Controlling the position and the dislocation of the middle ear transducer with high-resolution computed tomography and digital volume tomography: implications for the transducers’ design

Abstract

A minimal tip dislocation of the middle ear transducer (MET(®), Otologics Ltd) may result in poor hearing performance. Our objective was to examine if a defined MET dislocation can be diagnosed by high-resolution computed tomography (HRCT) or digital volume tomography (DVT). A human cadaver head was sequentially implanted with different MET tips (incus application) including a ceramic tip (T 1c), a titanium tip (T 1t), a new, thinner titanium tip (T 2), and a spherical titanium tip (Ts). HRCT and DVT studies were performed. Afterward, the tips were pulled back 0.5 mm, so that they were not attached to the incus. HRCT and DVT scans were repeated to identify the dislocation. Using the best plain in HRCT images, the dislocation of the transducer could be measured reliably and reproducibly in half of the cases. In particular, the precise positioning and the dislocation could be identified when T 1t and Ts were implanted, with the Ts showing the best visibility. DVT failed in recognizing the dislocation in all cases. The identification of MET tip's dislocation with HRCT depends on the shape, size, and material of the tip. This knowledge is useful for the design of the implants, as determination of the right position of the middle ear transducer may be proven important for the hearing outcome. In some cases, however, surgical exploration may still be required. Although DVT represents a promising imaging method for the otologists, it can barely help when MET dislocation is suspected.

Superior semicircular canal dehiscence: a narrative review

“…With respect to imaging, it is also worth mentioning that, following technological advances, cone beam CT, also known as digital volume tomography, has been utilised to provide radiological confirmation of superior semicircular canal dehiscence. 66 Being less prone to the partial volume effect, and offering high resolution with a voxel size as low as 0.08 mm 3 , the flexibility of reconstruction on multiple planes, and lower exposure to radiation, cone beam CT is a very appealing alternative to CT. [66][67][68] However, mostly for economic reasons, such equipment is not available in all units; accurate reporting also requires experienced, cone beam CT-accustomed radiologists. [66][67][68] On these grounds, to date, high-resolution CT remains the standard in imaging superior semicircular canal dehiscence.…”

The Cochlear MET middle ear implant in mixed hearing loss – a case study

“…Istotnym elementem mającym wpływ na uzyskane korzyści jest właściwe umieszczenie sztyftu lub couplera w odpowiednim miejscu. Nawet niewielkie osłabienie kontaktu pomiędzy przetwornikiem a strukturą ucha środkowego może wpłynąć negatywnie na uzyskane wyniki [15]. Tego typu problem w przypadku innych urządzeń wszczepialnych do ucha środkowego występuje tylko z couplerem na okienko owalne (OW-coupler) w systemie Vibrant Soundbridge.…”

Design and analysis of a flextensional piezoelectric actuator for incus-body driving type middle ear implant

“…From 1990, some types MEIs been investigated or developed in the world. According to the different stimulating positions of their actuators, MEIs can mainly be divided into three types: the incus-body driving [4][5][6], the round-window driving [7][8][9] and the incus-long-process driving [10][11][12]. Among them, as the incus-body driving type MEI, which has its actuator attached to the incus body, is one of the widely investigated types due to its minor damage to the structure of the human middle ear system.…”