ACNS EP Guidelines

What is the standard stimulus presentation method for Brainstem Auditory Evoked Potentials (BAEP)?

Monaural

Which two transducer types are recommended for BAEP stimulus delivery?

Headphones or ear inserts

In BAEP, masking is provided to the non-test ear using _____.

White noise at 60 dB SPL

What is the system bandpass for recording VEP?

1-100 Hz

Where is the cathode placed for Median nerve stimulation?

Between palmaris longus tendons and flexor carpi radialis, 2 cm proximal to the wrist crease

For the VEP montage, Channel 1 (Ch1) is _____.

LO-MF

List the three polarities commonly used for BAEP stimulus presentation.

Rarefaction, condensation, and alternating

What is the standard system bandpass for SSEP recordings?

30-3,000 Hz

What is the standard analysis time (time window) for VEP?

250 ms

In the Median SSEP montage, C5S-REF is found on which channel?

Channel 2 (Ch2)

What is the maximum allowable electrode impedance for VEP?

< 5 kOhms

For PTN SSEP, Channel 3 (Ch3) in the montage corresponds to which derivation?

CPz-Fpz

What is the standard system bandpass for recording BAEP?

10-30 to 2,500-3,000 Hz

Where is the anode placed for PTN stimulation?

3 cm distal to the cathode

For PTN SSEP, Channel 2 (Ch2) in the montage corresponds to which derivation?

Fpz-C5S

For the VEP montage, Channel 4 (Ch4) is _____.

MF-A1

How are Visual Evoked Potentials (VEP) presented to the patient?

Monocularly

SSEP waveform labeling is based on _____ and _____.

Polarity and latency

What is the standard analysis time for Median SSEP?

40 ms

For Median SSEP, Channel 3 (Ch3) in the montage corresponds to which derivation?

CPi-REF

What is the maximum allowable electrode impedance for BAEP?

< 5 kOhms

For Median SSEP, Channel 1 (Ch1) in the montage corresponds to which derivation?

EPi-REF

Which electrode placement system is used for BAEP recordings?

International 10-20 System

What is the specific stimulus pulse width (duration) for BAEP?

100 usec

What is the maximum stimulus rate recommended for VEP?

4/s

What is the range for repetitions (averages) required for VEP?

100-200

What is the maximum electrode impedance permitted for SSEP recordings?

5 kOhms

Where is the cathode placed for Posterior Tibial Nerve (PTN) stimulation?

Between the medial border of the Achilles tendon and the posterior border of the medial malleolus

Where is the anode placed for Median nerve stimulation?

2-3 cm distal to the cathode, or on the dorsum of the wrist

What is the minimum distance allowed between the patient and the VEP stimulus screen?

70 cm

What specific electrode type is used for SSEP?

Standard EEG disk electrodes

The stimulus type utilized for BAEP is _____ clicks.

Broadband

In the BAEP montage, what is the electrode derivation for Channel 1?

Cz-Ai

For the VEP montage, Channel 3 (Ch3) is _____.

RO-MF

What is the standard analysis time for PTN SSEP?

60 ms

What is the pulse width (duration) range for SSEP stimuli?

100-300 usec

What is the mid-size field size for VEP stimulation?

6-12°

BAEP waveforms are labeled in order sequence using _____.

Roman numerals

VEP waveform labeling follows the standard of _____ and _____.

Polarity and latency

Where should the patient maintain visual fixation during a VEP test?

Center of the stimulus screen

The number of SSEP repetitions typically ranges from _____ to _____.

Several hundred; several thousand

What is the standard stimulus rate for BAEP according to ACNS guidelines?

8-10/s

For PTN SSEP, Channel 1 (Ch1) in the montage corresponds to which derivation?

T12S-REF

What is the mid-size check size for VEP stimulation?

24-32'

What electrode type is standard for EP procedures?

Standard EEG disk electrodes

For the VEP montage, Channel 2 (Ch2) is _____.

MO-MF

For Median SSEP, Channel 4 (Ch4) in the montage corresponds to which derivation?

CPc-CPi

What is the recommended stimulus rate for SSEP?

3-5/s (or 3-5 Hz)

According to the ACNS table, what is the minimum number of replications required for BAEP?

At least 2

What type of electrical pulse is used for Somatosensory Evoked Potential (SSEP) stimulation?

Monophasic rectangular pulses using constant current or constant voltage

The standard analysis time (time window) for BAEP is _____.

10-15 ms

How many repetitions (averages/trials) are typically required for a BAEP study?

1,000-4,000

What is the specific stimulus type and contrast requirement for VEP?

High contrast (>50%) black and white checkerboard pattern

For PTN SSEP, Channel 4 (Ch4) in the montage corresponds to which derivation?

CPi-Fpz

How is stimulus intensity determined for SSEP?

The threshold that produces a consistent but adequately tolerated muscle twitch

In the PTN SSEP montage, CPz-Fpz is recorded on which channel?

Channel 3 (Ch3)

Which specific electrode placement system is used for VEP?

Queen Square System

What is the recommended stimulus intensity range for BAEP?

40-120 dB pe SPL

In the BAEP montage, what is the electrode derivation for Channel 2?

Cz-Ac

For Median SSEP, Channel 2 (Ch2) in the montage corresponds to which derivation?

C5S-REF

What is the minimum requirement for the differential input impedance of an EP amplifier?

At least 100 MΩ

The common mode rejection ratio (CMRR) of an EP amplifier must be at least _____ at its highest sensitivity.

80 dB (or 10,000:1)

With filters wide open, what is the required bandpass for an EP amplifier measured at the -3 dB points?

0.1-5,000 Hz

The noise level of an EP amplifier must not exceed _____ with a bandpass of 0.1-5,000 Hz.

2 uV rms

What is the required time (horizontal) resolution for an EP averager system?

20 us/data point or less

While 8-bit A-D converters are adequate, what bit-depth is preferred for its broader dynamic range in EP systems?

12-bit converters

An EP averager system should have a minimum of how many addresses of memory available for each channel?

At least 500 addresses.

What is the minimum number of channels required for performing Pattern Visual Evoked Potential (PVEP) and Somatosensory Evoked Potential (SSEP) studies?

A minimum of four channels.

What is the minimum number of channels required for Brainstem Auditory Evoked Potential (BAEP) studies?

A minimum of two channels.

What is the standard limit for chassis leakage current with the ground open for EP equipment?

Less than 300 uA rms

In the OR or ICU, what is the maximum allowable leakage current through patient leads to ground with 120 { VAC} applied?

10 uA rms

What is the effect of excessive low-frequency filtering on the timing of an EP peak or valley?

It causes the peak or valley to appear earlier.

How does excessive high-frequency filtering influence the recorded latency of an EP component?

It delays or prolongs the peak or valley.

To minimize filter-induced phase shifts, what should be the minimum ratio of high-to-low frequency filter settings?

A ratio of at least 100:1

Why is the use of a 60 Hz notch filter generally discouraged in EP recording?

It may 'ring' when activated by a stimulus artifact, creating a burst of 60 Hz activity that contaminates the response.

According to standard polarity convention, what direction is a negative event typically displayed for SSEP and PVEP studies?

Upward.

In BAEP studies, positive events are usually displayed in which direction?

Upward.

What is the typical amplitude range for calibration pulses used in EP systems?

0.5-100 uV

What is the primary purpose of obtaining two or more temporally independent averages (replication)?

To demonstrate that the responses are of neural and not artifactual origin.

EP latency replication is usually considered successful if it is within _____ of the total sweep time.

1%

What is the standard percentage for achieving amplitude replication between successive EP averages?

Within 15% of the peak-to-peak amplitude.

When establishing a new EP laboratory using reference norms, what is the minimum number of normal subjects that should be studied to verify accuracy?

At least 20 normal subjects.

How should age-specific norms be grouped for normative studies of EP in infants?

By month.

How should age-specific norms be grouped for normative studies of EP in adults?

By decade.

The standard gain adjustment for an EP amplifier should be in steps of no more than _____.

2.5 to 1

The EP amplifier must maintain specifications even in the presence of a sustained _____ differential offset.

300 mV

An EP system must allow for the averaging of at least how many trials?

At least 4,000 trials.

What essential averager mechanism allows for the exclusion of trials where the signal exceeds the limits of the A-D converter?

Artifact rejection.

For safety, a direct connection from the patient 'ground' to the equipment chassis should be prevented by using an _____.

Isolation amplifier (or solid-state current limiter).

What is the maximum allowable leakage current at the patient end of the cable when the power line ground is disconnected in clinical areas?

50 uA rms

What general term describes algorithms like 'smoothing' that affect amplitude/morphology but usually not latency?

Digital filtering.

In an EP display, what is the meaning of the abbreviation 'Input terminal 1' relative to 'Input terminal 2' regarding upward deflection?

Terminal 1 is negative relative to terminal 2 for an upward deflection (if negative is up).

In the documentation of EP results, what does 'derivation' refer to?

The abbreviated designations of electrode locations connected to input terminals 1 and 2.

What is the minimum number of years required for direct training and experience for an entry-level evoked potential technologist?

Not less than 12 months.

What term is used to describe the consistency of latency and amplitude measures across successive trials?

Replication.