The A to F of functional status in the acute setting: A scoping review.

Functional status (FSt) describes the phenomenon of prolonged non-epileptic attacks that may be misidentified as Status Epilepticus (SE). The early differentiation between epileptic and functional status is crucial in order to avoid unnecessarily invasive and costly medical escalation in the latter group, including the hazards of overmedication, intubation and intensive care admission. The authors conducted a literature review of available studies describing cases of functional status to extract the common aspects of FSt seizure semiology, investigations used to differentiate from SE, and guidance for managing FSt. A search was carried out using Medline, Embase and PsychInfo databases and 3909 papers were extracted for review. 30 papers were found relevant for inclusion, describing 260 cases of FSt. FSt was found to occur more commonly in younger, female patients with a family history of epilepsy, co-morbid psychiatric diagnosis and following a recent traumatic event. Common clinical features of FSt during and after, the events were identified. While video-EEG remains the gold standard investigation for differentiating FSt from SE, many of the included studies considered the utility of other investigation modalities including serum markers and neuroimaging. One key shortcoming identified within the literature reviewed was a lack of well-defined guidance on the acute management of FSt. We offer an A-F step management plan for the immediate and longer term assessment and treatment of FSt.

The relationship between interoception and agency and its modulation by heartbeats: an exploratory study.

Interoception, the sense of the internal physiological state of the body, theoretically underpins aspects of self-representation. Experimental studies link feelings of body ownership to interoceptive perception, yet few studies have tested for association between the sense of agency and interoceptive processing. Here, we combined an intentional binding paradigm with cardiac measures of interoceptive processing (behavioural performance on a heartbeat discrimination task, and effects of timing within the cardiac cycle) in twenty-six non-clinical participants as an exploratory study. We found performance accuracy on the heartbeat discrimination task correlated positively with the intentional binding effect, an index of sense of agency (ß = 0.832, p = 0.005), even after controlling for effects of age, sex, educational level, heart rate, heart rate variability and time accuracy. The intentional binding effect was enhanced during cardiac systole (compared to diastole) in individuals with greater heartbeat discrimination accuracy (ß = 0.640, p = 0.047). These findings support the proposal that interoception contributes to mechanisms underlying the emergence of sense of agency.

Trait and state interoceptive abnormalities are associated with dissociation and seizure frequency in patients with functional seizures.

OBJECTIVE: Dissociative traits represent a disturbance in selfhood that may predispose to, and trigger, functional seizures (FSs). The predictive representation and control of the internal physiological state of the body (interoception) are proposed to underpin the integrity of the sense of self ("minimal selfhood"). Therefore, discrepancies between objective and subjective aspects of interoception may relate to symptom expression in patients with FSs. Here, we tested whether individual differences in trait measures of interoception relate to dissociative symptoms, and whether state interoceptive deficits predict FS occurrence. METHODS: Forty-one participants with FSs and 30 controls completed questionnaire ratings of dissociation, and measures of (1) interoceptive accuracy (IA)-objective performance on heartbeat detection tasks; (2) trait interoceptive sensibility-subjective sensitivity to internal sensations (using the Porges Body Perception Questionnaire); and (3) state interoceptive sensibility-subjective trial-by-trial measures of confidence in heartbeat detection. Interoceptive trait prediction error (ITPE) was calculated from the discrepancy between IA and trait sensibility, and interoceptive state prediction error (ISPE) from the discrepancy between IA and state sensibility. RESULTS: Patients with FSs had significantly lower IA and greater trait interoceptive sensibility than healthy controls. ITPE was the strongest predictor of dissociation after controlling for trait anxiety and depression in a regression model. ISPE correlated significantly with FS frequency after controlling for state anxiety. SIGNIFICANCE: Patients with FSs have disturbances in interoceptive processing that predict both dissociative traits reflecting the disrupted integrity of self-representation, and the expression of FSs. These findings provide insight into the pathophysiology of functional neurological disorder, and could lead to novel diagnostic and therapeutic approaches.