Diagnostic performance of the "Huffing and Puffing" sign in psychogenic (functional) movement disorders.
ABSTRACT: OBJECTIVE:To determine the diagnostic value of effort-associated behaviors ("huffing and puffing" spectrum) in patients with psychogenic movement disorders. METHODS:Three blinded clinicians rated presence, severity, and duration of effort-associated features during standing and walking tasks on edited videos of 131 patients with psychogenic gait disorders and 37 patients with organic gait disorders. RESULTS:Huffing, grunting, grimacing, and breath holding were the most common effort-associated behaviors in patients with psychogenic gait disorders, with a combined prevalence of 44% and disproportionate to the severity of gait impairment compared to organic gait disorders. The presence of "huffing and puffing"-type behaviors yielded a relatively low sensitivity but high specificity for the diagnosis of psychogenic movement disorders, increasing the odds of diagnosis 13-fold (95%, CI: 4.2-43.8) compared to organic gait disorders. CONCLUSIONS:Demonstration of effort-associated behaviors during standing and walking strongly supports the psychogenic nature of disorders when gait is involved.
Project description:The aim of this article is to point out that an incongruity of gait disorder (either in relation to the presenting movement disorder or incongruity with any type of organic gait disorder) is a useful clue in diagnosing psychogenic movement disorders. To illustrate this, we present a case series of patients with various types of psychogenic movement disorders (rest tremor, myoclonus, dystonia, and chorea). Incongruity of the walking pattern with the presenting movement disorder was a revealing diagnostic clue in all cases. "Incongruity" is currently a main plank in the diagnosis of psychogenic conditions. Our series emphasizes that incongruity of the gait pattern may be the most important sign in a patient where it is otherwise difficult to establish whether the movement disorder is congruous or incongruous with an organic disorder.
Project description:Objectives:The aim of this study was to examine puffing behavior and topography over 24 hours among regular electronic cigarette (e-cigarette) users. Methods:Twenty-four adult e-cigarette users (15 male) vaped their personal e-cigarettes ad-lib over the course of 24 hours. Participants took each puff via calibrated CReSS pocket topography monitors. We analyzed: number of puffs per day per session, mean puff volume, mean puff flow rate, mean duration of puff, and mean interval between puffs. Results:Over 24 hours participants took on average 156.2±10.3 puffs, clustered in 10.2±7.9 puffs per puffing session with an average puff interval of 15.4±22.0 sec. A single puff lasted on average 3.0±1.2 sec, had a volume of 73.4±51.5 ml, and was taken with the average flow rate of 24.7±10.2 ml/sec. Conclusions:There is substantial variability among e-cigarette users in the way they puff on these devices. When e-cigarette aerosol is generated for laboratory studies, there is a need for validated puffing protocols that not only reflects the most-common pattern but also intensive puffing behaviors observed among some e-cigarette users.
Project description:BACKGROUND: Considerable effort has been devoted to mapping the functional and effective connectivity of the human brain, but these efforts have largely been limited to tasks involving stationary subjects. Recent advances with high-density electroencephalography (EEG) and Independent Components Analysis (ICA) have enabled study of electrocortical activity during human locomotion. The goal of this work was to measure the effective connectivity of cortical activity during human standing and walking. METHODS: We recorded 248-channels of EEG as eight young healthy subjects stood and walked on a treadmill both while performing a visual oddball discrimination task and not performing the task. ICA parsed underlying electrocortical, electromyographic, and artifact sources from the EEG signals. Inverse source modeling methods and clustering algorithms localized posterior, anterior, prefrontal, left sensorimotor, and right sensorimotor clusters of electrocortical sources across subjects. We applied a directional measure of connectivity, conditional Granger causality, to determine the effective connectivity between electrocortical sources. RESULTS: Connections involving sensorimotor clusters were weaker for walking than standing regardless of whether the subject was performing the simultaneous cognitive task or not. This finding supports the idea that cortical involvement during standing is greater than during walking, possibly because spinal neural networks play a greater role in locomotor control than standing control. Conversely, effective connectivity involving non-sensorimotor areas was stronger for walking than standing when subjects were engaged in the simultaneous cognitive task. CONCLUSIONS: Our results suggest that standing results in greater functional connectivity between sensorimotor cortical areas than walking does. Greater cognitive attention to standing posture than to walking control could be one interpretation of that finding. These techniques could be applied to clinical populations during gait to better investigate neural substrates involved in mobility disorders.
Project description:The neurobiological basis of psychogenic movement disorders remains poorly understood and the management of these conditions difficult. Functional neuroimaging studies have provided some insight into the pathophysiology of disorders implicating particularly the prefrontal cortex, but there are no studies on psychogenic dystonia, and comparisons with findings in organic counterparts are rare. To understand the pathophysiology of these disorders better, we compared the similarities and differences in functional neuroimaging of patients with psychogenic dystonia and genetically determined dystonia, and tested hypotheses on the role of the prefrontal cortex in functional neurological disorders. Patients with psychogenic (n = 6) or organic (n = 5, DYT1 gene mutation positive) dystonia of the right leg, and matched healthy control subjects (n = 6) underwent positron emission tomography of regional cerebral blood flow. Participants were studied during rest, during fixed posturing of the right leg and during paced ankle movements. Continuous surface electromyography and footplate manometry monitored task performance. Averaging regional cerebral blood flow across all tasks, the organic dystonia group showed abnormal increases in the primary motor cortex and thalamus compared with controls, with decreases in the cerebellum. In contrast, the psychogenic dystonia group showed the opposite pattern, with abnormally increased blood flow in the cerebellum and basal ganglia, with decreases in the primary motor cortex. Comparing organic dystonia with psychogenic dystonia revealed significantly greater regional blood flow in the primary motor cortex, whereas psychogenic dystonia was associated with significantly greater blood flow in the cerebellum and basal ganglia (all P < 0.05, family-wise whole-brain corrected). Group × task interactions were also examined. During movement, compared with rest, there was abnormal activation in the right dorsolateral prefrontal cortex that was common to both organic and psychogenic dystonia groups (compared with control subjects, P < 0.05, family-wise small-volume correction). These data show a cortical-subcortical differentiation between organic and psychogenic dystonia in terms of regional blood flow, both at rest and during active motor tasks. The pathological prefrontal cortical activation was confirmed in, but was not specific to, psychogenic dystonia. This suggests that psychogenic and organic dystonia have different cortical and subcortical pathophysiology, while a derangement in mechanisms of motor attention may be a feature of both conditions.
Project description:With the rapidly rising popularity and substantial evolution of electronic cigarettes (e-cigarettes) in the past 5-6 years, how these devices are used by vapers and consumers' exposure to aerosol emissions need to be understood. We used puffing topography to measure directly product use. We adapted a cigarette puffing topography device for use with e-cigarettes. We performed validation using air and e-cigarette aerosol under multiple regimes. Consumer puffing topography was measured for 60 vapers provided with rechargeable "cig-a-like" or larger button-activated e-cigarettes, to use ad-libitum in two sessions. Under all regimes, air puff volumes were within 1?mL of the target and aerosol volumes within 5?mL for all device types, serving to validate the device. Vapers' mean puff durations (2.0?s and 2.2?s) were similar with both types of e-cigarette, but mean puff volumes (52.2?mL and 83.0?mL) and mean inter-puff intervals (23.2?s and 29.3?s) differed significantly. The differing data show that product characteristics influence puffing topography and, therefore, the results obtained from a given e-cigarette might not read across to other products. Understanding the factors that affect puffing topography will be important for standardising testing protocols for e-cigarette emissions.
Project description:Studies on athletes or neurological patients with motor disorders have shown a close link between motor experience and motor imagery skills. Here we evaluated whether a functional limitation due to a musculoskeletal disorder has an impact on the ability to mentally rehearse the motor patterns of walking, an overlearned and highly automatic behaviour. We assessed the behavioural performance (measured through mental chronometry tasks) and the neural signatures of motor imagery of gait in patients with chronic knee arthrosis and in age-matched, healthy controls. During fMRI, participants observed (i) stationary or (ii) moving videos of a path in a park shown in the first-person perspective: they were asked to imagine themselves (i) standing on or (ii) walking along the path, as if the camera were "their own eyes" (gait imagery (GI) task). In half of the trials, participants performed a dynamic gait imagery (DGI) task by combining foot movements with GI. Behavioural tests revealed a lower degree of isochrony between imagined and performed walking in the patients, indicating impairment in the ability to mentally rehearse gait motor patterns. Moreover, fMRI showed widespread hypoactivation during GI in motor planning (premotor and parietal) brain regions, the brainstem, and the cerebellum. Crucially, the performance of DGI had a modulatory effect on the patients and enhanced activation of the posterior parietal, brainstem, and cerebellar regions that the healthy controls recruited during the GI task. These findings show that functional limitations of peripheral origin may impact on gait motor representations, providing a rationale for cognitive rehabilitation protocols in patients with gait disorders of orthopaedic nature. The DGI task may be a suitable tool in this respect.
Project description:Neural control of standing balance has been extensively studied. However, most falls occur during walking rather than standing, and findings from standing balance research do not necessarily carry over to walking. This is primarily due to the constraints of the gait cycle: Body configuration changes dramatically over the gait cycle, necessitating different responses as this configuration changes. Notably, certain responses can only be initiated at specific points in the gait cycle, leading to onset times ranging from 350 to 600 ms, much longer than what is observed during standing (50-200 ms). Here, we investigated the neural control of upright balance during walking. Specifically, how the brain transforms sensory information related to upright balance into corrective motor responses. We used visual disturbances of 20 healthy young subjects walking in a virtual reality cave to induce the perception of a fall to the side and analyzed the muscular responses, changes in ground reaction forces and body kinematics. Our results showed changes in swing leg foot placement and stance leg ankle roll that accelerate the body in the direction opposite of the visually induced fall stimulus, consistent with previous results. Surprisingly, ankle musculature activity changed rapidly in response to the stimulus, suggesting the presence of a direct reflexive pathway from the visual system to the spinal cord, similar to the vestibulospinal pathway. We also observed systematic modulation of the ankle push-off, indicating the discovery of a previously unobserved balance mechanism. Such modulation has implications not only for balance but plays a role in modulation of step width and length as well as cadence. These results indicated a temporally-coordinated series of balance responses over the gait cycle that insures flexible control of upright balance during walking.
Project description:Human smoking behavior influences exposure to smoke toxicants and is important for risk assessment. In a prospective observational study, the smoking behavior of Marlboro smokers was measured for 36 h. Puff volume, duration, frequency, flow and inter-puff interval were recorded with the portable CReSSmicro™ device, as has often been done by other scientists. However, the use of the CReSSmicro™ device may lead to some registration pitfalls since the method of insertion of the cigarette may influence the data collection. Participants demonstrated consistent individual characteristic puffing behavior over the course of the day, enabling the creation of a personalized puffing profile. These puffing profiles were subsequently used as settings for smoking machine experiments and tar, nicotine and carbon monoxide (TNCO) emissions were generated. The application of human puffing profiles led to TNCO exposures more in the range of Health Canada Intense (HCI)-TNCO emissions than for those of the International Standardization Organization (ISO). Compared to the ISO regime, which applies a low puff volume relative to human smokers, the generation of TNCO may be at least two times higher than when human puffing profiles were applied on the smoking machine. Human smokers showed a higher puffing intensity than HCI and ISO because of higher puffing frequency, which resulted in more puffs per cigarette, than both HCI and ISO.
Project description:Understandably, most locomotor analyses of bats have focused on flight mechanics and behaviors. However, we investigated nonflight locomotion in an effort to glean deeper insights into the evolutionary history of bats. We used high-speed video (300 Hz) to film and compare walking and climbing mechanics and kinematics between several species of the suborders Megachiroptera (Pteropodidae) versus Microchiroptera (Vespertilionidae and Phyllostomatidae). We found fundamentally distinctive behaviors, functional abilities, and performance outcomes between groups, but nearly homogeneous outcomes within groups. Megachiropterans exhibited climbing techniques and skills not found in microchiropterans and which aligned with other fully arboreal mammals. Megachiropterans climbed readily when placed in a head-up posture on a vertical surface, showed significantly greater ability than microchiropterans to abduct and extend the reach of their limbs, and climbed at a greater pace by using a more aggressive ipsilateral gait, at times being supported by only a single contact point. In addition, megachiropterans showed little ability to employ basic walking mechanics when placed on the ground, also a pattern observed in some highly adapted arboreal mammals. Conversely, microchiropterans resisted climbing vertical surfaces in a head-up posture, showed significantly less extension of their limbs, and employed a less-aggressive, slower contralateral gait with three points of contact. When walking, microchiropterans used the same gait they did when climbing which is representative of basic tetrapod terrestrial mechanics. Curiously, megachiropterans cycled their limbs significantly faster when climbing than when attempting to walk, whereas microchiropterans cycled their limbs at significantly faster rates when walking than when climbing. We contend that nonflight locomotion mechanics give a deep evolutionary view into the ancestral es locomotor platform on which flight was built in each of these groups.
Project description:Differentiating posterior cortical atrophy (PCA) from other diseases can be difficult and time-consuming, and there is a particularly high possibility of misdiagnosis when psychiatrists diagnose complaints related to visual perception. Here, a case of PCA involving prominent visual perceptual disorders is reported; PCA was difficult to distinguish from psychogenic disturbance of vision in this case. For a year, a 59-year-old woman had had visual perceptual disorders, including a distorted view and prosopagnosia. She underwent examinations at multiple clinical departments at several medical institutions before receiving a definitive diagnosis of PCA. This PCA diagnosis was based on clinical symptoms, including Gerstmann syndrome, Bálint's syndrome, and transcortical sensory aphasia, and hypoperfusion in the occipital lobe observed on single-photon emission computed tomography. This case was initially misdiagnosed as a psychogenic disease partly because characteristic clinical manifestations of PCA include visual agnosia with a disjunctive component. This patient displayed a disordered perception of stationary objects but an intact perception of moving objects. For example, she had to grope her way through a room at home, but she could visit a familiar hair salon on foot without hindrance. Behaviours like claiming to be blind while inexplicably moving without colliding with surrounding objects may lead to the misdiagnosis of PCA as a psychogenic or dissociative disorder involving histrionic or neurologically irrational symptoms with an expectation of sympathy or personal gain. It is critical to make every effort to exclude organic diseases, even in cases provisionally diagnosed as psychogenic disease. Despite its low prevalence, PCA should be considered a syndrome caused by Alzheimer's disease, dementia with Lewy bodies, or other dementias.