1. PART III THE USE OF EEG Epilepsy Periodic patterns Other

2. 1. Epilepsy 1. Yield after single seizure 50% (at best) higher if done sooner increases up to 80% with 4 th EEG 2. Epileptic abnormalities seen in approx. 0.5% of normals 2-14% with migraine, prior trauma, etc… 5-8% children 35% siblings of epileptics 3. Poor predictive value AAN practice parameter Neurology 2007; 69: 1996

3. 4. EEG most useful to classify the epileptic syndrome International classification of epilepsies Localization – idiopathic e.g. benign rolandic Localization – symptomatic/cryptogenic e.g. TLE Generalized – idiopathic e.g. JME Generalized – symptomatic/cryptogenic e.g. Lennox-Gastaut Age of onset Seizure Type(s) Family History Exam/Imaging EEG Epilepsia 2001; 42:796.

4. Epilepsy cont… King et al. Lancet 1998; 352: 1007 Syndrome diagnosed clinically in 47% With EEG, 77% EEG within 24hr, 51% vs. 34% Initial EEG 43%, after SD-EEG 61%

5. Epilepsy cont… Therefore…use the EEG to classify the epileptic syndrome, not to diagnose seizures e.g. TLE vs. JME

6. 2. Periodic Patterns Stereotypical sharp complexes repeating at a constant time interval for most or all of the recording.

7. Periodic Stereotypical Sharp Repeating Constant time interval Most of the recording

8. Rhythmic Rhythm = “the regular, measured flow of sound…or action” Rhythmic activity can be brief, and is continuous Hirsch et al. J Clin Neurophysiol 2005

9. Periodic Patterns cont… UNILATERAL PLEDs, Status BILATERAL Short latency (<4 sec) Triphasic waves, periodic complexes (of CJD) BiPLEDs, Status Long latency (>4 sec) Burst-suppression, SSPE

10. Alternatively… PLEDs BiPLEDs GPEDs Status, periodic complexes (CJD), SSPE, burst- suppression etc… triphasic waves??

11. PLEDs Considered to be an interictal epileptic pattern (but strongly assoc. with seizures) BiPLEDs occur independently over both hemispheres

12. PLEDs

13. Same patient (change timescale)

14. Periodic Complexes of CJD Can be biphasic, triphasic etc… Can be unilateral initially Not seen in nvCJD, FFI, only 10% other genetic CJD, rarely with v/v @ codon 129 Distinguish from triphasic waves based on clinical context Distinguish from PLEDs or status by reaction to stimuli, disappearance with sleep

15. Periodic complexes in CJD (from Ebersole and Pedley)

16. Periodic complexes in CJD (poor example)

17. Triphasic waves Toxic-metabolic encephalopathy Typical of (but not specific for) hepatic encephalopathy

18. Triphasic waves (Fisch and Spehlmann)

19. Triphasic waves

20. Burst-suppression

22. SSPE from Ebersole & Pedley)

23. Status Chong J Clin Neurophysiol 2005 adapted from Young Neurology 1996

24. Status NCSE post-arrest

25. 3. Other Coma Brain death EEG not indicated in headache* Can consider in certain situations (pregnancy EEG not useful in syncope 2003-2007 JGH 517 EEG’s for syncope, LOC, or fall 57 abnormal (0 epileptic, 6 potentially epileptic) Only 5 changed management *Neurology 1995;45:1263Neurology 2002;59:490 **Arch Int Med 1990;150:2027

26. PART IV SLIDESHOW

27. 3 Hz spike and wave with hyper

28. Focal interictal epileptic activity (right anterior temporal)

29. Cont… next page

30. Generalized interictal epileptic activity

31. Burst-suppression

32. Cont…next page

33. Focal seizure (glioma)

34. PLEDS

35. (Focal) non-convulsive status

36. Hypsarrythmia with infantile spasm

37. BECRS

38. Burst-suppression post-arrest

39. Triphasic waves

40. Periodic complexes in CJD (from Fisch and Spehlmann)

41. Focal slowing and epileptic activity, patient with sepsis

42. Independent seizures 37 week HIE Ebersole and Pedley

43. Cz-C3 Sp1- Sp2 Cz-C4 EOG Fp1-F7 T5-O1 Fp2-F8 T6-O2 Asystole secondary to a seizure

44. Cont…next page

45. PLEDS I year post TBI

46. REVIEW

47. TAKE-HOME MESSAGE 1. To read an EEG: -orient yourself -have an approach -describe what you see

48. TAKE-HOME MESSAGE 2. The EEG is prone to artifact. Findings such as epileptic activity or focal slowing are often a judgement call, and can be seen in normal people. Therefore, the EEG is not absolute.

49. TAKE-HOME MESSAGE 3. The EEG is not good at diagnosing or “ruling-out” seizures. It is far more useful for correctly classifying the epileptic syndrome.

50. TAKE-HOME MESSAGE 4. Exam questions will not be subtle (No artifacts, no subtle focal slowing)

51. REFERENCES

53. Drury I, Beydoun A. Pitfalls of EEG interpretation in epilepsy. Neurol Clin 1993; 11: 857-81. Noachtar S et al. A glossary of terms… Electroencephalogr Clin Neurophysiol Suppl 1999; 52: 21-41. Engel J. A proposed diagnostic scheme for people with epileptic seizures and with Epilepsy: Report of the ILAE Task Force on classification and terminology. Epilepsia 2001; 42: 796-803.

54. Sundaram et al. EEG in epilepsy: current perspectives. Can J Neurol Sci 1999; 26: 255- 62. Young GB. Metabolic and inflammatory cererbral diseases: electrophysiological aspects. Can J Neurol Sci 1998; 25: S16-S20. Blume WT. Clinical and basic neurophysiology of generalised epilepsies. Can J Neurol Sci 2002; 29: 6-18.