Cortical and spinal abnormalities in psychogenic dystonia

Espay, Alberto J.; Morgante, Francesca; Purzner, Jamie; Gunraj, Carolyn; Lang, Anthony E.; Chen, Robert

doi:10.1002/ana.20837

Cited by 180 publications

(142 citation statements)

References 49 publications

(58 reference statements)

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“…Most electrophysiologic studies have so far focused on patients with the fixed dystonia syndrome or psychogenic dystonia affecting limb, trunk, and neck muscles. While these patients show the same abnormalities of short-and long-interval intracortical inhibition, cortical silent period, and spinal reciprocal inhibition as patients with primary dystonia, 21,22 response to a plasticity protocol (paired associative stimulation) was abnormal only in primary dystonia. 23 These similarities and differences between psychogenic and primary dystonia have only been reported on a group level, hence their usefulness as a discriminating tool remains to be proven.…”

Section: Discussionmentioning

confidence: 77%

The blink reflex recovery cycle differs between essential and presumed psychogenic blepharospasm

Schwingenschuh¹,

Katschnig²,

Edwards³

et al. 2011

Neurology

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Section: Discussionmentioning

confidence: 77%

The blink reflex recovery cycle differs between essential and presumed psychogenic blepharospasm

Schwingenschuh¹,

Katschnig²,

Edwards³

et al. 2011

Neurology

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“…Short latency intracortical inhibition (SICI) has been shown to be impaired in three studies in psychogenic dystonia. [42][43][44] SICI involves a subthreshold conditioning stimulus applied 1-5 ms before the TMS pulse, which suppresses the amplitude of the MEP, an effect suggested to be mediated via intracortical GABA A mechanisms. 45 Espay et al 42 showed that both psychogenic dystonia (N=10) and organic dystonia (N=8) were associated with reduced SICI and long interval intracortical inhibition, along with shorter duration of the cortical silent period.…”

mentioning

confidence: 99%

“…[42][43][44] SICI involves a subthreshold conditioning stimulus applied 1-5 ms before the TMS pulse, which suppresses the amplitude of the MEP, an effect suggested to be mediated via intracortical GABA A mechanisms. 45 Espay et al 42 showed that both psychogenic dystonia (N=10) and organic dystonia (N=8) were associated with reduced SICI and long interval intracortical inhibition, along with shorter duration of the cortical silent period. The authors suggest that similarities between both disorders might point toward abnormal cortical and spinal excitability as a consequence of the dystonia or that these represent endophenotypic abnormalities.…”

mentioning

confidence: 99%

“…The authors suggest that similarities between both disorders might point toward abnormal cortical and spinal excitability as a consequence of the dystonia or that these represent endophenotypic abnormalities. 42 To extend these findings, Avanzino et al 43 measured inhibition of the unaffected arm of patients with fixed dystonia (N=12, of which four had complex regional pain syndrome) showing reduced SICI in both hemispheres. That the unaffected arm also showed reduced SICI suggested that decreased inhibition might predispose an individual to development of dystonia.…”

mentioning

confidence: 99%

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Functional Neuroanatomy and Neurophysiology of Functional Neurological Disorders (Conversion Disorder)

Voon¹,

Cavanna²,

Coburn³

et al. 2016

JNP

125

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Much is known regarding the physical characteristics, comorbid symptoms, psychological makeup, and neuropsychological performance of patients with functional neurological disorders (FNDs)/conversion disorders. Gross neurostructural deficits do not account for the patients' deficits or symptoms. This review describes the literature focusing on potential neurobiological (i.e. functional neuroanatomic/neurophysiological) findings among individuals with FND, examining neuroimaging and neurophysiological studies of patients with the various forms of motor and sensory FND. In summary, neural networks and neurophysiologic mechanisms may mediate "functional" symptoms, reflecting neurobiological and intrapsychic processes. J Neuropsychiatry Clin Neurosci 2016; 28:168-190; doi: 10.1176/appi.neuropsych.14090217 Functional neurological disorders (FNDs; or psychogenic neurological symptoms), also known as conversion disorder, are a classic neuropsychiatric disorder, existing in the border between neurology and psychiatry. Unexplained neurological symptoms are common, occurring in up to one-third of patients in neurological outpatient clinics.1 Relative to disorders such as Parkinson's disease, FND is associated with similar levels of disability and physical quality of life with poorer mental health quality of life. 2 The prognosis is poor, with a recent reviewshowing that up to 40% of patients with FND report similar or worse outcomes at 7-year follow-up. 3 Given the frequency, consequences, prognosis, and burden, FND has been called a "crisis for neurology." 4 Despite this, FND is poorly understood. In the last decade, an increasing number of studies have focused on underlying neurobiological mechanisms. FND is defined in DSM-5 as the presence of one or more symptoms of altered voluntary or sensory function, with clinical findings providing evidence of incompatibility between the symptom and recognized neurological or medical conditions.5 The DSM-5 diagnosis differs from that of the DSM-IV diagnosis of conversion disorder by adding the criterion of incorporating physical diagnostic features and by relegating to the accompanying text the criteria requiring (a) an association with psychological stressors and (b) the exclusion of malingering or factitious disorder to make the diagnosis. DSM-5 FND diagnosis criteria now allow for potential greater interrater reliability, making them appropriate for research studies and greater compatibility with specialtyspecific diagnoses including psychogenic movement disorder (PMD) and psychogenic nonepileptic seizures (PNES). 6The putative biopsychosocial mechanisms underlying FND are complex and have been extensively reviewed.7 Our review focuses on the physiological mechanisms that may underlie FND and does not specifically focus on the extensive literature on the antecedents of early childhood experiences and temperament (Figure 1). At the outset, regarding the proposed model, we acknowledge that predisposing factors for functional neurological symptoms are not limited to genetics, te...

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“…44 Interestingly, in two TMS studies in patients with psychogenic dystonia, the abnormalities of cortical inhibition seen in patients with organic dystonia were also seen in the psychogenic dystonia patients. 45,46 rTMS studies are also used as probes of cortical plasticity in dystonia.…”

Section: Myoclonus Dystoniamentioning

confidence: 99%

Advances in Our Understanding of Dystonia - Pathophysiology and Treatment Options

Lubarr¹,

Bressman²

2011

European Neurological Review

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Although the pathophysiology of dystonia remains incompletely understood, advances in two major areas of research over the past two decades have led to important insights into the mechanisms of dystonia. First, with the identification of dystonia genes, investigations using cellular and animal models of dystonia have become possible. Second, advances in functional neuroimaging have led to the possibility of identification of distinct functional, anatomical and neurochemical abnormalities in dystonia patients. Dystonia is currently conceptualised as a neurofunctional disorder characterised by alterations at various levels and multiple points along the sensorimotor circuit. There are multiple causes of these disruptions, and lesions along different points in interconnected pathways can yield similar motor dysfunction. The existence of dystonia endophenotypes in genetic forms of dystonia suggests that it may be a 'second hit' disorder, in which genetically predisposed brains can be thrown into an unbalanced dystonic state by environmental or genetic factors.Ultimately, a more complete understanding of the pathophysiology of dystonia should lead to better, more rational, targeted therapies.

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Cortical and spinal abnormalities in psychogenic dystonia

Cited by 180 publications

References 49 publications

The blink reflex recovery cycle differs between essential and presumed psychogenic blepharospasm

The blink reflex recovery cycle differs between essential and presumed psychogenic blepharospasm

Functional Neuroanatomy and Neurophysiology of Functional Neurological Disorders (Conversion Disorder)

Advances in Our Understanding of Dystonia - Pathophysiology and Treatment Options

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