Raphe Nuclei Echogenicity and Diameter of Third Ventricle in Schizophrenia Measured by Transcranial Sonography

Abstract

Introduction: Serotonergic system hyperactivity at 5-HT2A receptors on glutamate neurons in the cerebral cortex is one of the pathways that is theoretically linked to psychosis. In addition to neurotransmitter dysfunction, volumetric studies revealed loss of cortical gray matter and ventricular enlargement in patients with schizophrenia, although there is no case-control research on patients with schizophrenia in order to evaluate echogenicity of RN or DTV. To address these issues, the present study assessed midbrain raphe nuclei (RN) as the main source of brain serotonin and diameter of third ventricle (DTV) as an index of atrophy by transcranial sonography (TCS) in a group of patients with schizophrenia. Methods: 30 patients with schizophrenia and 30 controls were assessed by TCS for RN echogenicity and DTV. TCS was done through temporal bone window via a phased-array ultrasound using 2.5 MHz transducer in depth of 14-16 cm. RN echogenicity assessed by a semi-quantitative visual scale and DTV was measured in thalamic plane. Results: 23 patients (76.5%) and 15 (50 %) controls showed hypoechogenicity of RN which was marginally significant (p=0.06). DTV was in average larger in the patient’s group (0.388 cm vs 0.234 cm, p<0.001). Conclusion: Increased DTV in the patients with schizophrenia is consistent with previous neuroimaging findings. However, marginally lower echogenicity of midbrain RN on TCS in schizophrenia is a new finding that supports the serotonin hypothesis of schizophrenia.