Clinical Outcome of Patients with SREDA (Subclinical Rhythmic EEG Discharge of Adults)

OBJECTIVE: To clarify the clinical significance of subclinical rhythmic EEG discharge of adults' (SREDA) by analyzing characteristics of SREDA and the outcome of patients based on retrospective analysis of EEG data base. METHODS: EEGs were recorded soon after the onset of patient's initial symptoms and repeatedly recorded at various intervals of 2-3 months in all 4 patients. Neurological findings, MRI and SPECT were also investigated. SUBJECTS: Out of 340 consecutive inpatient population who had EEGs, 4 patients (1.2%) showed SREDA. They had a diagnosis of syncope, transient global amnesia, generalized tonic-clonic seizure and right temporal lobe epilepsy for each. RESULTS: There was no consistent abnormality in the brain MRI, CT or SPECT among the 4 patients. The acute and transient symptoms disappeared and did not recur within the follow-up period of 28 months in any patient. In 2 patients SREDA disappeared in the follow-up EEG taken 7-14 days after the first EEG showing SREDA. In the other 2 patients, the follow-up EEGs taken 5 days after the first EEG with SREDA when clinical symptoms disappeared showed less frequent occurrence of SREDA. CONCLUSION: Being different from the previous reports suggesting the relation with cardiogenic insults or persistent ischemic abnormality, SREDA can occur in patients with various acute brain dysfunctions followed by a favorable clinical outcome.