Periodic Lateralizing Epileptiform Discharges

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Periodic Lateralizing Epileptiform Discharges, PLEDS

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Periodic Lateralizing Epileptiform Discharges

  1. 1. Periodic Lateralized Epileptiform Discharges Dr.Roopchand.PS Senior Resident Academic TDMC, Alappuzha
  2. 2. • The term periodic lateralized epileptiform discharges (PLEDs), first coined by Chatrian and colleagues in 1964, is a peculiar electroencephalogram (EEG) pattern consisting of unilateral and focal spikes or sharp wave complexes that appear periodically, usually at the rate of 1~2 s.
  3. 3. Description: • Classically triphasic with a sharply contoured wave followed by a slow wave. • Incidence of 0.4% to 1% • Usually a singular focus – PLED’s • Duration is between 100 to 300 ms • Amplitude is 100 to 300mV
  4. 4. • It is the conserved recurrence pattern that is more important than morphology. • The regularity may vary – Can be highly regular – With out any set interval. • Recurrence frequency commonly fall in the range of one transient every 0.5 to 4 sec – 2 sec interval is mc • Low amplitude slow activity separates PLEDs.
  5. 5. PLEDs or ECG? • Both have similar morphology and periodicity. • Simultaneous ECG recording helps. • PLEDs not as regular as ECG. • ECG may be unilateral or bilateral • PLEDs are not bilateraly synchronous.
  6. 6. • BiPED – large frontal fields. • ECG – temporal region. • ECG usually 1Hz. • PLEDs can be differentiated from inter ictal discharges by periodicity. • IEDs can periodically recur but interval varies and occur only sporadically.
  7. 7. Clinical significance: • Indicated focal pathology that is acute or sub acute. • May indicate a cortical involvement and co existing metabolic abnormality. • Over all significance is same in children and adults. • 80% cases there will be a co localized focal deficit.
  8. 8. • PLEDs usually lasts day to weeks. – Rarely years. • Causes: • Cortical strokes (50%) – Embolism, watershed infarcts • Tumors and cerebral infections(20%) • Prion diseases, extra-axial hematoma, epilepsy.
  9. 9. • Rare causes: – Alzheimer's ds – Mitochondrial ds – MS – Intoxication with baclofen, lithium, levodopa, ifosfamide. – Trauma with out subsequent hemorrhage.
  10. 10. • PLEDs indicate clinically significant risk for seizures. • Seizure occur in up to 80% of patients with PLEDs. – Focal motor seizure MC • 20% with PLEDs are comatosed and 80% will have impaired consciousness. • Among infections HSE is the MC.
  11. 11. • Most HSE shoes PLEDs at some point of time. • MC with in a week of onset of symptoms. • Disappears by 2 weeks after the onset. • PLEDs due to HSE is almost always centered over one or both temporal lobes. • When B/L are synchronous and time locked. – Interval 1.5 to 2.5 sec • Inter discharge intervel almost always 1 to 5 sec.
  12. 12. • Other viruses producing temporal PLEDs: influenza B, LaCrosse. • CJD is the MC prion disease producing PLEDs. – Helps to differentiate CJD from other dementias. – 67 – 100% CJD will have PLEDs. – Recur every 0.5 to 2 sec – Usually hemispheric with focal predominance when they first manifest. – Present only during wakefulness. – Onset after several months of onset of clinical ds. – Evolve to BiPED as disease progress and disappears.
  13. 13. Reiher Classification(1991): • Reiher et al. (1991) described the brief and low amplitude focal stereotyped rhythmic discharges (RDs) closely associated in temporal and spatial distributions to higher amplitude interictal epileptiform discharges. • They subdivided PLEDs into two categories: • (1) PLEDs plus- associated with RDs and • (2) PLEDs proper-not associated with RD.
  14. 14. • PLEDs proper were subdivided into PLEDs of classes 1, 2, and 3 – Based on the metronomicity of the periodicity. • PLEDs plus could be subdivided into PLEDs of classes 4 and 5. – Based on the duration of RDs

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