Anchoring means for implantable microphone

p0001The invention relates to a fixation element for an implantable microphone that can be used with a provided with a sound entry membrane cylindrical housing part in a rear bony wall of the canal traversing bore and which can, for example, form a part of a partially or fully implantable hearing aid.

p0002An embodiment of a microphone of the aforementioned kind is the subject of earlier <patcit id="pcit0001" dnum="EP97114603A"><text>European Patent Application 97114603</text></patcit> and in the article "<nplcit id="ncit0001" npl-type="s"><text>An implantable microphone for electronic hearing implants "by H. Leysieffer et al, ENT. 45: 816-827 (October 1997</text></nplcit>) Explained. From the mentioned article, it is known to fix the microphone housing in the mastoid mechanically by means of bone cement. A cement fixation, however, has numerous problems. Thus, the bone cement may cause undesirable side effects may at the implantation site. The handling is difficult in view of the limited space and the low visibility conditions at the implant site. Bone cement can undesirably reach even in places where it disturbs. A subsequent correction of the microphone position in the bore of the ear canal wall is practically impossible. It would be conceivable to screw the microphone housing in the bore of the auditory canal wall. Clinical experiments show, however, that this is problematic because of the small thickness of the bony canal wall. Furthermore, screws are often perceived painful in the field of implant site and for a long time after surgery.

p0003The invention is based is to provide a fixation element of the aforementioned type which permits a substantially simplified and yet highly precise implantation of the microphone while avoiding the associated with the use of bone cement disadvantages the task.

p0004This object is achieved with a fixation element for an implantable microphone that can be used with a provided with a sound entry membrane cylindrical housing part in a the posterior bony wall of the canal traversing bore solved, the present invention is characterized by a sleeve which surrounds a cylindrical sleeve portion the cylindrical housing part and having the against the auditory canal facing the skin side of the canal wall can be applied, projecting, elastic flange.

p0005The fixation element according to the invention allows, in the bony canal wall traversing bore easy to clip the microphone housing. The use of bone cement is avoided. The is investing in the bony canal wall flange ensure precise alignment of the microphone housing with respect to the ear canal wall. Together with the engaged with the bore wall cylindrical sleeve portion they provide a safe and stable long-term retention of the implanted microphone safely.

p0006In a further embodiment of the invention the sleeve with further projecting flange is provided, which can be applied against the averted from the ear canal skin side of the bony canal wall. Characterized the support of the microphone is further improved in the implanted state. Further, an unintentional tilting of the microphone housing against the canal wall during the implantation process or later excluded reliably.

p0007Preferably, the entire sleeve made of biocompatible elastic material is made, which is suitably selected from the group consisting of silicones and polyurethanes. Such a material permits limited deformation of the sleeve during insertion into the bore of the bony canal wall. It allows the flange to create properly against the respective side of the canal wall. In the area of ​​the cylindrical sleeve portion can be provided in a simple manner for a clamping force.

p0008In a further embodiment of the invention may be part of a jacket cuff, which except for the sound entry membrane enclosing the microphone at least for the greater part, and preferably completely. A particularly secure anchoring of the sleeve with respect is achieved in the microphone housing.

p0009The flange parts which are intended to create in the implanted state against the auditory canal facing the skin side of the canal wall, can be kept in a position in which they can be inserted through the hole in the wall of the canal during implantation by means of a tool. But that implanting the microphone is particularly simple if, in a development of the invention, a holder is provided which against the auditory canal facing the skin side of the canal wall can be applied flange before implantation against an elastic restoring force of the flange in an insertion through the hole in the wall of the canal keeps permitting bent position. The against the auditory canal facing the skin side of the canal wall can be applied flange are preferably configured and dimensioned such that they jump up after removal of the bracket in a position in which they protrude radially from the cylindrical sleeve portion substantially. The surgeon needs in such a design of the fixation element only the jacketed cylindrical housing part of the microphone together with the holder inserted in the bore of the rear bony wall of the canal and then to make the holder ineffective or remove, to ensure the accurate and secure positioning of the microphone at the implant , As holder may simply a durchtrennbarer during the implantation yarn can be provided that first the associated flange does not keep interfering position in implanting and then allowed to pass because of their elastic properties in a relaxed position, the flange in question, in which your holding function take. As support can be provided according to an advantageous alternative embodiment also an attached on the bent flange cap.

p0010According to another embodiment of the invention, against the auditory canal facing the skin side of the canal wall can be applied flange are inclined starting from the cylindrical sleeve part towards this cuff part. This contributes to the proper application of the flange to the auditory canal facing the skin side of the canal wall, even if the relevant surface of the canal wall has certain irregularities due to the anatomical conditions. For the same reason, preferably, the wall thickness of the against the auditory canal facing the skin side of the canal wall can be applied flange radially outwards.

p0011The against the auditory canal facing the skin side of the ear canal wall can be applied flange portions may be formed substantially radially projecting annular flange in the relaxed state as a starting from the cylindrical sleeve part in particular. However, other geometric configurations are contemplated, provided that only one hand, the required holding function is ensured and on the other hand, see the flange in the space between the ear canal skin and ear canal wall can easily accommodate.

p0012Preferably against the auditory canal facing the skin side of the canal wall can be applied flange are provided with openings, in particular have the task of providing a nutritional transition between the bony wall of the canal and the ear canal skin in the region of the annular flange.

p0013It is understood that fixation element of the invention is basically suitable for microphones of any shape, for example, for microphones with a continuous cylindrical housing. When the microphone but in a conventional manner (essay "<nplcit id="ncit0002" npl-type="s"><text>An implantable microphone for electronic hearing implants "by H. Leysieffer et al, ENT. 45: 816-827 (October 1997)</text></nplcit>) Is provided with a multi-leg microphone housing, in which a first housing leg forming the cylindrical housing part and a second housing leg about an approximately the thickness of the rear bony wall of the meatus corresponding distance is set back relative to the plane of the sound entry membrane, advantageously forms the second housing leg itself or a second ummantelnder housing leg part of the fixation member at least a portion of the flange, which can be applied against the skin facing away from the ear canal side of the ear canal wall. In this case, one of the flange parts, which can be applied against the skin facing away from the ear canal side of the auditory canal wall, preferably a shoulder, which projects on the second housing leg diametrically opposite side from the cylindrical sleeve part.

p0014Suitably at least the sleeve is made of a material with a Shore A hardness of 20 to 70th

p0015Preferred embodiments of the invention are explained below with reference to the accompanying drawings. They show:<dl id="dl0001" compact="compact"><dt>FIG. 1</dt><dd>a schematic representation of an implanted in the posterior bony canal wall microphone that is held by means of a fixation element of the invention;</dd><dt>FIG. 2</dt><dd>larger scale, a view of the check with the microphone <figref idrefs="f0001">FIG. 1</figref> provided fixation element as viewed from arrow A in <figref idrefs="f0001">FIG. 1</figref>;</dd><dt>FIG. 3</dt><dd>a plan view of the fixation element according to <figref idrefs="f0002">FIG. 2</figref>;</dd><dt>FIG. 4</dt><dd>a sectional view of the fixation element according to the line IV-IV in <figref idrefs="f0002">FIG. 3</figref>;</dd><dt>FIG. 5</dt><dd>a detailed view on an even larger scale in the <figref idrefs="f0003">FIG. 4</figref> indicated by a circle V region of the fixation member;</dd><dt>FIG. 6</dt><dd>a view similar to <figref idrefs="f0002">FIG. 2</figref>, Except that the annular flange is shown schematically in the state in which it is brought to the implantation in preparation;</dd><dt>FIG. 7</dt><dd>similarly a plan view <figref idrefs="f0002">FIG. 3</figref> a fixation element according to a modified embodiment; </dd><dt>FIG. 8th</dt><dd>a side view of the fixation element according to a further modified embodiment, and</dd><dt>FIG. 9</dt><dd>a view similar to <figref idrefs="f0004">FIG. 6</figref>, But a cap for retaining against the auditory canal facing the skin side of the canal wall can be applied flange before and during the implantation is placed.</dd></dl>

p0016<figref idrefs="f0001">FIG. 1</figref> schematically shows a microphone 10 which may be part of a partly or fully implantable hearing aid. The hearing aid as such can be designed in a conventional manner. Examples of such hearing aids are described in the article "<nplcit id="ncit0003" npl-type="s"><text>Active electronic hearing implants for middle and inner ear hearing loss - a new era of ear surgery "HP Zenner et al, ENT. 45: 749-757 (October 1997</text></nplcit>) Explained. The microphone 10 has a two-leg microphone housing 11, which in<figref idrefs="f0001">FIG. 1</figref> is only indicated schematically for ease of illustration and therefore not illustrated in section. In a first leg 12 of the microphone housing 11 a microphone capsule is housed, and the leg 12 forms a provided with a sound entry membrane 13 cylindrically-shaped housing part 14. A second housing arm 15 takes a schematically indicated at 16 electrical feedthrough for an electrical supply line 17.

p0017The microphone 10 is equipped with a fixation element 20, which forms a whole microphone receiving the shroud in the illustrated embodiment. Part of the fixation element 20 is, as shown in detail in the<figref idrefs="f0002 f0003">Figures 2 to 5</figref> is shown, a collar 21 which surrounds the cylindrical housing part 14 with a cylindrical sleeve portion 22nd To the cuff 21 further include flange portions 23, 24 and 25, projecting at both axial ends of the cylindrical cuff portion 22 radially outward. correspondingly<figref idrefs="f0001">FIG. 1</figref> is the cylinder-shaped housing part 14 can be used together with the cylindrical sleeve portion 22 from a mastoid cavity 27 made in a bore 28 which crosses a rear bony wall of the meatus 29th In<figref idrefs="f0001">FIG. 1</figref> the lined ear canal skin ear canal 30 at 31 and the eardrum 32 are indicated. The dimensioning is chosen so that on the one hand invest in the implanted state of the microphone 10, the flange 23, 24 and 25 against the ear canal skin 30 the side facing 33 and the other hand against the averted from the ear canal skin side 34 of the wall of the canal 29 and thereby the sound inlet membrane 13 in direct mechanical contact with the ear canal skin 30 comes. Accordingly, the axial distance is<b><i><u>a</u></i></b> between the flange 23 and the flange portions 24 and 25 such that it coincides with the average wall thickness of the bony canal wall 29th The distance<b><i><u>a</u></i></b> is generally in the range of 1.0 to 2.5 mm. Preferably, it is about 1.6 mm. The sound inlet diaphragm 13 has in the interest of a good abutment against the ear canal skin 30 preferably has a diameter of less than 5.0 mm. For example, accordingly, the cylindrical housing part 14 has an outer diameter of about 4.5 mm, and the cylindrical sleeve portion 22 has an outer diameter of about 5.3 mm.

p0018When the <figref idrefs="f0001 f0002 f0003 f0004">Figures 1-6</figref> illustrated embodiment, the fixation element 20 is with the sound entry membrane 13 formed substantially flush lying flange portion 23 as an annular flange which projects radially substantially in the relaxed state of the auditory canal end of the cylindrical sleeve portion 22 in. The annular flange 23 is provided with a series of circumferentially arranged distributed perforations 36th The object of the openings 36, it is primarily a nutrient transport between the bony canal wall 29 and the ear canal skin 30 permit in the area of ​​the annular flange 23rd Shape and number of the perforations 36 are immaterial so long as the perforations fulfill this purpose and the necessary mechanical strength of the annular flange 23 remains received.

p0019Prior to implantation, is by the series of perforations 36, a surgical suture 37 is threaded and, for example, by twisting, knotting or the like temporarily fixed in a state in which the annular flange 23 corresponding to <figref idrefs="f0004">FIG. 6</figref> is gone axially folded and contracted by the flange 24 and 25th In this form, the 22 surrounded by the cylindrical sleeve part cylindrical housing part 14 can pass through the hole 28 in the wall of the canal 30th Then, when the yarn 37 is severed, the ring flange 23 returns to its relaxed shape in accordance with the<figref idrefs="f0001 f0002 f0003">Figures 1 to 4</figref> back. To enforce such a behavior, at least of the annular flange 23 forming part of the fixation element 20 is resilient.

p0020The annular flange 23 is located in the implanted state (<figref idrefs="f0001">FIG. 1</figref>) To the ear canal skin 30 the side facing the 33 canal wall 30 regardless of unevenness of wall surface as closely conform. To promote this, in addition to a suitable choice of material for at least the ring flange 23, in the illustrated embodiment, three measures provided particularly clear<figref idrefs="f0003">FIG. 5</figref> can be seen. On the one hand, the wall thickness of the annular flange 23 is reduced as far as possible without compromising the holding function of the annular flange. Further, the annular flange 23 is inclined, starting from the cylindrical sleeve part 22 in the direction towards the flange 24, 25th Finally, the wall thickness of the annular flange 23 decreases radially outward. The wall thickness of the annular flange 23 can be reduced advantageously from about 0.1 to 0.2 mm near the collar portion 22 to about 0.03 to 0.1 mm at the outer edge of the annular flange 23rd The inclination angle α of the annular flange 23 may be in the range of 0 to 20 degrees, preferably at about 5 degrees, lie.

p0021The flange portion 25 is formed by the part of the casing (fixation element 20) which covers the the annular flange 23 the side facing the housing leg 15th In the flange 24 there is a shoulder, which projects on the housing leg 15 diametrically opposite side of the cylindrical collar portion 22 (see in particular<figref idrefs="f0002">figures 3</figref> and <figref idrefs="f0003">4</figref>).

p0022In the implantation of the sheathed with the fixation element 20 microphone 10, the flange portions 23, 24 and 25 for an orientation of the sound entry membrane 13 and of the housing leg 15 provide parallel to the bony canal wall 29 in a position in which the sound entry membrane 13 is substantially flush with that of the ear canal skin 30 facing side 33 of the wall of the canal is 29. Even tilting the microphone 10, accidentally hit the microphone housing 11 and / or the feed line 17 applied for example by the implantation process force is effectively prevented. The fixation member 20 secures the headset at the implantation site, without additional measures, or means, for example, bone cement, may be required. If need be, the microphone 22 can during implantation, after introducing the cylindrical sleeve portion into the bore 28 to the in<figref idrefs="f0003">FIG. 4</figref> rotate at 40 indicated axis of the cylindrical housing part 14th

p0023The fixation element 20 is suitably a microphone housing 11 receiving molded part. The material used for the fixation element 20, in particular a biocompatible plastic with a Shore A hardness of 20 to 70. It is may be especially silicones or polyurethanes.

p0024The modified embodiment of the fixation element 42 in accordance with <figref idrefs="f0004">FIG. 7</figref> differs from the aforementioned fixation element 20 essentially only in that the lying when implanted between the canal wall 29 and the ear canal skin 30 flange are not formed by an annular flange 23, but by a series of circumferentially distributed the cylindrical sleeve portion flange segments 43rd Thereby, the flange segments 43, as shown, be provided with perforations 36th However, such perforations may also be dispensed with, especially if already due to the shape of the flange a nutrient transport between the ear canal wall 29 and the ear canal skin 30 is ensured.

p0025<figref idrefs="f0005">FIG. 8th</figref> shows a further modified, generally designated 46 embodiment of the fixation element, which is suitable for microphones with einschenkligem, a cylindrical microphone housing. The fixation element 46 again has a cuff 48 which encloses a cylindrical sleeve portion 49 has a cylindrical part of the microphone housing and in against the<figref idrefs="f0001">FIG. 1</figref> shown, the ear canal skin 30 the side facing 33 and facing away from the ear canal skin side 34 of the wall of the canal 29 can be placed against projecting flange parts 50 and 51 has. The flange 50 may, in particular according to the flange 23 of the<figref idrefs="f0002 f0003 f0004">Figures 2 to 6</figref> designed or under of flange segments 43 <figref idrefs="f0004">FIG. 7</figref> be formed. The flange 51 may be appropriately constructed as an annular shoulder.

p0026<figref idrefs="f0005">FIG. 9</figref> shows a view similar to <figref idrefs="f0004">FIG. 6</figref>Wherein, however, a cap 53 for retaining the can be laid against the side 33 of the ear canal wall 29 of flange 23, 43 and 50 before and during the implantation is provided instead of the thread 37th The cap 53 is made as thin at least in the region of the hollow cylindrical portion 54 that they put together with the cylindrical sleeve portion 22 or 49 in the bore 28 and then releasing the flange 23, 43 or 50 can be removed from the ear canal 31 of. To thereby facilitate grasping of the cap 53 by means of a tweezers or the like, the cap carries on its closed side of a nipple 55. In the hollow cylindrical part 54 of the cap 53 is a relatively stiff and hard plate 56 is advantageously used. The cap member 54 is preferably elastically stretchable to a limited extent. The cap material must be sterilizable; otherwise takes a variety of materials, especially metals and plastics, into consideration. The cap 53 provides, especially if it is equipped with the plate 56, before implantation for excellent protection of the sound entry membrane. 13