| The Nucleus multi-electrode Auditory Brainstem Implant (ABI), currently undergoing clinical trials in the U.S., is designed to provided auditory sensation to individuals deafened by Neurofibromatosis Type 2(NF2). Intraoperative monitoring of the Electrical Auditory Brainstem Response (EABR) has been helpful in verifying placement of the ABI on the cochlear nucleus. In addition, elements of the EABR may be helpful in predicting postoperative success. This study examined the relationship between intraoperative EABR and postoperative outcome with the Nucleus ABI in 6 subjects. EABR testing parameters were specified in the FDA clinical trial protocol. Success with the ABI was defined using 2 criteria: (1) postoperative lip-reading enhancement scores on CUNY Sentence test and (2) the number of possible electrode pairs that provided auditory percepts without side effects. These criteria where then compared with features of the EABR recorded intraoperatively. All six subjects had repeatable EABRs during surgery. Postoperatively, 5 subjects reported auditory perceptions using 5 to 8 electrode pairs and improved lip-reading enhancement scores. The remaining subject perceived only non-auditory side effects and her speech processor could not be programmed. The 5 "successful users" recorded 2- and 3-peak EABRs with peak latencies of the "last" peak in the series (P3) between 1.5 and 2.6 msec. The unsuccessful user had a recorded P3 at 3.5 msec. A correlation between user success measures and EABR latency was found. Not unexpectedly, this correlation was not statistically significant, as the sample size was small due to the rarity NF2. Results suggest that the latency and morphology of P3 may be useful in predicting user success with the ABI. However, continued study with a larger sample size is necessary to verify this observation. |
