Normal Variants Flashcards
Fast and slow alpha variants
Features
Supra harmonic (2x) and subharmonic (1/2) of the PDR
Can be notched like RMTTD but in the posterior head
reactive to EO EC
Alpha squeak
Transient increase in PDR immediately following eye closure, do not calculate in 0.5-1 second
Rhythmic mid-temporal theta bursts of drowsiness (RMTTBD)
Other names?
Frequency, region, characteristics
State
Rhythmic mid-temporal discharges Trains or bursts of theta (5-7Hz) with notched appearance Maximal in midtemporal regions Bilateral with shifting dominance No evolution Relaxed waking or drowsy
Midline theta rhythm Other names Location Features State Reactive to
Ciganek rhythm Central vertex Cz Rhythmic 5-7Hz theta arciform with smooth or spiky appearance Drowsiness or waking Reacts to EO and alerting sometimes
Subclinical rhythmic electrographic discharge in adults (SREDA) Age State Location Features
Uncommon pattern seen in people older than 50
Occurs at rest during hyperventilation
Abrupt onset of mixed frequencies in the Delta and theta range which evolve to rhythmic pattern consisting of sharply contoured 5 to 7 Hz activity lasting 20 seconds to a few minutes
Typically widespread with maximal and put it in the posterior parietal temporal region
Typically bilateral
Evolve slow to fast
14 and 6 Hz Positive Bursts Other name State Features Location Age Montage Disease
Ctenoids
Drowsiness and light sleep
Consist of short trains of arch shaped waves with alternating positive spike and a negative smooth rounded waveform with a sharp positive Phase
Usually asynchronous or bilateral was shifting predominance
Typically the 14 Hz seen more than the six Hz
Seen mostly in the posterior temporal region
Peaked at 13 to 14 and seeing less with increasing age
Referential to ipsilateral ear
Reye’s syndrome
6 Hz spike and wave bursts Other name State Location Special types
Phantom Spike and wave
5 to 7 Hz bursts of low amplitude spikes with a slow wave during relaxed waking
phone is drowsiness but not in sleep synchronous and bilateral
FOLD(female occipital low amplitude and drowsiness)
WHAM (wake high amplitude anterior and male)
FOLD is considered to be benign whereas WHAM can be associated with seizures
Benign sporadic sleep spikes (BSSS)
Other names
State
Description
Also called small sharp spikes or benign epileptiform transient of sleep
Seen usually an adults during drowsiness and light sleep but not in deep sleep
They are low-voltage less than 50 µV and short induration less than 50 ms with either a one or two phase spike with abrupt Ascension and steep descending without a slow wave
They do not occur in trains typically are in isolation on one side but can involve both hemispheres
Wickets
Description
State
Why they are not epileptiform
Intermittent trains of monophasic archlike waveforms or single spikelike waveforms
Typically occur on one side left is more common than right but can be bilateral was shifting dominance
Seen during wakefulness drowsiness and light sleep but not in deep sleep
If you’re concerned that it could be in epileptiform spike compare with the trains of wickets on other pages, should not be followed by a slow wave or distort the background
The third rhythm
Other name
Description
Suspected function
Also called temporal alphoid rhythm
Rhythmic activity in the Alpha and upper theta range in the middle temporal region
Open not seen on the scalp EEG unless there is a bony defect and may be related to cortical auditory function could be considered the resting or idling rhythm of the temporal lobe
Frontal Arousal Rhythm Description Frequency Population State
Trains of 7 to 20 Hz waveforms that occur in the frontal region lasting up to 20 seconds and may be notched in appearance and seen in children with arousal from sleep and it disappears once fully awake
My Rhythm
Description
Location
Related to what brain area
Arch like 7 to 11 Hz waveforms seen in the central head regions related to sensory and motor cortex and can be attenuated by active movement or passive movement or even the thought of movement of the contralateral extremity
Lambda waves
Location
Description
State
Resembles the Greek letter lambda two phases surface positive in the occipital regions when a person is visually scanning while awake. They typically are bilateral and synchronous but can be asymmetric possibly represents a visual evoked potential
Positive occipital sharp transients POSTs
Description
Sharp positive transient in the occipital regions during light sleep typically bilateral and synchronous but may
be asymmetric
Mitten
State
Description
Related to what
Present during sleep consisting of a fast way and slow wave which with symbols a mitten with the thumb being formed by the last wave of a spindle and hand by the slower wave is thought to be a variant of a vertex wave or K complex
