“Motoring in idle”: The default mode and somatomotor networks are overactive in children and adolescents with functional neurological symptoms

Abstract

ObjectiveChildren and adolescents with functional neurological symptom disorder (FND) present with diverse neurological symptoms not explained by a disease process. Functional neurological symptoms have been conceptualized as somatoform dissociation, a disruption of the brain's intrinsic organization and reversion to a more primitive level of function. We used EEG to investigate neural function and functional brain organization in children/adolescents with FND.MethodEEG was recorded in the resting eyes-open condition in 57 patients (aged 8.5–18 years) and 57 age- and sex-matched healthy controls. Using a topographical map, EEG power data were quantified for regions of interest that define the default mode network (DMN), salience network, and somatomotor network. Source localization was examined using low-resolution brain electromagnetic tomography (LORETA). The contributions of chronic pain and arousal as moderators of differences in EEG power were also examined.ResultsChildren/adolescents with FND had excessive theta and delta power in electrode clusters corresponding to the DMN—both anteriorly (dorsomedial prefrontal cortex [dmFPC]) and posteriorly (posterior cingulate cortex [PCC], precuneus, and lateral parietal cortex)—and in the premotor/supplementary motor area (SMA) region. There was a trend toward increased theta and delta power in the salience network. LORETA showed activation across all three networks in all power bands and localized neural sources to the dorsal anterior cingulate cortex/dmPFC, mid cingulate cortex, PCC/precuneus, and SMA. Pain and arousal contributed to slow wave power increases in all three networks.ConclusionsThese findings suggest that children and adolescents with FND are characterized by overactivation of intrinsic resting brain networks involved in threat detection, energy regulation, and preparation for action.

Quantitative EEG Findings in Patients With Psychogenic Nonepileptic Seizures

“…26,27 Processes involving activation of the cortical brain regions are associated with the higher frequency qEEG bands (alpha, beta, and gamma). 1 Our results, therefore, indicate overactivation in somato-motor and language areas and possibly in parietal executive areas.…”

Structural alterations in functional neurological disorder and related conditions: a software and hardware problem?

“…Overall, these seemingly contradictory findings may relate to a multiplicity of distinct sample characteristics, and may be disease-related or compensatory. Nonetheless, these emerging structural alterations complement neuroimaging evidence showing motor circuit abnormalities using resting-state (Kozlowska et al, 2018; Li et al, 2015a; Wegrzyk et al, 2018) and motor tasks (Burgmer et al, 2006; Cojan et al, 2009; Marshall et al, 1997; Spence et al, 2000; Stone et al, 2007; Voon et al, 2011) in FND.…”

“…Given links between adverse life events and aberrant neuroplasticity in brain areas also implicated in the pathophysiology of FND and SSD, it is noteworthy that parallel autonomic and neuroendocrine abnormalities have been described in FND (Apazoglou et al, 2017; Bakvis et al, 2010; Kozlowska et al, 2015; Reinsberger et al, 2012) and SSD (Janssens et al, 2012; Rief and Barsky, 2005). Altered skin conductance and startle eyeblink responses have also been reported in FND cohorts (Kozlowska et al, 2018; Pick et al, 2017; Seignourel et al, 2007). Similarly, patients with SSD compared to controls exhibit decreased parasympathetic and increased sympathetic tone at baseline and during emotional and nociceptive processing (Houtveen and van Doornen, 2007; Pollatos et al, 2011a; Pollatos et al, 2011b).…”

“…Emerging structural neuroimaging findings point towards a parallel “hardware” related neurobiology in some FND populations, further bridging the divide between neurologic and psychiatric conceptualizations (Perez et al, 2018a). In addition, FND frequently co-exists clinically with the somatic symptom disorders (SSD) as largely defined in DSM-IV (somatization disorder, somatoform pain disorder, and undifferentiated somatoform disorder) (Kozlowska et al, 2018; Sar et al, 2004; Stone et al, 2010b); a few FND studies reported comorbidities rates with somatoform disorders above 50% (Bowman and Markand, 1996; Sar et al, 2004). The SSD category in the DSM-5 was designed to consolidate the DSM-IV diagnostic categories of somatization disorder, somatoform pain disorder, and undifferentiated somatoform disorder, although this reconceptualization has markedly different criteria based on cognitive-affective and behavioral aspects and is more explicit about including patients with defined medical conditions (Dimsdale et al, 2013).…”

Use of respiratory rates and heart rate variability in the assessment and treatment of children and adolescents with functional somatic symptoms

“…Our findings are consistent with previous studies from our research programme which have also shown elevated breathing rates (coupled with difficulties in regulating blood carbon dioxide) and increased HR in patients with non-epileptic seizures (Kozlowska et al, 2017) and increased HR and decreased HRV in patients with mixed functional neurological symptoms (Kozlowska et al, 2015). Other studies with children and adolescents with FSS have demonstrated activation or dysregulation in various components of the stress system: abnormalities in cardiovascular autonomic control in children with chronic fatigue (Sulheim et al, 2012), dysregulation of the hypothalamic pituitary adrenal (HPA) axis (levels of cortisol) in adolescents with chronic pain (Janssens et al, 2012), activation of the immune-inflammatory system (elevated levels of C-reactive protein in adolescents with FSS (Jonker et al, 2017) and with children with functional neurological symptoms (Kozlowska, Chung et al, 2018), elevated cytokine levels in adolescents with fatigue and elevated antinuclear antibody titres in children and adolescents with pain and fatigue (Itoh, Shigemori, Igarashi, & Fukunaga, 2012;Katz & Jason, 2013) and concurrent activation of brain arousal/emotion processing systems and motor systems in children and adolescents with functional neurological symptoms (Kozlowska, Spooner et al, 2018). In addition, studies looking at children and adolescents with chronic pain document increased catastrophising, which activates the stress system in a top-down fashion (Edwards et al, 2008).…”