Auditory Brainstem Response (ABR) Testing in Babies
- Executive Summary
Effective and consistent hearing measurement in babies is important for early intervention.
Of particular importance are guidelines to unify testing, data reporting particularly as universal hearing screening is being implemented in EGYPT
● Choice of electrodes & application Skin should be gently abraded. Appropriate options include abrasive electrode paste and cleaning stick with soft cotton material. Single use disposable electrodes are recommended. (Strong recommendation).
● Sedation is not necessary in babies under 12 weeks of age and should be used in babies under 12 months of age only in exceptional circumstances. Sleep deprivation, feeding and diaper change in most situations will lead to natural sleep and lessen activity. (Strong recommendation)
● In order to achieve frequency specificity, thresholds should be measured for at least two frequency audiometric regions:
1. Low frequency thresholds using 0.5 kHz tone bursts or tone pips .
2. High frequency thresholds using 2 or 4 kHz TP / TB or clicks. (Strong recommendation)
● Definition of ABR threshold It is defined (BSA, NHSP 2013) as the lowest level at which a clear response (CR) is present, with a response absent (RA) 5 - 10dB below threshold, under good recording conditions.
● Criteria for ABR response & threshold:
1-Reproducibilty of at least two response traces: visual and graphic.
2-Reproducibility of responses for all intensity i/o functions.
3-Threshold is the reproducible response at the lowest stimulus intensity reached.
(Strong recommendation)
● Calibration :
1. Subjective stage A listening check using 50/sec RR.
2. Reference equivalent SPL for clicks and tone pips if and when feasible.
3. Psychoacoustic calibration control is feasible and easy and can be routinely done.
(Conditional recommendation)
● Reporting:
Results should be clearly marked using the symbols ‘=’, ‘≤’ or ‘<=’, and ‘>’ in addition to the descriptive statements, when important rehabilitation decisions are made.
(Conditional Recommendation)