Disturbed neural circuits in a subtype of chronic catatonic schizophrenia demonstrated by F-18-FDG-PET and F-18-DOPA-PET

Permanent verbal, visual scenic and coenaestetic hallucinations are the mos t prominent psychopathological symptoms aside from psychomotor disorders in speech-sluggish catatonia, a subtype of chronic catatonic schizophrenia ac cording to Karl Leonhard. These continuous hallucinations serve as an excel lent paradigm for the investigation of the assumed functional disturbances of cortical circuits in schizophrenia. Data from positron emission tomography (F-18 FDG-PET and F-18-DOPA-PET) fro m three patients with this rare phenotype were available (two cases of simp le speech-sluggish catatonia, one case of a combined speech-prompt/speech-s luggish subtype) and were compared with a control collective. During their permanent hallucinations, all catatonic patients showed a clea r bitemporal hypometabolism in the F-18-FDG-PET. Both patients with the sim ple speech-sluggish catatonia showed an additional bilateral thalamic hyper metabolism and an additional bilateral hypometabolism of the frontal cortex , especially on the left side. In contrast, the patient with the combined s peech-prompt/speech-sluggish catatonia showed a bilateral thalamic hypometa bolism combined with a bifrontal cortical hypermetabolism However, the left /right ratio of the frontal cortex also showed a lateralisation effect with a clear relative hypometabolism of the left frontal cortex. The F-18-DOPA-PET of both schizophrenic patients with simple speech-sluggis h catatonia showed a normal F-18-DOPA storage in the striatum, whereas in t he right putamen of the patient with the combined form a higher right/left ratio in F-DOPA storage was discernible, indicating an additional lateraliz ed influence of the dopaminergic system in this subtype of chronic catatoni c schizophrenia. Most likely, the prominent bitemporal F-18-FDG- hypometabolism in these chr onic schizophrenic patients with speech-sluggish catatonia suffering from p ermanent continuous hallucinations, reflects a deficit in sensoric gating f ollowing prenatal cortical neurodevelopmental disturbances. However, the functional disturbances underlying hallucinations in "the schi zophrenias" seem to be more complex; in different subtypes of the schizophr enic spectrum disorder hallucinations seem to be based on alterations in ad ditional cortical and subcortical brain regions.