Prognostic value of electrically evoked auditory brainstem responses in cochlear implantation

The aim of this study was to investigate whether electrical auditory brainstem responses (eABRs) obtained during cochlear implantation (CI) can predict CI outcomes. We also aimed to assess whether eABR can be used to select patients for auditory brainstem implantation (ABI).

This was a retrospective study. The latencies and quality of the eABR waveforms from adult patients implanted with CI in Uppsala from 2011 to 2013 (n = 74) and four children with severe cochlear abnormalities were analyzed. Speech perception was assessed through postoperative monosyllabic word (MS-word) recognition. A score was constructed for each patient based on wave II, III, and V patency.

eABR latencies increased towards base stimulation of the cochlea. Wave V for the mid- and low-frequency regions was the most robust. Significant latency shifts occurred in wave V from the low- to high-frequency regions (**P < 0.01) and from the mid- to high-frequency regions (**P < 0.01). No correlations were found between waveform score, wave V-III interval, wave V latency, and MS-word scores. A negative eABR always predicted a negative outcome. Among the patients with negative outcomes, 75% had eABRs.

Implant electrical stimulation and brain stem recordings can be used (eABRs wave V) to predict a negative functional outcome. Low-frequency waves V were observed in all patients with successful CI outcomes. Patients for whom eABR waveforms were completely absent had unsuccessful CI outcomes.