Neurologic symptoms deemed inconsistent, incongruent, or incompatible with recognised neurologic disease will likely garner a functional (formerly psychogenic) diagnosis, or Conversion Disorder in modern nomenclature. Functional neurological disorders (FND) embody a broad phenomenological spectrum, encompassing psychogenic nonepileptic seizures (PNES), abnormal movements, gait abnormalities, and sensorimotor deficits. The theory underlying the functional diagnosis presumes that in the absence of organic findings, the neurologic symptom must have a psychological aetiology and thus, symptom remission rests on psychological intervention. In fact, it is the absence of organic (neurologic) findings that distinguishes a functional disorder from ordinary neurologic disease. This paper explored the history that underlies the FND diagnosis and the modern clinical findings to assess whether the data supports or refutes the FND diagnosis. To generate and support the analysis, a wide sampling of articles on the relevant populations (FND patients and those with symptoms labelled ordinary neurologic disease) was reviewed. The results show that every premise of the psychogenic theory has been debunked by the empirical data. Studies show pervasive organic (neurologic) disease in FND and PNES patient populations; that in many FND and PNES patients, there is no discernible psychological factor that could be responsible for the ‘psychogenic’ symptom.; that physical therapies, not psychotherapy, have emerged as highly effective treatments for movement disorders labelled functional; that, like a substantial proportion of untreated epilepsy patients, many PNES patients show spontaneous remission of symptoms without any psychotherapy at all. The findings starkly expose the inherent flaws of the diagnostic practice promoted in the FND and PNES literature. The diagnosis of PNES relies on the scalp vEEG, a ‘gold standard’ that fails to capture a substantial proportion of epileptiform discharges, particularly those of a frontal lobe origin. The ‘positive signs’ underlying the diagnosis of functional movement disorders are fallible, have been observed in neurologic conditions, and label atypical presentations, and likely early-stage disease, as inconsistent with classic neurologic disorders. Despite compelling evidence that these patients indeed suffer from ordinary neurologic disease and epilepsy, FND and PNES investigators remain highly invested in the ‘functional’ aetiology and show confirmation bias in their interpretation of the empirical data. The ongoing misdiagnosis of neurologic disease and epilepsy as FND and PNES is the real crisis in neurology.
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Carlson CA
Minnesota Judicial Branch, Minneapolis, Minnesota 55487, USA.
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