Figures & data
Table 1. Common positive (rule-in) neurological signs found on physical examination in children with functional motor and sensory Symptomsa.
Table 2. Clinically useful neurological signs for diagnosis of functional seizures.
Figure 1. Circles metaphor of the stress-system model for functional somatic symptoms (including FND).
![Figure 1. Circles metaphor of the stress-system model for functional somatic symptoms (including FND).](/cms/asset/3646a73e-a2c9-49f4-9a43-a37cfa8bde90/iern_a_2333390_f0001_oc.jpg)
Figure 2. Common signs and symptoms associated with increased arousal © Kasia Kozlowska 2019, reproduced with permission.
![Figure 2. Common signs and symptoms associated with increased arousal © Kasia Kozlowska 2019, reproduced with permission.](/cms/asset/5a75b51f-e8f5-4794-8a9a-107628b65268/iern_a_2333390_f0002_oc.jpg)
Table 3. Functional somatic symptoms caused by hyperventilation and the associated low PCO2 and respiratory alkalosis.
Figure 3. Sustained beta activation following hyperventilation in children with functional seizures.
![Figure 3. Sustained beta activation following hyperventilation in children with functional seizures.](/cms/asset/531aea10-cf39-40dd-a4ff-93c3c17e6490/iern_a_2333390_f0003_oc.jpg)
Figure 4. Visual representation of the changes in connectivity in the resting state and during a functional seizure.
![Figure 4. Visual representation of the changes in connectivity in the resting state and during a functional seizure.](/cms/asset/aabf28e9-3bd9-4f66-bb1a-80d38205cf35/iern_a_2333390_f0004_oc.jpg)
Table 4. Most common comorbid mental health diagnoses in the Danish health register study of children with functional seizures.
Figure 5. Visual representation linking adverse life experiences, stress system activation, and epigenetic/plasticity processes that increase vulnerability for FND. © Kasia Kozlowska 2021, reproduced with permission.
![Figure 5. Visual representation linking adverse life experiences, stress system activation, and epigenetic/plasticity processes that increase vulnerability for FND. © Kasia Kozlowska 2021, reproduced with permission.](/cms/asset/1fdedbf5-44ac-4434-9e82-328735eee89e/iern_a_2333390_f0005_oc.jpg)
Figure 6. Conceptual model of developmental trajectories of early life stress leading to increased vulnerability to functional neurological disorder (FND) and other disparate health outcomes (including other comorbid functional conditions [e.g. chronic complex pain], comorbid mental health disorders, and concurrent physical health disorders). The model identifies the many different biological, psychological, and social factors that interact with adverse childhood experiences (ACEs) across development to alter allostatic processes and reduce adaptability to stress. Changed allostatic processes found in children with FND (discussed in this review) include the following: activation of autonomic nervous system, brain arousal systems, or immune system; dysregulation of HPA axis or sleep and circadian system; and, in the context of childhood abuse, epigenetic programming of genes modulating neuron development and brain network connectivity. The individual effects of ACEs on the organism depend on the specific genetic background and fetal programming (hit-1), the timing, duration, intensity, and type of ACEs (hit-2), and other later-life challenges, such as additional stressors, coping strategies, support availability, lifestyle, and aging (hit-3). Interactions among these factors explain inter-individual variations both in resilience and vulnerability to altered biopsychological functioning and in lifelong health outcomes.
![Figure 6. Conceptual model of developmental trajectories of early life stress leading to increased vulnerability to functional neurological disorder (FND) and other disparate health outcomes (including other comorbid functional conditions [e.g. chronic complex pain], comorbid mental health disorders, and concurrent physical health disorders). The model identifies the many different biological, psychological, and social factors that interact with adverse childhood experiences (ACEs) across development to alter allostatic processes and reduce adaptability to stress. Changed allostatic processes found in children with FND (discussed in this review) include the following: activation of autonomic nervous system, brain arousal systems, or immune system; dysregulation of HPA axis or sleep and circadian system; and, in the context of childhood abuse, epigenetic programming of genes modulating neuron development and brain network connectivity. The individual effects of ACEs on the organism depend on the specific genetic background and fetal programming (hit-1), the timing, duration, intensity, and type of ACEs (hit-2), and other later-life challenges, such as additional stressors, coping strategies, support availability, lifestyle, and aging (hit-3). Interactions among these factors explain inter-individual variations both in resilience and vulnerability to altered biopsychological functioning and in lifelong health outcomes.](/cms/asset/f79dd298-ead9-40b9-9d57-f3dc8e10afd4/iern_a_2333390_f0006_oc.jpg)