Clinical Study of Aided Cortical Auditory Evoked Potentials in Pediatric Auditory Brainstem Implantees
Raghunandhan Sampathkumar, Mohan Kameswaran, Prashant Sharma, Ranjith Rajeswaran, Chandrasekhar Reddy
(Tamil Nadu, India)
JHS 2013; 3(2): OA22-29
Cortical auditory evoked potentials (CAEPs) reflect the function of the auditory thalamo-cortical pathways and the auditory cortex, and so are a window to the ‘auditory brain’. They are a valuable prognosticator for predicting long-term outcomes in cochlear implantees. This preliminary study evaluated its use in pediatric auditory brainstem implantees (ABIs) who had bilateral Michel’s deformity with cochlear nerve hypoplasia.
Objectives: To profile the aided CAEPs in children with ABI and to assess its efficacy as a tool for evaluating ABI outcomes.
Material and Methods: This prospective clinical study was performed in 3 pre-lingually deaf, non-syndromic children (aged 3–5 yrs) who had congenital bilateral hypoplastic cochlear nerves with Michel’s cochlear deformity who underwent ABI at our institute. All implantees underwent CAEP testing at 6 months and 1 year post-implantation and their results were compared. To compare responses between the various electrodes in contact with the brainstem the 12 ABI electrodes were divided into 4 groups (G1–G4). These groups were sequentially activated and the CAEPs recorded; the responses were compared to the overall CAEP response obtained by stimulating the entire electrode array. Testing comprised /m/, /g/, and /t/ acoustic stimuli and responses to them were recorded from each group of electrodes. Latency of P1, amplitude of P1 complex, and morphology of the responses were analyzed.
Conclusions: Results from our preliminary study showed that CAEP can be successfully recorded in ABI, and CAEP profiling can be an objective method of analyzing the optimal placement and function of the ABI electrodes on the brainstem. Thus CAEP is an efficient adjunct to electrically evoked auditory brainstem response (EABR) for testing ABIs. When stimulated via the ABI, CAEP may reflect re-organization of higher auditory centers and hence may be a good prognosticator for long-term assessment of ABI performance.
Keywords: Cochlear Nucleus, auditory brainstem implant, Electrically Evoked Auditory Brainstem Response, Cortical Auditory Evoked Potentials, P1 Wave