Septum pellucidum, which forms the medial wall of the lateral ventricles, consists of two laminates. Cavum septum pellucidum (CSP) is defined when there is a space between these laminae. In some MRI studies have shown a higher rate of large CSP in patients with schizophrenia than in normal subjects. Looking at the literature on psychiatric disorders, CSP has been shown to be most associated with schizophrenia. Large CSP supports the neurodevelopmental model, which is one of the etiological explanations of schizophrenia. In our study, two patients with a diagnosis of CSP are mentioned. One of our patients is a first episode of schizophrenia, and the other one chronic schizophrenia patient with a history of multi-drug resistance. The first episode of schizophrenia is consistent with the information available in the literature in terms of the severity of symptoms, weak-response to treatment, and insufficiency of neuropsychological tests. The apparent deficit of the chronic schizophrenia patient suggests that CSP has a neurodevelopmental model in the etiology of schizophrenia, as well as the duration of the disease and non-compliance with treatment. There is no study in the literature comparing the response to treatment with large CSP in schizophrenia. It is thought that investigation of response to treatment in future studies is important for demonstrating the effects of neurodevelopmental model on the treatment of psychiatric disorders.

Choroidal fissure cyst (CFC), an intracranial space-occupying mass, is often incidentally identified and generally regarded not to present with overt clinical signs. The concurrence of space-occupying lesions with psychotic disorders have been reported in numerous cases; however, to the best of our knowledge, co-occurrent CFC and schizophrenia have not been published before in the literature. Electroconvulsive therapy (ECT) has been frequently considered relatively contraindicated in patients with spaceoccupying lesions in the brain; nevertheless, in the last few years, increased numbers of studies encourage clinicians to treat drugresistant psychiatric patients with ECT. Here we present 21-year-old male patient, who has been diagnosed with antipsychoticresistant schizophrenia with a coincidental CFC who have been clinically improved by bilateral and modified nine sessions of ECT. It is recommended to be deliberate if ECT will be applied to the patients with intracranial mass on the treatment phase. ECT may cause some side effects by increasing intracranial pressure on the patients, including rupture of cystic lesions. However, recent publications stated that ECT could be used safely in cysts, which do not cause edema or intracranial pressure increase. Our patient has not been presented any intracranial pressure signs nor neurological deficits. This report supports the safety and efficacy of ECT in the treatment of psychiatric disorders accompanied by intracranial structural lesions; nevertheless, all the risks ought to be taken into account cautiously when ECT becomes an issue for the psychiatric patients with intracranial mass and the opinion of neurosurgeons should be taken with calculating the benefit-loss ratio.