Evaluation of cisterna magna and cerebellum volumes in patients diagnosed with schizophrenia and bipolar disorder

Mega cisterna magna is a relatively common condition that represents nearly half of cystic posterior fossa malformations. It is usually asymptomatic and discovered incidentally. It is thought that cerebellar dysfunctions associated with mega cisterna magna cause psychotic disorders. The aim of this study is to investigate the effect of cerebellar dysfunction associated with mega cisterna magna on the emergence of psychiatric symptoms by comparing the volume of the cisterna magna and cerebellum, as well as the cerebellar cortical thicknesses, in cranial magnetic resonance images of patients diagnosed with schizophrenia and bipolar disorder with those of healthy individuals. In the study, cranial magnetic resonance images of a total of 78 individuals, including 26 patients diagnosed with schizophrenia and 26 with bipolar disorder who applied to the Psychiatry Clinic of Balıkesir University Faculty of Medicine Hospital, and a control group of 26 healthy individuals, were retrospectively examined. Cerebellum volume and cerebellar cortical thicknesses were volumetrically evaluated using VolBrain, while the cisterna magna volume was assessed using ITK-SNAP 4.0 software. The obtained data were transferred to the Statistical Package for the Social Sciences version 25 software and statistically analyzed. According to the statistical analysis results of the variables, the cisterna magna volume was found to be larger in patients diagnosed with schizophrenia and bipolar disorder compared to healthy controls. In patients diagnosed with bipolar disorder, a significant reduction was found in the cortical thickness of lobules V, VI, VIIIA, and VIIIB compared to the control group, and in patients diagnosed with schizophrenia, a significant reduction was found in the cortical thickness of lobules VIIIA and X compared to the control group. In patients diagnosed with schizophrenia, a significant reduction in the asymmetry of cortical thickness in lobule X was observed compared to patients diagnosed with bipolar disorder. Additionally, a positive correlation was found between age and the volume of the cisterna magna, and a negative correlation was found between age and the volume of the cerebellum. In conclusion, the mega cisterna magna represents a neuroimaging finding recently associated with schizophrenia and bipolar disorder, but limited to case reports. The findings suggest that mega cisterna magna may serve as a biomarker for underlying neurodevelopmental anomalies that cause cerebellar dysfunction and lead to psychiatric symptoms in individuals.