Middle ear implants provide a suitable alternative for some patients with a certain degree of sensorineural or mixed hearing loss, not wanting a hearing aid. Vibrant SounBridge® (VSB) middle ear implant (MEI), of Med-El®firm, is one such implant. In this procedure, the floating mass transducer (FMT) is fixed by a clip on the long process of the incus (LPI). The FMT is connected to a demodulator which communicates with an external processor through a magnetic antenna. The authors reported successful treatment of LPI lysis in two patients with previous VSB MEI surgery, using hydroxyapatite bone cement application on the clip and incudo-stapedial joint. The case series involved two patients, aged 64 and 79 years old. Both patients had bilateral VSB for mixed hearing loss and poor speech discrimination. They had good improvement in the speech discrimination scores (SDS) in the initial postoperative phase. Following decline of the implant efficiency, they underwent revision surgery (three years for the 64-year-old patient and one year for the 79-year-old after primary surgery). During revision surgery, there was lysis of the LPI with incudo-stapedial discontinuity and disconnection of the clip from the ossicular chain in both cases. Re-crimping of the clip around the LPI and applying two drops of hydroxyapatite bone cement onto the incudo-stapedial joint and clip resulted in a stable mount. Both patients had improved postoperative SDS which was maintained at 12 months of follow-up. This case series demonstrates that LPI lysis is a delayed complication of VSB middle ear implant surgery resulting in implant malfunction. Moreover, the authors showed that hydroxyapatite bone cement can be a reliable and effective treatment in such cases. Middle ear implant surgeons should consider this to achieve a stable mount, particularly during revision cases.

Lysis of the long process of the incus secondary to Vibrant SounBridge® middle ear implants, treated with hydroxyapatite bone cement.
Pitiot V, Hermann R, Coudert A, Truy E.
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Praneta Kulloo

Lewisham and Greenwich NHS Trust, UK.

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