Observations on hearing preservation in patients with hybrid-L electrode implanted at Poznan University of Medical Sciences in Poland.

The objective of the paper is to evaluate the hearing preservation rate in patients with high frequency hearing loss, treated with Cochlear Nucleus Freedom Hybrid-L implant in the Otolaryngology Department, Poznan University of Medical Sciences in Poland. Study was designed as the retrospective analysis. Twenty-one patients were operated and implanted with Nucleus Freedom Hybrid-L implant. Pure tone thresholds were recorded prior to the surgery and at the time of speech processor switch-on. Patients were subdivided into two groups with respect to their PTA thresholds: group A-classic indications and group B-extended indications. Average PTA for three frequencies (250, 500, 1,000 Hz) were calculated for each patient pre- and postoperatively. In the group of 21 implanted patients in 17 cases we have observed preservation of hearing (12 patients from group A, 5 patients from group B) with a mean value of 13.1 dB. In 4 out of 21 patients deafness on the implanted ear was noted. Our results clearly indicate that with standard procedure hearing preservation can be obtained in majority of patients. Hearing preservation was not achieved in 19 %, but owing to design of the electrode of the Cochlear Nucleus Hybrid-L that enables to work as CI platform alone, in patients who lost their hearing after surgery re-implantations were not required. This proves that EAS is a safe and reliable method to help patients with specific type of hearing loss.