Periodic lateralized epileptiform discharges (PLEDs) in herpetic encephalitis

Descargas periódicas lateralizadas na encefalite herpética

An 86-year-old male presented with confusion, fever and tonic-clonic seizures. CSF analysis showed lymphocytic pleocytosis and high protein count, leading to initiation of acyclovir. EEG revealed PLEDs in the left hemisphere (figure 1C) and MRI demonstrated left hippocampal and insular hyperintensities (figure 1A, 1B). Herpes simplex virus (HSV) encephalitis was confirmed by PCR.

Figure
(A, B) Brain MRI; axial FLAIR sequence showing hyperintensities in the insular cortex and parahippocampal gyrus, respectively; (C) EEG demonstrating unilateral and focal sharp wave complexes that appear periodically in the left hemisphere, as the electrographic reflection of the HSV lesion (arrow).

PLEDs represent periodic sharp discharges lateralized to one hemisphere usually due to acute neuronal injury¹,². Since not all patients present seizures, the acronym LPDs (Lateralized Periodic Discharges) may be more accurate³. Besides encephalitis, several etiologies produce PLEDs, including stroke, metabolic disarrangements, brain tumors, intracranial hemorrhage, anoxic encephalopathy, among others¹, ². Nevertheless, HSV encephalitis should always be considered and CSF studies obtained in the appropriate clinical scenario⁴.

References

• ¹
  Fitzpatrick W, Lowry N. PLEDs: clinical correlates. Can J Neurol Sci. 2007;34(4):443-50. doi:10.1017/S0317167100007332
• ²
  Andraus ME, Andraus CF, Alves-Leon SV. Periodic EEG patterns: importance of their recognition and clinical significance. Arq Neuropsiquiatr. 2012;70(2):145-51. doi:10.1590/S0004-282X2012000200014
• ³
  Hirsch LJ, La Roche SM, Gaspard N, Gerard E, et al. American Clinical Neurophysiology Society's Standardized Critical Care EEG Terminology: 2012 version. J Clin Neurophysiol 2013;30(1):1-27. doi:10.1097/WNP.0b013e3182784729
• ⁴
  Rigamonti A, Lauria G, Mantero V, Salmaggi A. A case of late herpes simplex encephalitis relapse. J Clin Virol. 2013;58(1):269-70. doi:10.1016/j.jcv.2013.05.010

Publication Dates

• Publication in this collection
  06 Oct 2015
• Date of issue
  Dec 2015

History

• Received
  21 May 2015
• Reviewed
  29 June 2015
• Accepted
  24 July 2015