ABR for Cochlear Implant Evaluation
Yes, you should order an ABR (or MRI) as part of the pre-operative work-up for cochlear implant evaluation to screen for retrocochlear pathology, particularly when behavioral audiometry is unreliable. 1
Primary Guideline Recommendation
The American Academy of Otolaryngology-Head and Neck Surgery explicitly recommends that clinicians evaluate patients with sensorineural hearing loss for retrocochlear pathology by obtaining either MRI or ABR. 1 While MRI is the most sensitive modality for diagnosing retrocochlear pathology (such as vestibular schwannoma or cochlear nerve deficiency), ABR with follow-up MRI if abnormal is an acceptable alternative for initial assessment, provided you counsel patients about the limitations of this modality. 1
When ABR is Particularly Indicated
ABR becomes essential in specific clinical scenarios:
Unreliable behavioral audiometry: When patients cannot provide reliable behavioral responses (infants, young children, developmental delays), ABR provides objective threshold estimation and confirms the degree and configuration of hearing loss. 1, 2
Suspected auditory neuropathy/dyssynchrony: Use click-evoked ABR with both condensation and rarefaction stimuli to determine if a cochlear microphonic is present, as this directly impacts candidacy and expected outcomes. 1, 3
"No response" on initial screening: Children with bilateral no response on multifrequency ABR testing have a 96.8% likelihood of proceeding to cochlear implantation, making ABR a reliable predictor of candidacy. 4
The Complete Pre-Operative Imaging Strategy
For optimal surgical planning, you need both anatomical and functional assessment:
High-resolution CT temporal bone (without IV contrast) is mandatory first-line imaging for surgical planning, detecting cochlear malformations, round window occlusion, labyrinthitis ossificans, variant facial nerve anatomy, and measuring cochlear dimensions. 5, 6, 7
MRI with high-resolution T2-weighted sequences is essential for detecting cochlear nerve deficiency or absence (present in only 71% of inner ear malformation cases), cochlear malformations not visible on CT, and central causes of hearing loss. 5, 6, 7
ABR serves as the functional complement when MRI is contraindicated or when you need objective confirmation of auditory pathway integrity, particularly in patients who cannot undergo MRI or when assessing neural synchrony. 1, 2
Frequency-Specific ABR Requirements
When permanent hearing loss is detected and you're proceeding with cochlear implant evaluation, perform frequency-specific ABR testing using air-conducted tone bursts (and bone-conducted when indicated) to determine the precise degree and configuration of hearing loss in each ear for optimal device programming. 1, 2
Critical Timing Considerations
Obtain audiometry (including ABR when behavioral testing is unreliable) as soon as possible and within 14 days of symptom onset for sudden sensorineural hearing loss cases. 1 For congenital hearing loss, complete the full audiological evaluation including ABR before 3 months of age to avoid delays in speech and language development. 1, 5
Common Pitfalls to Avoid
Do not rely on CT head alone for retrocochlear screening—it provides insufficient detail and cannot visualize the cochlear nerve directly. 5, 6
Do not skip ABR in children with "no response" on screening—this population requires frequency-specific ABR with tone bursts to guide amplification and surgical planning. 1, 4
Do not delay cochlear implantation while waiting for behavioral audiometry in children with bilateral no response on multifrequency ABR, as behavioral testing rarely changes the clinical course toward implantation. 4
Do not proceed without assessing for auditory neuropathy—use both condensation and rarefaction stimuli in any infant with "no response" on tone-burst ABR to detect cochlear microphonic, as this fundamentally alters candidacy assessment. 1
Post-Operative Role of ABR
Electrically evoked ABR (EABR) through the cochlear implant provides valuable objective assessment of auditory nerve integrity and device function, particularly in infants, young children, and patients with cochlear malformations who cannot provide reliable behavioral feedback. 3, 2, 8 EABR can be recorded even when acoustic ABR is absent (as in auditory neuropathy), confirming that cochlear implantation can restore neural synchrony. 3, 8