Artifacts Pg

Front 1

What causes glossokenetic artifact and how do you monitor it?

Back 1

Artifact from tongue mmovement; tip of tongue is negative, root of tongue is positive.
Monitor by placing one electrode above the mouth and one electrode below the mouth. Ask the patient to say "Lilt" La La La" to reproduce the artifact."

Front 2

Describe respiration artifact and how to monitor it.

Back 2

Fairly rhythmic slow activity that is synchronous with body movement related to respiration; this movement causes mechanically induced impedance changes in an electrode.
2) Low or sharp wave occurring synchronously with inhalation or exhalation involving only the lectrodes on which the patient is lying.
Try to eliminate by repositioning patient's head. Monitor by marking EEG recording with each inhalation and-or exhalation or use thermocouple or respirometer.

Front 3

Describe EKG artifact and how to monitor it.

Back 3

There is no way to elimanate EKG artifact, although using a bipolar rather than referential montage to earleads; can put both A1 and A2 together in input 2 and this decreases the amplitude of the EKG artifact.
Try to decrease by turning patient's head relative to trunk. Monitor by recording EKG using two chest leads-one on the upper left chest; second on the upper right chest-or a lead on each wrist. Should monitor EKG on every patient throughout the entire EEG recording.

Front 4

Describe pacemaker artifact and how to monitor it.

Back 4

Seen as a fast spike which is the electrical stimulus delivered to the heart by an internal cardiac pacemaker.
Pacemaker artifact will be seen in the channel monitoring EKG; should monitor EKG on every patient throughout entire EEG recording.

Front 5

Describe tremor artifact and how to monitor it.

Back 5

Rhythmic theta activity with myogenic potentials (muscle artifact) superimposed that occurs at 4 to 7 Hz as the head or body tremors: often seen in patient's with Parkinson's disease. Monitor by placing electrode over extremity with tremor, can also be directly monitored by an accelerometer. An accelerometer is an electromagnetic detector that records sudden movement and change in direction of movement.

Front 6

Describe electroretinogram artifact and how to eliminate it.

Back 6

Seen during photic stimulation in the prefrontal leads (Fp1and Fp2) most often at high sensitivities needed for recording suspected electrocerebral inactivity. The artifact will match the frequency of the photic stimulation. Hold an opaque card over eye to block photic stimulation flash from reaching the retina.

Front 7

Decsribe skin potential artifact and how to eliminate and monitor it.

Back 7

Areas of skin with many sweat glands are electrically negative; sweat glands generate electrical potentials when active. Sweating can cause slow waves, most likely slow rolling delta waves. Try to eliminate by reducing cause of sweating, e.g., cool head, wipe area with alcohol, air conditioning.
Monitor by placing two leads on the hand: one pn the palm and one on the dorsum.

Front 8

How are 60 Hz artifacts caused by electrostatic effects? How do you eliminate them?

Back 8

Caused by capacitance between 60 Hz conductors i.e., electrode wires, metal bed frames, the patient, or the technologist. Eliminate by determining cause of 60 Hz and remove, put on battery power, or turn off. Cover wires with sheet or towel.
Use 60 Hz filter only if absolutely unable to remove artifact and document it use on the EEG.

Front 9

How are 60 Hz artifacts caused by electromagnetic effects? How do you eliminate them?

Back 9

Caused by electrical appliances or equipment, i.e., transformers, motors, high intensity lamps, power supplies, TV sets, radio, etc. Eliminate by determining cause of 60 Hz and remove, put on battery power, or turn off. Cover wires with sheet or towel.
Use 60 Hz filter only if absolutely unable to remove artifact and its use document on the EEG.

Front 10

Describe an electrode malfunction artifact and how to eliminate it.

Back 10

Caused by an electrically unstable electrode of high impedance. May appear as a spike or sharp wave or random slow wave with no field - an electrode "pop"
Eliminate by repairing electrode and improving impedance.

Front 11

Describe an intravenous (IV) drip artifact and how to monitor it.

Back 11

Resembles EKG artifact.
Monitor drip by typing an "X" on EEG recording. Eliminate by asking nurse to turn of IV or use battery power when possible.

Front 12

Describe pulse artifact and how to monitor it.

Back 12

Periodic slow wave that has a slight delay from but is timelocked to the EKG waveform.
Monitor by recording EKG; especially useful if the heart rate is irregular.

Front 13

Describe muscle artifact and how to eliminate it.

Back 13

Very short duration potentials that usually occur in clusters or periodic runs. They may resemble cerebral spike discharges except cerebral spikes are of much longer duration and will have a field.
To eliminate ask patient to relax, drop the jaw or open mouth slightly.

Front 14

Why is the use of the high frequency filter (HFF) not recommended to reduce muscle artifact?

Back 14

Excessive high frequency filtering will reduce the amplitude of these fast potentials and will also change their form. Single muscle potentials may look like spikes and repetitive potentials may look like cerebral fast waves.

Front 15

What is the corneoretinal potential?

Back 15

The cornea (the front of the eye) is positive relative to the retina (the back of the eye) which is negative

Front 16

Describe how to monitor eye movement artifact.

Back 16

To distinguish eye movements from cortical slowing, place additional elelctrodes infraorbitally on the outer canthus of each eye (depending if the eye movement is horizontal or lateral). Reference the eye elcetrodes to the ear electrodes. Eye movements will be out-of-phase and cortical slowing will be in-phase.