Aetiological factors in functional seizures and functional motor symptoms: shared and distinct features

Functional seizures (FS) and functional motor symptoms (FMS), subtypes of functional neurological disorder, may involve shared and distinct predisposing, precipitating, perpetuating and triggering (PPPT) factors. This study investigated potential self-reported PPPT factors in FS and FMS separately.

200 participants (FS=50, FMS=50, individuals with anxiety and/or depression (clinical controls [CC]=50, healthy controls [HC]=50) completed an in-depth medical history interview and online questionnaires to assess potential aetiological factors including traumatic/adverse life events, alexithymia, autistic traits, psychological and physical symptoms, illness perceptions, cognitive-behavioural responses and outcome measures of general functioning and health-related quality of life (HRQoL).

Participants with FS more frequently reported traumatic/adverse events and psychopathology (eg, dissociation, posttraumatic stress disorder) as possible illness causes/precipitating factors and sensory symptom triggers, relative to FMS and/or CCs. In contrast, participants with FMS endorsed physical illness causes/precipitating factors and physical activity and emotion-related symptom triggers more frequently than FS and/or CCs. Physical and dissociative symptoms were elevated, alongside reductions in HRQoL and general functioning in FS/FMS compared with CCs/HCs. Greater current, threatening illness-related beliefs/cognitions were disclosed in FS/FMS compared with CCs. Negative associations between HRQoL, cognitive-behavioural responses and traumatic/adverse events were also seen in FS/FMS.

Traumatic events and psychopathology may be more prominently involved in the development/maintenance of FS and physical illness/injury, physical functioning and alexithymia may be more central to FMS. Unhelpful illness-related beliefs and impacts on HRQoL and general functioning are shared between these subtypes. The results of this study provide insight into potential unique and overlapping characteristics of FS/FMS, with implications for treatment.