Regional brain function in hallucinations: a study of regional cerebral blood flow with 99m-Tc-HMPAO-SPECT in patients with auditory hallucinations, tactile hallucinations, and normal controls.

From the supposition that there exists a possible connection between certain psychopathological symptoms, and/or syndromes (e.g., hallucinations) and regional cerebral dysfunction, patients suffering from auditory and tactile hallucinations were investigated, in a symptom-oriented study, using the method of technetium-99m-Hexamethyl-propylenamine Oxime (99m-Tc-HMPAO)-Single Photon Emission Computed Tomography (SPECT) and compared with normal controls. The results support Jackson's hypothesis to the effect that hallucinatory phenomena will primarily occur when the normally inhibitive influence of the upper cortical centers over the lower brain structures diminishes, resulting in relative hyperactivity in the basal regions. In addition to the brain activity-changes generally observed in hallucinating patients, it was possible to identify regional cerebral blood flow (rCBF)-distribution patterns characteristic in certain forms of hallucinatory phenomena, i.e., a significant increase of activity in the hippocampal regions (including hippocampus, parahippocampus, and amygdala) only in patients with auditory hallucinations, and a significant reduction of rCBF in the inferior temporal regions in patients with tactile hallucinations.