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NDT EEG TERM 2 F 10 INAL WI0% VERIFTHIED!! CORRECT ANSWERS
Which of the following is used to activate absence seizures? - ANSWER Hyperventilation What is the typical duration for a hyperventilation procedure during EEG? - ANSWER 3minutes
Photostimulation involves what kind of stimulus? - ANSWER Flashing lights, gettinggradually faster.
What contraindication is most relevant for photic stimulation? - ANSWER PhotosensitiveEpilepsy
Which activation procedure is most effective during drowsiness or sleep onset? -ANSWER Sleep Deprivation
During hyperventilation, a normal EEG response may include: - ANSWER Generalizedtheta/delta slowing
60 Hz artifact typically results from: - ANSWER External electrical interference Which filter reduces 60 Hz artifact? - ANSWER Notch filter Which filter setting helps reduce muscle artifact? - ANSWER Low pass filter How is a pulse artifact confirmed? - ANSWER If its syncing with ekg channel
Upward eye movement on EG appears as: - ANSWER Positive, pupil=positive,retina=negative
Which is a feature of an electrode pop? - ANSWER Sudden sharp transient Phase reversal helps identify: - ANSWER Seizure onset What defines a contaminated reference? - ANSWER electrode that has become impureor has its electrical potential altered due to contamination by foreign substances or artifacts Glossokinetic artifact is caused by: - ANSWER Tongue movement How do you confirm glossokinetic artifact? - ANSWER Ask patient to move tongue Over-filtering muscle artifact can: - ANSWER Remove true epileptiform discharges Asymmetric eye movement may mimic: - ANSWER Focal seizure 60 Hz artifact in every EEG channel likelyindicates: - ANSWER Bad impedance
Which artifact is time-locked with QRS complex? - ANSWER EKG Which artifact often appears in A1/A2? - ANSWER Pulse Best way to reduce sweat artifact: - ANSWER Cool the patient
What artifact shows as rhythmic noise at temporal electrodes? - ANSWER Pulse Which activation is most useful for detecting juvenile myoclonic epilepsy? - ANSWERPhotic
Which artifact is best reduced with notch filtering? - ANSWER 60Hz An example of a non-physiological artifact is: - ANSWER 60Hz Blink artifact appears in which leads most commonly? - ANSWER Fp1 and Fp How do you confirm if artifact is EKG-related? - ANSWER Check QRS synchronization Which setting is ideal to reduce eye blink artifact? - ANSWER Monitor EOG channels Sharp transient not time-locked to cardiac cycle is likely: - ANSWER Electrode pop Pulse artifact is often seen where? - ANSWER Temporal regions Muscle artifact becomes more prominent when the patient: - ANSWER Clenches jaw What EEG pattern is seen during normal photic driving? - ANSWER Occipital alphaentrainment
What artifact is influenced by tongue movements? - ANSWER Glossokinetic Which artifact may disappear when the patient relaxes facial muscles? - ANSWER
Muscle Which is the best strategy to eliminate respiration artifact? - ANSWER Ask the patient tohold breath briefly
Hyperventilation Activation Procedure - ANSWER Involves asking the patient to breathedeeply and rapidly for 3-5 minutes to provoke epileptiform discharges, especially in absence epilepsy. Photostimulation Activation Procedure - ANSWER Involves flashing lights at variousfrequencies to elicit photoparoxysmal responses in photosensitive epilepsy.
Sleep Deprivation Activation Procedure - ANSWER Patient is deprived of sleep toincrease the likelihood of capturing epileptiform activity during drowsiness or sleep.
Contraindications for Hyperventilation - ANSWER Asthma, COPD, recent stroke, andsickle cell disease are contraindications due to risk of complications.
Contraindications for Photostimulation - ANSWER Patients with known photosensitiveepilepsy or recent seizures may require caution or adjusted protocols.
Normal Response to Hyperventilation - ANSWER Bilateral slowing, especially in thetheta and delta range, that resolves after cessation.
Abnormal Response to Photostimulation - ANSWER Photoparoxysmal responsecharacterized by generalized spike-and-wave or polyspike discharges.
Physiological Artifact - ANSWER Artifacts arising from normal body functions, such aseye movement, EKG, muscle, and pulse artifacts.
Non-Physiological Artifact - ANSWER Artifacts caused by external interference or
60 Hz Artifact in All Channels - ANSWER Suggests a grounding issue or strong externalelectrical interference.
Minimizing sweat artifact - ANSWER -Cool the patient: Sweat causes slow drifts; coolingthe forehead or room can reduce sweating.
- Wipe with Alcohol -Improve skin prep: Reduce skin impedance to minimize salt bridge formation fromsweat.
Minimizing Muscle Artifact - ANSWER -Ask patient to relax jaw and facial muscles.-Reposition electrodes away from temporalis muscle. -Use a low-pass filter (e.g., 70 Hz): Helps reduce high-frequency muscle activity. -Avoid excessive talking, chewing, or tension.-Record during drowsiness or sleep when muscle tone naturally decreases.
Minimizing 60Hz artifact - ANSWER -Check and improve impedence: Ensure the EEGmachine and patient are properly grounded. -Use a notch filter at 60 Hz (or 50 Hz in some countries) to suppress electrical noise.-Keep electrode wires separated and untangled. -Eliminate nearby electronic devices (phones, monitors, etc.). Minimizing Respiration Artifact - ANSWER -Ask the patient to breathe normally or brieflyhold breath to see if the artifact resolves. -Check for lead movement due to breathing.-Secure electrodes well to prevent movement during chest expansion.
Minimize EKG/ECG in A1/A2 - ANSWER -Re-reference electrodes: Change from linkedears to another neutral reference (e.g., average or contralateral mastoid).
-Use bipolar montages: Can help minimize EKG spread into channels. -Identify and subtract using ECG channel: If available, use software tools to subtractECG artifact. -Place electrodes properly: Ensure ear electrodes are not too close to carotid pulsation. Minimize pulse artifact - ANSWER -Place electrodes away from pulsating vessels:Especially in temporal areas like T3/T4. -Use a pulse oximeter or ECG channel to confirm artifact origin.-Re-reference or adjust electrode placement. -Avoid placing electrodes over superficial arteries. How to differentiate an electrode pop from a phase reversal - ANSWER An electrodepop is a sudden, single-channel artifact caused by a change in electrode impedance, while a phase reversal is a pattern seen across multiple channels indicating a truesource of electrical activity
Which filter settings can be used to reduce specific artifacts - ANSWER Muscle: LowPass set to < Why it works: Specifically targets and suppresses the 60 Hz frequency without affectingsurrounding EEG frequencies too much.
Sweat: High pass set to 1<Why it works: Attenuates slow frequency shifts caused by sweat or temperature fluctuations. Respiration or movement: High pass filter ~1Hz Why it works: Helps reduce slow wave interference without removing clinical delta/thetaactivity
Electrode Pop: Fix Impedence
during light sleep (N1/N2) -Hypsarrhythmia or burst-suppression patterns (in infants) -Paroxysmal discharges triggered by transitions between sleep stages What it possibly means: Benign epilepsy of childhood with centrotemporal spikes(BECTS), Temporal lobe epilepsy, Juvenile absence or JME, Infantile spasms (West Syndrome) Abnormal Eye Closure Response - ANSWER -Fixation-off sensitivity: Abnormaldischarges appear only when eyes are closed and disappear when eyes open -Occipital spikes or paroxysmal discharges What it possibly means: Occipital lobe epilepsy, Fixation-off sensitivity syndromes Hyperventilation Protocols - ANSWER -Ask the patient to take deep, rapid breaths for 3minutes. -Instruct to inhale and exhale fully (around 30 breaths per minute).-Monitor for signs of distress (dizziness, tingling, light-headedness). -Note the exact start and stop time of HV.-If an abnormal response appears, HV may be terminated earlier. -In children or those unable to cooperate, use encouragement and visual prompts. Photic Protocols - ANSWER Performed with eyes closed, eyes open, and eye closure. Use a strobe light positioned about 30 cm (12 in) from patient's face. Flash 1-30 Hz, increasing gradually:1, 3, 6, 9, 12, 15, 18, 21, 24, 27, 30 Hz. Flash for ~10 seconds per frequency with ~5 seconds rest between. Observe for:Photomyogenic response (muscle artifact in facial muscles)
Photoparoxysmal response (epileptiform discharges time-locked to flashes) Sleep Deprivation Protocols - ANSWER -Ask the patient to stay awake all night or allowonly 2-4 hours of sleep before EEG. -EEG is recorded during natural drowsiness and sleep the following day. -If sleep is not achieved naturally, sedatives may be considered (with caution).-Include a full wake-drowsy-sleep-arousal cycle.
Sleep Protocols - ANSWER -Conduct in a quiet, dimly lit room. -Schedule EEG during normal nap time (especially for children). -Ask patient to reduce sleep the night before if necessary. Eye Closure / Eye Opening protocols - ANSWER -Have the patient open and close theireyes on command. -Alternate every 5-10 seconds for 3-5 repetitions. -Observe for alpha block (normal) or abnormal paroxysmal discharges. Pacemaker artifact - ANSWER generalized high frequency polyphasic potentials of shortduration caused by the electrical impulse delivered by a pacemaker
