Concepts in Periodic Discharges: A Descriptive Study
Received: 10 January 2019
Accepted after revision: 05 May 2019
06 July 2019 (online)
Introduction Periodic discharges are now known as the ictal–interictal continuum and represent ongoing injury in acute or chronic neurological illnesses.
Objective The aim of our study was to identify periodic discharges in patients who have undergone continuous bedside electroencephalography (EEG) monitoring and to classify the EEG according to the current American Clinical Neurophysiology Society terminology.
Materials and Methods The continuous bedside EEG records of intensive care patients admitted from August 2017 to July 2018 were analyzed. The clinical spectrum, the treatment, and outcome of each of these patients were monitored.
Results Fifty cases of periodic discharges (11 children, 39 adults) were identified over 1 year from 2017 to 2018. The clinical presentation included 32% seizures, 16% status epilepticus, 20% coma, 16% fever with altered sensorium, 8% abnormal behavior, 4% strokes, and 4% traumatic brain injury. The diagnosis was 20% autoimmune encephalitis, 8% herpes encephalitis, 20% multiorgan failure, 4% traumatic brain injury, 16% status epilepticus, 16% posthypoxic encephalopathy, 4% strokes, 4% intracerebral bleeds, 4% meningitis, and 4% severe dementia. Lateralized periodic discharges were identified in 20%, bilateral independent periodic discharges in 20%, and generalized periodic discharges in 60%. Fifty-six percent patients recovered with residual neurological deficits and 44% succumbed to their illness.
Conclusions Continuous bedside EEG monitoring has revolutionized the approach to seizures in critically ill patients. Despite a vigilant approach and diligent diagnosis of these abnormal rhythms, the mortality rate was 20% in patients with lateralized periodic discharges and 60% with bilateral and generalized periodic discharges (p ≤ 0.05).
- 1 Chatrian GE, Shaw CM, Leffman H. The significance of periodic lateralised epileptiform discharges in the EEG: an electrographic, clinical and pathologic study. Electroencephalogr Clin Neurophysiol 1964; 17: 177-193
- 2 Andraus ME, Andraus CF, Alves-Leon SV. Periodic EEG patterns: importance of their recognition and clinical significance. Arq Neuropsiquiatr 2012; 70 (02) 145-151
- 3 Johnson EL, Kaplan PW. Population of the ictal-interictal zone: the significance of periodic and rhythmic activity. Clin Neurophysiol Pract 2017; 2: 107-118
- 4 Reiher J, Rivest J, Grand’Maison F, Leduc CP. Periodic lateralized epileptiform discharges with transitional rhythmic discharges: association with seizures. Electroencephalogr Clin Neurophysiol 1991; 78 (01) 12-17
- 5 Claassen J, Jetté N, Chum F. et al. Electrographic seizures and periodic discharges after intracerebral hemorrhage. Neurology 2007; 69 (13) 1356-1365
- 6 Kalamangalam GP, Slater JD. Periodic lateralized epileptiform discharges and afterdischarges: common dynamic mechanisms. J Clin Neurophysiol 2015; 32 (04) 331-340
- 7 Kim BS, Sila C.. Seizures in ischemic stroke. In: Seizures in Cerebrovascular Disorders. A clinical guide. New York, NY: Springer; 2015:17– 29
- 8 Rodriguez Ruiz A, Vlachy J, Lee JW. et al. Critical Care EEG Monitoring Research Consortium. Association of periodic and rhythmic electroencephalographic patterns with seizures in critically ill patients. JAMA Neurol 2017; 74 (02) 181-188
- 9 Aurangzeb S, Symmonds M, Knight RK, Kennett R, Wehner T, Irani SR. LGI1-antibody encephalitis is characterised by frequent, multifocal clinical and subclinical seizures. Seizure 2017; 50: 14-17
- 10 Camilo O, Goldstein LB. Seizures and epilepsy after ischemic stroke. Stroke 2004; 35 (07) 1769-1775
- 11 Cruz-Flores S, Alshekhlee A. . Seizures in intracerebral haemorrhage. In: M. Z. Koubeissi et al. eds. Seizures in Cerebrovascular Disorders. A clinical guide. New York: Springer; 2015: 31–40
- 12 Téllez-Zenteno JF, Pillai SN, Hill MD, Pillay N. Chronic PLEDs with transitional rhythmic discharges (PLEDs-plus) in remote stroke. Epileptic Disord 2007; 9 (02) 164-169
- 13 Kate MP, Dash GK, Radhakrishnan A. Long-term outcome and prognosis of patients with emergent periodic lateralized epileptiform discharges (ePLEDs). Seizure 2012; 21 (06) 450-456
- 14 Kennedy PGE. Viral encephalitis: causes, differential diagnosis, and management. J Neurol Neurosurg Psychiatry 2004; 75 (Suppl 1) i10-i15
- 15 Lai CW, Gragasin ME. Electroencephalography in herpes simplex encephalitis. J Clin Neurophysiol 1988; 5 (01) 87-103
- 16 Sakakibara E, Takahashi Y, Murata Y, Taniguchi G, Sone D, Watanabe M. Chronic periodic lateralised epileptic discharges and anti-N-methyl-D-aspartate receptor antibodies. Epileptic Disord 2014; 16 (02) 218-222
- 17 Lancaster E. The diagnosis and treatment of autoimmune encephalitis. J Clin Neurol 2016; 12 (01) 1-13
- 18 van Putten MJ, Hofmeijer J. Generalised periodic discharges: pathophysiology and clinical considerations. Epilepsy Behav 2015; 49: 228-233
- 19 Sakellariou DF, Kostopoulos GK, Richardson MP, Koutroumanidis M. Topography of generalized periodic epileptiform discharges in postanoxic nonconvulsive status epilepticus. Epilepsia Open 2017; 2 (04) 472-475
- 20 Witsch J, Frey HP, Schmidt JM. et al. Electroencephalographic periodic discharges and frequency-dependent brain tissue hypoxia in acute brain injury. JAMA Neurol 2017; 74 (03) 301-309
- 21 Krish S, Bazil CW. Interpreting periodic and rhythmic electroencephalographic patterns in critically ill patients. JAMA Neurol 2017; 74 (02) 150-151
- 22 Li HT, Wu T, Lin WR. et al. Clinical correlation and prognostic implication of periodic EEG patterns: a cohort study. Epilepsy Res 2017; 131 (March) 44-50
- 23 Chong DJ, Hirsch LJ. Which EEG patterns warrant treatment in the critically ill? Reviewing the evidence for treatment of periodic epileptiform discharges and related patterns. J Clin Neurophysiol 2005; 22 (02) 79-91
- 24 San-Juan OD, Chiappa KH, Costello DJ, Cole AJ. Periodic epileptiform discharges in hypoxic encephalopathy: BiPLEDs and GPEDs as a poor prognosis for survival. Seizure 2009; 18 (05) 365-368
- 25 Fitzpatrick W, Lowry N. PLEDs: clinical correlates. Can J Neurol Sci 2007; 34 (04) 443-450