Concussed patients with visually induced dizziness exhibit increased ocular torsion and vertical vergence during optokinetic gaze-stabilization.

Visually Induced Dizziness (VID) is a common post-concussion sequalae that remains poorly understood and difficult to quantify. The present study aims to identify biomarkers for VID in the form of gaze-stabilizing eye movements. Nine patients with post-commotio VID and nine age-matched healthy controls were recruited by physiotherapists at a local neurorehabilitation centre. Torsional and vergence eye movements were recorded while participants viewed a series of optokinetic rotations where the central- and peripheral regions moved coherently, incoherently, or semi-randomly. Results showed that vergence and torsional velocities were increased in VID patients, reflecting increased oculomotor gain to visual motion, and that responses correlated with symptom severity. Coherent stimulation produced fastest torsional slow-phases across all participants; when faced with confliction directional information, eye movements tended to follow the direction of the central visual field, albeit at slower velocities than during coherent motion, meaning that while torsion was sensitive to visual content of the entire visual field it expressed directional preference to the central stimulation. In conclusion, post-commotio VID was associated with faster slow-phases during optokinetic gaze-stabilization, with both vergence and torsion being correlated to symptom intensity. As torsional tracking remains inaccessible using commercial eye-trackers, vertical vergence may prove particularly accessible for clinical utility.

Visual influence on the slow oscillatory eye movement discovered during a visual fixation task.

A slow oscillatory movement (SOM) has previously been discovered superimposed on the three well known components of fixational eye movements. The purpose of the present study was to explore the visual influence on the control mechanism of the SOM. Three tests with different fixation targets and backgrounds were prepared. The eye position during a fixation task on healthy test subjects has been recorded by the Chronos eye tracking device. The visual stimuli with no or less information triggered larger SOM amplitudes. None of the investigated conditions significantly influenced on SOM frequency.

Slow oscillatory eye movement during visual fixation.

A slow oscillatory eye movement was discovered in a 20-min-long recording. The frequency of this slow oscillation was lower than any known eye movement. Fixational eye movements were recorded in seven healthy subjects with four different recording techniques and with different sampling frequencies. The frequency of the oscillation is 0.04-0.10 Hz, and the amplitude is less than 0.2°. Right and left eyes oscillate conjugately in the vertical direction implying a neural control. We suggest the oscillation to be a fourth movement in the fixational eye movement system. The influence of the oscillation on visual function is not known nor the underlying mechanism controlling the eye movement.

Different underlying neurocognitive deficits in developmental dyslexia: a comparative study.

The aim of this study was to investigate the role of several specific neurocognitive functions in developmental dyslexia (DD). The performances of 60 dyslexic children and 65 age-matched normally reading children were compared on tests of phonological abilities, visual processing, selective and sustained attention, implicit learning, and executive functions. Results documented deficits in dyslexics on both phonological and non-phonological tasks. More stringently, in dyslexic children individual differences in non-phonological abilities accounted for 23.3% of unique variance in word reading and for 19.3% in non-word reading after controlling for age, IQ and phonological skills. These findings are in accordance with the hypothesis that DD is a multifactorial deficit and suggest that neurocognitive developmental dysfunctions in DD may not be limited to the linguistic brain area, but may involve a more multifocal cortical system.

[The influence of professional values in the emergence of work stress and burn-out in newly graduated nurses]. / L'influenza dei valori professionali nell'emergere dello stress lavorativo e del burn-out negli infermieri neolaureati.

The aim of this study is to evaluate the work importance values in nurse population in their first years of employment to analyse if they could change and if they could be considered as predictors of job stress and burn-out which developed during this period. A group of nurses has been analysed at the beginning of their employment and during the first three years concerning the work importance values measured with the Scala dei Valori Professionali (SVP), the job stress factors evaluated with the Job Content Questionnaire (JCQ) and the burn-out measured with Maslach Burn-out Inventory MBI. The work importance values has changed during the first three years of employment. Although also the job situation has changed during this period increasing the stress, these changes are not related to a particular configuration of the work importance values. Nevertheless, the work importance scale has found to be related to a specific burn-out scale, that is emotional exhaustion. In details, the importance given to career development is related to an increase of emotional exhaustion while the importance given to social aspects decreases it. These results suggest that the work importance values evaluated at the beginning of the working period could be considered as predictors of specific burn-out aspects such as those related to emotional exhaustion.

Saccadic eye movement velocity measured with the infrared reflection and search coil eye-tracking systems in patients with thyroid-associated ophthalmopathy.

BACKGROUND: Assessment of changes in saccade velocity may be useful in the early detection of thyroid-associated ophthalmopathy (TAO). Two eye-tracking systems were used to measure the velocity of saccadic eye movements in patients with TAO. METHOD: Fourteen patients with active TAO and 14 healthy controls were enrolled for recordings with two eye-tracking systems: the magnetic scleral search coil (MSC; Skalar Medical) and the infrared reflection systems (IR; Orbit XY-1000). The MSC is generally considered the "gold standard" method for tracking of rapid eye movements. The IR system uses novel computer technology and is based on sampling of reflected infrared light from the surface of the eyes. Main sequence plots constructed from the recorded saccadic peak velocity and amplitude were analyzed for differences between patients and healthy controls. RESULTS: There were no significant differences between patients with TAO and healthy controls in the constructed main sequence plots of maximum velocity (V(MAX)) and the slope constant (C). CONCLUSIONS: Main sequence analysis of saccadic eye movements was not useful for detecting TAO in this experimental setting with either of the two eye-tracking methods. This is hypothesized to be due to compensation for the early orbital changes in TAO by neural adaptation of the saccades in the brain stem. The contradictory results between this and previous studies cannot be easily explained. We assume that there is a large heterogeneity in the saccadic eye movement performance in both the normal population and the TAO-population. Also, differences in the study design may cause dissimilar outcomes and hence incoherent conclusions. A non-invasive recording system that is able to generate a minimum amount of intra- and inter-individual variability and a study design where normal variability can be reduced to a minimum may be useful for future identification of early eye muscle changes in TAO.

Intra-individual variability of saccadic velocity measured with the infrared reflection and magnetic scleral search coil methods.

BACKGROUND: The infrared (IR) and the magnetic scleral search coil (MSC) systems for eye tracking were studied with regard to the intra-individual variability in saccadic eye movement recordings. METHOD: Three healthy subjects performed similar saccadic eye movement tasks at five different occasions with both the IR (Orbit XY-1000) and the MSC (Skalar Medical) techniques. The maximum velocity (VMAX) and slope constant (C) of the main sequence plots were analyzed with regard to the coefficient of variation (CV) and the intraclass correlation coefficient (Ricc). In addition, the possible reasons for variability in the IR recordings, especially different causes for noise, were analyzed and discussed. RESULTS: The main sequence data showed intra-individual variation with both recording systems, but the coefficient of variation was higher for VMAX with the IR compared to the MSC method. Ricc analysis showed that 36% of the variance of VMAX and 49% of the variance of C resulted from intra-individual variability in recordings of the IR system. The corresponding results for the MSC recordings regarding VMAX and C were 48% and 88%. CONCLUSIONS: Saccadic eye movement recordings yielded a larger intra-individual variability with the IR system than with the MSC system. The effect that the MSC annulus may have on the ocular motor command signal and the possible low pass filter caused by the coil slipping on the surface of the eye may partly explain the relatively lower velocity in the MSC recordings. Also, noise in the IR recordings induces peaks of eye velocity, which can be reduced considerably by filtering. However, the variability in the recordings, which was larger in the IR than in the MSC recordings, did not seem to be decreased by filtering. The basic level of noise in the recordings was not clearly associated with the amount of reduction of VMAX when the IR recordings were filtered. We suggest that artefacts of the saccadic signal, which can be related to changes in the reflecting surface of the eyes and eyelids, are important factors for explaining the variability and high-velocity peaks in the IR recordings. Lighting conditions was confirmed as a cause for noise, but temperature and air humidity changes in the goggles were not suspected to influence data in the normal experimental setting. Although noise, shortcomings of the recording technique and procedure may offer explanations for the intra-individual variability, the calibration procedure and changes in attention and fatigue of the subject should also be considered.

A comparison between the magnetic scleral search coil and infrared reflection methods for saccadic eye movement analysis.

BACKGROUND: A non-invasive eye tracking system, based on pulsed infrared light (IR), was compared with the magnetic scleral search coil method (MSC) for saccadic eye movement recordings. METHODS: Ten normal subjects performed horizontal and vertical saccades recorded with both methods. Eight recordings were complete and analysed for maximum peak velocity (V(MAX)) and constant (C) of the main sequence curve. RESULTS: The IR recordings showed significantly higher peak velocity values than the MSC system and generally more inter-individual variability. No significant difference regarding peak velocity was detected between abducting and adducting saccades or between upward and downward saccades with either of the systems. Horizontal saccades had higher peak velocities with both techniques. CONCLUSIONS: Comparison of the main sequence plots of the IR and MSC eye tracking techniques reveals that the IR system yields higher values of maximum peak velocity and the constant, the differences being similar for eye movements in different directions. There are various possible explanations for the lower maximum velocity of the MSC recordings, e.g. slipping of the coil annulus on the surface of the eye and a change of the oculomotor command signal induced by wearing the coil. Also, artefacts associated with the IR recording system may cause over-estimations of the saccadic velocity and, furthermore, contribute to the higher variability of the IR recordings.

Visual recognition time in strabismus: small-angle versus large-angle deviation.

PURPOSE: To measure the possible differences in monocular detection time of a threshold visual acuity stimulus (recognition time [RT]) between patients with small-angle and large-angle strabismus. METHODS: Ten patients with free alternating esotropia were tested (10 to 18 years old): five with small-angle esotropia (< or = 7 degrees), five with large-angle esotropia (15 degrees to 20 degrees). Six age-matched normal subjects served as controls. The RT of the threshold stimulus was measured in both eyes sequentially for stimuli presented in the center of a computer monitor (RT 1). Moreover, we measured the time necessary for identifying the same threshold visual acuity stimulus generated on the computer screen in the moment in which fixation is taken up by one eye after occlusion of the second eye (RT 2). Using the same setting, RT was also measured monocularly in all strabismic and normal subjects who were originally looking at a luminous fixation point positioned horizontally at 6.5 and 15 degrees from the center of the monitor (RT 3). RESULTS: The multivariate analysis of variance for repeated measures indicated that there was no statistical difference in RT 1 between groups. The mean RT 2 was significantly longer (p<0.001) in large-angle strabismic eyes when compared with that of normal control eyes. The mean RT 2 in small-angle strabismic eyes did not differ significantly from that of normal eyes. Finally, RT 3 (both at 6.5 degrees and 15 degrees of eccentricity) did not show any significant difference in the three different study groups. CONCLUSIONS: The authors hypothesized that alternating strabismus patients may have a significant advantage in maintaining a small-angle deviation, as a large-angle deviation would require longer RT in the moment the deviated eye takes up fixation. It can be speculated that the extension of re-fixation movement, obviously shorter in small-angle strabismus patients, is the main factor responsible for longer RT occurring in large-angle strabismus patients.

The validity of informant report for grading the severity of Alzheimer's dementia.

The validity of informant-based techniques has been established for the detection of dementia cases by non-pathological individuals, but is still controversial for the assessment of the severity of dementia. This study aimed at ascertaining whether informant-based evaluation (the so-called informant report) of the cognitive and behavioral impairment of a patient is valid for grading the severity of dementia, and consistent with objective assessment of the patient's cognitive and behavioral functioning. We enrolled 96 community-dwelling outpatients and 56 controls assessed at the Geriatric Evaluation Unit of the University of Modena, Italy. All patients scored lower than 27 on the MMSE, and met DSM-IV inclusion criteria for Alzheimer's dementia. Patients and controls were administered the CAMDEX interview, containing a section which collects participant (patient or control) and informant evaluations on dementia-related cognitive and behavioral deficits. The informant report resulted effective at MANOVA for grading the severity of dementia in 4 of its 5 measures (namely, memory, everyday activities, general mental functioning and depressed mood), and was correlated with the scores of several scales of the CAMDEX cognitive section (i.e., CAMCOG). Instead, the participant's (patient or control) report showed a lower capacity for grading dementia, and was poorly correlated with the psychometric outcomes of cognitive functioning. On the whole, the results corroborated the validity of the informant report in the diagnostic work-up for grading dementia, given its sensitivity to the severity of dementia, and its consistency with cognitive psychometric outcomes.

Autonomic reactivity during viewing of an unpleasant film.

The effect of an aversive, high-arousing film on heart rate, respiratory sinus arrhythmia, and electrogastrographic activity (EGG) was investigated. Previous studies have indicated a larger heart-rate deceleration for visual stimuli depicting surgery or blood compared to neutral content, and this phenomenon is similar to the bradycardia observed in animals in response to fear. The heart-rate deceleration is clearly parasympathetically driven, and it is considered a general index of attention. An accurate index of cardiac vagal tone can be obtained by means of quantification of the amplitude of respiratory sinus arrhythmia. The relationship between cardiac vagal tone and EGG is complex, but animal research has shown that suppressing vagal activity dampens gastric motility. We have investigated whether a movie depicting surgery is associated with greater heart-rate deceleration, larger increase in respiratory sinus arrhythmia, and greater increase in EGG activity compared to a neutral movie. In addition, if both respiratory sinus arrhythmia and EGG are indices of vagal tone, a positive correlation between these physiological responses was expected. Analysis indicated an effect of the surgery movie on heart rate and respiratory sinus arrhythmia, but not on EGG activity. Moreover, the expected correlation was not found. Implications for future studies are discussed.

Active processing of declarative knowledge during REM-sleep dreaming.

The ability to process recently acquired knowledge is clearly maintained during sleep. Here we assess whether and how far the sleeper controls this processing (in a non-volitional and non-conscious manner). We posit that during sleep, the cognitive concerns of previous waking may guide access to, and processing of, items of declarative knowledge with which those concerns are associated. In a delayed recall task, before each of three sleep onsets in the same night, 12 subjects heard a different nonsense sentence. When awakened in rapid eye movement (REM) sleep, they were asked to report their dream experience and to recall the last sentence heard. Occurrences of incorporation into dream content were more frequent for this sentence than for the sentences heard before previous sleep onsets, and also more frequent than occurrences of similar contents in reports from a control night. However, the modalities of elaboration of dream contents did not vary. These findings indicate that cognitive concern can affect the accessing of recently acquired declarative knowledge during sleep, but not the modalities by which this is inserted into dream content. They also suggest that cognitive concern may help consolidate knowledge by increasing the likelihood of it being processed during sleep.

Coupled plasma filtration-adsorption in a rabbit model of endotoxic shock.

OBJECTIVE: To test the hypothesis that nonselective adsorption by a hydrophobic resin of cytokines and other proinflammatory mediators could improve 72-hr survival in a rabbit model of endotoxic shock. DESIGN: Prospective, randomized, controlled animal trial. SETTING: Animal care facility at a research institution. SUBJECTS: A total of 109 New Zealand white male rabbits. INTERVENTIONS: Anesthetized rabbits were cannulated with indwelling femoral arterial and venous lines. Septic shock was induced by a single intravenous injection of Escherichia coli lipopolysaccharide. The dose was experimentally assessed in 40 rabbits receiving 1.0, 0.5, 0.1, and 0.05 mg/kg body weight to determine LD80 at 72 hrs. Extracorporeal circulation consisted of plasma filtration coupled with passage of the plasma filtrate through a hydrophobic sorbent and reinfusion into the venous line. The extracorporeal treatment lasted for 3 hrs. Rabbits injected with endotoxin (0.05 mg/kg) were submitted to plasma filtration with (19 rabbits) or without (20 rabbits) sorbent adsorption. As controls, rabbits injected with vehicle alone were treated with plasma filtration (ten rabbits) or without (ten rabbits) sorbent adsorption. Ten rabbits were monitored under anesthesia to determine basal survival. MEASUREMENTS AND MAIN RESULTS: Plasma concentrations of endotoxin, bioactive tumor necrosis factor, resin-adsorbed platelet-activating factor, mean arterial pressure, base excess, and white cell count were assessed and a global severity score was established. At 72 hrs, cumulative survival was significantly (p = .0041) improved in septic rabbits treated with coupled plasma filtration-adsorption. Circulating tumor necrosis factor bioactivity remained similar in control and treated rabbits. Biologically significant amounts of platelet activating factor were eluted from the sorbent during the entire treatment time. The severity score inversely correlated with survival (p < .001). CONCLUSIONS: Coupled plasma filtration-adsorption improved survival in a rabbit model of endotoxic shock. Coupled plasma filtration-adsorption may be an extracorporeal treatment capable of removing structurally different inflammatory mediators associated with sepsis.

Assessing behavioural and cognitive impairment in dementia using an informant's report: evidence from the CAMDEX interview.

The consistency of measures from informants' report and from objective testing, both incorporated into the CAMDEX interview, was tested for elderly persons with mild dementia (n = 46), with moderate dementia (n = 41), and without cognitive impairment (controls, n = 56). Informants' reports permitted grading severity of dementia and provided measures of memory and mental functioning in everyday activities highly related to indices derived from objective testing.

Story-like organization of dream experience in different periods of REM sleep.

Four dream reports, collected from each of 16 subjects in an experimental night, were analysed using the criteria of Mandler and Johnson's story grammar. The experimental night was the first of the four nights where subjects had spontaneously given a dream report after each of the four awakenings planned in REM sleep. A multivariate analysis of covariance, taking the order of the nights where the experimental night occurred and the order of reports as factors, the number of stories per report as covariate and the number of statements in the setting, the number of statements in the event structure and number of episodes per story as dependent variables, showed that the greater length and complexity of reports collected in the second half of the night depends on a greater effectiveness of the dream production system rather than on a greater accuracy of recall. This increase concerns the organization of individual stories rather than the number of stories developed in a given time. These findings raise the issue of how dream production is re-triggered during REM sleep. To cast light on this issue, it seems important to establish whether and how the themes of the various stories developed in a given dream experience are interrelated.

Acetate-free biofiltration versus bicarbonate haemodialysis in the treatment of patients with diabetic nephropathy: a cross-over multicentric study.

BACKGROUND: Morbidity and mortality rates in diabetic patients on regular dialysis treatment (RDT) are higher than in non-diabetic-subjects on RDT. Moreover, diabetic patients experience an intradialitic morbidity unacceptably higher than in patients with other causes of terminal renal failure. The aim of the present investigation was to compare standard bicarbonate haemodialysis (BHD) with acetate-free biofiltration (AFB) in a group of 41 diabetic patients stable on dialysis treatment for 25 +/- 22 months. METHODS: Twenty-four type II and 17 type I diabetic patients, all requiring insulin therapy, were included and were followed for 1 year in a 6-month cross-over randomized study for both methods. The analysis was carried out on dialysis symptoms, interdialysis symptoms, and nutritional status, and the multivariate analysis of variance for repeated measures on the same subjects in the two techniques was used. RESULTS: AFB significantly reduced dialytic and extradialytic symptoms (P=0.003 and 0.001 respectively). Cardiovascular collapses decreased by 43%, and other dialysis symptoms showed a similar trend (-35%). The interdialysis symptoms decreased by 28% and were accompanied by an increase in subjective wellbeing (39%) when patients were switched from traditional haemodialysis to AFB. Acid base control was better with AFB (P=0.01), both at the beginning and during the session. Slightly significant differences were also obtained for Kt/V (AFB 1.48 +/- 0.29 vs BHD 1.38 +/- 0.30), while no significant difference was noted with respect to sodium mass balance, nutritional status, calorie-protein intake, nPCR, blood glucose profile, and insulin requirements. The number of hospital admissions and the mortality rate, which were much lower during the AFB than the BHD period, were not analysed statistically. CONCLUSIONS: AFB allows better control of some metabolic aspects, reduces intra- and extradialysis symptoms, and improves patient quality of life. Whether the long-term prognosis can be improved by AFB remains to be established with further studies.

The validity of informant reports in assessing the severity of dementia: evidence from the CAMDEX interview.

The evaluation of a patient's mental state, overall clinical profile and behavioural disturbance in the process of diagnosing dementia requires at least two sources of information: the patient and the informant. Since the severity of the dementia may interfere with the subjective perception of these disorders, it is important to evaluate the consistency between these two sources of information and the clinical and psychometric evaluation made by the physician. Accordingly, in this study five behavioural areas, derived from the semi-structured interview schedule provided by the Cambridge Examination for Mental Disorders of the Elderly (CAMDEX, i.e., Sleep, Depressed Mood, Everyday Activity, Memory and Global Mental Functioning) have been tested on the patient and his/her informant. Eighty dementia patients (mean age = 74 years) and their informants participated in the study. The dementia group was subdivided into two levels of severity according to DSM-IIIR criteria: 41 with mild dementia and 39 with moderate dementia, respectively, matched for age and schooling. The rating of impairment was found to increase along with the severity of dementia in all the above-mentioned areas, except for sleep. However, the source of information per se significantly influenced the evaluation of memory functioning. Moreover, the significant interaction between the two factors considered indicates that memory functioning is evaluated quite differently by the patients and the informants, as only in the assessment made by the latter group did the impairment increase in parallel with severity of dementia. Finally, whereas none of the subjective measures recorded in the patients were significantly correlated with their test scores, the correlations between the informant memory appraisals and patient test results proved to be significant. The present findings confirm the validity of informant reports in assessing cognitive and memory disorders in early-stage dementia, as well as in distinguishing patients with mild from those with moderate dementia.

Binocular vertical perceptual adaptation in essential infantile esotropia.

This study assessed whether dissociated vertical deviation, corresponding to an occasional elevation of the deviated eye, is accompanied by a binocular vertical perceptual adaptation. Dissociated vertical deviation was elicited by means of neutral filters in 16 patients, 8 who had undergone operations for the disorder of essential infantile esotropia and 8 who had not. Neutral filters elicited dissociation vertical deviation, which was accompanied by binocular vertical perceptual adaptation. This effect was significantly greater for patients who had operations and was enhanced by the filter density. Surgical elimination of inhibitory mechanisms for dissociated vertical deviation in patients with essential infantile esotropia appears to facilitate a loose sensory adaptation, which permits a binocular vertical perceptual adaptation.

Four diopters prism test recording in small angle esotropia: a quantitative study using a magnetic search coil.

PURPOSE: To determine the vergence response, if any, in a homogenous group of patients suffering from strabismus and submitted to environmental induction of retinal disparity with respect to a control group of subjects. MATERIALS AND METHODS: A series of 13 subjects was included in the present study (5 normal subjects and 8 patients suffering from small angle esotropia). The patients were evaluated in an illuminated environment where they were told to stare at a target which subtended a visual angle of 20 degrees and, successively, in the dark using a luminous stimulus which subtended a visual angle of 3.5 minutes. The vergence movements were evaluated using a four diopter base-out prism; eye movements were recorded under conditions of both binocular and monocular vision. Ocular movements were recorded by means of a magnetic search coil; the amplitude and peak velocity of the vergence movements were evaluated by computer analysis. Statistical analysis was performed using the Multiple Anova test for repeated measures. RESULTS: The data obtained in the present study demonstrate that: 1) there is a significant difference between binocular and monocular vision in both groups of subjects; however, the ocular response in the patients affected by strabismus was significantly different from that in the control group of subjects; 2) during monocular vision in the dark, the response of the strabismic patients was highly variable; 3) for both groups of subjects no significant differences were observed in the vergence response when a large-angle stimulus was employed in light conditions nor when a small-angle stimulus was utilized in a dark environment.