[Background] Catatonia is motor dysregulation syndrome that presents with several psychiatric and neurological symptoms, including stupor. The first-line treatment for catatonia includes discontinuing antipsychotic medication and initiating benzodiazepine. Electroconvulsive therapy is also recommended for intractable cases. It is often difficult to differentiate acute schizophrenia patients with catatonia from those without catatonia, especially when excitation and/or agitation are exhibited. However, prompt differentiation may affect the prognosis because the treatment of schizophrenia with catatonia differs from that of other types of schizophrenia. In this study, as patients with catatonia often have visual hallucinations, we investigated the prevalence of catatonia with visual hallucinations among schizophrenia patients.
 [Method] Subjects were diagnosed with schizophrenia and admitted to the Psychiatric Center of Yokohama City University Medical Center between April 2016 and March 2017. The diagnosis of schizophrenia and catatonia was according to DSM-5 criteria. We analyzed the frequency of visual hallucinations in these patients.
 [Result] We examined 55 patients with schizophrenia, including 11 who presented catatonia. Eleven out of 55 patients exhibited visual hallucinations. Among them, 7 presented catatonia and 4 did not. The group exhibiting catatonia had a significantly higher frequency of visual hallucinations than that not exhibiting catatonia.
 [Discussion] In this study, the prevalence of visual hallucinations was significantly higher in the group presenting catatonia among patients with schizophrenia. Although the diagnostic criteria for catatonia in DSM-5 and BFCRS do not include visual hallucinations, our study suggested that visual hallucinations are associated with catatonia. The pathophysiology of the visual hallucinations in patients with catatonia is unknown, but evaluating the presence of visual hallucinations may aid in early differentiation and treatment of catatonia.
 <Authors' abstract>