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Neurostimulation for the treatment of functional neurological disorder: A systematic review.

ABSTRACT: Functional Neurological Disorder (FND), also known as conversion disorder, is characterized by neurological symptoms that are incompatible with any known structural disorder and best explained by a biopsychosocial model. Evidence-based treatments for FND are limited, with cognitive behavioral therapy (CBT) and physiotherapy being the most effective interventions [1]. In recent years, functional neuroimaging studies have provided robust evidence of alterations in activity and connectivity in multiple brain networks in FND. This body of evidence suggests that neurocircuitry-based interventions, such as non-invasive brain stimulation techniques (NIBS), may also represent an effective therapeutic option for patients with FND. In this systematic review, we outline the current state of knowledge of NIBS in FND, and discuss limitations and future directions that may help establish the efficacy of NIBS as a therapeutic option for FND.

SUBMITTER: Gonsalvez I

PROVIDER: S-EPMC8671519 | biostudies-literature | 2021

REPOSITORIES: biostudies-literature

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Neurostimulation for the treatment of functional neurological disorder: A systematic review.

Gonsalvez Irene I Spagnolo Primavera P Dworetzky Barbara B Baslet Gaston G

Epilepsy & behavior reports 20211109

Functional Neurological Disorder (FND), also known as conversion disorder, is characterized by neurological symptoms that are incompatible with any known structural disorder and best explained by a biopsychosocial model. Evidence-based treatments for FND are limited, with cognitive behavioral therapy (CBT) and physiotherapy being the most effective interventions [1]. In recent years, functional neuroimaging studies have provided robust evidence of alterations in activity and connectivity in mult ...[more]

PMID: 34950864

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Project description:In functional neurological disorder (FND), there is a fundamental disconnect between an apparently intact nervous system and the individuals' ability to consistently perform motor actions, perceive sensory signals and/or access effective cognition. Metacognition, the capacity to self-evaluate cognitive performance, appears highly relevant to FND pathophysiology. Poor metacognition is a potential mechanism via which abnormal models of self and the state of the world could arise and persist unchecked. There is therefore a justified enthusiasm that studies of metacognition may give substance to FND's intangible nature. However, many assume an impairment in metacognition even though experimental studies are still in their infancy. This systematic review provides an analytical checkpoint of the evidence after the first five years of experimental work. We firstly summarize current methods for testing metacognition, prerequisite knowledge that allows readers to independently evaluate the evidence. Using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, we then screened the 21 articles on this topic and review the experimental data of the eight studies that specifically tested metacognition in subjects with FND. Questionnaire metrics used to estimate global metacognition and general confidence in FND revealed a mixed picture of low or normal confidence. Of the five studies that used performance-controlled metrics, the gold-standard to estimate local metacognition in FND, four found metacognition to be equivalent to healthy controls and one paper supported impaired metacognition. We consequently try and broaden the debate and discuss alternative headline scenarios. We review how positive studies may offer insight and debate whether null studies could represent false negatives. However, since most studies find equivalent metacognition to controls, we also discuss whether metacognition could be intact and how this could inform mechanistic models of FND and have potential clinical utility. In summary, this review highlights signal of interest within the data, exposes current limitations and flags the many open questions.

Project description:Background and purposeCognitive complaints are common in functional neurological disorder (FND), but it is unclear whether objective neurocognitive deficits are present. This systematic review summarized validated/standardized cognitive test performance in FND samples across cognitive domains.MethodsEmbase, PsycInfo and MEDLINE were searched from inception to 15 May 2023, combining terms for FND and cognitive domains (e.g., attention, memory, executive functioning). Studies included a range of FND phenotypes (seizures, motor, cognitive disorder, mixed), compared to healthy or clinical controls. Risk of bias was assessed with the modified Newcastle-Ottawa Scale and a qualitative synthesis/narrative review of cognitive performance in FND was conducted. Test performance scores were extracted, and random effects meta-analyses were run where appropriate. This review was registered on PROSPERO, CRD42023423139.ResultsFifty-six studies including 2260 individuals with FND were eligible. Although evidence for some impairments emerged across domains of executive functioning, attention, memory and psychomotor/processing speed, this was inconsistent across studies and FND phenotypes. Common confounds included group differences in demographics, medication and intellectual functioning. Only 24% of studies objectively assessed performance validity. Meta-analyses revealed higher scores on tests of naming (g = 0.67, 95% confidence interval [CI] 0.50, 0.84) and long-term memory (g = 0.43, 95% CI 0.13, 0.74) in functional seizures versus epilepsy, but no significant differences in working (g = -0.08, 95% CI -0.44, 0.29) or immediate (g = 0.25, 95% CI -0.02, 0.53) memory and cognitive flexibility (g = -0.01, 95% CI -0.29, 0.28).ConclusionsThere is mixed evidence for objective cognitive deficits in FND. Future research should control for confounds, include tests of performance validity, and assess relationships between objective and subjective neurocognitive functioning.

Project description:BackgroundStudies have reported elevated rates of dissociative symptoms and comorbid dissociative disorders in functional neurological disorder (FND); however, a comprehensive review is lacking.AimsTo systematically review the severity of dissociative symptoms and prevalence of comorbid dissociative disorders in FND and summarise their biological and clinical associations.MethodWe searched Embase, PsycInfo and MEDLINE up to June 2021, combining terms for FND and dissociation. Studies were eligible if reporting dissociative symptom scores or rates of comorbid dissociative disorder in FND samples. Risk of bias was appraised using modified Newcastle-Ottawa criteria. The findings were synthesised qualitatively and dissociative symptom scores were included in a meta-analysis (PROSPERO CRD42020173263).ResultsSeventy-five studies were eligible (FND n = 3940; control n = 3073), most commonly prospective case-control studies (k = 54). Dissociative disorders were frequently comorbid in FND. Psychoform dissociation was elevated in FND compared with healthy (g = 0.90, 95% CI 0.66-1.14, I2 = 70%) and neurological controls (g = 0.56, 95% CI 0.19-0.92, I2 = 67%). Greater psychoform dissociation was observed in FND samples with seizure symptoms versus healthy controls (g = 0.94, 95% CI 0.65-1.22, I2 = 42%) and FND samples with motor symptoms (g = 0.40, 95% CI -0.18 to 1.00, I2 = 54%). Somatoform dissociation was elevated in FND versus healthy controls (g = 1.80, 95% CI 1.25-2.34, I2 = 75%). Dissociation in FND was associated with more severe functional symptoms, worse quality of life and brain alterations.ConclusionsOur findings highlight the potential clinical utility of assessing patients with FND for dissociative symptomatology. However, fewer studies investigated FND samples with motor symptoms and heterogeneity between studies and risk of bias were high. Rigorous investigation of the prevalence, features and mechanistic relevance of dissociation in FND is needed.

Dataset Information

Neurostimulation for the treatment of functional neurological disorder: A systematic review.

Publications

Neurostimulation for the treatment of functional neurological disorder: A systematic review.

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