Raphe nuclei echogenicity changes in obsessive-compulsive disorder

Background: Dysregulation of serotonin system is hypothesized to play the main role in the etiology of obsessive-compulsive disorder (OCD). Transcranial sonography (TCS) is a helpful noninvasive and low-cost tool for the assessment of subcortical brain architectures, mainly basal nuclei, cerebellar central structures, and midbrain. In this study, an ultrasound assessment was performed for a sample of the patients with OCD and healthy control group to evaluate echogenicity of midbrain raphe nuclei (RN). Methods: A total of 35 patients with OCD and 35 healthy controls of similar age and sex entered the study. Semi-structured clinical interview was performed according to the DSM IV-TR criteria to verify OCD. Echogenicity of the midbrain RN was assessed by an experienced neurologist applying TCS. The echogenicity of the 2 groups was compared using chi- square test. SPSS software (version 18, PASW) was used for statistical analysis and p-value of less than 0.05 was considered significant. Results: In this study, 15 OCD patients (42.9%) and 11 (31.4%) controls showed decreased echogenicity of midbrain RN. Also, the results of the chi-square test showed that the midbrain RN echogenicity was not significantly lower in patients with OCD compared to the control group (p= 0.322). Conclusion: Although decreased midbrain RN echogenicity is a characteristic of patients with major depression, it was not shown in OCD patients in this study, which can be explained by the involvement of RN projections rather that RN serotoninergic neurons.