WO2018024312A1

WO2018024312A1 - Surgical instrument for introducing a cochlear implant

Info

Publication number: WO2018024312A1
Application number: PCT/EP2016/068296
Authority: WO
Inventors: Marco BENAZZO; Pietro CANZI; Stefania MARCONI; Ferdinando Auricchio
Original assignee: Universita' Degli Studi Di Pavia
Priority date: 2016-08-01
Filing date: 2016-08-01
Publication date: 2018-02-08

Abstract

It is described a surgical instrument to facilitate the introduction of the internal component of a cochlear implant, CI, comprising two crossed arms connected by a joint, wherein each arm acts as a first class lever and the joint acts as a fulcrum, wherein the tool comprises two rings, one for each arm, configured to accommodate two fingers of the hand of a surgeon, characterized by comprising a retainer for retaining a portion of said inner cochlear implant component, wherein said retainer comprises two movable half-cylinders which are hinged one to each other.

Description

SURGICAL INSTRUMENT FOR INTRODUCING A COCHLEAR

IMPLANT

DESCRIPTION

The present invention relates to the field of audiological devices and particularly to the field of cochlear implants. More in detail, it relates to a surgical instrument that facilitates the introduction of the internal component of a cochlear implant.

Recent scientific and technological advances made in the field of audiology allowed to positively alter the natural history of hearing loss occurred at any age: childhood, adulthood and elderhood. To date, more than one child in every thousand is born with or acquires a profound deafness with important implications in language development and the number of elderly people with severe hearing loss is increasing. The cochlear implant (CI) represented a revolutionary element in the landscape of deafness allowing the completely replacement of a sense organ (cochlea) by creating an interface between the auditory nerve and the implant ("artificial ear").

Typically, a known type of CI comprises two main components: an external component and an internal component.

The external component generally includes an external audio- processor, a microphone and an external antenna.

The external component is the component that is not surgically implanted and that is worn by the patient as a normal hearing aid. The audio-processor processes the ambient sound signal picked up by the microphone and converts them into digital information that is then transmitted via an antenna to a receiver-stimulator of the internal component.

The internal component generally comprises a receiver-stimulator with an array of electrodes. Typically, the receiver-stimulator is in the form of an elongated body of very small diameter with a set (array) of sensitive electrodes and their connections arranged on its outer surface. The internal component is also simply referred to as "array"

The internal component is the component implanted in the patient. The receiver-stimulator, arranged in the surgical pocket in the temporal- occipital area, receives the signal from the audio-processor (magnetically adhering to it, with the interposition of the cutaneous plane) and sends it to the array electrodes.

The array electrodes allow the electro-magnetic direct stimulation of the cochlear nerve in its modiolus portion, thereby allowing the patient's auditory perception.

Encoded by years, the surgical placement of a CI requires an access to the patient's cochlea through a surgical corridor called "facial recess". This anatomical area is bounded anteriorly by the chorda tympani (responsible for taste perception of the anterior 2/3 of the tongue) and posteriorly by the mastoid portion of the facial nerve (responsible for essentially motor innervation of mimic muscles of the face).

The facial recess is therefore an anatomical window of reduced size (average 2.6 mm) which allows the surgeon to access the middle ear region (rear mesotympanum) where is positioned the round window that constitutes the "door" for the array insertion in the cochlea.

The array insertion is an extremely delicate surgery and requires great skill. In fact, the surgeon must introduce the receiver-stimulator (which has the array of delicate electrodes on its surface) passing in a limited anatomical space, between extremely delicate nerve structures. This involves a few degrees of movement with the risk of covering the surgical visual, and therefore damaging the implant or even inserting the array in a wrong way, thus frustrating the outcome of surgery.

Technological advances have led to the creation of internal components more and more thin and delicate in order to preserve the residual hearing of the impaired patient. The thin internal components bring benefit for the patient, but make the procedure of introduction even more complex. In fact, these thin interior components are inherently delicate and must be handled carefully otherwise there's the risk of breaking them (and make them unusable) or even just ruining them (degrading the performances).

Micro-surgical instruments for the insertion, by a oto-neuro-surgeon, of the internal component of a CI are known.

For example, a modified Hartmann-type forceps is known. It is a micro forceps in which the mechanical elements aimed at grasping the electrodes are represented by straight or angled endings with a degree of minimum and maximum opening that is pre-defined by the manufacturer.

The inventors have observed that this tool mainly has limitations due to the geometric conformation of the endings. In particular the inventors have observed that, through the modified Hartmann micro forceps, the array is only grasped at a single point. However, since the array has a structural elasticity, it is not easy for the surgeon to control its movements.

The inventors have also observed that the use of this instrument can lead to a damage of the electrodes. This occurs both when the surgeon exerts an inadequate pressure, both when he exerts a force not perfectly tangent to the direction of the internal component, during the insertion into the cochlea. In this case the array may be subject to a distortion ("kinking").

Another known micro tool for the array introduction into the cochlea is the bayonet-shaped forceps. This tool allows the surgeon to grab the array at its basal end, by impressing a force tangential to the array direction. The inventors have observed that the grasping of the array only at its base greatly reduces the handling of the electrodes at the apical end, which are the first to be introduced in the cochlea. It should be remarked that the apical end electrodes are the more difficult to handle as they have a smaller diameter than the basal electrodes. Therefore they are more delicate and are the first to be inserted into the cochlea. So, if not properly positioned, they negatively affect the insertion of the subsequent electrodes.

A third known instrument for the array introduction is the so-called "surgical fork" or "surgical-claw". It is basically a micro-instrument similar to a fork with two prongs, configured to handle the array electrodes and follow them through the cochlea without covering the surgical view.

The inventors have observed that the usefulness of the surgical fork is limited by at least two factors.

Firstly, the surgical fork is only employed when the apical end electrodes (as mentioned above, the apical end of the array is the most difficult to manage) have already been correctly inserted. Then, the surgical fork is not useful for the apical end introduction.

Secondly, the distance between the two prongs of the surgical claw can not be varied. Therefore, since electrodes have different diameters (smaller at the apical end, larger at the base), the instrument can only be used for some of the electrodes of the array, resulting ineffective for smaller electrodes and potentially harmful for the larger.

In view of drawbacks and limitations of known instruments, the inventors aimed at providing a surgical instrument configured for the introduction into the cochlea of the internal component (array) of a CI, overcoming the above-mentioned drawbacks. In particular, the inventors aimed at providing a tool able to adapt to arrays of different section, thus minimizing damages to the electrodes.

According to the present invention, the above aim is achieved with a tool configured for retaining the array in correspondence of a substantially cylindrical surface, in order to distribute the pressure exerted on the array and to avoid damages to the electrodes.

According to one aspect of the present invention, there is provided a surgical instrument configured to facilitate the introduction of the internal component of a cochlear implant comprising two crossed arms connected by a joint, wherein each arm acts as a first class lever and the joint acts as a fulcrum, wherein the tool comprises two rings, one for each arm, configured to accommodate two fingers of a surgeon's hand, characterized by comprising a retainer for retaining a portion of said inner component of the cochlear implant, wherein said retainer comprises two half-cylinders mutually movable respect to one another.

Preferably, the half-cylinders are hinged, wherein said hinge axis is substantially parallel to a longitudinal axis of the half-cylinders.

Preferably, a half-cylinder is fixed and a half-cylinder is movable as a function of the movement of an arm of the tool.

Preferably, the instrument further comprises a mechanism for moving the movable half cylinder relative to the fixed half-cylinder.

Preferably, the instrument also comprises a guide channel open at the top to accommodate a portion of said inner component of the cochlear implant.

In preferred embodiments, each half-cylinder has a length between about 2 mm and about 5 mm.

In preferred embodiments, each half-cylinder has a section shaped as an arc of a circle with an inner diameter of about 0.5 mm or less.

Preferably, the two arms of the tool are detachable relative to one another.

In preferred embodiments, the tool is of a metallic material such as steel or titanium. The present invention will become clearer from the following description, provided as an example and not as a limitation, to be read with reference to the accompanying drawings, in which,

- Figures 1 and 2 are two axonometric views of an embodiment of a surgical instrument according to the present invention;

- Figure 3a is an enlarged axonometric view of the cylindrical retainer in the closed configuration and of the joint;

- Figure 3b is an exploded view of what is shown in Figure 3a;

- Figure 4 is another view of the cylindrical retainer in its closed configuration;

- Figure 5 is a view of the cylindrical retainer in its open configuration;

- Figure 6 is a retainer view while it is closing to retain an array;

- Figures 7a and 7b are enlarged views of the area in which the two arms are jointed;

- Figure 8a is an enlarged view of the area in which the two arms are jointed in the unlocked configuration; and

- Figure 8b is an exploded view of what is shown in Figure 8a.

With reference initially to Figures 1 and 2, the surgical instrument 10 according to an embodiment of the present invention comprises a main part 30, which comprises a handle arm 34 and a portion 26 configured to house the array gripping system and two movable parts 24 and 36. The part 24 terminates at its apical end with a joint 40. Each arm 20, 30 acts as a first class lever and the joint 40 acts as a fulcrum, by moving part 36 with respect to part 26, the latter being integral with the arm 30. To facilitate the use of the instrument, the instrument preferably comprises two rings 22, 32, one for each branch 24, 34, in which are introduced typically the thumb and middle finger of the hand of the surgeon.

The branches 24, 34, i.e. the portions of the arms connected to the rings 22, 32, are offset with respect to the portion of the arms between the joint and the free end 26, 36 of the arms. This is beneficial because it leaves more visibility to the surgeon during the operation.

Preferably, it is provided a block 60 to lock and hold the arm 20 in its locked configuration on the pivoted part 36. In the unlocked configuration, however, the arm 20 can be extracted from its housing in order to facilitate the sterilization operations of the most hidden parts of the instrument.

In the closed configuration, the two arms form a V-shape and are spaced apart in correspondence of the gripping rings 22, 32. The 24, 34 branches preferably have a section that tapers towards the joint 40.

The surgical instrument 10 according to the present invention comprises a retainer 50 configured to retain an array 70 (Figure 6). The retainer 50 comprises a cylindrical body. Preferably, the cylindrical body is formed by two pieces, namely a first lower half-cylinder 52 and a second upper half-cylinder 54.

The two half-cylinders 52, 54 are movable with respect to one another. Preferably one of the two half-cylinders is fixed (52) and the other (54) is movable away from and towards the fixed half-cylinder. In the presented embodiment, the fixed half-cylinder 52 represents the lower one while the movable half cylinder 54 is the upper one.

Preferably, the two half-cylinders 52, 54 are pivoted with respect to one another. Figures 3a and 3b show the joint 56 through which the upper half-cylinder 54 can be rotated relative to the lower half-cylinder 52. In this way, the extremities opposite to the joint side move away and provide a wider opening to insert the array 70. Figure 4 is another view (from the side opposite to the hinge 56) of the two closed half-cylinders; Figure 5 is a view, at the same side, with the two half-cylinders in open configuration.

The joint axis is preferably substantially parallel to the axis of the cylindrical body 50. The movement of the upper semi-cylindrical body 54 with respect to the semi-cylindrical lower body 52 is preferably actuated by a kinematic mechanism 58 connected to the lower arm 26. In practice, starting from the closed configuration, by distancing the two rings 22, 32, the two half-cylinders 52, 54 open with respect to one another.

Therefore, the tool 10 according to the present invention is configured for facilitating the correct introduction of the array 70 of a CI. As a ring fits the finger of the wearer, the instrument 10 according to the present invention, has, at its terminal end, a grasping system formed by two half-cylinders 52, 54 that fits the conformation of the array 70, handling the electrodes and thus allowing their introduction in the cochlear canal.

The main characteristics of the instrument are therefore evident according to the present invention:

- The cylindrical shape reduces the possibility of damaging the electrodes, with respect to a known forceps in which a greater pressure is exercised, due to a distribution of the force over a smaller surface area.

- The possibility of a ring shape with a variable diameter allows the introduction of different caliber electrodes, successfully accompanying both the apical electrodes and the baseline electrodes, thus reducing surgical difficulties, allowing a greater directionality of the array and reducing the risks of distortion ("kinking") of the array.

- The ring shaped end part of the device (aimed to grab the array) is lateral and slightly elevated and offset with respect to the surgeon's hand, thus allowing for better vision within the limited surgical corridor. Preferably, a device for the right side and one for the left side is provided. - The terminal part of the instrument is configured to exert a force perfectly tangent to the array and distributed on it, therefore reducing the risk of distortion of the array ("kinking") or of damage.

According to a preferred embodiment of the present invention, the retainer 50 comprises two jointed half-cylinders having a length of 2.0- 5.0 mm, for example 2.5 mm. Considering the diameter of the arrays currently on the market (about 0.3-0.4 mm), the two half-cylinders preferably have an internal diameter of about 0.35 mm and an outer diameter of about 0.6 mm, to limit as much as possible the impediment of the visual field of the surgeon.

The instrument 10 is configured to allow the opening and closing of the upper half-cylinder, while the lower one is fixed and integral with the structure of the instrument. The opening system is based on a system of joints that allow the opening of the upper half-cylinder when the two handles of the instrument are distanced and its closure at their approximation.

Preferably, the tool 10 can be disassembled to allow a correct sterilization and is equipped with a system of controlled opening and closing, in order to avoid the application of excessive pressure on the array.

Preferably the tool is made of metal, preferably titanium.

Preferably, the tool also comprises a channel, upwardly opened, for housing at least part of the array, retained by the retainer. Preferably, the channel is straight and its bottom is shaped as an arc of a circle or a semicircle.

Claims

1 . A surgical instrument (10) to facilitate the introduction of the internal component (70) of a cochlear implant comprising two crossed arms (20, 30) connected by a joint (40), wherein each arm (20, 30) acts as a first class lever and the joint (40) acts as a fulcrum, wherein the tool (10) comprises two rings (22, 32), one for each arm, configured to accommodate two fingers of a surgeon's hand, characterized by comprising a retainer (50) for retaining a portion of said inner component (70) of the cochlear implant, wherein said retainer (50) comprises two half-cylinders (52, 54) mutually movable respect to one another.

2. The instrument (10) of claim 1 , wherein said half-cylinders (52, 54) are hinged (56), wherein an hinge axis between said half-cylinders (52, 54) is substantially parallel to a longitudinal axis of the half- cylinders (52, 54).

3. The instrument (10) of claim 1 or 2, wherein a half-cylinder is fixed (52) and a half-cylinder (54) is movable as a function of the movement of an arm (22) of the tool (10).

4. The instrument (10) of claim 3, further comprising a mechanism (58) for moving the movable half cylinder (54) relative to the fixed half-cylinder (52).

5. The instrument (10) of any one of the preceding claims, also comprising a guide channel (38) open at the top to accommodate a portion of said inner component (70) of the cochlear implant.

6. The instrument (10) of any one of the preceding claims, wherein each half-cylinder (52, 54) has a length between about 2 mm and about 5 mm.

7. The instrument (10) of any one of the preceding claims, wherein each half-cylinder (52, 54) has a section shaped as an arc of a circle with an inner diameter of about 0.5 mm or less.

8. The instrument (10) of any one of the preceding claims, wherein the two arms (20, 30) of the tool are detachable relative to one another.

9. The instrument (10) of any one of the preceding claims, wherein said tool is of a metallic material such as steel or titanium.