Posterior slow waves of youthBy: Mohibullah Fazli Kakar

Posterior slow waves of youth(youth waves or poly phasic waves)• Physiologically high-voltage theta or delta waves accompanied

by the AR and creating spike wave-like phenomenon• Most commonly seen in children aged 8–14 years and are

uncommon in children under 2 years.• A 15% incidence in healthy individuals aged 16–20 years but

rare in adults above 21 years of age.• Typically seen both unilaterally and bilaterally in a single

recording. • They are always accompanied by the AR, attenuated with eye

opening, disappear with the AR during drowsiness and light sleep, and may be accentuated by hyperventilation and stress.

Posterior slow waves of youth(youth waves or polyphasic waves)• Characteristic findings:• Monorhythmic occipital rhythm attenuates with eye opening• Normal slower waveforms rarely >1.5 times the amplitude of

AR.• Normal slower waveforms attenuate with AR during alerting.• Slower waveforms has the same asymmetry in the ongoing AR

Index of abnormality of theta/delta slowing.• Complexity and variability of waveforms• Incidence (how often slow waves occur)• Voltage ratio (normal slow waves rarely >1.5 times the

amplitude of AR)• Persistence with eye opening • Symmetry (consistently predominant on one side).

EEG of a 9-year old boy with recurrent headaches

and numbness shows bilateral occipital slow waves (Box) intermixed with and briefly interrupting the alpha rhythm.

Posterior Slow Waves of Youth

Posterior Slow Waves of Youth

EEG of a 10-year-old boy with syncope showing occipital slow theta and delta waves (arrows) mixed with and briefly interrupting the alpha rhythm in both occipital regions but maximally expressed in the left.

Posterior Slow Waves of Youth Attenuated with Eye Opening

Posterior Slow Waves of Youth Attenuated with Eye Opening

Posterior Slow Waves of Youth Attenuated with Eye Opening

An 8-year-old boy with autism and few generalized

tonic-clonic seizures. The 24-hour ambulatory EEG performed to rule out

ESES persistently shows decreased alpha reactivity to eye closure (open arrow) and intermittent polymorphic delta slowing (arrow head) in the right occipital region without shifting lateralization.

This EEG can simulate “posterior slow waves of youth,” which is a physiologic finding.

However, persistent lateralization raises a concern of abnormality in the right posterior quadrant

Intermittent Right Occipital Delta Slowing; Simulating

Posterior Slow Wave of Youth.

Intermittent Right Occipital Delta Slowing; Simulating

Posterior Slow Wave of Youth.

Reference: Atlas of pediatric EEG