Periodic lateralized epileptiform discharges: Do they represent an ictal pattern requiring treatment?

The goal of this report is to review periodic lateralized epileptiform discharges (PLEDs), especially their associated symptoms, the possibility that the pattern represents a focal status epilepticus and finally the usefulness of anti-epileptic drugs (AEDs). The associated symptoms often include an “altered state of consciousness” or “confusional state”, but also more specific symptoms have been noted, like nystagmus retractorius, cortical blindness, depression, apraxia, amnesia, hemianopsia, hemiparesis, gaze preference or deviation, dysphasia and speech impediment. PLEDs have often been referred to as an ictal pattern and many investigators have called the condition an example of subclinical status epilepticus. Intense hypermetabolism and increased blood flow from PET and SPECT scans have often been reported to support the ictal nature of this waveform. Although the pattern is difficult to treat, the AEDs that have been reported as successful include carbamazepine, midazolam, pentobarbital, sodium valproate and felbamate. Since only subtle symptoms are, at times, present and therefore may be missed and the pattern is known to be difficult to treat, epileptologists who view the PLED pattern as only an EEG curiosity and decide against treatment may wish to re-evaluate the electroclinical evidence related to this interesting and significant pattern.