A Multi‐Institutional Study on a New Five‐Axial Classification Sys‐ tem for Epileptic Psychoses.
Authors: Matsuura Masato , Kojima Takuya , Adachi Naoto , Oana Yasunori , Okubo Yoshiro , Hara Tunekatsu , Onuma Teiichi 
Published: August 2005

Purpose: The pathophysiology and clinical phenomenology of epileptic psychoses are wide and varied, and an internationally accepted classification system has yet to be established. A multi‐axial classification should be developed to capture the complexity of clinicai situations and to describe the heterogeneity of individuals presenting with the same diagnosis. We propose a new 5‐axial classification system based on a review of the previous literature and evaluate its validity and applicability in Japan by a multi‐institutional design. Methods: According to the ICD‐10 guidelines, psychosis is defined as the presence of hallucination, delusions, or a limited number of behavioral abnormalities, such as gross excitement and overactivity, marked psychomotor retardation, and catatonic behavior, without disturbance of consciousness. Among the patients with epilepsy and psy‐ choses treated by the authors at 6 epilepsy clinics, 128 patients were randomly selected to participate as subjects. Those patients who developed epilepsy after the onset of their psychoses were excluded. The average age of the subjects was 39.4 years, average age of onset of epilepsy was 13.3 years, and average age of onset of psychoses was 27.9 years. Results: The first axis codes the type of epilepsy and laterality of epileptic focus. Temporal lobe epilepsy (48%) and other localization‐related epilepsies (14%) were prevalent, but all types of epilepsy were seen. Left‐sided (29%) and right‐sided foci (27%) were in equal proportion, and bilateral foci (9%) also were found. The second axis codes the type of psychoses and clinical course. Paranoid schizophrenia‐like disorder (41%) and delusional disorder (19%) were prevalent; whereas acute transient psychotic disorder (9%), catatonic disorder (7%), hallucinosis (6%), and hebephrenic schizophrenia‐like disorder (4%) were relatively infrequent. Single episode (24%), recurrent episodes (34%), and chronic course (34%) were found in almost equal proportion. Therc were several cases with chronic course after recurrent episodes (3%). The third axis codes the temporal relationship between seizure occurrence and EEG changes during psychoses. lnterictal onset (69%) was most frequent followed by postictal (15%), para‐ictal (6%), and other (5%). EEG changes during psychoses were seen in 38%, and normalization of the EEG was seen in 4%of patients. In 22%, EEG could not be recorded during psychoses (22%). The fourth axis codes the precipitating factors of psychoses. Specific personality trait (20%), changes in drug‐regimen (l4%), co‐morbidity with other psychiatric disorders (12%), and psychosocial factors (10%) were seen. The fifth axis codes the organic background. Abnormal findings by brain imaging techniques (38%). mild intelligence deficiency (30%), and previous history of brain damage (27%) were noted. Conclusions: The present results demonstrate the heterogeneity of epileptic psychoses. We have proposed a 5‐axial classification that appears to provide a convenient format for organizing and communicating clinical information to assist clinical practice and facilitate research. Using those guidelines, we may be able to improve our under‐ standing of the pathogenesis, develop suitable treatment, predict the prognosis, and ultimately establish appropriate intervention strategies.