Click ABR with SmartEP - Intelligent Hearing Systems
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1. and type of hearing loss at specific frequencies i e hearing threshold depending on the cause of hearing impairment ABR testing can also provide information about existing acoustic neuromas that may be causing a degree of hearing loss and the presence of nervous system abnormalities particularly referring to the VIII nerve and auditory brainstem INTELLIGENT HEARING BAHEN Q T5 Z T5 _ lt W Patient Preparation The patient must be placed in a comfortable and quiet environment preferably a sound booth where the patient lies down on a comfortable bed The patient must be instructed to relax during testing It is recommended that the patient avoid stimulants such as caffeine before testing Electrode Placement Electrodes may be connected using the following configuration Right Inverting right ear mastoid or ear lobe Left Inverting left ear mastoid or ear lobe e Non Inverting high forehead use a Y adapter to join channels Ground low forehead Ground Right Left N P A When testing using a single channel amplifier connect the electrode socket to the Right mastoid the Brue electrode socket to the Left mastoid and the Black electrode socket to the high forehead Remember to flip the amplifier switch to the correct position before starting acquisition When using the USBLite hardware platform make sure to choose the Right Left2. designation option in the EEG and Amplifier window if using this setup Fig 1 Electrode positions Keep in mind that using different electrode locations will yield recordings with slightly different wave morphology Consult the SmartEP manual for additional electrode placement details SNSEPO10 EN 12079 Auditory Brainstem Response Electrode Usage Surface electrodes are sufficient for acquiring ABR recordings Clean and prepare electrode sites in order to reduce the impedance and acquire a clearer recording Setting up SmartEP Acquiring ABRs is SmartEP s main function The system may be setup with a few clicks of the mouse Complete the following steps in the order outlined use the test settings that best fit your requirements or use the recommended settings shown on the next section 1 Under Stimutus gt Mopatity in the main menu make sure Aupitory gt ABR is selected 2 Set the stimulus click on the Stim button from the control panel and set the stimulus type duration frequency window masking and transducer as necessary 3 Click on the EEG ann Amptirier button on the control panel and set the filters notch filter artifact rejection ratio and region and desired amplification for each channel 4 On the control panel set rate polarity intensity and the number of sweeps 5 Press the Acquire button to start Repeat acquisition 2 to 4 times SmartEP allows automation of the a
3. What is ABR Auditory Brainstem Responses are potential differences generated when a person s ear is stimulated with any kind of sound The potential difference originates in the VIII cranial nerve and the auditory brainstem system These potential differences can be evoked using controlled stimulation allowing acquisition of these differences by averaging the acquired signal over a specified period of time The ABR response is commonly found between one and fifteen milliseconds from the time of stimulation The recordings acquired will contain certain peaks and valleys A standard ABR recording will contain seven peaks some more identifiable than others peak five being the most prominent The amplitudes latencies and relationship of those peaks and valleys can be used to diagnose certain pathological conditions ABR responses are most commonly acquired using surface electrodes Why acquire ABRs Auditory brainstem responses may be used to diagnose certain auditory conditions This type of testing can provide the physician with very useful information about hearing loss in a patient This technique is especially helpful to test infants and newborns that cannot yet respond to behavioral testing many states now require hearing screening of newborns It may also be helpful to test adult patients with a certain degree of mental impairment such as the autistic and developmentally delayed ABR testing can help determine the amount
4. cquisition process consult your user s manual to learn how to create your own automated testing protocol or how to save settings files for future use Make sure to carefully select your filter settings in the EEG and Amplifier window Note that an unfiltered recording can always be filtered digitally to obtain a smoother waveform however hardware filtering cannot be undone Recommended Test Settings This list shows the recommended settings for ABR acquisition Stimulus click Duration 0 1 milliseconds e Masking optional e Rate 27 7 per second slower rates can be used to enhance wave e Polarity rarefaction use alternating if there is stimulus artifact Transducers insert earohones Intensity 70 dB HL to start then up or down using SmartEP in 10 dB steps for threshold search 80 to 95 dB HL for neurodiagnosis e Filters 100 3000 Hz for adults 100 1500 Hz for smoother recordings 30 1500 Hz for infants Notch Filter OFF turn ON only when power line noise is present Amplification gain 100K Analysis Time window 0 12 milliseconds Sweeps 1024 Electrode Placement ipsilateral or contralateral array Marking Peaks To accurately diagnose a condition you may need to obtain latencies and amplitudes by marking peaks Peaks to VII may be marked when recognizable by following these steps for each of the peak markers to be placed 1 Click on the peak label you wish
5. to mark I Vil from the tool bar it will turn red when chosen 2 Click the location on the waveform where the label should be placed 3 Once placed drag the top marker of the labels to the top of the peak if needed 4 To obtain waveform amplitudes drag the bottom marker to the valley following the peak 2 00uV hy N 0 1 2 3 4 5 6 7 8 9 10 11 12ms Fig 2 Sample click ABR recording The graph shows suggested label placement for an acquired waveform Since label placement is subjective all results must be evaluated by an audiologist or medical professional trained in ABR techniques Printing Select Print Report or Print Page from the SmartEP main menu to print a report of the currently displayed waveforms You may also save page or report to PDF for an electronic version See the SmartEP manual for other report generation options SNSEPO10 EN 12079
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