Patent Description:
Individuals suffer from a variety of hearing problems, such as tinnitus, Meniere's disease, vertigo, hearing loss, etc. Hearing loss, for example, which may be due to many different causes, is generally of two types, conductive and/or sensorineural. Conductive hearing loss occurs when the normal mechanical pathways of the outer and/or middle ear are impeded, for example, by damage to the ossicular chain or ear canal. Sensorineural hearing loss occurs when there is damage to the inner ear, or to the nerve pathways from the inner ear to the brain.

Individuals who suffer from conductive hearing loss typically have some form of residual hearing because the hair cells in the cochlea are undamaged. As such, individuals suffering from conductive hearing loss typically receive an auditory prosthesis that generates motion of the cochlea fluid. Such auditory prostheses include, for example, acoustic hearing aids, bone conduction devices, and direct acoustic stimulators.

In many people who are profoundly deaf, however, the reason for their deafness is sensorineural hearing loss. Those suffering from some forms of sensorineural hearing loss are unable to derive suitable benefit from auditory prostheses that generate mechanical motion of the cochlea fluid. Such individuals can benefit from implantable auditory prostheses that stimulate nerve cells of the recipient's auditory system in other ways (e.g., electrical, optical and the like). <CIT> relates to intra-cochlear drug delivery to the central nervous system. <CIT>) relates to a drug delivery apparatus. Both documents disclose the features in the preamble of claim <NUM>.

Embodiments of the present invention are described herein in conjunction with the accompanying drawings, in which:.

Presented herein are implantable systems and methods for long-term delivery of substances (e.g., biological or bioactive), chemicals, pharmaceutical agents, nanoparticles, ions, drugs, etc. (generally and collectively referred to herein as "treatment substance") to a target location within a recipient of a treatment substance delivery system and/or implantable auditory (hearing) prosthesis (e.g., bone conduction device, direct acoustic stimulator, cochlear implant, etc.). The target location may be, for example, the recipient's middle ear, inner ear, vestibular system, round window, oval window, cochleostomy, etc. Before describing illustrative embodiments of the treatment substance delivery systems and methods presented herein, a brief description of the human anatomy of a recipient's ear is first provided with reference to <FIG>.

As shown in <FIG>, a recipient's ear comprises an outer ear <NUM>, a middle ear <NUM> and an inner ear <NUM>. In a fully functional ear, outer ear <NUM> comprises an auricle <NUM> and an ear canal <NUM>. An acoustic pressure or sound wave <NUM> is collected by auricle <NUM> and channeled into and through ear canal <NUM>. Disposed across the distal end of ear canal <NUM> is a tympanic membrane <NUM> which vibrates in response to sound wave <NUM>. This vibration is coupled to oval window or fenestra ovalis <NUM>, which is adjacent round window <NUM>, through the bones of the middle ear <NUM>. The bones of the middle ear <NUM> comprise the malleus <NUM>, the incus <NUM> and the stapes <NUM>, collectively referred to as the ossicles <NUM>. The ossicles <NUM> are positioned in the middle ear cavity <NUM> and serve to filter and amplify the sound wave <NUM>, causing oval window <NUM> to articulate (vibrate) in response to the vibration of tympanic membrane <NUM>. This vibration of the oval window <NUM> sets up waves of fluid motion of the perilymph within cochlea <NUM>. Such fluid motion, in turn, activates tiny hair cells (not shown) inside of cochlea <NUM>. Activation of the hair cells causes appropriate nerve impulses to be generated and transferred through the spiral ganglion cells (not shown) and auditory nerve <NUM> to the brain (also not shown) where they are perceived as sound.

The human skull is formed from a number of different bones that support various anatomical features. Illustrated in <FIG> is the temporal bone <NUM> which is situated at the side and base of the recipient's skull <NUM>. For ease of reference, the temporal bone <NUM> is referred to herein as having a superior portion <NUM> and a mastoid portion <NUM>. The superior portion <NUM> comprises the section of the temporal bone <NUM> that extends superior to the auricle <NUM>. That is, the superior portion <NUM> is the section of the temporal bone <NUM> that forms the side surface of the skull. The mastoid portion <NUM>, referred to herein simply as the mastoid <NUM>, is positioned inferior to the superior portion <NUM>. The mastoid <NUM> is the section of the temporal bone <NUM> that surrounds the middle ear <NUM>.

As shown in <FIG>, semicircular canals <NUM> are three half-circular, interconnected tubes located adjacent cochlea <NUM>. Vestibule <NUM> provides fluid communication between semicircular canals <NUM> and cochlea <NUM>. The three canals are the horizontal semicircular canal <NUM>, the posterior semicircular canal <NUM>, and the superior semicircular canal <NUM>. The canals <NUM>, <NUM> and <NUM> are aligned approximately orthogonally to one another. Specifically, horizontal canal <NUM> is aligned roughly horizontally in the head, while the superior <NUM> and posterior canals <NUM> are aligned roughly at a <NUM> degree angle to a vertical through the center of the individual's head.

Each canal is filled with a fluid called endolymph and contains a motion sensor with tiny hairs (not shown) whose ends are embedded in a gelatinous structure called the cupula (also not shown). As the orientation of the skull changes, the endolymph is forced into different sections of the canals. The hairs detect when the endolymph passes thereby, and a signal is then sent to the brain. Using these hair cells, horizontal canal <NUM> detects horizontal head movements, while the superior <NUM> and posterior <NUM> canals detect vertical head movements.

It may be advantageous to have an extended delivery solution for use in the delivery of treatment substances to a target location of a recipient. In general, extended treatment substance delivery refers to the delivery of treatment substances over a period of time (e.g., continuously, periodically, etc.). The extended delivery may be activated during or after surgery and can be extended as long as is needed. The period of time may not immediately follow the initial implantation of the auditory prosthesis. As such, embodiments of the present invention are directed to different features that facilitate extended delivery of treatment substances. More specifically, certain embodiments are directed to passive actuation (drive) mechanisms that eliminate the need for an implanted active (i.e., powered) pump and power source to deliver treatment substances to a target location. Additional embodiments are directed to optional fixation mechanisms that retain various components of a delivery system at a selected implanted location. Further embodiments are directed to accretion prevention (anti-accretion) mechanisms that prevent the buildup of undelivered particles within the system that can inhibit subsequent delivery of treatment substances.

<FIG> illustrates an implantable delivery system <NUM> having a passive actuation mechanism in accordance with embodiments presented herein. The delivery system <NUM> is sometimes referred to herein as an inner ear delivery system because it is configured to deliver treatment substances to the recipient's inner ear (e.g., the target location is the interior of the recipient's cochlea <NUM>). <FIG> illustrates a first portion of the delivery system <NUM>, while <FIG> is a cross-sectional view of a second portion of the delivery system <NUM>.

Delivery system <NUM> of <FIG> comprises a reservoir <NUM>, a valve <NUM>, a delivery tube <NUM>, and a delivery device <NUM> (<FIG>). The delivery system <NUM> may include, or operate with, an external magnet <NUM>. For ease of illustration, the delivery system <NUM> is shown separate from any implantable auditory prostheses. However, it is to be appreciated that the delivery system <NUM> could be used with, for example, cochlear implants, direct acoustic stimulators, bone conduction devices, etc. In such embodiments, the implantable components (e.g., reservoir, valve, delivery tube, etc.) of delivery system <NUM> could be separate from or integrated with the other components of the implantable auditory prosthesis.

In the embodiment of <FIG>, the reservoir <NUM> is positioned within the recipient underneath a portion of the recipient's skin/muscle/fat, collectively referred to herein as tissue <NUM>. The reservoir <NUM> may be positioned between layers of the recipient's tissue <NUM> or may be adjacent to a subcutaneous outer surface <NUM> of the recipient's skull. For example, the reservoir <NUM> may be positioned in a surgically created pocket at the outer surface <NUM> (i.e., adjacent to a superior portion <NUM> of the temporal bone <NUM>).

The reservoir <NUM> is, prior to or after implantation, at least partially filled with a treatment substance for delivery to the inner ear <NUM> of the recipient. The treatment substance may be, for example, in a liquid form, a gel form, and/or comprise nanoparticles or pellets. In certain arrangements, the treatment substance may initially be in a crystalline/solid form that is subsequently dissolved. For example, a reservoir could include two chambers, one that comprises a fluid (e.g., artificial perilymph or saline) and one that comprises the crystalline/solid treatment substance. The fluid may be mixed with the crystalline/solid treatment substance to form a fluid or gel treatment substance that may be subsequently delivered to the recipient.

In certain embodiments, the reservoir <NUM> includes a needle port (not shown) so that the reservoir <NUM> can be refilled via a needle injection through the skin. In other embodiments, the reservoir <NUM> may be explanted and replaced with another reservoir that is, prior to or after implantation, at least partially filled with a treatment substance. In accordance with certain embodiments, the reservoir <NUM> may have a preformed shape and the reservoir is implanted in this shape. In other embodiments, the reservoir <NUM> may have a first shape that facilitates implantation and a second shape for use in delivering treatment substances to the recipient. For example, the reservoir <NUM> may have a rolled or substantially flat initial shape that facilitates implantation. The reservoir <NUM> may then be configured to expand after implantation. Such embodiments may be used, for example, to insert the reservoir through a tympanostomy into the middle ear or ear canal, through an opening in the inner ear, or to facilitate other minimally invasive insertions.

The delivery tube <NUM> includes a proximal end <NUM> and a distal end <NUM>. The proximal end <NUM> of the delivery tube <NUM> is fluidically coupled to the reservoir <NUM> via the valve <NUM>. As shown in <FIG>, the distal end <NUM> of the delivery tube <NUM> is fluidically coupled to the recipient's round window <NUM>. A delivery device <NUM> disposed within the distal end <NUM> of the delivery tube <NUM> is positioned abutting the round window <NUM>. As described further below, the delivery tube <NUM> may be secured within the recipient so that the distal end <NUM> remains located adjacent to the round window <NUM>.

<FIG> illustrate embodiments that utilize a passive actuation mechanism to produce a pumping action to transfer a treatment substance from the reservoir <NUM> to the delivery device <NUM> at the distal end <NUM> of the delivery tube <NUM>. More specifically, in these illustrative embodiments, the reservoir <NUM> is compressible in response to an external force <NUM>. That is, at least one part or portion of the reservoir <NUM>, such as wall <NUM> or a portion thereof, is formed from a resiliently flexible material that is configured to deform in response to application of the external force <NUM>. In certain embodiments, the positioning of the reservoir <NUM> adjacent the superior portion <NUM> of the mastoid <NUM> provides a rigid surface that counters the external force <NUM>. As a result, a pressure change occurs in the reservoir <NUM> so as to propel (push) a portion of the treatment substance out of the reservoir through valve <NUM>.

<FIG> and <FIG> illustrate a specific arrangement in which the reservoir <NUM> includes a resiliently flexible wall <NUM>. It is to be appreciated that the reservoir <NUM> may be formed from various resiliently flexible parts and rigid parts. It is also to be appreciated that the reservoir <NUM> may have a variety of shapes and sizes (e.g., cylindrical, square, rectangular, etc.) or other configurations. For example, in one embodiment the reservoir <NUM> could further include a spring mounted base that maintains a pressure in the reservoir <NUM> until the reservoir is substantially empty. Other mechanisms for maintaining a pressure in the reservoir may be used in other arrangements.

In certain embodiments, the external force <NUM> is applied manually using, for example, a user's finger. The user (e.g., recipient, clinician, caregiver, etc.) may press on the tissue <NUM> adjacent to the reservoir <NUM> to create the external force <NUM>. In certain embodiments, a single finger press may be sufficient to propel the treatment substance through valve <NUM>. In other embodiments, multiple finger presses may be used to create a pumping action that propels the treatment substance from the reservoir <NUM>.

In other embodiments, the external force <NUM> is applied through a semi-manual method that uses an external actuator <NUM> (<FIG>). That is, the external actuator <NUM> may be pressed onto the soft tissue <NUM> under which the reservoir <NUM> is located. The movement (e.g., oscillation/vibration) of the actuator <NUM> deforms the reservoir <NUM> to create the pumping action that propels the treatment substance out of the reservoir.

In certain embodiments, internal and/or external magnets and/or magnetic materials may be used in the arrangements of <FIG> and <FIG> to ensure that the actuator <NUM> applies force at an optimal location of the reservoir <NUM>. For example, the reservoir <NUM> may include a magnetic positioning member <NUM> located at or near an optimal location for application of an external force from the actuator <NUM>. The actuator <NUM> may include a magnet <NUM> configured to magnetically mate with the magnetic positioning member <NUM>. As such, when actuator <NUM> is properly positioned, the magnet <NUM> will mate with the magnetic positioning member <NUM> and the force from the actuator <NUM> will be applied at the optimal location.

In other embodiments, a remote control, remotely placed actuator (subcutaneous or otherwise) may be alternatively used. For example, in a further arrangement, the implant includes implanted electronics <NUM> (shown using dotted lines in <FIG>). These implanted electronics <NUM> may be configured to, for example, control the valve <NUM> and/or include an actuation mechanism that can force treatment substance from the reservoir <NUM>. In certain embodiments, the implanted electronics <NUM> may be powered and/or controlled through a transcutaneous link (e.g., RF link). As such, the implanted electronics <NUM> may include or be electrically connected to an RF coil, receiver/transceiver unit, etc..

In accordance with certain embodiments, the implanted electronics <NUM> may include or be connected to a sensor that is used, at least in part, to assist in control of delivery of the treatment substance to the recipient. For example, a sensor (e.g., a temperature sensor, a sensor to detect infection or bacteria growth, etc.) may provide indications of when a treatment substance should be delivered and/or when delivery should be ceased for a period of time. A sensor may also be configured to determine an impact of the treatment substance on the recipient (e.g., evaluate effectiveness of the treatment substance).

As noted, the treatment substance is released from the reservoir <NUM> through the valve <NUM>. The valve <NUM> may be a check valve (one-way valve) that allows the treatment substance to pass there through in one direction only. This assures that released treatment substances do not back-flow into the reservoir <NUM>. In certain embodiments, the valve <NUM> is a valve that is configured to open in response to the pressure change in the reservoir <NUM> (e.g., a ball check valve, diaphragm check valve, swing check valve or tilting disc check valve, etc.). The valve <NUM> may be a stop-check valve that includes an override control to stop flow regardless of flow direction or pressure. That is, in addition to closing in response to backflow or insufficient forward pressure (as in a normal check valve), a stop-check value can also be deliberately opened or shut by an external mechanism, thereby preventing any flow regardless of forward pressure. The valve <NUM> may be a stop-check value that is controlled by an external electric or magnetic field generated by, for example, the external magnet <NUM>, an electromagnet, etc. In the embodiments, of <FIG> and <FIG>, the valve is responsive to a magnetic field generated by external magnet <NUM>. As such, the valve <NUM> will temporarily open when the external magnet <NUM> is positioned in proximity to the valve <NUM> and will close when the external magnet <NUM> is removed from the proximity of the valve <NUM>. In certain embodiments, variable magnet strengths of external magnets may be used to control the dosage of the treatment substance. Additionally, an electromagnet may be used in place of the external magnet <NUM>.

The use of a stop-check valve may prevent unintended dosing of the treatment substance when, for example, an accidental external force acts on the reservoir <NUM>. The reservoir <NUM> is formed such that an increase in pressure of the reservoir <NUM> without an accompanying treatment substance release will not damage (i.e., rupture) the reservoir.

It is to be appreciated that the use of a magnetically activated stop-check valve is merely exemplary and that other types of valves may be used in alternative embodiments. For example, in alternative embodiments the valve <NUM> may be actuated (i.e., opened) in response to an electrical signal (e.g., piezoelectric valve). The electrical signal may be received from a portion of an auditory prosthesis (not shown) that is implanted with the delivery system <NUM> or the electrical signal may be received from an external device (e.g., an RF actuation signal received from an external sound processor, remote control, etc.). In other embodiments, manually applied (e.g., finger) force be also able to open the valve <NUM>.

Once the treatment substance is released through valve <NUM>, the treatment substance flows through the delivery tube <NUM> to the delivery device <NUM>. The delivery device <NUM> operates as a transfer mechanism to transfer the treatment substance from the delivery tube <NUM> to the round window <NUM>. The treatment substance may then enter the cochlea <NUM> through the round window <NUM> (e.g., via osmosis). The delivery device <NUM> may be, for example, a wick, a sponge, permeating gel (e.g., hydrogel), etc..

In accordance with further embodiments presented herein, the reservoir <NUM> may include a notification mechanism that transmits a signal or notification indicating that the reservoir <NUM> is substantially empty and/or needs refilled. For example, one or more electrode contacts (not shown) may be present and become electrically connected when the reservoir is substantially empty. Electronic components associated with or connected to the reservoir <NUM> may accordingly transmit a signal indicating that reservoir needs filled or replaced.

<FIG> illustrate a specific example in which the round window <NUM> is the target location. As noted above, the round window <NUM> is an exemplary target location and other target locations are possible in accordance with embodiments presented herein.

<FIG> illustrate an embodiment in which the reservoir <NUM> is positioned adjacent to the outer surface <NUM> of the recipient's skull so that an external force may be used to propel the treatment substance from the reservoir. <FIG> illustrate another embodiment where an external force is not utilized to propel the treatment substance from the reservoir <NUM>. More specifically, in the embodiments of <FIG> the reservoir <NUM> is positioned between a recipient's muscle <NUM> (e.g., temporalis (temporal muscle), jaw, etc.) and hard tissue <NUM> (e.g., bone, teeth, etc.). As shown in <FIG>, the muscle <NUM> may be in a relaxed state where little or no pressure is placed on the reservoir <NUM>. As shown in <FIG>, the muscle <NUM> may alternatively be in a contracted state that compresses the reservoir <NUM>. The compression of the reservoir <NUM> in response to the muscle contraction propels the treatment substance from the reservoir <NUM> into the delivery tube <NUM> via the valve <NUM>. In certain circumstances, the muscle <NUM> may be contracted through mastication. As noted, the valve <NUM> may be a check valve or a stop-check valve (e.g., a magnetically operated valve).

<FIG> illustrates a further embodiment where an external force may not be needed to propel a treatment substance from an implantable reservoir. More specifically, in delivery system <NUM> of <FIG>, a reservoir <NUM> is positioned in the recipient's middle ear cavity <NUM>. The reservoir <NUM> is, at least in part, formed from a resiliently flexible material that is deformable in response to pressurization of the middle ear cavity <NUM>. <FIG> illustrates an example in which the reservoir <NUM> includes first and second opposing walls <NUM>(<NUM>) and <NUM>(<NUM>) that may deform in response to pressurization of the middle ear cavity <NUM>. Deformation of the walls <NUM>(<NUM>) and <NUM>(<NUM>) pressurizes the interior of the reservoir <NUM> so as to propel the treatment substance through the valve <NUM> and into the delivery tube <NUM>. Similar to the embodiments of <FIG>, the valve <NUM> may be a check valve or a stop-check valve (e.g., a magnetically operated valve).

In certain examples, ear equalization techniques can be used to pressurize the middle ear cavity <NUM> and deform the flexible reservoir <NUM>. For example, the Valsalva maneuver (i.e., where the recipient pinches his/her nostrils closed and blows gently through the nose), the Frenzel maneuver (i.e., where the recipient performs a gentle Valsalva maneuver by breathing against pinched nostrils and swallowing at the same time), etc. may be used.

<FIG> illustrates an embodiment in which the reservoir <NUM> includes first and second opposing walls <NUM>(<NUM>) and <NUM>(<NUM>) that may deform in response to pressurization of the middle ear cavity <NUM>. The reservoir <NUM> is secured within the middle ear cavity such that the pressure may act on both walls <NUM>(<NUM>) and <NUM>(<NUM>). In an alternative embodiment, the reservoir <NUM> may secured such that one wall of the reservoir <NUM> abuts hard tissue. In such embodiments, the reservoir wall that abuts the hard tissue may be compressible or substantially rigid.

<FIG> illustrates an embodiment where magnetic attraction is used to force a treatment substance from an implantable reservoir. More specifically, in the embodiment of <FIG> a magnetic element <NUM> is implanted abutting the outer surface <NUM> of the recipient's skull. The magnetic element <NUM> may be formed from a ferromagnetic or ferrimagnetic material. The ferromagnetic or ferrimagnetic material may be magnetized (i.e., a permanent magnet) or non-magnetized. <FIG> illustrates a specific embodiment in which the magnetic element <NUM> is a permanent magnet. The magnetic element <NUM> may be (optionally) secured to the superior portion <NUM> of recipient's temporal bone <NUM> using, for example, a bone screw (not shown) or another fixation mechanism (e.g., adhesive). Alternatively, the magnetic element <NUM> may be held in place by the recipient's tissue <NUM>.

As shown, the reservoir <NUM> is implanted so as to abut an externally-facing surface <NUM> of the magnetic element <NUM> (i.e., a surface facing away from the recipient's temporal bone <NUM>). The reservoir <NUM> may be secured to the magnetic element <NUM> and/or the recipient's temporal bone using one or more fixation mechanisms described further below or may be held in place by the recipient's tissue <NUM>.

In the embodiment of <FIG>, an external magnet <NUM> may be placed adjacent to the recipient's tissue <NUM> that at least partially covers the reservoir <NUM>. The poles of the external magnet <NUM> and the magnetic element <NUM> are oriented so that the external magnet <NUM> and the magnetic element <NUM> will be magnetically attracted to one another when in proximity to one another. As shown by arrows <NUM> in <FIG>, the mutual attraction between the external magnet <NUM> and the magnetic element <NUM> compresses the recipient's tissue <NUM> adjacent to the reservoir <NUM>. The compression of the tissue, in turn, compresses the wall <NUM> of the reservoir <NUM>. The positioning of the reservoir <NUM> abutting the magnetic element <NUM> and the superior portion <NUM> of the mastoid <NUM> provides a rigid surface that counters the compression of the tissue <NUM>. As a result, a pressure change occurs in the reservoir <NUM> so as to propel a portion of the treatment substance out of the reservoir through valve <NUM>.

As noted, the valve <NUM> may be a check valve or a stop-check valve (e.g., a magnetically operated valve). In embodiments in which the valve <NUM> is a magnetically operated valve, the external magnet <NUM> may be configured so as to compress the reservoir <NUM> and additionally open valve <NUM>.

The magnetic element <NUM> and external magnet <NUM> may have a variety of shapes and sizes (e.g., cylindrical, square, rectangular, etc.). In certain embodiments, the magnetic element <NUM> and external magnet <NUM> have corresponding generally annular shapes to enhance the alignment of the magnetic elements with one another.

<FIG> illustrates another embodiment where magnetic attraction is used to force a treatment substance from an implantable reservoir. More specifically, in the embodiment of <FIG> a reservoir <NUM> comprises a first end plate <NUM> connected to a second plate <NUM> by a substantially flexible outer wall <NUM>. The end plates <NUM> and <NUM> may be, for example, circular, oval, square, rectangular, etc. so as to, along with flexible outer wall <NUM>, form a closed body in which a treatment substance may be disposed. One or both of the end plates <NUM> and <NUM> may be formed from ferromagnetic or ferrimagnetic material (magnetized or non-magnetized) such that when an external magnet <NUM> is in proximity to the reservoir <NUM>, the treatment substance may be forced through valve <NUM>. For example, in one such embodiment the end plates <NUM> and <NUM> may be configured such that the presence of the magnet <NUM> causes plate <NUM> to be forced away from the magnet <NUM> (as shown by arrows <NUM>), while the end plate <NUM> is pulled towards the magnet <NUM> (as shown by arrows <NUM>). This "squeezing" action produced by the presence of external magnet <NUM> forces the treatment substance through valve <NUM>.

<FIG> illustrate embodiments in which drugs that are forced from an implantable reservoir pass through a valve and directly into a delivery tube. <FIG> illustrates an embodiment where a secondary reservoir <NUM> is added to enable extended treatment substance release. More specifically, in the embodiment of <FIG>, when the treatment substance is released from reservoir <NUM>, the treatment substance passes through valve <NUM> and into a connector tube <NUM>. The distal end <NUM> of the connector tube <NUM> is connected to the secondary reservoir <NUM> such that application of the external force <NUM> propels the treatment substance from reservoir <NUM> into the secondary reservoir <NUM>. A valve <NUM> at the output of the secondary reservoir <NUM> may be configured to release the treatment substance from the secondary reservoir to the delivery tube <NUM> at a predetermined rate (e.g., at certain time periods). As such, the arrangement of <FIG> can utilize the secondary reservoir <NUM> to deliver the treatment substance to the delivery device <NUM> (<FIG>) over a period of time without the need for application of additional external forces <NUM>.

<FIG> illustrates the use of a secondary reservoir and a primary reservoir positioned adjacent to the outer surface <NUM> of the recipient's skull. It is to be appreciated that a secondary reservoir may also be used in other embodiments presented herein (e.g., with a primary reservoir positioned in the middle ear cavity).

<FIG> illustrates another embodiment where the external force is applied to a section of tubing rather than a reservoir. More specifically, <FIG> illustrates a delivery system <NUM> that comprises a reservoir <NUM>, a valve <NUM>, an expansion tube <NUM>, a delivery tube <NUM>, a secondary valve <NUM>, and a delivery device (not shown). The delivery system <NUM> may include, or operate with, an external magnet <NUM>.

In the embodiment of <FIG>, the reservoir <NUM> and the expansion tube <NUM> are positioned underneath the recipient's tissue <NUM> adjacent to outer surface <NUM> of the recipient's skull. The reservoir <NUM> is at least partially filled with a treatment substance for delivery to the inner ear <NUM> of the recipient. The reservoir <NUM> may include a needle port (not shown) so that the reservoir can be refilled via a needle injection through the skin or the reservoir <NUM> may be explanted and replaced with another reservoir that is configured to be at least partially filled with a treatment substance.

The expansion tube <NUM> is a tubing section formed from a resiliently flexible (e.g., elastomer) element configured to compress in response to application of an external force <NUM> applied, for example, manually or semi-manually as described above. The positioning of the expansion tube <NUM> adjacent the superior portion <NUM> of the mastoid <NUM> provides a rigid surface that counters the external force <NUM>. As a result, that application and subsequent removal of the external force <NUM> causes rapid pressurization and depressurization of the expansion tube <NUM> so as to pull the treatment substance from reservoir <NUM> through the valve <NUM>. As a result, the expansion tube <NUM> expands as it is substantially or partially filled with the treatment substance.

It is to be appreciated that the positioning of expansion tube <NUM> adjacent the superior portion <NUM> of the mastoid <NUM> is merely illustrative. The expansion tube <NUM> may be positioned to other natural or surgical implanted semi-rigid elements so as to enable rapid pressurization and depressurization of the expansion tube <NUM>.

The expansion tube <NUM> may fill up to a certain volume in response to the repeated application and removal of the external force <NUM>. The valve <NUM> at the output of the expansion tube <NUM> may be configured to release the treatment substance from the secondary reservoir to the delivery tube <NUM> at a predetermined rate (e.g., at certain time periods). As such, the arrangement of <FIG> can utilize the expansion tube <NUM> to deliver the treatment substance to the delivery device over a period of time without the need for application of additional external forces <NUM>.

As noted, the treatment substance is released from the reservoir <NUM> through the valve <NUM>. The valve <NUM> may be a check valve that allows the treatment substance to pass there through in one direction only. This assures that released treatment substances do not back-flow into the reservoir <NUM>. In certain embodiments, the valve <NUM> is a valve that is configured to open in response to the pressure change in the expansion tube <NUM>. In certain embodiments, the valve <NUM> is a stop-check valve that includes an override control to stop flow regardless of flow direction or pressure. For example, the valve <NUM> may be a stop-check value that is controlled by the external magnet <NUM>. In such embodiments, the valve <NUM> will temporarily open when the external magnet <NUM> is positioned in proximity to the valve <NUM> and will close when the external magnet <NUM> is removed from the proximity of the valve <NUM>. The use of a stop-check valve may prevent unintended dosing of the treatment substance when, for example, an accidental external force acts on the expansion tube <NUM>.

It is to be appreciated that the use of magnetically activated stop-check valve is merely exemplary and that other types of valves may be used in alternative embodiments. For example, in alternative embodiments the valve <NUM> may be actuated (i.e., opened) in response to an electrical signal. The electrical signal may be received from a portion of an auditory prosthesis (not shown) that is implanted with the delivery system <NUM> or the electrical signal may be received from an external device (e.g., an RF actuation signal received from an external sound processor, remote control, etc.).

<FIG> illustrate embodiments that utilize an implantable reservoir and a passive actuation mechanism to transfer treatment substances from the reservoir to a target location. In alternative embodiments not forming part of the claimed invention, treatment substances are delivered to a recipient's middle ear/inner ear using a substantially external system where the reservoir and actuation unit (e.g., pump) need not be implanted in the recipient. More specifically. <FIG> illustrate a delivery system <NUM> comprising an external component <NUM>, a delivery tube <NUM>, and delivery device <NUM>. The external component <NUM> is a behind-the-ear component that is configured to be worn on the outer ear <NUM> of the recipient.

As shown in <FIG>, the external component <NUM> comprises a reservoir <NUM> that is configured to be at least partially filled with a treatment substance. The external component <NUM> also comprises a valve <NUM> (e.g., check valve), a pump <NUM> and a power source (e.g., battery) <NUM>. In operation, the pump <NUM> propels the treatment substance in the reservoir <NUM> through the valve <NUM> and into the delivery tube <NUM>.

The delivery tube <NUM> has a proximal end <NUM> (<FIG>) that is fluidically coupled to the valve <NUM>, and a distal end <NUM> (<FIG>) that is fluidically coupled to the round window <NUM>. As shown in <FIG> and <FIG>, the delivery tube <NUM> extends from the external component <NUM> and into the recipient's ear canal <NUM>. The delivery tube <NUM> also extends through the recipient's tympanic membrane <NUM> to the round window <NUM>. In particular, the delivery tube <NUM> passes through a surgically formed opening within the tympanic membrane <NUM>. A surgically placed grommet <NUM> seals the opening in the tympanic membrane <NUM> around the delivery tube.

Once the treatment substance is released through valve <NUM>, the treatment substance flows through the delivery tube <NUM> to the delivery device <NUM> (passing through the ear canal <NUM> and the tympanic membrane <NUM>). The delivery device <NUM> operates as a transfer mechanism to transfer the treatment substance from the delivery tube <NUM> to the round window <NUM>. The treatment substance may then enter the cochlea <NUM> through the round window <NUM> (e.g., via osmosis). The delivery device <NUM> may be, for example, a wick, a sponge, permeating gel (e.g., hydrogel), etc..

External components, such as behind-the-ear components, are used with a number of implantable auditory prostheses. It is to be appreciated that the external component <NUM> of <FIG> and <FIG> may also include the components of an external component used with an implantable auditory prosthesis (e.g., sound processor, sound input element, etc.). That is, external component <NUM> may be integrated with the components of an external component of an implantable auditory prosthesis.

<FIG> illustrates another delivery system <NUM> not forming part of the claimed invention comprising an external component <NUM>, a delivery tube <NUM>, and a delivery device (not shown). The external component <NUM> is an in-the-ear component positioned in the pinna <NUM> or ear canal <NUM> of the recipient.

The external component <NUM> comprises a reservoir <NUM> that is configured to be at least partially filled with a treatment substance. The external component <NUM> also comprises a valve <NUM> (e.g., check valve), a pump <NUM>, and a power source <NUM>. In operation, the pump <NUM> propels the treatment substance in the reservoir <NUM> through the valve <NUM> and into the delivery tube <NUM>.

The delivery tube <NUM> has a proximal end <NUM> that is fluidically coupled to the valve <NUM> and a distal end (not shown) that is fluidically coupled to the round window <NUM>. The delivery tube <NUM> extends from the external component <NUM> through the recipient's tympanic membrane <NUM> to the round window <NUM>. In particular, the delivery tube <NUM> passes through a surgically formed opening within the tympanic membrane <NUM>. A surgically placed grommet <NUM> seals the opening in the tympanic membrane <NUM> around the delivery tube.

Once the treatment substance is released through valve <NUM>, the treatment substance flows through the delivery tube <NUM> to a delivery device (not shown) by passing through the tympanic membrane <NUM>. The delivery device may be substantially similar to delivery device <NUM> of <FIG> and operates as a transfer mechanism to transfer the treatment substance from the delivery tube <NUM> to the round window <NUM>.

Delivery systems in accordance with embodiments presented herein are intended for delivery of treatment substances to a target location within a recipient. As noted, the target location may be, for example, the recipient's middle ear, inner ear, round window, oval window, through a cochleostomy, on/at a cochleostomy, etc. In certain examples, the target location may be a portion of the inner ear that enables the treatment substance to travel to a further location such as, for example, the auditory brainstem or brain. In accordance with certain arrangements, the delivery systems may include one or more fixation mechanisms that retain various components of the delivery systems at a selected implanted location to ensure that the treatment substance is properly delivered to the target location. <FIG> illustrate fixation mechanisms that may be used in accordance with embodiments presented herein.

10A-10D illustrate mechanisms for securing components of an implantable delivery system to tissue of a recipient. More specifically, <FIG> illustrates a reservoir <NUM>(A) that includes first and second anchor loops <NUM>(<NUM>) and <NUM>(<NUM>). The anchor loops <NUM>(<NUM>) and <NUM>(<NUM>) may be integrated with the reservoir <NUM> or attached to the reservoir using, for example, a bonding agent (e.g., bone cement or other biocompatible adhesive). In certain embodiments, the anchor loops <NUM>(<NUM>) and <NUM>(<NUM>) are formed from a resiliently flexible material (e.g., a similar material used to form the reservoir <NUM>(A)). In other embodiments, the anchor loops <NUM>(<NUM>) and <NUM>(<NUM>) are formed from a substantially rigid material (e.g., titanium).

The anchor loops <NUM>(<NUM>) and <NUM>(<NUM>) each include an aperture <NUM>. The reservoir <NUM> is configured to be positioned adjacent to the recipient's tissue. Bone screws <NUM> or other fasteners may then be inserted through the apertures <NUM> and into the tissue. In this way, the bone screws secure the reservoir <NUM>(A) in position. In alternative embodiments, the anchor loops <NUM>(<NUM>) and <NUM>(<NUM>) may be replaced with pads or other members that enable the reservoir <NUM>(A) to be secured to the recipient using, for example, a bonding agent (e.g., bone cement or other biocompatible adhesive), sutures, etc..

<FIG> illustrates another reservoir <NUM>(B) with a first fastening bracket <NUM>(<NUM>) and a second fastening bracket <NUM>(<NUM>). The first fastening bracket <NUM>(<NUM>) includes an anchor loop <NUM>(<NUM>) at a first end of the bracket and an anchor loop <NUM>(<NUM>) at a second end of the bracket. The second fastening bracket <NUM>(<NUM>) includes an anchor loop <NUM>(<NUM>) at a first end of the bracket and an anchor loop <NUM>(<NUM>) at a second end of the bracket. Each of the anchor loops <NUM>(<NUM>), <NUM>(<NUM>), <NUM>(<NUM>), and <NUM>(<NUM>) include an aperture <NUM>.

The reservoir <NUM>(B) is configured to be positioned adjacent to the recipient's tissue. The fastening brackets <NUM>(<NUM>) and <NUM>(<NUM>) are configured to fit around the reservoir <NUM>(B) and bone screws <NUM> (<FIG>) or other fasteners may then be inserted through the apertures <NUM> and into the tissue. In this way, the brackets <NUM>(<NUM>) and <NUM>(<NUM>) secure the reservoir <NUM>(B) in position. In alternative embodiments, the anchor loops <NUM>(<NUM>), <NUM>(<NUM>), <NUM>(<NUM>), and <NUM>(<NUM>) may be replaced with pads or other members that enable the reservoir <NUM>(B) to be secured to the recipient using, for example, a bonding agent (e.g., bone cement or other biocompatible adhesive), sutures, etc..

For ease of illustration, <FIG> illustrate anchor loops and brackets, respectively, with reference to implantable reservoirs. It is to be appreciated that these fixation mechanisms may be used with other implantable components of a delivery system to facilitate attachment of those components to a recipient's tissue.

<FIG> illustrates a fixation mechanism for the distal end of a delivery tube <NUM> of a delivery system. In this embodiment, the delivery tube <NUM> includes surface features <NUM> that are configured to facilitate attachment of a bonding agent (e.g., bone cement or other biocompatible adhesive) to the surface of the delivery tube or to allow natural retention of the tube by body tissue, fibrotic response, etc. The bonding agent then secures the distal end of the delivery tube <NUM> to the recipient's tissue.

The surface features <NUM> (i.e., the fixation mechanism) may have a number of different configurations. In one embodiment, the surface features comprise a plurality of recesses in the form of spaced grooves or troughs and/or ridges. The grooves/ridges may have different shapes and configurations. For example, grooves/ridges may have cross-sectional shapes that are rectangular, triangular, trapezoidal, etc. It is also to be appreciated that grooves in alternative embodiments may have geometries that include different undercut regions. For example, alternative grooves may be T-shaped, J-shaped, dovetailed, frustoconical, etc. The undercut regions may function to create a mechanical lock, or an interlock between a bonding agent and the surface of the delivery tube <NUM>.

In another embodiment, the surface features <NUM> comprise a collection of depressions and/or protrusions. The protrusions may have a number of different shapes (e.g., parabolic, square, rectangular, arcuate, etc.).

In a still other embodiment, the surface features <NUM> comprise include a plurality of recesses in the form of pores. The pores may have irregular shapes that potentially result in mechanical locking. That is, the irregular shape of the pores may cause the bonding agent and/or tissue to undergo one or more turns when the bonding agent fills the pore.

For ease of illustration, <FIG> illustrates surface features in/on the surface of a delivery tube. It is to be appreciated that these and other surface features may be used in/on the surfaces of other implantable components of a delivery system to facilitate attachment of a bonding agent thereto for subsequent securement to tissue.

<FIG> illustrates a delivery tube positioning mechanism <NUM> that may be used in accordance with embodiments presented herein to locate the distal end of a delivery tube (not shown in <FIG>) adjacent to a target location (e.g., the round window <NUM>). Delivery tube positioning mechanism <NUM> comprises two sub-components, namely extension arm <NUM> and extension arm <NUM>.

Sub-component <NUM> includes arm <NUM> which is an integral part of housing <NUM> (where the cross-hatching of housing <NUM> seen in <FIG> corresponds to the wall of the housing). Arm <NUM> may be part of the same casting forming at least part of housing <NUM> (i.e., the arm <NUM> and at least a portion of the housing <NUM> form a monolithic component), although in an alternate exemplary embodiment, arm <NUM> may be a separate component that is attached to the housing <NUM> (e.g., via laser welding). In an exemplary embodiment, the casting may be made partially or totally out of titanium. In this regard, it is noted that the delivery tube positioning mechanism <NUM> may be partially or totally formed from titanium, and the housing <NUM> may be formed from a different material. Sub-component <NUM> also includes flange <NUM> which forms a female portion of ball joint <NUM>.

The delivery tube positioning mechanism <NUM> further includes subcomponent <NUM>. Sub-component <NUM> comprises the male portion of the ball joint <NUM>, in the form of a ball <NUM>, arm <NUM>, trolley <NUM> and delivery tube support <NUM>. Delivery tube support <NUM> is depicted as being in the form of a collar, and receives and otherwise holds a delivery tube therein. For ease of illustration, the delivery tube has been omitted from <FIG>.

Ball joint <NUM> permits the ball <NUM> of sub-component <NUM> to move within the female portion, thereby permitting sub-component <NUM> to articulate relative to sub-component <NUM>. This articulation permits the delivery tube to likewise articulate. Ball joint <NUM> also enables the delivery tube to be positioned at an adjustably fixed location relative to the target location. In an exemplary embodiment, the ball joint <NUM> permits the location of the delivery tube to be adjustable in two degrees of freedom, represented by arrows <NUM> and <NUM> (first and second degrees of freedom, respectively), in <FIG>. In some embodiments, the joint may permit the location of the delivery tube to be adjustable in only one degree of freedom or in more than two degrees of freedom.

While delivery tube positioning mechanism <NUM> is depicted with a ball joint <NUM>, other types of joints may be utilized. By way of example, the joint may comprise a malleable portion of a structural component of the delivery tube positioning mechanism <NUM> that permits the delivery tube to be positioned as just detailed or variations thereof. In an exemplary embodiment, the joint is an elastically deformable portion or plastically deformable portion or is a combination of elastically deformable and plastically deformable portions so as to enable the adjustment of the location of the delivery tube in the at least one degree of freedom.

The collar <NUM> has an exterior surface <NUM>(<NUM>) and an interior surface <NUM>(<NUM>), configured to receive the delivery tube. The interior diameter of the collar, formed by interior surface <NUM>(<NUM>) is approximately the same as the outer diameter of the cylindrical body of the delivery tube.

As noted, delivery tube support <NUM> secures the delivery tube to the delivery tube positioning mechanism <NUM>. This removable securement may be, in some embodiments, sufficient to prevent the delivery tube from substantially moving from the retained location in the delivery tube support <NUM>. In an exemplary embodiment, interlock between the delivery tube support <NUM> and the delivery tube is provided by an interference fit between inner surface <NUM>(<NUM>) and the delivery tube. In an alternate embodiment, interlock between the delivery tube support <NUM> and the delivery tube is implemented as corresponding mating threads on inner surface <NUM>(<NUM>) and the delivery tube.

In another embodiment, O-rings or the like may be used to secure the delivery tube within the delivery tube support <NUM>. Grooves on the delivery tube and/or on the collar may be included to receive the <NUM>-ring. Alternatively, compression of the <NUM>-ring between the delivery tube and the collar provides sufficient friction to retain the delivery tube in the delivery tube support <NUM>.

In a further embodiment, delivery tube support <NUM> or the delivery tube includes a biased extension that is adjusted against the bias to insert the delivery tube into the support. The extension may engage a detent on the opposing surface to interlock the delivery tube and the support. Other embodiments include protrusions and corresponding channels on opposing surfaces of the delivery tube and the delivery tube support <NUM>. An exemplary embodiment includes a spring-loaded detent that interfaces with a detent receiver of the opposing surface to hold the delivery tube in the delivery tube support <NUM>. Adhesive may be used to interlock the delivery tube in the delivery tube support <NUM>.

The trolley <NUM>, which is rigidly connected to delivery tube support <NUM>, is configured to move linearly in the direction of arrow <NUM> parallel to the longitudinal direction of extension of arm <NUM>. In this exemplary embodiment, arm <NUM> includes tracks with which trolley <NUM> interfaces to retain trolley <NUM> to arm <NUM>. These tracks also establish trolley <NUM> and arm <NUM> as a telescopic component configured to enable the adjustment of the location of delivery tube support <NUM>, and thus the delivery tube when received therein, in at least one degree of freedom (i.e., the degree of freedom represented by arrow <NUM>). It is noted that other embodiments may permit adjustment in at least two or at least three degrees of freedom. Thus, when the trolley component is combined with the aforementioned joint <NUM>, the delivery tube positioning mechanism <NUM> enables the location of the delivery tube to be adjustable in at least two or at least three degrees of freedom.

Movement of the trolley <NUM> along arm <NUM> may be accomplished via a jack screw mechanism where the jack screw is turned via a screw driver or a hex-head wrench. Movement of the trolley <NUM> may also or alternatively be achieved via application of a force thereto that overcomes friction between the trolley <NUM> and the arm <NUM>. Any device, system or method that permits trolley <NUM> to move relative to arm <NUM> may be used in some embodiments detailed herein and variations thereof.

It may be seen that arm <NUM> of delivery tube positioning mechanism <NUM> includes screw hole <NUM>. Screw hole <NUM> is configured to receive a bone screw (not shown in <FIG>) for securing of the delivery tube positioning mechanism <NUM> to the recipient's tissue. While screw hole <NUM> is depicted as being located on (in) arm <NUM>, in other embodiments, screw holes may be located elsewhere on the delivery tube positioning mechanism <NUM>.

In certain embodiments, the fixation mechanisms used to retain a distal end of a delivery tube in place at a target location are the physical properties of the delivery tube. For example, <FIG> are cross-sectional views illustrating a delivery tube <NUM> that is conformable, but also has sufficient rigidity to provide stability and to remain in a selected position and configuration. <FIG> illustrates a lateral cross-sectional view of the delivery tube <NUM>, while <FIG> illustrates an elongate cross-sectional view of the delivery tube <NUM>.

The delivery tube <NUM> comprises a carrier <NUM> that forms a lumen <NUM>. A treatment substance is delivered from a reservoir to a target location through the lumen <NUM>. The carrier <NUM> may be formed from, for example, a biocompatible elastomer (e.g., silicone rubber) or similar substantially comfortable/pliable material. The carrier <NUM> has material properties so as to prevent egress of a treatment substance from the lumen <NUM> as well as to prevent the ingress of bodily fluids.

The delivery tube <NUM> also comprises a stiffening element <NUM> extending along all or part of the elongate length of the delivery tube. In the embodiments of <FIG>, the stiffening element <NUM> is an elongate wire (e.g., platinum, titanium, etc.) embedded in the carrier <NUM>. In other embodiments, the stiffening element <NUM> may be formed from a polymer material. In general, the carrier <NUM> and stiffening element <NUM> are conformable to a selected configuration (e.g., location, position, orientation, etc.). The stiffening element <NUM> has mechanical properties (e.g., rigidity, malleability, etc.) such that the delivery tube <NUM> remains in the selected configuration.

<FIG> illustrate another delivery tube <NUM> that is conformable, but also has sufficient rigidity to provide stability and to remain in a selected position. The delivery tube <NUM> comprises a carrier <NUM> surrounded by a stiffening sheath <NUM>. <FIG> illustrates a lateral cross-sectional view of the delivery tube <NUM>, while <FIG> is a side view from which part of the stiffening sheath <NUM> has been omitted.

The carrier <NUM> forms a lumen <NUM> that carries a treatment substance from a reservoir to a target location. The carrier <NUM> may be formed from, for example, a biocompatible elastomer or similar substantially conformable/pliable material. The carrier <NUM> has material properties so as to prevent egress of a treatment substance from the lumen <NUM> as well as to prevent the ingress of bodily fluids.

The stiffening sheath <NUM> substantially surrounds the carrier <NUM> and extends along all or part of the elongate length of the delivery tube. In the embodiments of <FIG>, the stiffening sheath is a mesh (e.g., titanium, wire, polymer, etc.). In general, the carrier <NUM> and stiffening sheath <NUM> are conformable to a selected configuration. The stiffening sheath <NUM> has mechanical properties (e.g., rigidity, malleability, etc.) such that the delivery tube <NUM> remains in the selected configuration.

It is to be appreciated the embodiments of <FIG> are illustrative and other stiffening elements or mechanisms may be used to form a delivery tube with physical properties that assist in retention of the distal end of the delivery tube at a target location. For example, the carrier of the delivery tube may be formed from a flexible material that protects against external force (e.g., using shape memory materials).

One potential issue with certain delivery systems is the accretion (build-up) of undelivered treatment substance particles within the system. For example, if the delivery of a treatment substance is started and is then stopped for a period of time (e.g., in cases of pain relief or to combat infections), portions of the treatment substance may remain in the system outside of the reservoir. These undelivered portions of the treatment substance outside of the reservoir may precipitate (e.g., crystalize) and potentially clog the system at the delivery tube, the delivery device, etc. so as to inhibit subsequent delivery of the treatment substance. As noted above, certain embodiments presented herein are directed to accretion prevention (anti-accretion) mechanisms that prevent the buildup of precipitated particles within a delivery system that can inhibit subsequent treatment substance delivery. <FIG> illustrates an example delivery system <NUM> that includes a flushing module <NUM> that operates as an anti-accretion mechanism.

The delivery system <NUM> is similar to the arrangement of <FIG> where a magnetic attraction is used to propel a treatment substance from an implantable reservoir. More specifically, the delivery system <NUM> comprises a magnetic element <NUM> implanted abutting a first section of the outer surface <NUM> of the recipient's skull. The magnetic element <NUM> may be formed from a ferromagnetic or ferrimagnetic material and may be magnetized (i.e., a permanent magnet) or non-magnetized. <FIG> illustrates an embodiment in which the magnetic element <NUM> is a permanent magnet. The magnetic element <NUM> may be secured to the superior portion <NUM> of recipient's temporal bone <NUM> using, for example, a bone screw (not shown) or another fixation mechanism (e.g., adhesive).

As shown, a treatment substance reservoir <NUM> is implanted so as to abut an externally-facing surface <NUM> of the magnetic element <NUM> (i.e., a surface facing away from the recipient's temporal bone <NUM>). The treatment substance reservoir <NUM> may be secured to the magnetic element <NUM> and/or the recipient's temporal bone using one or more fixation mechanisms described elsewhere herein. The treatment substance reservoir <NUM> is at least partially filled with a treatment substance.

The flushing module <NUM> comprises a second magnetic element <NUM> implanted abutting a second section of the outer surface <NUM> of the recipient's skull. The magnetic element <NUM> may be formed from a ferromagnetic or ferrimagnetic material and may be magnetized or non-magnetized. <FIG> illustrates an embodiment in which the magnetic element <NUM> is a permanent magnet. The magnetic element <NUM> may be secured to the superior portion <NUM> of recipient's temporal bone <NUM> using, for example, a bone screw (not shown) or another fixation mechanism.

As shown, a flushing reservoir <NUM> is implanted so as to abut an externally-facing surface <NUM> of the magnetic element <NUM> (i.e., a surface facing away from the recipient's temporal bone <NUM>). The treatment substance reservoir <NUM> may be secured to the magnetic element <NUM> and/or the recipient's temporal bone using one or more fixation mechanisms described elsewhere herein. As described further below, the flushing reservoir <NUM> is at least partially filled with a flushing solution (e.g., saline).

The treatment substance reservoir <NUM> is fluidically coupled to the proximal end of a connector tube <NUM> via a one-way valve <NUM>. Similarly, the flushing reservoir <NUM> is fluidically coupled to a proximal end of connector tube <NUM> via a one-way valve <NUM>. The connector tubes <NUM> and <NUM> terminate at a three-port valve <NUM>. That is, the valve <NUM> has a first port connected to the connector tube <NUM>, a second port connected to the connector tube <NUM>, and third port connected to a delivery tube <NUM>.

In general, the valves <NUM> and <NUM> allow a treatment substance or flushing solution, respectively, to pass from the respective reservoirs to the valve <NUM>. The valve <NUM> is configured to allow either the treatment substance or the flushing solution to pass to the delivery tube <NUM>. The valve <NUM> is configured to prevent the treatment substance from passing into the connector tube <NUM> and to prevent the flushing solution from passing into the connector tube <NUM>.

It is to be appreciated that the use of a three-port valve <NUM> is merely illustrative and that other valves may be used in alternative embodiments. For example, in certain embodiments, the three-port valve <NUM> may be replaced with separate one-way valves positioned at the distal end of each of the connector tunes <NUM> and <NUM>.

In the embodiment of <FIG>, an external magnet <NUM> may be placed adjacent to the recipient's tissue <NUM> that covers the treatment substance reservoir <NUM>. The poles of the external magnet <NUM> and the magnetic element <NUM> may be oriented so that the external magnet and the magnetic element will be magnetically attracted to one another when in proximity to one another. The mutual attraction between the external magnet <NUM> and the magnetic element <NUM> compresses the recipient's tissue <NUM> adjacent to the treatment substance reservoir <NUM>. The compression of the tissue, in turn, compresses the reservoir <NUM>. The positioning of the reservoir <NUM> abutting the magnetic element <NUM> and the superior portion <NUM> of the mastoid <NUM> provides a rigid surface that counters the compression of the tissue <NUM>. As a result, a pressure change occurs in the treatment substance reservoir <NUM> so as to force a portion of the treatment substance out of the reservoir through valve <NUM>. Once the magnet <NUM> is removed, the flow of treatment substance from the reservoir <NUM> terminates.

The valve <NUM> may be a check valve or a stop-check valve (e.g., a magnetically operated valve). In embodiments in which the valve <NUM> is a magnetically operated valve, the external magnet <NUM> may be configured so as to compress the treatment substance reservoir <NUM> and additionally open valve <NUM>.

Additionally, the external magnet <NUM> may be placed adjacent to the recipient's tissue <NUM> that covers the flushing reservoir <NUM> so as to activate the flushing module <NUM>. More specifically, the poles of the external magnet <NUM> and the magnetic element <NUM> may be oriented so that the external magnet and the magnetic element will be magnetically attracted to one another when in proximity to one another. The mutual attraction between the external magnet <NUM> and the magnetic element <NUM> compresses the recipient's tissue <NUM> adjacent to the flushing reservoir <NUM>. The compression of the tissue, in turn, compresses the reservoir <NUM>. The positioning of the reservoir <NUM> abutting the magnetic element <NUM> and the superior portion <NUM> of the mastoid <NUM> provides a rigid surface that counters the compression of the tissue <NUM>. As a result, a pressure change occurs in the flushing reservoir <NUM> so as to force a portion of the flushing solution out of the reservoir through valve <NUM>. Once the magnet <NUM> is removed, the flow of the flushing solution from the reservoir <NUM> terminates.

The valve <NUM> may be a check valve or a stop-check valve (e.g., a magnetically operated valve). In embodiments in which the valve <NUM> is a magnetically operated valve, the external magnet <NUM> may be configured so as to compress the reservoir <NUM> and additionally open valve <NUM>.

The activation of the flushing module <NUM> to release the flushing solution may occur after delivery of a treatment substance. The flushing solution is designed to clean the downstream portions of the delivery system, including the delivery tube <NUM> and the delivery device <NUM>. That is, the flushing solution substantially removes any remaining treatment substance from the system so that the treatment substance does not precipitate and accrete within the system.

In the embodiment of <FIG>, the same external magnet <NUM> is used to activate both the treatment substance delivery and the flushing mechanisms. In certain arrangements, the flushing reservoir <NUM> is implanted a certain distance away from the reservoir <NUM> such that activation of the treatment substance delivery mechanism does not affect the flushing module <NUM>, and vice versa. However, in another arrangement shown in <FIG>, the treatment substance delivery and the flushing mechanisms are responsive to different poles of the magnet <NUM>.

A magnet, such as magnet <NUM>, is an object that produces a magnetic field that interacts with other magnetic fields. Magnets have two poles, typically referred to as the "north pole" and the "south pole. " The magnetic field may be represented by field lines that start at a magnet's north pole and end at the magnet's south pole. The magnetic force (attraction) between to magnetic objects is caused by the magnet's magnetic field and points in the direction of the field lines. For example, if two magnets are next to each other and their north poles are facing towards one another (or conversely if their south poles are facing towards one another), the field lines move away from each other and thus the magnets repel one another. In contrast, if two magnets are next to each other and a north pole of one magnet faces the south pole of the other magnet, the magnets will be attracted to one another.

The embodiment of <FIG> makes use of the opposing poles of the magnets to ensure that only one of the treatment substance delivery or the flushing mechanism is activated at any one time. More specifically, the magnetic element <NUM> may be implanted such that either the north or the south pole of the magnetic element <NUM> faces the tissue of the <NUM> of the recipient. The magnetic element <NUM> is implanted such that the opposing pole faces the tissue <NUM> of the recipient (i.e., if the magnetic element <NUM> has a north pole facing the tissue, the magnetic element <NUM> has a south pole facing the tissue). Similarly, in embodiments using magnetic valves, the valves <NUM> and <NUM> may be similarly responsive to different magnet poles.

The opposing surfaces <NUM>(<NUM>) and <NUM>(<NUM>) of the external magnet may be selected positioned adjacent the recipient's tissue <NUM> to activate either the treatment substance delivery or the flushing mechanisms. The opposing surfaces <NUM>(<NUM>) and <NUM>(<NUM>) may also be labeled so that user can easily identify how the external magnet <NUM> should be placed to activate each mechanism.

In an alternative embodiment of <FIG>, the flushing reservoir <NUM> could also or alternatively be coupled to the treatment substance reservoir <NUM> so as to flush both the treatment substance reservoir <NUM> and the delivery tube <NUM>. Alternatively, a double valve or other mechanism may be present to enable selective and independent flushing of the treatment substance reservoir <NUM> and the delivery tube <NUM>.

Accretion prevention (anti-accretion) mechanisms in accordance with embodiments presented herein may further include different shapes/configurations for the delivery device <NUM> that prevent accretion. For example, the delivery device <NUM> may include grooves, a sharp bevel, and/or a sponge/del device that is held below a groove in the tube to absorb any treatment substance that might be residually in the delivery tube <NUM>.

<FIG> is a cross-sectional view of part of another delivery system <NUM> configured to prevent accretion resulting from treatment substance precipitation. In this embodiment, the delivery system <NUM> is similar to the arrangements of <FIG> or <FIG>, but further includes a replaceable delivery tube <NUM> that passes through the recipient's tympanic membrane <NUM>.

More specifically, a replaceable delivery tube <NUM> has a proximal end that is fluidically coupled to a valve or reservoir and a distal end <NUM> that is fluidically coupled to the round window <NUM>. A delivery device <NUM> is positioned in the distal end <NUM> adjacent to the round window <NUM>. Additionally, an elongate fixed sheath <NUM> is extends from the valve or reservoir and to distal end <NUM> that is attached to the round window <NUM> and/or another area of the recipient.

The delivery tube <NUM> and the outer fixed sheath <NUM> extend through the recipient's tympanic membrane <NUM> to the round window <NUM>. In particular, the delivery tube <NUM> and the outer fixed sheath <NUM> pass through a surgically formed opening within the tympanic membrane <NUM>. A surgically placed grommet <NUM> is disposed around the fixed sheath <NUM> so as to seal the opening in the tympanic membrane <NUM> around the fixed sheath <NUM>.

As shown, the fixed sheath <NUM>, and not the delivery tube <NUM>, is affixed to the tympanic membrane <NUM> (via the grommet <NUM>) and the recipient's inner ear <NUM>. Additionally, the delivery tube <NUM> is slideably engaged with the fixed sheath <NUM>. As a result, the delivery tube <NUM> may be removed from the recipient's ear canal without damaging the tympanic membrane <NUM> or the inner ear <NUM>. A replacement delivery tube <NUM> may then be inserted. Periodic replacement of the delivery tube <NUM> (and the delivery device <NUM> therein) prevents accretion of precipitated treatment substance particles.

Embodiments have been primarily described above with reference to the coupling of the distal end of the delivery tube to a recipient's inner ear (e.g., round window) for delivery of the treatment substances to the cochlea. It is to be appreciated that treatment substances may be delivered to other regions of the recipient's ear. For example, the distal end of the delivery tube can be attached to or formed as a pouch or a sheet to envelope or cover a component of another device (e.g., a cochlear implant, direct acoustic stimulator, etc.) that has been infected or implanted in high risk location.

It is also to be appreciated that other locations and/or configurations for the various components disclosed herein are possible. For example, in one alternative arrangement a reservoir, valve, etc. may be positioned inside the recipient's cochlea.

Additionally, embodiments have been primarily described with reference to the use of a single reservoir for a treatment substance. It is to be appreciated that other embodiments may use two different reservoirs for different treatment substances. Alternatively, one reservoir may be subdivided in two sections for independent delivery of two different treatment substances. In one such embodiment, the two reservoirs or sub-reservoirs may be activated independently or a single push could activate both of the reservoirs or sub-reservoirs simultaneously.

It is to be appreciated that embodiments presented herein are not mutually exclusive and can be combined in various manners and arrangements.

Claim 1:
An apparatus, comprising:
an implantable reservoir (<NUM>, <NUM>, <NUM>, <NUM>) configured to have a treatment substance disposed therein;
an implantable delivery tube (<NUM>,<NUM>, <NUM>, <NUM>) having a proximal end fluidically coupled to the reservoir (<NUM>, <NUM>, <NUM>, <NUM>) and a distal end positionable adjacent an inner ear (<NUM>) of a recipient; and
characterized by
a passive activation mechanism configured to transfer a portion of the treatment substance in the reservoir (<NUM>, <NUM>, <NUM>, <NUM>) to the delivery tube (<NUM>, <NUM>, <NUM>, <NUM>) for delivery to the inner ear (<NUM>), wherein the passive activation mechanism comprises at least one resiliently flexible portion (<NUM>, <NUM>) of the reservoir (<NUM>, <NUM>, <NUM>, <NUM>) configured to deform in response to application of a force (<NUM>) so as to propel a portion of the treatment substance from the reservoir (<NUM>, <NUM>, <NUM>, <NUM>) to the delivery tube (<NUM>, <NUM>, <NUM>, <NUM>), wherein the passive activation mechanism does not comprise an implanted active pump and a power source.