Electro-Clinical and Imaging Characteristics of Ictal Periodic Lateralized Epileptiform Discharges (PLEDs) during Continuous EEG (cEEG) Monitoring: A Retrospective Analysis of 10 Cases (S58.002)

Abstract

Objective: To investigate EEG features, clinical semiologies, and neuroimaging findings in patients with ictal PLEDs. Background PLEDs are classically viewed as acute interictal phenomena associated with seizures. Less frequently, however, PLEDs may represent the sole EEG correlate during clinical seizure activity. Limited case reports describing such ictal PLEDs cannot comment on their frequency or common characteristics. We present here the first systematic case series on ictal PLEDs. Design/Methods: We identified all records containing PLEDs and ictal PLEDs from our cEEG archives, which included all adult ward and ICU patients undergoing prolonged EEG monitoring for non-elective indications between 2007 and 2011. PLEDs were considered ictal when they were reported as being clearly time-locked to clinical symptoms. Source EEGs were reviewed for confirmation. Results: A total of 1452 patients underwent cEEG monitoring. PLEDs were reported in 90 patients, with ictal PLEDs observed in 10 (11.1% of those with PLEDs; 0.7% overall). Eight patients with ictal PLEDs were male and two were female. Nine had motor epilepsia partialis continua (EPC) and one experienced repetitive, stereotyped sensory symptoms. In all 10 patients, PLEDs were maximal over either central, parietal, or frontal regions contralateral to the side of clinical symptoms. Eight patients had identifiable lesions involving sensorimotor cortex ipsilateral to the PLEDs. These underlying lesions were neoplastic (5), anoxic (1), post-traumatic (1), or vascular (1) in etiology. Conclusions: Ictal PLEDs were overall uncommon but occurred in 11% of patients with PLEDs on cEEG. The vast majority of patients in whom PLEDs were considered ictal experienced motor EPC. Most had lesions involving sensorimotor cortex and all had PLEDs maximal over the central, parietal, or frontal regions contralateral to their clinical symptoms. These findings raise important questions about the substrate for ictal PLEDs as well as the significance of isolated PLEDs occurring over non-eloquent cortex or without an obvious time-locked clinical correlate. Disclosure: Dr. Sen-Gupta has nothing to disclose. Dr. Schuele has received personal compensation for activities with UCB pharma and GlaxoSmithKline as a speaker. Dr. Macken has received personal compensation for activities with Cyberonics and Lundbeck Research USA, Inc. as a speaker. Dr. Macken has received research support from UCB Pharma. Dr. Gerard has nothing to disclose.