Based on Washington State Department of Health Recommendations, for Follow-up of Newborn Hearing Screenings, 2002
High Risk Factors for Hearing Loss in Newborns:
- Birth weight of less than 1500g
- Apgar 7 or less at 5 minutes (Severe asphyxia-arterial pH level lower than 7.25, coma seizure or the need for assisted ventilation)
- Identification of a syndrome associated with hearing loss (e.g. Waardenburg, Alport, Usher)
- Neurodegenerative Disorders (E.g. Hunter Syndrome)
- NICU stay of >5 days after birth
- Exposure to ototoxic medications (e.g. gentamycin)
- Maternal substance abuse
- Jaundice-hyperbilirubinemia: history of exchange transfusions.
- Skeletal or crainial defects (skull abnormalities, short neck, absent clavicles, dwarfism, malformations of extremities and digits, cleft lip, cleft palate (overt or submucous), underdeveloped maxillae or mandible, external ear abnormalities, pre-auricular tag or pit.
- Family history of deafness
- Congenital Perinatal infections (toxoplasmosis, Syphilis, Rubella, Cytomegalovirus, Herpes Simplex Virus)
Otoacoustic Emissions (OAE) – A measure of cochlear (outer hair cell) function. A small rubber plug is placed in the patient’s ear. A series of sounds are presented in frequency pairs. The normally functioning ear will create a harmonic (or distortion product) that can be measured by a computer probe. Normal responses indicate normal outer hair cells and middle ear function. This test requires the child to be still and quiet (or sleeping) for approximately 10-15 minutes.
Immittance Assessment (low, mid, and high frequency) – A measure of middle ear function. A small rubber plug containing a miniature sonar is placed in the ear canal. Pressure in the canal is varied slightly. The resulting volume measures across the pressure range allow for the detection and documentation of middle ear fluid or negative middle ear pressure. Very little patient cooperation is required.
Click Evoked Auditory Brainstem Response (ABR/BAER) – A measure of travel time along the nerve pathway. Surface electrodes are placed on the head to measure brainstem level EEG activity in response to a clicking sound. The signal is averaged across numerous stimulus presentations, revealing a characteristic waveform. The time required for the signal to travel along the nerve is calculated, and compared to age appropriate normative data. This procedure requires the child to be quiet and still (or sleeping) for up to 60 minutes. For this reason, the younger the child the better.
Toneburst Evoked Auditory Brainstem Response (ABR/BAER) – A more frequency specific ABR/BAER. The same recording techniques are utilized as with click evoked ABR/BAER. The stimulus utilized is a Blackman gated tone burst. The resulting waveform can be tracked down to near threshold. Patient cooperation is required for up to 60 minutes.
Bone Conduction Click Evoked Auditory Brainstem Response (ABR/BAER) – Differentiates between conductive and sensorineural hearing loss. This procedure allows for the click stimulus to be transmitted past any potential middle ear conditions directly to the cochlea. The stimulus, procedures, and patient requirements are similar to the Click Evoked ABR/BAER.
Behavioral Evaluations including VRA/COR, Play, and Conventional Techniques – A full range of behavioral techniques can be utilized to assess younger children. Visual reinforcement (VRA) and Conditioned Orientation (COR) use sound field speakers and animated toys to condition responses for children ages 4 months and older. Play and conventional techniques are used once a child is able to provide a consensus behavioral response to a presented stimuli.