Conversion disorder and its subtypes: a need for a reclassification

Dissociation and its biological and clinical associations in functional neurological disorder: systematic review and meta-analysis

BACKGROUND

Studies have reported elevated rates of dissociative symptoms and comorbid dissociative disorders in functional neurological disorder (FND); however, a comprehensive review is lacking.

AIMS

To systematically review the severity of dissociative symptoms and prevalence of comorbid dissociative disorders in FND and summarise their biological and clinical associations.

METHOD

We 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).

RESULTS

Seventy-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.

CONCLUSIONS

Our 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.

Psychological and psychiatric aspects of psychogenic non-epileptic seizures (PNES): A systematic review

Psychogenic non-epileptic seizures (PNES) are common in neurological settings and often associated with considerable distress and disability. The psychological mechanisms underlying PNES are poorly understood and there is a lack of well-established, evidence-based treatments. This paper advances our understanding of PNES by providing a comprehensive systematic review of the evidence pertaining to the main theoretical models of this phenomenon. Methodological quality appraisal and effect size calculation were conducted on one hundred forty empirical studies on the following aspects of PNES: life adversity, dissociation, anxiety, suggestibility, attentional dysfunction, family/relationship problems, insecure attachment, defence mechanisms, somatization/conversion, coping, emotion regulation, alexithymia, emotional processing, symptom modelling, learning and expectancy. Although most of the studies were only of low to moderate quality, some findings are sufficiently consistent to warrant tentative conclusions: (i) physical symptom reporting is elevated in patients with PNES; (ii) trait dissociation and exposure to traumatic events are common but not inevitable correlates of PNES; (iii) there is a mismatch between subjective reports of anxiety and physical arousal during PNES; and (iv) inconsistent findings in this area are likely to be attributable to the heterogeneity of patients with PNES. Empirical, theoretical and clinical implications are discussed.

Dissociation and functional neurologic disorders

Dissociation has been cited as a possible psychologic mechanism underpinning functional neurologic disorders (FND) since the 19th century. Since that time, changes in psychiatric classification have created confusion about what the term dissociation actually means. The available evidence suggests that it now refers to at least two qualitatively distinct types of phenomena: detachment (an altered state of consciousness characterized by a sense of separation from the self or world) and compartmentalization (a reversible loss of voluntary control over apparently intact processes and functions), as well as their underlying mechanisms. This chapter considers some of the problems with conflating these phenomena under a single heading as well as the relationship between detachment, compartmentalization, and FND. It is argued that FNDs are fundamentally compartmentalization disorders, but that detachment is often part of the clinical picture and may contribute to the development and maintenance of functional symptoms in many cases. By this view, understanding compartmentalization requires an appreciation of the mechanisms involved in controlling and accessing mental processes and contents. Two possible mechanisms in this regard are described and the evidence for these is considered, followed by a discussion of clinical and empiric implications.

Conceptualization and treatment of psychogenic non-epileptic seizures

Psychogenic non-epileptic seizures (PNES) frequently present co-morbidly with a range of somatic and psychiatric conditions. This review discusses the relationship between PNES, a number of co-morbid psychiatric symptoms, early attachment trauma, and disruption of neurological development. We suggest that it may be clinically useful to understand PNES with reference to three patterns of co-morbidity and trauma history. In the first group, PNES are one symptom of a response to severe, chronic trauma and invalidation in attachment relationships, or a response to a recent event that overwhelms an emotion regulation system shaped by attachment trauma. For a second group, PNES occur in the context of ongoing interruptions to self and memory with or without a history of attachment trauma. For a third group, PNES occur in the absence of extensive co-morbidity and apparent trauma, primarily as a panic reaction, in a population with under-developed emotion regulation skills. Treatment approaches consistent with these conceptualizations are suggested.