Classic EEG Abnormalities

Academic Half-DayJune 5th 2013

HOW DO YOU READ AN EEG?

HOW CAN AN EEG BE ABNORMAL?

1. Epileptic1. Focal or Generalized Interictal2. Focal or Generalized Seizure3. Non-convulsive Status

2. Periodic1. PLEDs/BiPLEDs2. GPEDs3. Burst-suppression4. Triphasic waves5. Periodic complexes (CJD)

3. Background Abnormality

Case One

Case One

• How do you decide it is epileptic activity?(inter-ictal)

• Sharp, asymmetrical (rapid rise)• Voltage maximum• “Field”• Slow wave• Recurs

Fisch and Spehlman’s EEG Primer

Case Two

Case Two

• It is generalized

• It is “inter-ictal”

• There is normal background

Case Three

Case Three

• “it is what it sounds like”

• No normal background

• It is periodic (which means…)

• It is bilateral

Case Four

Case Four

• It looks epileptic

• Generalized

• “Neat and orderly”

• Normal background

• Don’t get thrown off by high amplitude

Case Five

Case Five

Case Five

• “it is what it sounds like”

• Epileptic, Periodic, Lateralized

• Don’t worry about volume conduction

Chong DJ and 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;22:79.

Case Six

Case Six

• Repetitive spikes or sharp waves (alone or in complexes with slow waves) at > 2.5 / sec

• Above, < 2.5 / sec, with either clinical ictal phenomena or response to AED

• Rhythmic slow waves with evolution in frequency or location

Kaplan P. EEG criteria for non-convulsive status epilepticus. Epilepsia 2007; 48 (suppl 8):39-41.

Case Seven

Case Seven

• Generalized

• Synchronous

• Periodic

Foreman et al. Generalized periodic discharges in the critically ill. A case control study of 200 patients. Neurology 2012;79:1951-60.

Case Eight

Case Eight

• Focal or generalized

• Looks epileptic (sharp)

• Continuous

Case Eight

Case Nine

Case Nine

• Fairly strict criteria; it does have to be periodic and triphasic

• But…mimics

• So…clinical context

Kaplan P. EEG criteria for non-convulsive status epilepticus. Epilepsia 2007; 48 (suppl 8):39-41.

Case Ten

Case Ten

• Periodic

• Clinical context

• “The least unique”• Usually bilateral but can be unilateral• Sharp waves but variable morphology

Weiser et al. EEG in Creutzfeld-Jakob disease. Clin Neurophysiol 2006; 117: 935-51.

EEG ELECTIVES…