Health effects related to exposure of static magnetic fields and acoustic noise-comparison between MR and CT radiographers.

OBJECTIVES: We explored the prevalence of health complaints subjectively associated with static magnetic field (SMF) and acoustic noise exposure among MR radiographers in Sweden, using CT radiographers as a control group. Additionally, we explored radiographers' use of strategies to mitigate adverse health effects. METHODS: A cross-sectional survey was sent to all hospitals with MR units in Sweden. MR and/or CT personnel reported prevalence and attribution of symptoms (vertigo/dizziness, nausea, metallic taste, illusion of movement, ringing sensations/tinnitus, headache, unusual drowsiness/tiredness, forgetfulness, difficulties concentrating, and difficulties sleeping) within the last year. We used logistic regression to test associations between sex, age, stress, SMF strength, working hours, and symptom prevalence. Data regarding hearing function, work-environmental noise, and strategies to mitigate adverse symptoms were also analysed. RESULTS: In total, 529 out of 546 respondents from 86 hospitals were eligible for participation. A ≥ 20 working hours/week/modality cut-off rendered 342 participants grouped into CT (n = 75), MR (n = 121), or mixed personnel (n = 146). No significant differences in symptom prevalence were seen between groups. Working at ≥ 3T increased SMF-associated symptoms as compared with working at ≤ 1.5T (OR: 2.03, CI95: 1.05-3.93). Stress was a significant confounder. Work-related noise was rated as more troublesome by CT than MR personnel (p < 0.01). MR personnel tended to use more strategies to mitigate adverse symptoms. CONCLUSION: No significant differences in symptom prevalence were seen between MR and CT radiographers. However, working at 3T increased the risk of SMF symptoms, and stress increased adverse health effects. Noise nuisance was considered more problematic by CT than MR personnel. KEY POINTS: • No significant differences in symptom prevalence were seen between MR and CT radiographers. • Working at ≥ 3 T doubled the odds of experiencing SMF symptoms (vertigo/dizziness, nausea, metallic taste, and/or illusion of movement) as compared to working exclusively at ≤ 1.5 T. • Work-related acoustic noise was less well mitigated and was rated as more troublesome by CT personnel than by MR personnel.

Room tilt illusion and subclavian steal - a case report.

BACKGROUND: Room tilt illusion (RTI) is a rare symptom of higher vestibular dysfunction, consisting of a transient vertical rotation of the visual scene in the sagittal or coronal plane, most often 90o or 180o, without any alteration in shape, size and color of objects. CASE PRESENTATION: A 63-year-old woman with a history of hypertension and chronic obstructive pulmonary disease went through an uncomplicated aortobifemoral graft surgery due to aortoiliac occlusive disease. Post-operatively she experienced five episodes, lasting from 10 to 30 min, with RTI; 90o forward rotation of the visual scene in the sagittal plane. Work-up revealed subclavian steal grade 3, and transient ischemia of the central vestibular system of the brainstem was the presumed mechanism. CONCLUSION: The course of episodic RTIs is often benign, but RTI may represent ischemia in the posterior cerebral circulation. Both stroke and otoneurologic workup are recommended. To our knowledge, this is the first case of RTI associated with subclavian steal reported.

Visual hallucinations and illusions in Parkinson's disease: the role of ocular pathology.

INTRODUCTION: Whether different mechanisms, particularly ocular pathology, could lead to the emergence of visual hallucinations (VH) (defined as false perceptions with no external stimulus) versus visual illusions (VI) (defined as a misperception of a real stimulus) in Parkinson's disease (PD) remains debated. We assessed retinal, clinical and structural brain characteristics depending on the presence of VH or VI in PD. METHODS: In this case-control study, we compared retinal thickness using optical coherence tomography (OCT), between PD patients with: VI (PD-I; n = 26), VH (PD-H; n = 28), and without VI or VH (PD-C; n = 28), and assessed demographic data, disease severity, treatment, anatomical and functional visual complaints, cognitive and visuo-perceptive functions and MRI brain volumetry for each group of PD patients. RESULTS: Parafoveal retina was thinner in PD-H compared to PD-C (p = 0.005) and PD-I (p = 0.009) but did not differ between PD-I and PD-C (p = 0.85). Multivariate analysis showed that 1/retinal parafoveal thinning and total brain gray matter atrophy were independently associated with the presence of VH compared to PD-I; 2/retinal parafoveal thickness, PD duration, sleep quality impairment and total brain gray matter volume were independent factors associated with the presence of VH compared to PD-C; 3/anterior ocular abnormalities were the only factor independently associated with the presence of illusions compared to PD-C. CONCLUSION: These findings reinforce the hypothesis that there may be different mechanisms contributing to VH and VI in PD, suggesting that these two entities may also have a different prognosis rather than simply lying along a continuous spectrum. REGISTRATION NUMBER: Clinicaltrials.gov number NCT01114321.

A standardized, incremental protocol to increase human tolerance to the cross-coupled illusion.

BACKGROUND: Humans can adapt to the "Coriolis" cross-coupled illusion with repeated exposure, improving the tolerability of faster spin rates and enabling short-radius, intermittent centrifugation for artificial gravity implementation. OBJECTIVE: This investigation assesses the criticality of personalization in acclimation to the cross-coupled illusion. METHODS: We used the median stimulus sequence of our previous effective and tolerable personalized, threshold-based protocol to develop a standardized (non-personalized) approach. During each of 10, 25-minute sessions, the spin rate was incremented independent of whether each subject reported experiencing the cross-coupled illusion. RESULTS: In comparison to the previous personalized protocol, the standardized protocol resulted in significantly reduced acclimation to the cross-coupled illusion (17.7 RPM threshold for the personalized protocol versus 11.8 RPM threshold for the standardized) and generally increased motion sickness reports (average reporting of 1.08/20 (personalized) versus 1.98/20 (standardized)), on average. However, the lack of individualization also leads to significantly less variance in subjects' acclimation. CONCLUSIONS: These findings are critical for future missions that may require several astronauts to be acclimated concurrently, due to resource and time constraints. Assessing feasibility of fast spin rate, short-radius centrifugation is crucial for the future of artificial gravity implementation during spaceflight.

Diplopia in Parkinson's disease: visual illusion or oculomotor impairment?

INTRODUCTION: Approximately 20% of patients with Parkinson's disease (PD) experience diplopia; however, the cause of the diplopia is unclear. We aimed to explore the association of diplopia, and its subtypes, with oculomotor abnormalities, impaired vision, and visual hallucinations, in patients with PD. METHODS: This exploratory study included 41 PD patients, recruited from two general hospitals, of whom 25 had diplopia and 16 did not have diplopia, as well as 23 healthy controls (HCs). We defined subtypes of diplopia as selective diplopia, i.e., diplopia of single objects, and complete diplopia, i.e., diplopia of the entire visual field. All participants underwent a full orthoptic and ophthalmologic examination. RESULTS: PD patients with diplopia had a high prevalence of oculomotor abnormalities (84%), impaired vision (44%), and visual hallucinations (44%), compared to PD patients without diplopia (33%, 6%, and none, respectively, p < 0.01), and compared to HCs (23%, 9%, and none, respectively, p < 0.01). Oculomotor abnormalities were equally prevalent in both subtypes of diplopia (selective and complete), whereas impaired vision was predominantly found in patients with selective diplopia. Moreover, only patients with selective diplopia had visual hallucinations. CONCLUSIONS: In PD patients, diplopia may be indicative of oculomotor or visual impairments. Hence, it is worthwhile to refer PD patients with diplopia to an orthoptist and an ophthalmologist for evaluation and, possibly, treatment of diplopia. Furthermore, in the case of selective diplopia, the neurologist should consider the presence of visual hallucinations, which may require the adjustment of the patient's medication.

No evidence for abnormal priors in early vision in schizophrenia.

The predictive coding account of psychosis postulates the abnormal formation of prior beliefs in schizophrenia, resulting in psychotic symptoms. One domain in which priors play a crucial role is visual perception. For instance, our perception of brightness, line length, and motion direction are not merely based on a veridical extraction of sensory input but are also determined by expectation (or prior) of the stimulus. Formation of such priors is thought to be governed by the statistical regularities within natural scenes. Recently, the use of such priors has been attributed to a specific set of well-documented visual illusions, supporting the idea that perception is biased toward what is statistically more probable within the environment. The Predictive Coding account of psychosis proposes that patients form abnormal representations of statistical regularities in natural scenes, leading to altered perceptual experiences. Here we use classical vision experiments involving a specific set of visual illusions to directly test this hypothesis. We find that perceptual judgments for both patients and control participants are biased in accordance with reported probability distributions of natural scenes. Thus, despite there being a suggested link between visual abnormalities and psychotic symptoms in schizophrenia, our results provide no support for the notion that altered formation of priors is a general feature of the disorder. These data call for a refinement in the predictions of quantitative models of psychosis.

Visual motion processing in migraine: Enhanced motion after-effects are related to display contrast, visual symptoms, visual triggers and attack frequency.

Background Visual after-effects are illusions that occur after prolonged viewing of visual displays. The motion after-effect (MAE), for example, is an illusory impression of motion after viewing moving displays: subsequently, stationary displays appear to drift in the opposite direction. After-effects have been used extensively in basic vision research and in clinical settings, and are enhanced in migraine. Objective The objective of this article is to assess associations between ( 1 ) MAE duration and visual symptoms experienced during/between migraine/headache attacks, and ( 2 ) visual stimuli reported as migraine/headache triggers. Methods The MAE was elicited after viewing motion for 45 seconds. MAE duration was tested for three test contrast displays (high, medium, low). Participants also completed a headache questionnaire that included migraine/headache triggers. Results For each test contrast, the MAE was prolonged in migraine. MAE duration was associated with photophobia; visual triggers (flicker, striped patterns); and migraine or headache frequency. Conclusions Group differences on various visual tasks have been attributed to abnormal cortical processing in migraine, such as hyperexcitability, heightened responsiveness and/or a lack of intra-cortical inhibition. The results are not consistent with hyperexcitability simply from a general lack of inhibition. Alternative multi-stage models are discussed and suggestions for further research are recommended, including visual tests in clinical assessments/clinical trials.

A New Symptom, 'Palinendophonia', Associated with Pure Verbal Palinacousis Induced by a Right Inferior Temporal Lesion.

We describe the case of a patient with pure verbal palinacousis and perseveration of inner speech after a right inferior temporal lesion. The superior temporal lobe, including the superior temporal sulcus and the interhemispheric connection between the 2 superior temporal lobes, explored by tractography, were preserved. These regions are involved in voice processing, verbal short-term memory and inner speech. It can then be hypothesised that abnormal activity in this network has occurred. Palinacousis and 'palinendophonia', a term proposed for this symptom not previously reported, may be due to common cognitive processes disorders involved in both voice hearing and inner speech.

The rubber foot illusion.

BACKGROUND: Lower-limb amputation causes the individual a huge functional impairment due to the lack of adequate sensory perception from the missing limb. The development of an augmenting sensory feedback device able to restore some of the missing information from the amputated limb may improve embodiment, control and acceptability of the prosthesis. FINDINGS: In this work we transferred the Rubber Hand Illusion paradigm to the lower limb. We investigated the possibility of promoting body ownership of a fake foot, in a series of experiments fashioned after the RHI using matched or mismatched (vibrotactile) stimulation. The results, collected from 19 healthy subjects, demonstrated that it is possible to elicit the perception of possessing a rubber foot when modality-matched stimulations are provided synchronously on the biological foot and to the corresponding rubber foot areas. Results also proved that it is possible to enhance the illusion even with modality-mismatched stimulation, even though illusion was lower than in case of modality-matched stimulation. CONCLUSIONS: We demonstrated the possibility of promoting a Rubber Foot Illusion with both matched and mismatched stimulation.

PSYCHOTIC DISORDERS GENERATED BY AUTOIMMUNE ENCEPHALITIS (CLINICAL CASE).

Encephalitis is a brain inflammation, which could involve also the meninges. The etiology of encephalitis could be: viral, bacterial, fungal or autoimmune. Anti-NMDAR encephalitis is an immune disorder, easy to diagnose and is a treatable condition. Most patients with anti-NMDAR encephalitis develop a multistage illness that progresses from psychosis, memory deficits, seizures, to catatonic state and breathing instability. We present a case report of a 20-year old woman, who presented: amnesia, visual hallucination, illusions, seizures after that occurred following autoimmune encephalitis. The exact incidence of anti-NMDAR encephalitis is unknown, but it seems to be more frequent than any other known paraneoplastic encephalitis. The present case is important considering that autoimmune encephalitis is a rare frequency disorder in Romania, with patients presenting resounding psychiatric and neurological manifestations.

On the vertigo due to static magnetic fields.

Vertigo is sometimes experienced in and around MRI scanners. Mechanisms involving stimulation of the vestibular system by movement in magnetic fields or magnetic field spatial gradients have been proposed. However, it was recently shown that vestibular-dependent ocular nystagmus is evoked when stationary in homogenous static magnetic fields. The proposed mechanism involves Lorentz forces acting on endolymph to deflect semicircular canal (SCC) cupulae. To investigate whether vertigo arises from a similar mechanism we recorded qualitative and quantitative aspects of vertigo and 2D eye movements from supine healthy adults (n = 25) deprived of vision while pushed into the 7T static field of an MRI scanner. Exposures were variable and included up to 135s stationary at 7T. Nystagmus was mainly horizontal, persisted during long-exposures with partial decline, and reversed upon withdrawal. The dominant vertiginous perception with the head facing up was rotation in the horizontal plane (85% incidence) with a consistent direction across participants. With the head turned 90 degrees in yaw the perception did not transform into equivalent vertical plane rotation, indicating a context-dependency of the perception. During long exposures, illusory rotation lasted on average 50 s, including 42 s whilst stationary at 7T. Upon withdrawal, perception re-emerged and reversed, lasting on average 30 s. Onset fields for nystagmus and perception were significantly correlated (p<.05). Although perception did not persist as long as nystagmus, this is a known feature of continuous SSC stimulation. These observations, and others in the paper, are compatible with magnetic-field evoked-vertigo and nystagmus sharing a common mechanism. With this interpretation, response decay and reversal upon withdrawal from the field, are due to adaptation to continuous vestibular input. Although the study does not entirely exclude the possibility of mechanisms involving transient vestibular stimulation during movement in and out of the bore, we argue these are less likely.

[Difficult road to diagnosing dementia with lewy bodies (DLB). case report]. / Trudna droga do rozpoznania otepienia z cialami Lewy'ego. opis przypadku.

AIM: The main aim of the study was to present the case of a patient with neurological, depressive and psychotic symptoms, most probably connected with progressing dementia with Lewy bodies (DLB). METHOD: The systematic symptom analysis based on the clinical examination and medical documentation. RESULTS: During the first hospitalisation, the presented patient was diagnosed with acute and transient psychotic disorders (F23). After being discharged from the ward, the patient experienced recurrence of previous symptoms with a short period of time. The two following diagnoses after hospital treatment were established as a depressive episode with psychotic symptoms. During the fourth hospitalisation, the patient was diagnosed with organic delusional (schizophrenia-like) disorder (F06.2). After six years, thorough analysis of clinical history as well as the course of existing disorder made it possible to diagnose the patient as having dementia with Lewy bodies-DLB (F02.8). Since that time, the patient has been taking rivastigmine, which has turned out to be a successful treatment. It has been 6 months since the patient left the hospital and still remains in remission. Social functioning of the woman is similar to the period before the first episode. CONCLUSIONS: The presented case demonstrates, that DLB symptomatology is a difficult problem in everyday psychiatric practice. A differential diagnosis of psychopathological and neurological symptoms covers many disorders, which together, with the clinical picture variation may delay effective treatment.

Distinct illusory own-body perceptions caused by damage to posterior insula and extrastriate cortex.

Recent research in cognitive neuroscience using virtual reality, robotic technology and brain imaging has linked self-consciousness to the processing and integration of multisensory bodily signals. This work on bodily self-consciousness has implicated the temporo-parietal, premotor and extrastriate cortex and partly originated in work on neurological patients with different disorders of bodily self-consciousness. One class of such disorders is autoscopic phenomena, which are defined as illusory own-body perceptions, during which patients experience the visual illusory reduplication of their own body in extrapersonal space. Three main forms of autoscopic phenomena have been defined. During autoscopic hallucinations, a second own body is seen without any changes in bodily self-consciousness. During out-of-body experiences, the second own body is seen from an elevated perspective and location associated with disembodiment. During heautoscopy, subjects report strong self-identification with the second own body, often associated with the experience of existing at and perceiving the world from two places at the same time. Although it has been proposed that each autoscopic phenomenon is associated with different impairments of bodily self-consciousness, past research on neurological patients and the development of experimental paradigms for the study of bodily self-consciousness has focused on out-of-body experiences and the association with temporo-parietal cortex. Here, we performed quantitative lesion analysis in the-to date-largest group of patients with autoscopic hallucination and heautoscopy and compared the location of brain damage with those of control patients suffering from complex visual hallucinations. We found that heautoscopy was associated with lesions to the left posterior insula, and that autoscopic hallucinations were associated with damage to the right occipital cortex. Autoscopic hallucination and heautoscopy were further associated with distinct symptoms and deficits. The present data suggest that the autoscopic hallucination is a visuo-somatosensory deficit implicating extrastriate cortex and is, despite the visual hallucination of the own body, not associated with major deficits in bodily self-consciousness. Based on the symptoms and deficits in patients with heautoscopy and the implication of the left posterior insula, we suggest that abnormal bodily self-consciousness during heautoscopy is caused by a breakdown of self-other discrimination regarding affective somatosensory experience due to a disintegration of visuo-somatosensory signals with emotional (and/or interoceptive) bodily signals. These brain mechanisms are distinct from those described for out-of-body experiences. The present data extend previous models of autoscopic phenomena and provide clinical evidence for the importance of emotional and interoceptive signal processing in the posterior insula in relation to bodily self-consciousness.

Positive illusions in adolescents: the relationship between academic self-enhancement and depressive symptomatology.

Positive illusions are systematically inflated self-perceptions of competence, and are frequently seen in areas of great difficulty. Although these illusions have been extensively documented in children and adults, their role in typical adolescent emotion regulation is unclear. This study investigated the relationship between positive illusions, depressive symptomatology, and school stress in a sample of 71 school-based adolescents. Findings revealed that adolescents who were achieving slightly below average in math significantly overestimated their performance, but adolescents did not overestimate their performance in spelling. Positive illusions in math were negatively related to depressive symptomatology. Implications for positive illusions theory are discussed.

Cerebral venous sinus thrombosis presenting with auditory hallucinations and illusions.

OBJECTIVE: Cerebral venous sinus thrombosis may present with seizures or neuropsychiatric symptoms, but does not typically present with hallucinations. We present a case of venous thrombosis of the right sigmoid and transverse sinuses that presented with auditory hallucinations and illusions. METHODS: We describe a 45-year-old woman with a history of myasthenia gravis, stable on oral prednisone and monthly intravenous immunoglobulin infusions, who started on a progesterone/estrogen combination contraceptive pill for menorrhagia 3 weeks before admission and presented with symptoms of headache, fever, and auditory hallucinations and illusions. RESULTS: The patient's cerebrospinal fluid showed lymphocytic pleocytosis. Two electroencephalograms showed significant right temporal lobe slowing. Magnetic resonance venogram of the brain showed venous sinus thrombosis of the right sigmoid and transverse sinuses. Magnetic resonance imaging showed a cortical venous infarct in the right middle temporal gyrus. The patient's auditory hallucinations and illusions resolved spontaneously weeks after presentation. CONCLUSIONS: This case suggests that auditory hallucinations and illusions should be added to the already broad spectrum of presenting features of cerebral venous sinus thrombosis. The nondominant right middle temporal gyrus may play a role in such auditory hallucinations.

Multisensory stimulation can induce an illusion of larger belly size in immersive virtual reality.

BACKGROUND: Body change illusions have been of great interest in recent years for the understanding of how the brain represents the body. Appropriate multisensory stimulation can induce an illusion of ownership over a rubber or virtual arm, simple types of out-of-the-body experiences, and even ownership with respect to an alternate whole body. Here we use immersive virtual reality to investigate whether the illusion of a dramatic increase in belly size can be induced in males through (a) first person perspective position (b) synchronous visual-motor correlation between real and virtual arm movements, and (c) self-induced synchronous visual-tactile stimulation in the stomach area. METHODOLOGY: Twenty two participants entered into a virtual reality (VR) delivered through a stereo head-tracked wide field-of-view head-mounted display. They saw from a first person perspective a virtual body substituting their own that had an inflated belly. For four minutes they repeatedly prodded their real belly with a rod that had a virtual counterpart that they saw in the VR. There was a synchronous condition where their prodding movements were synchronous with what they felt and saw and an asynchronous condition where this was not the case. The experiment was repeated twice for each participant in counter-balanced order. Responses were measured by questionnaire, and also a comparison of before and after self-estimates of belly size produced by direct visual manipulation of the virtual body seen from the first person perspective. CONCLUSIONS: The results show that first person perspective of a virtual body that substitutes for the own body in virtual reality, together with synchronous multisensory stimulation can temporarily produce changes in body representation towards the larger belly size. This was demonstrated by (a) questionnaire results, (b) the difference between the self-estimated belly size, judged from a first person perspective, after and before the experimental manipulation, and (c) significant positive correlations between these two measures. We discuss this result in the general context of body ownership illusions, and suggest applications including treatment for body size distortion illnesses.