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

Abstract

The goal of this report is to review periodic lateralized epileptiform discharges (PLEDs), particularly their associated symptoms, the possibility that the pattern represents a focal status epilepticus, and finally the usefulness of antiepileptic drugs (AEDs). The associated symptoms often include an "altered state of consciousness" or "confusional state," but also more specific symptoms have been noted, such as 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 viewed the condition an example of subclinical status epilepticus. The intense hypermetabolism and increased blood flow revealed by PET and SPECT scans have been considered 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. As 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 reevaluate the electroclinical evidence related to this interesting and significant pattern.

Incidence of recurrent seizures following hospital discharge in patients with LPDs (PLEDs) and nonconvulsive seizures recorded on continuous EEG in the critical care setting

“…The three subgroups did not differ by the number of patients who had epileptiform activity on the follow-up EEG, but the presence of epileptiform activity on follow-up EEG was almost a certain marker for recurrent seizures in patients with NCS, which was not the case in patients with only PLEDs. It is quite likely that the epileptiform activity seen in four of the seven PLEDs only patients with no seizures during followup may be a residual 'forme fruste' of the PLEDs, which have been claimed to be just an epiphenomenon [21]. Another possible and more likely explanation is that these patients may develop seizures if followed for longer periods of time.…”

Periodic lateralized epileptiform discharges can survive anesthesia and result in asymmetric drug-induced burst suppression

“…PLEDs are resistant to treatment with antiepileptic drugs (AEDs). 22 In this regard, PLEDs resemble focal interictal spikes more than seizures. It may very well be the case that PLEDs represent neurophysiological processes that are distributed along an interictal-ictal continuum.…”

Brief Potentially Ictal Rhythmic Discharges in Critically Ill Adults

“…Substantial efforts have been made to standardize critical care EEG terminology and to associate EEG patterns with clinical course and outcome. [1][2][3][4][5] One of the main indications for CEEG is to detect electrographic seizures. Most electroencephalographers use a definition of seizures that includes a minimal duration of 10 seconds, [2][3][4][5][6][7] which reflects the typical duration of partial seizures in patients with chronic epilepsy.…”

“…[1][2][3][4][5] One of the main indications for CEEG is to detect electrographic seizures. Most electroencephalographers use a definition of seizures that includes a minimal duration of 10 seconds, [2][3][4][5][6][7] which reflects the typical duration of partial seizures in patients with chronic epilepsy. [8][9][10] Rhythmic ictal-appearing patterns lasting less than 10 seconds have been described in neonates under different acronyms: brief rhythmic discharges (BRDs), brief electroencephalography rhythmic discharges (BERDs), and brief ictal rhythmic discharges (BIRDs).…”