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The objective of the current study was to develop a computer-controlled mechanical system for the generation of impulsive head rotations to measure eye movements induced by angular horizontal vestibulo-ocular reflex. This is a clinical eye movement test recently introduced for the usage of otoneurological balance laboratories. We built the system and modified our prior computer software developed for other types of eye movement tests. Motor controlled stimulation has fulfilled the requirement of more uniform and constant acceleration stimulation than obtained with manually administrated impulses. After having executed preliminary experiments at our balance laboratory we found the system to be efficient, reliable and secure. [ABSTRACT FROM AUTHOR]

Influence of two filtering modes were researched with electro-oculographically recorded impulse-like eye movements. Linear finite impulse response (FIR) and non-linear hybrid median filters were explored by considering gain and latency parameters that yield the most important information in the case of these eye movements. It is stated that carefully selected lowpass filtering can securely be run without considerable changes in parameter values in order to discard noise stemming from physiological or other reasons. [ABSTRACT FROM AUTHOR]

Military personnel needs to be resilient to be able to remain effective, motivated, and in good mental and physical health. Military organizations select on resilience to determine whether candidates are psychologically fit for their job. The INSPIRE Resilience Scale (IRS) is such a selection instrument that aims to assess the psychological resilience potential of candidates in high-risk professions. A longitudinal predictive validity study was conducted in five European Defense organizations and in the Dutch National Police. The IRS was submitted in selection (N = 11,404), and criterion data about performance and health were collected in the second half of the first training year (N = 726). The results based on correlational and regression analyses showed that the IRS scores significantly predicted the criterion measures. Emotional stability, part of the IRS, turned out to be the best predictor. Results also showed that candidates who dropped out of training had significantly lower means on the IRS in selection than candidates who were still in training in the second half of the first training year. Overall, the IRS proved to be a valid instrument to assess resilience potential in candidates for high-risk professions. Selecting on resilience may therefore contribute to training success and reduction of health problems.

Molecular imaging is the future of personalized medicine; however, it requires effective contrast agents. Hyperpolarized chemical exchange saturation transfer (HyperCEST) can boost the signal of Hyperpolarized 129 Xe MRI and render it a molecular imaging modality of high efficiency. Cucurbit[6]uril (CB6) has been successfully employed in vivo as a contrast agent for HyperCEST MRI, however its performance in a clinical MRI scanner has yet to be optimized. In this study, MRI pulse sequence parameter optimization was first performed in CB6 solutions in phosphate-buffered saline (PBS), and subsequently in whole sterile citrated bovine blood. The performance of four different depolarization pulse shapes (sinusoidal, 3-lobe sinc (3LS), rectangular (block), and hyperbolic secant (hypsec) was optimized. The detectability limits of CB6 in a clinical 3.0T MRI scanner was assessed using the optimized pulse sequences. The 3LS depolarization pulses performed best, and demonstrated 24 % depletion in a 25 μM solution of CB6 in PBS. It performed similarly in blood. The CB6 detectability limit was found to be 100 μM in citrated bovine blood with a correspondent HyperCEST depletion of 30 % ±9 %. For the first time, the HP 129 Xe HyperCEST effect was observed in red blood cells (RBC) and had a similar strength as HyperCEST in plasma., (© 2023 The Authors. ChemPhysChem published by Wiley-VCH GmbH.)

Hyperpolarized (HP) xenon-129 ( 129 Xe), when dissolved in blood, has two NMR resonances: one in red blood cells (RBC) and one in plasma. The impact of numerous blood components on these resonances, however, has not yet been investigated. This study evaluates the effects of elevated glucose levels on the chemical shift (CS) and T2* relaxation times of HP 129 Xe dissolved in sterile citrated sheep blood for the first time. HP 129 Xe was mixed with sheep blood samples premixed with a stock glucose solution using a liquid-gas exchange module. Magnetic resonance spectroscopy was performed on a 3T clinical MRI scanner using a custom-built quadrature dual-tuned 129 Xe/ 1 H coil. We observed an additional resonance for the RBCs ( 129 Xe-RBC1) for the increased glucose levels. The CS of 129 Xe-RBC1 and 129 Xe-plasma peaks did not change with glucose levels, while the CS of 129 Xe-RBC2 (original RBC resonance) increased linearly at a rate of 0.015 ± 0.002 ppm/mM with glucose level. 129 Xe-RBC1 T2* values increased nonlinearly from 1.58 ± 0.24 ms to 2.67 ± 0.40 ms. As a result of the increased glucose levels in blood samples, the novel additional HP 129 Xe dissolved phase resonance was observed in blood and attributed to the 129 Xe bound to glycated hemoglobin (HbA 1c ).

Objective: To explore clinical features of patients with bilateral vestibular hypofunction (BVH) verified in motorized head impulse test (MHIT)., Materials and Methods: We examined clinical records of 23 adult patients (10 males and 13 females), whose gain of the vestibulo-ocular reflex in the MHIT was bilaterally lowered. Fifteen of 62 unilateral cochlear implant (CI) recipients routinely tested both pre- and postoperatively with the MHIT had BVH. Eight of 198 vestibular outpatients selected to the MHIT due to clinical causes had BVH. Clinical characteristics and a questionnaire regarding current sensations were analyzed., Results: The mean gain±SD in the MHIT was 0.26±0.17 on the right and 0.26±0.14 on the left side. The mean gain in the CI recipients did not differ from that of vestibular outpatients (p>0.05). All outpatients with BVH suffered from oscillopsia, whereas only 46% of CI recipients experienced oscillopsia (p=0.048). Instability was more prominent (p=0.004) and quality of life further decreased (p=0.012) among vestibular outpatients compared with CI patients. Most common etiology for the BVH was meningitis. Other causes were either sudden or progressive loss of labyrinthine function, bilateral Meniére's disease, and ototoxicity., Conclusion: BVH is rare even in a specialized clinic. Vestibular outpatients were more disabled than CI recipients with the BVH.

The study aimed to measure utricular function by directly quantifying head tilt in vestibular schwannoma (VS) patients using regular video-oculography (VOG) equipment with integrated head-position sensor, and to correlate the results with patients' symptoms and signs. We recorded head tilting after exclusion of visual cues (static head tilt), and after returning to the centre following lateral head rolls towards each side [subjective head vertical (SHV)]. Head tilt in 43 patients was measured preoperatively and approximately 4 months postoperatively, and compared to that of 20 healthy subjects. Symptoms were assessed with a structured questionnaire. Static head tilt in patients was significantly greater than in controls (1.0° ± 0.9°) preoperatively (1.6° ± 1.5°, p = 0.04) and postoperatively (1.7° ± 1.5°, p = 0.01). Mean SHV in patients was significantly greater than in controls (1.2° ± 1.0°) preoperatively (2.0° ± 1.9°, p = 0.03) and postoperatively (2.5° ± 1.8°, p = 0.001), increasing non-significantly after surgery (p = 0.3). Side-specific SHV after ipsilateral head rolls was significantly greater than after contralateral head rolls preoperatively (2.8° ± 3.3° vs. -0.5° ± 3.0°, p = 0.001) and postoperatively (3.3° ± 3.0° vs. 0.6° ± 3.2°, p < 0.001). The intensity of dizziness increased postoperatively (p = 0.04), but its effect on quality of life remained unchanged. In conclusion, commercial VOG equipment including a head-position sensor allows direct evaluation of head tilt in VS patients. The slight head tilt towards the ipsilateral side becomes most evident after returning from an ipsilateral head roll.

Central dopamine regulation is involved in postural control and in the pathophysiology of restless legs syndrome (RLS) and Parkinson's disease (PD). Postural control abnormalities have been detected in PD, but there are no earlier studies with regard to RLS and postural control. Computerized force platform posturography was applied to measure the shift and the velocity (CPFV) of center point of forces (CPF) with eyes open (EO) and eyes closed (EC) in controls (n = 12) and prior and after a single day intervention with pramipexole in RLS subjects (n = 12). CPFV (EO) was significantly lower in the RLS group (p < 0.05) than in controls. After pramipexole intake, the difference disappeared and the subjective symptom severity diminished. Pramipexole did not significantly influence CPFV (EC) or CPF shift direction. Subjects with RLS used extensively visual mechanisms to control vestibule-spinal reflexes to improve or compensate the postural stability. Further research is needed to clarify altered feedback in the central nervous system and involvement of dopamine and vision in the postural control in RLS.

Earlier we developed signal analysis for nystagmus measured from otoneurological patients suffering from vertigo and dizziness. It was based on three rotation directions of the eye: horizontal, vertical and torsional. However, nystagmus frequently appears only in two of the former directions. In order to enable two-dimensional analysis approach on the basis of various pairs from the original three, we designed and implemented an advanced method from our earlier one. These signals can be used to investigate and model the dysfunction of semicircular canals in the inner ear. Nystagmus has to be stimulated for healthy subjects, but in patients it can also be spontaneous. The method developed was tested with the signals of 30 otoneurological patients.

Objective: To show that both hearing and vestibular loss can be reversible and quantified in Cogan's syndrome., Patient and Methods: Immunosuppressive medication was continued for more than 6 years in a young woman with Cogan's syndrome. Standard pure tone audiometry (PTA) and speech discrimination score (SDS) for hearing, motorized head impulse test (MHIT) for horizontal, angular vestibulo-ocular reflex, and erythrocyte sedimentation rate were followed serially., Results: The PTA before medication was 59/74 dB, and it stabilized to 13/46 dB in 2 years. The initial SDS of 92/72% improved later to 100/100%, respectively. The gain of the vestibulo-ocular reflex was asymmetric (32%) and decreased to 0.48/0.25 at the beginning. Two years after the treatment, both the asymmetry (7%) and the gain (0.95/0.82) were recovered within normal limits. Erythrocyte sedimentation rate improved from 40 to 5 mm/h., Conclusion: Our case report of Cogan's syndrome demonstrates objective, simultaneous deterioration of hearing and vestibular function, which improved and stabilized after the introduction of immunosuppressive medication. The efficacy of immunosuppressive medication on vestibular function may be followed repetitively using MHIT in patients with Cogan's syndrome.

Conclusion: Vestibular disturbance is frequent, but mild even immediately after stapes surgery. Vestibular symptoms improved or disappeared quickly, and they did not correlate with nystagmus. Outpatient stapes surgery performed under local anaesthesia is a feasible approach., Objective: Vestibular symptoms are common and may prevent outpatient surgery. The time course of vestibular disturbance is unclear, and we aimed to evaluate it immediately after the operation in the recovery room., Methods: Twenty patients with otosclerosis undergoing stapedotomy were prospectively included in the study. Postoperative symptoms were collected and nystagmus was recorded with video-oculography (VOG) on average 29 min after the surgery., Results: None of the patients had spontaneous nystagmus with gaze fixation. Nine patients (45%) had slow spontaneous horizontal nystagmus (mean slow phase velocity of 1.1°/s) in the primary position without gaze fixation. In seven of these, the nystagmus obeyed Alexander's law. Nine patients (45%) had vestibular symptoms at the end of the surgery, and four patients at the time of VOG recording. Vertigo was experienced immediately after the operation in five, floating sensation in two, and unspecific dizziness in two patients. Vestibular symptoms were mild or moderate in most patients. The occurrence of nystagmus did not correlate with vestibular symptoms (p > 0.05).

Analysis of spontaneous nystagmus is important in the evaluation of dizzy patients. The aim was to measure how different visual conditions affect the properties of nystagmus using three-dimensional video-oculography (VOG). We compared prevalence, frequency and slow phase velocity (SPV) of the spontaneous nystagmus with gaze fixation allowed, with Frenzel's glasses, and in total darkness. Twenty-five patients (35 measurements) with the peripheral vestibular pathologies were included. The prevalence of nystagmus with the gaze fixation was 40%, and it increased significantly to 66% with Frenzel's glasses and regular room lights on (p < 0.01). The prevalence increased significantly to 83% when the regular room lights were switched off (p = 0.014), and further to 100% in total darkness (p = 0.025). The mean SPV of nystagmus with visual fixation allowed was 1.0°/s. It increased to 2.4°/s with Frenzel's glasses and room lights on, and additionally to 3.1°/s, when the regular room lights were switched off. The mean SPV in total darkness was 6.9°/s. The difference was highly significant between all test conditions (p < 0.01). The frequency of nystagmus was 0.7 beats/s with gaze fixation, 0.8 beats/s in both the test conditions with Frenzel's glasses on, and 1.2 beats/s in total darkness. The frequency in total darkness was significantly higher (p < 0.05) than with Frenzel's glasses, and more so than with visual fixation (p = 0.003). The VOG in total darkness is superior in detecting nystagmus, since Frenzel's glasses allow visual suppression to happen, and this effect is reinforced with gaze fixation allowed. Strict control of visual surroundings is essential in interpreting peripheral nystagmus.

Conclusion: Decreased horizontal vestibulo-ocular reflex (VOR) gain measured with the motorized head impulse rotator usually recovers at least partially within a few months after sudden unilateral vestibular loss. In addition to traditional evaluation of nystagmus, head impulse test responses provide valuable information on the severity and recovery of vestibular loss., Objectives: To quantify recovery of vestibular function with the motorized head impulse test in patients with acute unilateral peripheral vestibular loss, and to compare these results with other signs and symptoms., Methods: We recorded prospectively the horizontal VOR with the motorized head impulse rotator in 30 patients with sudden unilateral vestibular deficit on average 3 days after the onset (early). Twenty patients were measured sequentially on average 3 months later (late). We calculated VOR gain and asymmetry (mean ± standard deviation)., Results: The early ipsilesional gain of 0.49 ± 0.21 improved highly significantly to the late gain of 0.79 ± 0.23 (p = 0.0000). The respective asymmetry improved highly significantly from 32 ± 18% to 12 ± 14% (p = 0.0002). Gain or asymmetry recovered at least partially in 80% of the patients. The late high symptom score correlated with low gain (p = 0.043) and high asymmetry (p = 0.018).

In this article, the effect of spray solvent on the analysis of selected lipids including fatty acids, fat-soluble vitamins, triacylglycerols, steroids, phospholipids, and sphingolipids has been studied by two different ambient mass spectrometry (MS) methods, desorption electrospray ionization-MS (DESI-MS) and desorption atmospheric pressure photoionization-MS (DAPPI-MS). The ionization of the lipids with DESI and DAPPI was strongly dependent on the spray solvent. In most cases, the lipids were detected as protonated or deprotonated molecules; however, other ions were also formed, such as adduct ions (in DESI), [M-H](+) ions (in DESI and DAPPI), radical ions (in DAPPI), and abundant oxidation products (in DESI and DAPPI). DAPPI provided efficient desorption and ionization for neutral and less polar as well as for ionic lipids but caused extensive fragmentation for larger and more labile compounds because of a thermal desorption process. DESI was more suitable for the analysis of the large and labile lipids, but the ionization efficiency for less polar lipids was poor. Both methods were successfully applied to the direct analysis of lipids from pharmaceutical and food products. Although DESI and DAPPI provide efficient analysis of lipids, the multiple and largely unpredictable ionization reactions may set challenges for routine lipid analysis with these methods., (Copyright © 2012 John Wiley & Sons, Ltd.)

Utricular dysfunction has been indirectly measured with subjective visual horizontal or vertical testing. Video-oculography equipment with integrated head position sensor allows direct evaluation of head tilt. The aim was to assess head tilt after peripheral vestibular lesion by recording tilting of the head after excluding visual cues (static test condition), and after three lateral head tilts to both sides [subjective head vertical (SHV)]. Thirty patients with unilateral, peripheral vestibular loss were measured in the acute state, and 3 months later. Twenty healthy, age- and sex-matched subjects served as controls. Mean static tilt of 2.6 ± 1.1° in patients with acute vestibular loss differed significantly from that of 1.0 ± 0.4° in healthy subjects (p = 0.004), and from that of 1.1 ± 0.5° during the follow-up visit (p = 0.008). The mean SHV of 3.4 ± 0.7° in patients with acute vestibular loss was significantly more than that of 1.2 ± 0.5° in controls (p < 0.001). The SHV towards the lesion was 4.9 ± 1.0° while returning from the lesion side and 2.0 ± 1.0° while returning from the healthy side. The SHV was definitely abnormal in 60%, moderately abnormal in 20% and normal in 20% of the patients in acute state. Abnormal SHV persisted in only 20% of the patients indicating that recovery of the peripheral utricular function is occurring within months. In summary, head tilts slightly towards acute peripheral lesion, and this tilting is reinforced, when the head is actively moved on the lesion side.

Three-dimensional signal analysis can be applied to eye movements called nystagmus in order to study otoneurological patients suffering from vertigo and other balance problems. We developed an analysis and modeling algorithm for three-dimensional nystagmus measured by a video-oculography system. We were also interested in verifying an otoneurological hands-on convention called Ewald's first law in a strict physiological sense in vestibular patients. We recorded nystagmus from 42 patients all suffering from vertigo or dizziness. The underlying pathology was unilateral in 39 patients, bilateral in one patient, and central in two patients. Video-oculography was used to record three-dimensional nystagmus to separately produce horizontal, vertical, and torsional signals for each eye. On the basis of signal analysis techniques and straightforward vector calculus, we were able to recognize slow phases of nystagmus to compute their angular velocities to estimate from which part of the inner ear the disorder originated. We found that for all 42 patients the plane of one of the two horizontal semicircular canals was the closest. We were able to quantitatively estimate the influence of different semicircular canals, and, despite the pathology, horizontal canals seemed to be predominant in driving the nystagmus. The signal analysis and modeling algorithm developed is effective in studying otoneurological problems registered with nystagmus and opens new insights in three-dimensional nystagmography. Our results strongly support Ewald's first law.

Lateralized motor and attentional abnormalities contribute to schizophrenia, but little is known about possible abnormalities in neural machinery involved in postural control. We examined postural stability of 22 patients with schizophrenia taking medication and 14 healthy control participants using computerized force platform posturography. The shift in the center point of pressure in the condition of eyes open versus eyes closed characterizes the effect of visual information on body posture. Closing the eyes had less of an effect on the center point of velocity (velocity sm/s) in the patients with schizophrenia than in the control group (median change, 36% vs. 70%, p = 0.0006). Change in the body position during eye closure tended to be directed rightwards in the control group but leftwards in the group with schizophrenia (p = 0.025). The results show that visual component had less dominance in the balance control of these patients with schizophrenia. The lateralized effect of visual information on posture was also impaired.

Vestibular symptoms are common after stapes surgery and may prevent outpatient treatment. The cause of vestibular symptoms is unclear, and in previous studies objective measurements have been obtained few days after the surgery. The aim of the study was to evaluate the existence and nature of any early, and possibly temporary vestibular irritation that occurs immediately after surgery. Twenty-one patients who had an opening of the oval window were prospectively included. Postoperative symptoms were collected and eye position curves were recorded with video-oculography (VOG) an average of 4 h after surgery. Early vestibular symptoms were found in 11 (52%) patients. Four patients had rotatory vertigo, three had floating sensation, one experienced a tilting sensation, and two had unspecific dizziness. Two patients vomited after surgery. When VOG was performed all but one were free of symptoms. After surgery, spontaneous nystagmus was found in three (14%) asymptomatic patients when gaze fixation was prevented. The prevalence of 33% (7 of 21 patients) of latent, spontaneous, horizontal-torsional nystagmus seen only during lateral gaze towards the direction of fast phase was significantly higher (P = 0.0001) than in healthy controls. The occurrence of nystagmus did not correlate with vestibular symptoms (P = 0.30). Slight, direction-fixed, latent, spontaneous horizontal-torsional nystagmus in some patients is consistent with a minor disturbance of semicircular canals, although it was not related to the sensation of dizziness. Recordings during stapes surgery may be needed to ascertain the origin of vestibular symptoms. Regarding vestibular symptoms and signs, patients may be safely discharged a few hours after stapes surgery.