Normal Variants Quiz

What is the normal location of the Mu rhythm in the EEG?

• Central or centro-parietal

• Posterior

• Frontocentral regions

• Frontal vertex

Identify this normal variant.

• Mu

• Lambda

• Wickets

• RMTD

• SSS

Answer explanation

Mu Rhythm

• * Arch-shaped, comb-like

• * Frequency: 7-11 Hz

• * Location: Central or Centro-parietal

• * Level of Consciousness: wakefulness

• * Reactivity: blocked by actual or imagined contralateral limb movement

Identify this normal variant.

• Mu

• Lambda

• Wickets

• RMTD

• SSS

Answer explanation

RMTD

"Rhythmic Mid-temporal Theta Drowsiness"

• * Theta w/ flat-topped, sharply contoured, often notched

• * Duration: 5-10 sec

• * Location: mid- or anterior temporal

• * Level of consciousness: drowsiness or relaxed. attenuates in deeper levels of sleep

Identify this normal variant.

• Mu

• Lambda

• Wickets

• RMTD

• SSS

Answer explanation

SSS

Small Sharp Spikes

• * Sharp, often followed by small theta; single monophasic or biphasic spike or sharp

• * Duration: brief, <50msec

• * Location: temporal

• * Level of consciousness: deep drowsiness, very light sleep

Identify this normal variant.

• Mu

• Lambda

• Wickets

• RMTD

• SSS

Answer explanation

SSS

Small Sharp Spikes

• * Sharp, often followed by small theta; single monophasic or biphasic spike or sharp

• * Duration: brief, <50msec

• * Location: temporal

• * Level of consciousness: deep drowsiness, very light sleep

Identify this normal variant.

• Mu

• Lambda

• Wickets

• RMTD

• SSS

Answer explanation

Mu Rhythm

* Arch-shaped, comb-like

* Frequency: 7-11 Hz

* Location: Central or Centro-parietal

* Level of Consciousness: wakefulness

* Reactivity: blocked by actual or imagined contralateral limb movement

Identify this normal variant.

• Mu

• Lambda

• Breach

• RMTD

• SSS

Answer explanation

Mu Rhythm

* Arch-shaped, comb-like

* Frequency: 7-11 Hz

* Location: Central or Centro-parietal

* Level of Consciousness: wakefulness

* Reactivity: blocked by actual or imagined contralateral limb movement

Identify this normal variant.

• Mu

• Lambda

• Wickets

• RMTD

• SSS

Answer explanation

Mu Rhythm

* Arch-shaped, comb-like

* Frequency: 7-11 Hz

* Location: Central or Centro-parietal

* Level of Consciousness: wakefulness

* Reactivity: blocked by actual or imagined contralateral limb movement

Identify this normal variant.

• Mu

• Lambda

• Wickets

• RMTD

• SSS

Answer explanation

Lambda

Sawtooth-shaped, biphasic or triphasic

POSTS during wakefulness

• * Location: O1, O2

  • * Level of consciousness: awake during visual exploration

  • * Reactivity: blocks with blank sheet of paper in front of the eyes, darkening the room, or eye closure

Identify this normal variant.

• Mu

• Lambda

• Breach

• RMTD

• SSS

Answer explanation

Mu Rhythm

* Arch-shaped, comb-like

* Frequency: 7-11 Hz

* Location: Central or Centro-parietal

* Level of Consciousness: wakefulness

* Reactivity: blocked by actual or imagined contralateral limb movement