A Bayesian account of 'hysteria'

This article provides a neurobiological account of symptoms that have been called 'hysterical', 'psychogenic' or 'medically unexplained', which we will call functional motor and sensory symptoms. We use a neurobiologically informed model of hierarchical Bayesian inference in the brain to explain functional motor and sensory symptoms in terms of perception and action arising from inference based on prior beliefs and sensory information. This explanation exploits the key balance between prior beliefs and sensory evidence that is mediated by (body focused) attention, symptom expectations, physical and emotional experiences and beliefs about illness. Crucially, this furnishes an explanation at three different levels: (i) underlying neuromodulatory (synaptic) mechanisms; (ii) cognitive and experiential processes (attention and attribution of agency); and (iii) formal computations that underlie perceptual inference (representation of uncertainty or precision). Our explanation involves primary and secondary failures of inference; the primary failure is the (autonomous) emergence of a percept or belief that is held with undue certainty (precision) following top-down attentional modulation of synaptic gain. This belief can constitute a sensory percept (or its absence) or induce movement (or its absence). The secondary failure of inference is when the ensuing percept (and any somatosensory consequences) is falsely inferred to be a symptom to explain why its content was not predicted by the source of attentional modulation. This account accommodates several fundamental observations about functional motor and sensory symptoms, including: (i) their induction and maintenance by attention; (ii) their modification by expectation, prior experience and cultural beliefs and (iii) their involuntary and symptomatic nature

Symptom severity in patients with functional motor symptoms : patient's perception and doctor's clinical assessment

BACKGROUND: Beliefs and expectations about symptoms and an abnormal direction of attention towards the body have been proposed as important mechanistic factors in the pathophysiology of functional motor symptoms (FMS). We therefore aimed to evaluate patients' awareness/perception of the presence and severity of their own symptoms before and while watching themselves in a video and to compare this with doctors' assessment of the presence and severity of FMS, based on video evaluation. METHODS: We evaluated 16 patients affected by FMS. Patients were invited to give a "subjective evaluation" of their symptoms. Afterwards, patients were invited to watch a video of themselves and to judge the presence of symptoms in the different body parts and, if so, to rate the severity. Patients' videos were also assessed by a rater with expertise in FMS. RESULTS: Patients judged their symptoms to be more severe on subjective evaluation than when viewing a video of themselves (p = 0.002; t = 3.656). Subjective evaluation of symptom severity by patients was higher than that of raters viewing a video of the patient (p < 0.001, t = 4.860), but there was only a trend towards a difference between video ratings of severity by patients and independent raters (p = 0.017, t = 2.962 with p set at 0.016 according to Bonferroni correction). CONCLUSIONS: Our study shows that patients with FMS tend to overestimate the severity of their symptoms compared independent rating. However, when viewing a video of themselves they rated their symptoms as less severe and closer to those of independent raters

Diagnosis of psychogenic tremor using a smartphone

Same embryo as in Confocal 2, centered more vegetally, and progressing further laterally. Shows that the entire vegetal endoderm is now internal, with the “vegetal” surface of the embryo being covered by cells that are much smaller than the initial vegetal endoderm cells, which can be seen inside the embryo. Confocal slices are 7 μm apart

Movement disorders in adult patients with classical galactosemia

Classical galactosemia is an autosomal recessive inborn error of metabolism leading to toxic accumulation of galactose and derived metabolites. It presents with acute systemic complications in the newborn. Galactose restriction resolves these symptoms, but long-term complications, such as premature ovarian failure and neurological problems including motor dysfunction, may occur despite adequate treatment. The objective of the current study was to determine the frequency and phenotype of motor problems in adult patients with classical galactosemia. In this cross-sectional study, adult patients with a biochemically confirmed diagnosis of galactosemia attending our clinic were assessed with an interview and neurological examination and their notes retrospectively reviewed. Patients were classified according to the presence/absence of motor dysfunction on examination. Patients with motor dysfunction were further categorized according to the presence/absence of reported motor symptoms. Forty-seven patients were included. Thirty-one patients showed evidence of motor dysfunction including: tremor (23 patients), dystonia (23 patients), cerebellar signs (6 patients), and pyramidal signs (4 patients). Tremor and dystonia were often combined (16 patients). Thirteen patients reported motor symptoms, with 8 describing progressive worsening. Symptomatic treatment was effective in 4 of 5 patients. Nonmotor neurological features (cognitive, psychiatric, and speech disorders) and premature ovarian failure were more frequent in patients with motor dysfunction. Motor dysfunction is a common complication of classical galactosemia, with tremor and dystonia the most frequent findings. Up to one third of patients report motor symptoms and may benefit from appropriate treatment. Progressive worsening is not uncommon and may suggest ongoing brain damage in a subset of patients. \ua9 2013 Movement Disorder Society