1348 REM Sleep EEG Pattern Mimicking Seizures: A Case of Subclinical Rhythmic Electrographic Discharges of Adults

Abstract Introduction Rhythmic electrographic patterns encountered during polysomnography (PSG) may closely resemble ictal activity, particularly when they occur in unexpected sleep stages. Subclinical Rhythmic Electrographic Discharges of Adults (SREDA) is a benign EEG variant that may be mistaken for seizures but is rarely described during rapid eye movement (REM) sleep. We report an unusual case of REM-restricted rhythmic activity initially concerning for seizures that was ultimately recognized as SREDA. Report of case(s) A 67 year old man with obstructive sleep apnea (OSA) presented with persistent non-restorative sleep and excessive daytime sleepiness despite of optimal adherence to auto-adjusting positive airway pressure (APAP) therapy. He had undergone prior neurologic evaluation for suspected seizures and was empirically treated with lacosamide, which was later discontinued after identification of SREDA on EEG. He subsequently returned for reassessment of OSA, and an in-laboratory PAP titration demonstrated effective control of respiratory events at APAP setting of 5 to 11 cmH2O. During REM sleep, recurrent episodes of rhythmic, sharply contoured theta activity lasting 10–20 seconds were observed. These discharges displayed uniform morphology, lacked temporal or spatial evolution and were unaccompanied by clinical, behavioral or autonomic changes. Although initially raising concern for ictal activity, detailed electrographic analysis favored a benign pattern. Conclusion Rhythmic discharges confined to REM sleep are uncommon and may be misinterpreted as seizures, particularly given that epileptic events rarely arise during this sleep stage. In this case, careful morphologic assessment supported a diagnosis of SREDA rather than ictal activity, therby preventing unnecessary antiseizure therapy and additional neurologic evaluation. Awareness that benign EEG variants such as SREDA may rarely present during REM sleep is essential for accurate interpretation of sleep EEG recordings Support (if any)