Activation procedure Flashcards
Hyperventilation (HV) – to induce changes in brain activity
particularly in detecting generalized epilepsy
Photic Stimulation (PS) – Flashing lights at various frequencies to assess photoparoxysmal responses
commonly used in patients with suspected photosensitive epilepsy.
What is the purpose of activation procedures in EEG?
To bring out abnormalities not seen in the baseline EEG and to enhance abnormalities already seen in the baseline EEG.
What is the effect of activation techniques on epileptiform activity?
They can amplify epileptiform activity, making abnormalities clearer.
Fill in the blank: Activation procedures in EEG can be used to _______ abnormalities already seen in the baseline EEG.
[enhance]
True or False: Activation procedures in EEG can only bring out new abnormalities.
False
What should be explained to the patient before starting the procedure?
The procedure itself to ensure cooperation
Clear communication enhances patient compliance and comfort.
What is the recommended breathing rate for the patient during the procedure?
18–24 deep breaths per minute (approximately 3–4 seconds per breath cycle)
This breathing rate helps optimize the effectiveness of the procedure.
What is the minimum duration for which HV should be performed?
3 minutes
Adequate duration is critical for capturing accurate results.
What should be minimized during the procedure to reduce artifact?
Movement of the head and body
Stillness is essential to ensure clean EEG recordings.
What is the role of the technologist during the procedure?
To pace the breathing rate and encourage the patient
Active engagement helps maintain the patient’s focus and adherence to the procedure.
What tool can be used to assist children in maintaining an effective HV rate?
A pinwheel
This playful tool can make the process more engaging for younger patients.
Why is timing important in the procedure?
It should be timed accurately
Proper timing ensures that the data collected is reliable and valid.
What should be noted regarding the patient during the procedure?
The patient’s effort level
Assessing effort helps evaluate the effectiveness of HV.
How long should EEG recording continue post-HV?
At least 1 minute
This allows for capturing any delayed responses that may occur after the procedure.
What happens to carbon dioxide levels due to increased breathing rate?
CO₂ is expelled faster than it is produced
This process leads to a reduction of carbon dioxide (PCO₂) levels.
What is hypocapnia?
Low CO₂ levels
Hypocapnia can lead to vasoconstriction.
What effect does hypocapnia have on cerebral blood vessels?
Causes narrowing of cerebral blood vessels
This narrowing reduces blood flow to the brain.
How does decreased cerebral blood flow affect the brain?
Can make the brain more excitable
This increased excitability can potentially trigger generalized 3 Hz spike-and-wave discharges in individuals with absence epilepsy.
Why is hyperventilation (HV) an important activation procedure in EEG?
It is important for evaluating absence seizures and other epilepsy types
The physiological effects of HV explain its significance in EEG testing.
What can recent intracranial hemorrhage cause in relation to cerebral blood flow?
HV can alter cerebral blood flow, increasing the risk of further bleeding.
HV refers to hyperventilation.
What effect can HV-induced vasoconstriction have after a recent TIA?
It may trigger another ischemic event.
TIA stands for Transient Ischemic Attack.
How can HV affect patients with a recent CVA?
Reduced cerebral blood flow from HV could worsen brain injury.
CVA stands for Cerebrovascular Accident or Stroke.
What is Moyamoya disease?
A condition causing abnormal blood vessel growth; HV can lead to dangerous ischemia.
Name a significant cardiopulmonary disease that can be affected by HV.
Significant cardiopulmonary diseases include:
* Recent heart attack
* COPD
* Asthma
COPD stands for Chronic Obstructive Pulmonary Disease.
What risk does HV pose to patients with a recent heart attack?
Increased respiratory demand could stress the heart.
What complications can HV cause in patients with COPD?
HV can lead to hypoxia and respiratory distress.
How can HV affect asthma patients?
It may trigger bronchospasm and breathing difficulties.
True or False: HV is safe for patients with significant cardiopulmonary disease.
False
These conditions make HV unsafe due to the risk of worsening cerebral or cardiopulmonary function.
What is HV commonly used for in EEG?
To help diagnose generalized epilepsy, especially absence seizures.
HV stands for hyperventilation.
What does persistent or asymmetric slowing in EEG suggest?
Neurological pathology and requires further evaluation.
This can indicate underlying conditions that need to be addressed.
What is photic stimulation (PS)?
Intermittent flashes of light delivered at various frequencies to assess photosensitivity in patients
PS is a method used to evaluate how a patient’s brain reacts to light.
What is the purpose of photic stimulation?
Determines if the patient is prone to seizures triggered by light, also known as photosensitive epilepsy
This assessment helps identify individuals at risk for light-induced seizures.
What does photic stimulation help detect?
Photoparoxysmal responses (PPR)
PPR includes abnormal spike-and-wave discharges or polyspike activity in response to flashing lights.
Which patients may exhibit a photoparoxysmal response?
Patients with generalized epilepsy syndromes, such as juvenile myoclonic epilepsy (JME)
JME is a common type of generalized epilepsy that often shows PPR during photic stimulation.
What precautions should be taken before photic stimulation testing?
Patients should be warned about potential seizure triggers before testing
This warning is crucial for patient safety to prevent unexpected seizures.
What is the recommended distance to position the strobe light from the patient’s eyes?
12 inches (30 cm)
This distance is crucial for optimal visibility and effectiveness.
What is the Photic Driving Response?
A normal occipital EEG rhythm that follows the flash frequency of the strobe light
This response is observed in electroencephalography (EEG) during exposure to flashing lights.
Where is the Photic Driving Response best seen?
At posterior electrodes (occipital region, O1 & O2)
O1 and O2 are standard electrode placements in EEG recording.
What frequency range is the Photic Driving Response strongest in?
Between 8–15 Hz
This range corresponds to the alpha frequency range in EEG.
Fill in the blank: The Photic Driving Response is strongest between _______ Hz.
8–15 Hz
True or False: The Photic Driving Response is associated with the beta frequency range.
False
The strongest response occurs in the alpha frequency range, not the beta range.
What are abnormal responses that may indicate photosensitive epilepsy?
Photoparoxysmal responses (PPR)
PPR includes spike-and-wave or polyspike discharges.
What types of discharges are included in photoparoxysmal responses?
Spike-and-wave or polyspike discharges
These discharges are characteristic of certain epileptic conditions.
What does PMR stand for?
Photomyogenic response
What was PMR formerly referred to as?
Photomyoclonic response
What does PMR consist of?
EMG artifacts time locked with the flash frequency
What factors may enhance PMR?
Alcohol or in a barbiturate withdrawal state
Is PMR considered an abnormal response?
No
What is the Photo-convulsive Response?
A response characterized by paroxysmal spike and wave activity originating from the cortex.
What type of activity is observed in the Photo-convulsive Response?
High voltage diffuse spikes and/or spike/wave or polyspike/wave.
What indicates an abnormal Photo-convulsive Response?
A response that continues after the flash ends.
What flash frequency often elicits paroxysmal activity?
15/sec.
What is frequently associated with eye closure during the Photo-convulsive Response?
Paroxysmal activity.
What happens to the Photo-convulsive Response until the patient has a seizure?
It continues on.
What should the tech document during the Photo-convulsive Response?
All changes including:
* Twitches
* Jerks
* Eye flutter
What is natural (spontaneous) sleep?
EEG recorded as the patient naturally falls asleep
This type of sleep is observed without any external intervention.
How does sleep deprivation affect epileptiform activity?
Lack of sleep can increase epileptiform activity, useful in epilepsy diagnosis
This phenomenon is often utilized in clinical settings to assess seizure disorders.
What is drug-induced sleep?
Sedatives (e.g., chloral hydrate, benzodiazepines) may be used if needed
This approach is typically employed when natural sleep is not achievable.
What is a powerful activation method for revealing epileptiform discharges?
Sleep deprivation
What seizure type has a >80% photo paroxysmal response?
GTC, JME
What is the purpose of activation procedures?
Eliciting abnormal EEG activity
Hyperventilation consists of
Deep breathing for 3 - 5 minutes
T or F: Unilateral diffuse and synchronous slow-wave bursts are normal in HV.
FALSE
Anteriorly dominant theta-delta buildup during HV is most common in what age groups?
Adolescents and adults
HV is most effective in what age group?
8 - 12 years
What does HV do physiologically?
Reduces carbon dioxide concentration and causes vasoconstriction of blood vessels
T or F: Numbness and tingling during and after HV is an abnormal response.
FALSE
What seizure type is activated 80% of the time by HV?
Absence
HV should not be performed on patients with:
Moya Moya, Sickle cell, Acute stroke, Recent TIA
Photic stimulation is performed to elicit
Photoparoxysmal response
In photic stimulation, the stimulations are given
For 10 seconds with 10 seconds between stimuli
What is a photic driving response?
A normal occipitally dominant response that occurs at a 1:1 rate with photic stimulation
A photic driving response occurs
At a frequency closest to the patient’s alpha rhythm
What is the most effective frequency to elicit a photoparoxysmal response?
15 - 20 Hz
T or F: 70% - 80% of patients with photo paroxysmal response have epilepsy.
TRUE
The photo paroxysmal response is _____ of the photic stimulations.
Independent
T or F: When a photoparoxysmal response is seen, the photic stimulation should be immediately stopped and the frequency that induced the response should be repeated.
TRUE
EMG artifact that is time locked with photic stimulation is called
Photomyogenic response
T or F: An asymmetric photic response is abnormal.
FALSE
Sleep is important to obtain because it brings out
Generalized interictal epileptiform activity
T or F: Drug withdrawal may provoke GTC seizures in patients that did not previously have generalized seizures.
TRUE
How far the photic lamp should be from the patient’s face
30cm from patient’s face
When photic stimulation should be performed in adults
Before HV or after HV-related EEG changes have resolved
A possible contraindication for photic stimulation, but is not specified in the ACNS guidelines
Glaucoma
Normal response to photic stimulation
Photic driving or ERG
Abnormal finding with photic stimulation consisting of a burst of generalized spikes and/or polyspikes-and-slow-wave complexes
Photoparoxysmal response
Minimum amount of time to perform hyperventilation
three minutes
Normal response to HV consisting of high-amplitude theta and delta frequencies that are frontally predominant and subsides within 2 minutes after HV ends
HV Buildup
Contraindications of HV
Abnormal EEG finding with HV
Absence seizures, focal slowing in those with underlying structural lesion
