ICU Clinical Correlates

39 Questions

What is a characteristic feature of triphasic waves?

Each phase is longer than the preceding

What is the typical frequency of Frontally Predominant Intermittent Rhythmic Delta Activity (FIRDA)?

2-2.5 Hz

What percentage of patients undergoing cEEG monitoring showed Stimulus Induced Rhythmic, Periodic, or Ictal Discharges (SIRPIDS)?

33%

What is a critical question to ask when evaluating EEG patterns?

Are these discharges causing neuronal damage?

What is a common association of Frontally Predominant Intermittent Rhythmic Delta Activity (FIRDA)?

Subcortical or brainstem damage

What is a characteristic of triphasic waves that distinguishes them from seizures?

Responds to benzodiazepines

What is the significance of Stimulus Induced Rhythmic, Periodic, or Ictal Discharges (SIRPIDS) in patient care?

Associated with focal or ictal appearing discharges

What is a limitation of EEG in evaluating patients with seizures?

EEG cannot differentiate between status epilepticus and encephalopathy

What is a common etiology of Frontally Predominant Intermittent Rhythmic Delta Activity (FIRDA)?

Toxic-metabolic disturbances

What is the percentage of patients with poor outcome in the study of 116 patients who underwent cEEG and were assessed with modified Rankin Scale at 3 months?

69%

Which of the following is an independent predictor of poor outcome in patients with subarachnoid hemorrhage (SAH)?

Absence of sleep architecture

What is the odds ratio of poor outcome in patients with SAH who have any periodic discharges (PEDs)?

9.0

What percentage of management decisions were influenced by cEEG monitoring in the study of 73 patients?

82%

What is the most common management change made as a result of cEEG monitoring?

Initiation or change of antiepileptic drugs (AEDs)

What is the minimum duration of a pattern required to meet the criteria for non-convulsive seizure (NCSE)?

10 seconds

What is the frequency of repetitive spikes or sharp waves required to meet the criteria for NCSE?

3 Hz

What is the significance of triphasic waves in the context of NCSE?

They can be abolished by administration of benzodiazepines

What is the term for the spectrum of cerebral activity that includes monomorphic, generalized periodic discharges (GPDs), low-voltage delta, and burst suppression?

Spectrum of cerebral activity

What is the term for the type of discharge that is characterized by a rhythmic, localized, and evolving pattern?

Lateralized periodic discharges (LPDs)

What is a major concern in a patient with refractory status epilepticus being treated with multiple antiepileptic drugs?

Hepatotoxicity

What is the primary goal of managing a patient with status epilepticus?

Preventing increase in ICP

What is the characteristic of a monomorphic EEG pattern?

Repetitive and stereotyped waveforms

What is the significance of PLEDs in a patient with seizures?

They are associated with acute infarct, infection, or hematoma

What is the typical outcome of patients with GPEDs?

Nearly 100% mortality

What is the significance of a triphasic wave pattern on EEG?

It is a variant of GPEDs

What is the significance of SIRPIDs on EEG?

They are associated with acute infarct or infection

What is the primary goal of cerebral activity monitoring in a patient with status epilepticus?

Detecting seizures

What is the characteristic of LPDs with a high frequency?

They are a sign of ictal activity

What is the significance of a burst-suppression pattern on EEG?

It is a sign of neuronal injury

What is the primary reason for continuous EEG monitoring in the NICU?

To detect subclinical seizures

According to DeLorenzo's study, what percentage of patients had electrographic seizures after GCSE?

32%

What is the level of evidence for absent pupil response, corneals, and motor response at 3 days as predictors of outcome in comatose survivors of cardiac arrest?

Level A

What percentage of patients with NCSE had a mortality rate independent of etiology?

36%

What is the primary goal of EEG monitoring in the ICU?

To detect seizures

According to Vespa's study, what percentage of patients with TBI had NCS detected by cEEG?

22%

What is the term for the slowing of EEG activity during a seizure?

Ictal discharge

What is the definition of non-convulsive status epilepticus (NCSE)?

A seizure that is not accompanied by convulsive movements

According to the AAN Practice Parameter, what is the level of evidence for bilaterally absent cortical responses on SSEPs at 3 days as predictors of outcome in comatose survivors of cardiac arrest?

Level B

What is the primary benefit of continuous EEG monitoring in terms of seizure detection?

It allows for the detection of seizures that are not clinically apparent

Study Notes

Triphasic Waves

High amplitude, positive discharge
Each phase longer than the preceding
Frontally predominant +/- A-P lag
Associated with hepatic or renal encephalopathy and anoxia
Can be suppressed with benzodiazepines, but this does not prove the pattern is a seizure

Frontally Predominant Intermittent Rhythmic Delta Activity (FIRDA)

High amplitude, bisynchronous slow waves
Typical frequency of 2-2.5 Hz
May be abolished by alerting or eye opening
Often seen with triphasic waves
Usually implies distal, subcortical or brainstem damage (projected rhythm)
Typically seen in toxic-metabolic disturbances
May be seen with large midline structural lesions or increased ICP with herniation

Stimulus Induced Rhythmic, Periodic, or Ictal Discharges (SIRPIDS)

22% of patients undergoing cEEG (33/150)
Includes PLEDs, GPEDs, triphasics, focal or generalized ictal patterns
50% experienced clinical or subclinical seizures during hospitalization
33% in status epilepticus at some point
Associated with focal or ictal appearing discharges

Periodic Patterns

Distinction between ictal, interictal, and not ictal is often not clear
EEG alone can fail to clearly differentiate status from encephalopathy
Critical questions:
- Do these discharges cause neuronal damage or neurological consequences?
- Do they have prognostic significance?
- Are they treatable, and will suppressing them improve outcome?

cEEG Findings Predictive of Outcome in SAH

116 patients underwent cEEG and were assessed with modified Rankin Scale at 3 months
Overall poor outcome in 69%
Independent predictors of poor outcome:
- Any periodic discharges (PEDs) - 90% vs. 63%, OR 9.0
- Absence of sleep architecture - 80% vs. 47%, OR 4.3
- Absence of reactivity - 100%
- GPEDs or BiPLEDs - 100%
- NCSE in first 24 hours - 100%

cEEG Influences Medical Decision Making

73 patients undergoing cEEG
Decisive management changes in 51% and contributing management changes in 31%
Most common management changes:
- Initiate or change AED
- Emergent CT scan

Spectrum of Cerebral Activity

Probably not ictal: monomorphic delta, FIRDA, SIRPIDs
Interictal: LPDs, GPEDs, triphasics
Ictal: LPDs+, rhythmic spikes and waves, clinical correlates

Criteria for Non-Convulsive Seizure

Any pattern >10 seconds and one of the following:
- Repetitive spikes or sharp waves at least 3 Hz
- Rhythmic discharges >1 Hz and unequivocal evolution in frequency, morphology, location
- Repetitive spike or sharp waves < 3 Hz AND significant clinical improvement and appearance of normal EEG pattern after administration of rapid-acting AED