The diagnostic outcomes of electroencephalogram performed on adult psychiatric patients at Dr George Mukhari Hospital, Garankuwa” over a period of January 2006 to December 2008

Abstract

INTRODUCTION: The yield of EEG amongst psychiatric patients has been reported to be low and the value of EEG in the practice of psychiatry is questionable.EEG is used as part of a diagnostic work up for patients with psychiatric disorders .Often the reason given for its use is to exclude epilepsy as a cause of psychiatric symptoms. Epilepsy is primarily a clinical diagnosis, but the EEG may provide strong support by the findings of inter – ictal Epileptogenic discharge METHOD: All the adult EEGs requested at Dr George Mukhari psychiatric hospital, over a 36 month period,were reviewed to describe the outcome of the requested EEG reports. The study is a simple retrospective analysis of 111 consecutive EEG requested to the department of Neurology at DGMH from psychiatric unit at DGMH. Subjects were both inpatients and outpatients. All the EEG was reported by a qualified Neurologist. Data were extracted from the EEG request form and the patients’ clinical files, which reported on the clinical reason for the EEG test, nature of psychiatric diagnosis of patients, the psychiatric treatment received prior to the EEG test and the nature of the EEG results RESULTS: There were 111 EEG reports analysed, and 69 EEG reports for males and 42 EEG reports for females. The reason for EEG request was dominated mainly by exclusion of epilepsy. Majority of the patients were diagnosed with a psychotic disorder , followed second by a mood disorder , all of which was attributed to GMC (epilepsy).About 62.73% of patients were on a combination of treatment of antipsychotic drug and anticonvulsants, whilst 34.55% were on antipsychotic monotherapy prior to the EEG test. Further analysis of the requested EEG form was carried out in whom the test was to determine whether or not the patients were suffering from epilepsy. EEG abnormalities were identified amongst 24% of the patients. About 11,7% of patients presented with non specific EEG results. Out of a total number of 111 patients whom an EEG test was requested and epilepsy was highly suspected from clinical presentation, only 14 patients (12.6%),presented with epileptiform discharge on their EEG results. However majority of the patients (76%) demonstrated normal EEG pattern, which doesn’t exclude a diagnosis of epilepsy. CONCLUSION: The yield of EEG in psychiatry is low. To diagnose epilepsy as a cause of psychiatric presentation,clinicians should continue to rely on the clinical history of attacks and not the EEG. In the practice of psychiatry it is not recommended to routinely order an EEG to exclude a diagnosis of epilepsy, more so to confirm a psychiatric diagnosis. The presence of a psychiatric symptoms in patients who presents with epilepsy, is rarely associated with meaningful EEG changes