Normal Encephalography-Neuromedicine and Psychiatry

Normal Encephalography

1. BENIGN EEG VARIANTS PRESENTER: DR. SUDESH KHANAL PSYCHIATRY 3 RD YEAR RESIDENT NEPALGUNJ MEDICAL COLLEGE TEACHING HOSPITAL

2. CONTENTS Introduction Types of benign variants Rhythmic EEG variants Epileptiform EEG variants Lambda and lambdoids Age related variants References

3. INTRODUCTION Variants are the EEG patterns that look like abnormal but considered as normal under given circumstances.

4. TYPES OF VARIANTS 1. Rhythmic patterns. 2. Epileptiform patterns. 3. Lambda and lambdoids . 4. Age-related variants

5. RHYTHMIC VARIANT PATTERNS Alpha variant. Mu rhythm. Rhythmic temporal theta burst of drowsiness (“psychomotor variant”). Subclinical rhythmic electrographic (theta) discharges in adults (SREDA). Midline theta rhythm.

6. ALPHA VARIANTS There are two types of alpha variants, "slow” and “fast.” The slow (sub harmonic) alpha variant appears as an abrupt, usually has a bifurcated configuration rhythm and half the frequency of the patient’s more typical waking background rhythm, and often of greater voltage.

7. ALPHA VARIANTS The fast (harmonic) ….“double” the frequency of the patient’s more typical waking background rhythm, appearing as beta activity. The fast alpha variant rhythm can be induced by hypnotic or anxiolytic medications such as barbiturates or benzodiazepines . Alpha variants behave like alpha rhythm and occurs less than 1% of the normal adult population

8. ALPHA VARIANTS

9. ALPHA VARIANTS

10. ALPHA VARIANTS

11. SMALL SHARP SPIKES Amplitude:< 50 micro volt Frequency:< 50 m.sec Morphology: Monomorphic, mono/biphasic/polymorphic Distribution: Anterior/mid temporal Rhythmicity: Intermittent Reactivity: Enhanced with stage 1 sleep/medications, disappear in slow wave sleep

12. SMALL SHARP SPIKES

13. 14-6 HZ POSITIVE SPIKES AND WAVES Amplitude:< 20 micro volt Frequency: 14 Hz and 6 Hz Morphology: Arch shape wave form, alternating with positivespike and negative smooth rounded wave forms Distribution: Posterior temporal Rhythmicity: Independent bursts Reactivity: Drowsiness and during sleep/Adolescents

14. 14-6 HZ POSITIVE SPIKES AND WAVES

15. RHYTHMIC MID-TEMPORAL THETA ACTIVITY IN DROWSINESS (RMTD) Amplitude:50-60 micro volt Frequency: Delta Morphology: Biphasic/Triphasic, Triangular with notching Distribution: Mid-temporal Rhythmicity: Rhythmic Reactivity: Drowsiness/Adolescents, young adults

16. RHYTHMIC MID-TEMPORAL THETA ACTIVITY IN DROWSINESS (RMTD)

17. SUBCLINICAL RHYTHMIC ELECTROGRAPHIC DISCHARGE OF ADULT (SREDA) Amplitude:20-50 micro volt Frequency: 4.5-7 Hz Morphology: Sharp contoured Distribution: Parietal, posterior temporal region Rhythmicity: Rhythmic, evolving Reactivity: Drowsiness/occasionally in hyperventilation, >50 years old, waking state

18. SUBCLINICAL RHYTHMIC ELECTROGRAPHIC DISCHARGE OF ADULT (SREDA)

19. WICKET WAVES Amplitude: High 200 micro volt Frequency: 6-11 Hz Morphology: Spikes like wicket Distribution: Temporal Rhythmicity: Single or brief series Reactivity: Drowsiness and light sleep, adult> 30 years

20. WICKET WAVES

21. BREACH RHYTHM Amplitude: High Frequency: Fast, occasionally mix with slow, spikes and sharp Morphology: Monomorphic Distribution: Focal ( Skull defect) Rhythmicity: Rhythmic Reactivity:Persistent

22. BREACH RHYTHM

23. FOLD Amplitude: Low amplitude Frequency: 6 Hz Morphology: Spike and wave Distribution: Occipital Rhythmicity: Single or brief serials Reactivity: Drowsiness, Benign Female Occipital Low amplitude Drowsiness

24. FOLD

25. WHAM Amplitude: High amplitude Frequency: 6 Hz Morphology: Spike and wave Distribution: Frontal Rhythmicity: Single or brief serials Reactivity: Wakefulness/Persist into slow wave sleep, association with seizure Wakefulness High amplitude Anterior Male

26. WHAM