Kahlbaum's catatonia revisited.

Modern psychiatric nosologies separate catatonia along the lines of presumed etiology: bipolar, major depression, schizophrenia and due to a general medical condition. The presence of catatonia has always held diagnostic and prognostic value. Kahlbaum's description of catatonia includes careful documentation of phenomenology and the course of the illness. Since there were no effective treatments in his time, Kahlbaum was documenting the natural history of the illness. A review of classic studies of the natural history of catatonia demonstrates that the syndrome is episodic, may have few other psychotic signs, may have periods of remission and may, in some cases, be associated with the disorganized subtype of schizophrenia. The literature of the past 100 years supports the validity of Kahlbaum's description for a subset of patients with catatonia.