflex parameters associated with PLR and pupillary unrest index (PUI) were recorded using F²D Fit-For-Duty, a commercially available system made by AMTech Pupilknowlogy GmbH. Baseline pupil diameter, oscillations, reflex latency, maximum reaction time, pupil constriction time, pupil dilation time, and constriction amplitude were recorded. As a result of the study, we were able to demonstrate correlation and confirm the usefulness of PLR and PST methods in the assessment of sleep deprivation. Parameters of PLR that may indicate human fatigue were identified. The effect of light impulse sequences on the dynamics of pupillary reflex and the relationship between PUI (pupillary unrest index) measurement duration and sleepiness assessment validity, were assessed. The results of the pilot studies were sufficient to develop minimum requirements for a PLR sensor that would be capable of estimating the level of fatigue with accuracy of a PUI method, but at a 5 times faster rate.

Comprehensive neuromechanical assessment in stroke patients: reliability and responsiveness of a protocol to measure neural and non-neural wrist properties

BackgroundUnderstanding movement disorder after stroke and providing targeted treatment for post stroke patients requires valid and reliable identification of biomechanical (passive) and neural (active and reflexive) contributors. Aim of this study was to assess test-retest reliability of passive, active and reflexive parameters and to determine clinical responsiveness in a cohort of stroke patients with upper extremity impairments and healthy volunteers.MethodsThirty-two community-residing chronic stroke patients with an impairment of an upper limb and fourteen healthy volunteers were assessed with a comprehensive neuromechanical assessment protocol consisting of active and passive tasks and different stretch reflex-eliciting measuring velocities, using a haptic manipulator and surface electromyography of wrist flexor and extensor muscles (Netherlands Trial Registry number NTR1424).Intraclass correlation coefficients (ICC) and Standard Error of Measurement were calculated to establish relative and absolute test-retest reliability of passive, active and reflexive parameters. Clinical responsiveness was tested with Kruskal Wallis test for differences between groups.ResultsICC of passive parameters were fair to excellent (0.45 to 0.91). ICC of active parameters were excellent (0.88-0.99). ICC of reflexive parameters were fair to good (0.50-0.74). Only the reflexive loop time of the extensor muscles performed poor (ICC 0.18). Significant differences between chronic stroke patients and healthy volunteers were found in ten out of fourteen parameters.ConclusionsPassive, active and reflexive parameters can be assessed with high reliability in post-stroke patients. Parameters were responsive to clinical status. The next step is longitudinal measurement of passive, active and reflexive parameters to establish their predictive value for functional outcome after stroke.Electronic supplementary materialThe online version of this article (doi:10.1186/s12984-015-0021-9) contains supplementary material, which is available to authorized users.

Cortical Reorganization Is Associated with Surgical Decompression of Cervical Spondylotic Myelopathy.

Background. Cervical spondylotic myelopathy (CSM) results in sensorimotor limb deficits, bladder, and bowel dysfunction, but mechanisms underlying motor plasticity changes before and after surgery are unclear. Methods. We studied 24 patients who underwent decompression surgery and 15 healthy controls. Patients with mixed upper and lower limb dysfunction (Group A) and only lower limb dysfunction (Group B) were then analysed separately. Results. The sum amplitude of motor evoked potentials sMEP (p < 0.01) and number of focal points where MEPs were elicited (N) (p < 0.001) were significantly larger in CSM patients compared with controls. For Group A (16 patients), sMEP (p < 0.01) and N (p < 0.001) showed similar findings. However, for Group B (8 patients), only N (p = 0.03) was significantly larger in patients than controls. Group A had significantly increased grip strength (p = 0.02) and reduced sMEP (p = 0.001) and N (p = 0.003) after surgery. Changes in sMEP (cMEP) significantly correlated inversely with improved feeding (p = 0.03) and stacking (p = 0.04) times as was the change in number of focal points (NDiff) with improved writing times (p = 0.03). Group B did not show significant reduction in sMEP or N after surgery, or significant correlation of cMEP or NDiff with all hand function tests. No significant differences in H reflex parameters obtained from the flexor carpi radialis, or central motor conduction time changes, were noted after surgery. Discussion. Compensatory expansion of motor cortical representation occurs largely at cortical rather than spinal levels, with a tendency to normalization after surgery. These mirrored improvements in relevant tasks requiring utilization of intrinsic hand muscles.