Karl Ludwig Kahlbaum's concept of catatonia.

Catatonia is a neuropsychiatric syndrome described by Karl Ludwig Kahlbaum in 1874. Based on Kahlbaum's own description and Carl Wernicke's hypothesis about the mechanism of catatonia, we describe two types of catatonic domain: the akinetic motality psychosis, which is characterized by rigid immobility, fixed gaze, lack of blink, and cogwheel rigidity, and catatonia sensu strictu, which is characterized by spasms, iterations and verbigerations. The loss of motility allows the 'hypobulic levels' described by Kretschmer in 1920, which consist of aggressive acts, furious shouting, hyperactivity and orality, to break through. These behaviours are present in the hyperkinetic variant of catatonia and may result from a reduction of dopaminergic innervation and the release of limbic and neocortical mechanisms containing behavioural programmes.