Patterns: Abnormal Variants Flashcards
faster or slower
frequency
higher or lower
voltage
varies from usual
location
differs from usual
morphology
fails to react
reactivity
what can be seen on an abnormal EEG
- background slowing
- slow waves
- paroxysmal discharge
- specific patterns
what can abnormal EEGs present as?
- focal
- lateralized
- generalized
the dominant activity of wakefulness and rest. Alpha activity is considered the most common background activity
normal
the dominant activity recorded in abnormal patients during resting asymptomatic periods
abnormal
when is delta abnormal?
in an awake patient
delta intermixed with other frequencies
polymorphic (arrhythmic)
- lesion of cerebrum
- white matter of dysfunction
- structural lesions (tumors, CVA, Abscess, Dementias)
Focal (polymorphic)
- toxic encephalopathy
- metabolic encephalopathy
- degenerative disorders
- demyelinating disorders
- infectious diseases
- cerebral ischemia
generalized (polymorphic)
- IRDA
- generalized brain dysfunction
- repeating delta waves of the same frequency
monomorphic (rhythmic)
- frontal predominance
- adults
- bursts of sinusoidal, bilaterally synchronous, monomorphic activity
FIRDA
what attenuates FIRDA?
- eye closure
- HV
- drowsiness
what are causes of FIRDA?
- tumors
- toxic/ metabolic encephalopathy
- increased ICP
- occipital predominance
- children
- absence seizures
OIRDA
- temporal predominance
- usually associated with temporal lobe epilepsy
TIRDA
- spike or sharp waves or mixed theta-delta waves
- background always disrupted
- biphasic or triphasic spike or wave discharges occur after acute insult
- non-reactive
Periodic Lateralized Epileptiform Discharges (PLEDS)
what are causes of PLEDS
- ischemic CVA
- herpes simplex encephalitis
- tumors
- encephalitis
- cerebral abscess
- voltage 100-200 uV
- asynchronous
- bi/triphasic spike or sharp wave discharges
- background always disrupted
- non-reactive
BIPLEDS
what are causes of BIPLEDS
- anoxic encephalopathy
- herpes simplex
- 9-10 Hz
- generalized
- fronto-central maximum
- usually no slow waves
- non-reactive
- poor prognosis
alpha coma
what are causes of alpha coma
- cerebral anoxia
- brainstem lesions
- drug overdose
- small negative, large positive, negative waveform
- generalized with frontal maximum
- anterior- posterior phase lag of 60-120 ms
- abnormal background
triphasic waves
causes of triphasic waves
- metabolic disturbances
- primarily hepatic encephalopathy
- periods of moderate-high amplitude activity usually lasting a few seconds
- bursts consist of spikes, sharps, and other frequencies
- generalized
- deepest level of coma before brain death
- non responsive
burst suppression
causes of burst suppression
- anoxic encephalopathy
- acute intoxication
- hypoxia
- head injury
- may be reversible if due to drug overdose, hypothermia, or anesthesia
waveforms that repeat with approximately the same interval each time
periodic patterns
Give examples of periodic patterns
- PLEDS
- BIPLEDS
- CJD
- Herpes Simplex Encephalitis
- ECI
- biphasic and triphasic periodic sharp waves
- excessive slow activity
- disorganized background
- prion diseased
- rapidly progressive dementia
Jakob-Creuzfeldt Disease (CJD)
balance disturbance
ataxia
- usually affects temporal lobes
- viral infection
- lies dormant in the trigeminal nerve
Herpes Simplex Encephalitis
list symptoms of HSE
- drowsy or confusion
- nuchal rigidity
- fever
- HA
- seizures
list examples of CJD
- rapidly progressive dementia
- speech impairment
- myoclonus
- ataxia
- seizures
> 2uV
ECI
