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Longterm Results of the MET T1 and T2 Transducers coupled to the Incus
18 April 2018 (online)
The semi-implantable MET system is admitted for sensorineural hearing loss and with coupling elements for combined hearing loss. In this study the long-term results are shown for T1 and T2 transducers coupled to the incus.
52 ears implanted with a MET from 2008 and 2015 were analyzed in retrospective. All patients suffered from sensorineural hearing loss and the actuator was coupled to the body of the incus (standard coupling). 23 ears were implanted with the T1 transducer between 2008 and 2011 and 29 ears with the latest T2 transducer since 2011. Latest available in situ and bone conduction thresholds were exploited for a follow up period of up to 7 years after first fitting. Long term stability of coupling and actuator performance was evaluated by differences between in situ and bone conduction (BC) thresholds.
In the T1 group, 9 out of 23 implants were still used by the patients at their last follow-up visit. In 10 patients a technical failure identified by a decrease of in situ threshold of more than 20 dB compared to BC thresholds lead to non-usage of the implant and 8 explantations. Four other explantations occurred due to medical reasons such as BC threshold decrease, infection or low speech intelligibility with the device. In the T2 group, 23 out of 29 implants are still in use. No technical failures were observed up to more than 4 years after implantation. Five patients stopped using the device due to insufficient benefit; two of these patients were explanted. One additional patient had to be explanted before the activation of the device due to disorders of wound healing.
MET systems with T2 transducers seem consistently more long term stable regarding efficacy of amplification, coupling and technical failures.