Neurologic approaches to hysteria, psychogenic and functional disorders from the late 19th century onwards.

The history of functional neurologic disorders in the 20th century from the point of view of the neurologist is U-shaped. A flurry of interest between the 1880s and early 1920s gave way to lack of interest, skepticism, and concern about misdiagnosis. This was mirrored by increasing professional and geographic divisions between neurology and psychiatry after the First World War. In the 1990s the advent of imaging and other technology highlighted the positive nature of a functional diagnosis. Having been closer in the early 20th century but later more separate, these disorders are now once again the subject of academic and clinical interest, although arguably still very much on the fringes of neurology and neuropsychiatry. Revisiting older material provides a rich source of ideas and data for today's clinical researcher, but also offers cautionary tales of theories and treatments that led to stagnation rather than advancement of the field. Patterns of treatment do have a habit of repeating themselves, for example, the current enthusiasm for transcranial magnetic stimulation compared to the excitement about electrotherapy in the 19th century. For these reasons, an understanding of the history of functional disorders in neurology is arguably more important than it is for other areas of neurologic practice.