Objective Foreign accent syndrome (FAS) is widely understood as an unusual consequence of structural neurological damage, but may sometimes represent a functional neurological disorder. This observational study aimed to assess the prevalence and utility of positive features of functional FAS in a large group of individuals reporting FAS.
Methods Participants self-reporting FAS recruited from informal unmoderated online support forums and via professional networks completed an online survey. Speech samples were analysed in a subgroup.
Results Forty-nine respondents (24 UK, 23 North America, 2 Australia) reported FAS of mean duration 3 years (range 2 months to 18 years). Common triggers were: migraine/severe headache (15), stroke (12), surgery or injury to mouth or face (6) and seizure (5, including 3 non-epileptic). High levels of comorbidity included migraine (33), irritable bowel syndrome (17), functional neurological disorder (12) and chronic pain (12). Five reported structural lesions on imaging. Author consensus on aetiology divided into, ‘probably functional (n=35.71%), ‘possibly structural’ (n=4.8%) and ‘probably structural’ (n=10.20%), but positive features of functional FAS were present in all groups. Blinded analysis of speech recordings supplied by 13 respondents correctly categorised 11 (85%) on the basis of probable aetiology (functional vs structural) in agreement with case history assignment.
Conclusions This largest case series to date details the experience of individuals with self-reported FAS. Although conclusions are limited by the recruitment methods, high levels of functional disorder comorbidity, symptom variability and additional linguistic and behavioural features suggest that chronic FAS may in some cases represent a functional neurological disorder, even when a structural lesion is present.
- conversion disorder
- functional neurological disorder
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Contributors LM designed the study, collected the data, analysed the data and prepared and revised the manuscript. NM designed the study, analysed and reported the audio data and revised the manuscript. CC drafted the manuscript. IH designed the study and drafted the survey. AL collected the audio recording data. AC designed the study, interpreted the data and revised the manuscript for intellectual content. JS designed the study, interpreted the data and revised the manuscript for intellectual content.
Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
Competing interests LM is undertaking a research fellowship funded philanthropically by Baillie Gifford. IH is supported by and ABN/Patrick Berthoud Charitable Trust Research Training Fellowship. AC is a paid editor of the Journal of Neurology, Neurosurgery and Psychiatry. He is a director of a limited personal services company that provides independent medical testimony in court cases on a range of neuropsychiatric topics on a 50% pursuer 50% defender basis. JS is a Chief Scientists Office NHS Research Scotland Career Researcher. JS provides independent medical testimony in court cases regarding patients with functional disorders.
Patient consent for publication Obtained.
Ethics approval The study received NHS Ethical approval.
Provenance and peer review Not commissioned; externally peer reviewed.
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