Left superior temporal blood flow increases in schizophrenic and schizophreniform patients with auditory hallucination: a longitudinal case study using 123I-IMP SPECT.

Serial assessments of regional cerebral blood flow were performed using 123I-IMP SPECT in two schizophrenic and three schizophreniform patients with persistent auditory hallucination. The initial SPECT study in the period with prominent auditory hallucination revealed an increased accumulation of 123I-IMP in the left superior temporal area which corresponded to the auditory association cortex. In the follow-up SPECT study performed after clinical improvement, the distribution of 123I-IMP had normalized. One of the case with schizophrenia showed a similar increased uptake of 123I-IMP in the left superior temporal area in the third SPECT scan performed when a psychotic relapse with auditory hallucination occurred. MRI scans in two of the five patients demonstrated reduced volume of the temporal lobes. These findings suggest that the auditory hallucinations in schizophrenia may be involved in functional hyperactivity in the left superior temporal cortex which might be based partly on structural abnormalities in the temporal lobes.