BACKGROUND OF THE INVENTION
The invention concerns a catheter for administering medication into the endolymphatic sacs of the inner ear in humans, through at least one membrane of the inner ear. The catheter has at least one outflow aperture at one end for the medication being administered. There is an anchoring element for the catheter at this end to anchor the catheter to the membrane. There is also a medication dosage system connected to the other end of the catheter.
THE PRIOR ART
This kind of catheter is used to administer medication into the endolymphatic sacs of the inner ear. Administration of medication to the inner ear is sometimes necessary to combat ear diseases and for balance. In particular, it is used for treating symptoms such as loss of hearing, vertigo or ringing in the ears (tinnitus). Tinnitus is described as the awareness of sound, such as ringing or whistling, within the inner ear without there actually being any external sound source.
The reasons for the emergence of these noises, only audible to the patient, are numerous, and the pathogenesis of such has not been clearly explained to date. Due to the difficulty in accessing the inner ear to treat the respective illnesses, the administration of medication has been standard. It has not been possible to effectively treat diseases of the inner ear, or treatment has only been performed with difficulty, due to the side effects of medication. Nowadays, treatment for hearing loss in the inner ear, vertigo or tinnitus is performed by vasoactive infusions, steroids or hyperbaric oxygen therapy. Anaesthetics and antidepressants are also used along with physical, surgical and psychotherapeutic measures.
Systemically administered medication not only affects the area of the inner ear but also the whole body. Side effects thereby occur even with minimal dosage, which makes specific therapy of the disorder of the inner ear impossible. The result of this is that the majority of patients today cannot be effectively treated. Physical, psychotherapeutic and surgical measures can only help in a very small percentage of cases.
Meaningful and effective therapy to the inner ear can only be achieved with a localized dose of drugs or by electrically induced stimuli. However, specific application of drugs has always posed problems.
In one known procedure, medication is administered via a tympanic tube in the middle ear with subsequent uncontrolled diffusion into the inner ear via the round window membrane. With this type of known procedure, the only medication that can be applied is that which is also diffusible, which is not the case with some types of medication. In addition, it is virtually impossible to determine, predict and monitor the diffusion rate of diffusible substances. Therefore, the amount of medication selected must err on the high side, so that an adequate amount of the applied substance per diffusion can reach the inner ear.
A generically known catheter, such as that produced by Neuro-Biometrix USA (now called Intra Ear) distributed under its trading name “Round Window μ Cath” and “Round Window E Cath”, has a somewhat spherical flexible end portion, which is clamped into the niche of the membrane of the round window and anchors itself there. This ending has several apertures, from which the medication can be discharged and diffuses right through the membrane of the round window. These outflow apertures are spaced at a distance from the membrane of the round window. However this known catheter can only apply diffusible medication, as these substances must be able to diffuse right through the membrane of the round window.
It would be desirable to have a controllable direct administration of medication into the lymph filled compartments of the cochlea, as only then is specific therapy of the symptoms of the disease possible. Since the lymphatic fluid in the cochlea directly bathes the sensory cells requiring therapy, as a blood supply for the sensory cells is not however immediately available, it is therefore not possible to administer medication via the bloodstream directly to the location of the damaged cells. Therefore, the ability to control the direct administration of medication into the inner ear fluids is desired. Until now, only the following substances and methods have been available: steroids and osmotically effective substances, tinnitus suppressant medications from the group of membrane-effective drugs and transmitter substances, neurotrophine (i.e., substances that facilitate regeneration or protection of damaged inner ear auditory cells and attacked aural nerve tissues), antioxidants, gene therapy, the application of electrically charged particles for the treatment of tinnitus and ototoxic medication for eliminating equilibrium sensitive cells.
SUMMARY OF THE INVENTION
It is therefore an object of this invention to design a catheter of the kind mentioned previously, so that it facilitates direct application of medication into the inner ear, and which also offers safe and secure anchoring in the inner ear.
It is another object of the invention to provide a catheter that will not negatively affect the auditory performance of the patient and which can be removed again without any problems, once therapy is complete.
These and other objects are achieved by way of a catheter according to the invention having at least one outflow aperture at one end for the medication being administered and with an anchoring element. A medication dosage system can be connected to the other end of the catheter. The outflow aperture can be fed through the membrane of the inner ear, and the anchoring element is designed so that it can anchor itself against this membrane.
The invention envisages a catheter of the type mentioned above, designed so that the outflow aperture can be fed through the tympanic membrane and the anchoring element anchors itself directly against the membrane.
A catheter of this kind can be created in a surprisingly simple manner to facilitate the direct application of medication into the inner ear and provide safe and durable anchoring within the inner ear. The catheter is designed so that it can be affixed to the round window membrane, to the base of the stapes at the oval window, or to the membrane of the endolymphatic sac, and the medication is then fed into the compartment behind the membrane.
The catheter according to the invention can also be combined with a medication dosage system, particularly one for micro-dosage system.
Depending upon whether the catheter according to the invention is to be anchored at the round window membrane, to the base of the stapes at the oval window, to the membrane of the endolymphatic sac or to the bone between the scala tympani and the cochlea duct, a posterior tympanotomy (starting at the drilled tympanic membrane) is well suited as the access route to these membranes for access to the round and oval windows, and the transmeatal access route (via the auditory canal) is also suitable for positioning the catheter according to the invention. A combined access route can offer additional advantages where appropriate. The catheter for the endolymphatic sac can be anchored within the parameters of a mastoidectomy (starting at the drilled tympanic membrane) and then exposing the sac in the area of the sigmoid sinus. A diagonal incision in the area of the upper and lateral sections is made. The catheter (depending on the size of the system) is fed into the opening and anchors itself.
The configuration of the elements facilitates adequate sealing of the exposed cochlear duct. The connective tissue membrane offers additional security. Due to the flexible nature of the suspending catheter at the respective membrane, deterioration of auditory performance is not expected. Removal of the catheter can be performed without damage, and closure of the lumens can be achieved with connective tissue or similar tissue. A measuring instrument or other instruments make the selection of size, positioning, and fixing of the catheter very simple. It is possible to integrate a wide variety of sensors and electrodes into the catheter. It is also possible to design the catheter extremity with various coupling elements to facilitate the attachment of a micro-dosage system.
Another advantage of the catheter according to the present invention is that it can be easily removed upon completion of therapy. Upon removal of the catheter, the aperture left behind in the corresponding membrane can be covered and closed up initially with grafted tissue, so that fluid cannot flow through the opening out of the inner ear. Subsequently, the scar tissue heals as a natural process, whereupon the aperture completely closes up. This scar tissue does not affect auditory performance.
In a preferred embodiment of the invention, one end is designed with a disc arranged across and encompassing the catheter tube for anchoring it to the round window membrane (or for anchoring it to the basilar membrane) and having a cannula point with an outflow aperture, which can be fed through the membrane. The disc has at least one anchoring element on its edge, which is designed to anchor against the osseous border of the round window (or the basilar membrane). The cannula point can be combined with an electro-conductive cable and may be made of a metallic material. The disc can have a diameter of between 0.7 mm and 1.2 mm.
This catheter can take advantage of the anatomical geometry of the round window and its membrane in a surprisingly simple way. Then with the cannula point, disc and anchoring stays, it is only necessary to pierce through the membrane of the round window with the cannula point, after which the anchoring stay or stays snap into the osseous border of the round window. This is because this osseous border of the round window already has overhanging edges that are well suited for positioning the anchoring elements.
In another embodiment of the invention, one end of the catheter has a bulbous extension, the end wall of which has an outflow aperture and at least two anchoring stays made of a flexible material having memory and arranged concentrically around the outflow aperture. The anchoring stays can be fed through the footplate of the stapes at the oval window and anchor themselves against the inner surface of the footplate. In further embodiments of this configuration, the bulbous extension is fitted with a clip, which anchors itself against the base of stapes. Another configuration has the catheter, the bulbous extension, and the stays enveloped in a removable tube, which has an internal diameter corresponding to the outer diameter of the bulbous extension.
This embodiment of the catheter is very suitable for attachment to the footplate of the stapes at the oval window. Also, attachment of the catheter to the footplate is performed in a conceivably simple manner. First, an aperture is made in the footplate of the oval window. Then, the catheter with its bulbous extension is anchored at the footplate of the oval window so that the anchoring elements are fed through the aperture in the footplate.
Due to the memory characteristics of the material of the anchoring stays, they flex themselves outwards after they have been inserted, by way of which the catheter is thereby anchored. The optional enveloping tube extends the anchoring stays in an axial direction and anchors the bulbous extension to the footplate of the oval window using anchoring stays, and the anchoring stays are fed through the opening in the footplate. As soon as the anchoring stays have been fed through the footplate and have left the rigid mantle of the enveloping tube, the anchoring stays flex according to the memory characteristic of the material and anchor themselves against the inner surface of the footplate. Subsequently, the enveloping tube can be pulled out towards the rear and removed. It is possible to remove the catheter by pulling it, because the metal has the property of memory and has a flectional resistance lower than the tensile resistance of the footplate.
In a third embodiment of the invention, one end of the catheter is fitted with a conical body having a front outflow aperture, whose minimum diameter is greater than the diameter of the catheter tube. The body is fitted with at least two hook-like anchoring elements bent backwards to its outer mantle, which together with a front sub-section of the conical body can be fed through the membrane of the endolymphatic sac, and anchor themselves against the inner surface of the membrane of the endolymphatic sac.
It is also easy to feed this kind of catheter through the membrane of the endolymphatic sac and to anchor it against the membrane of the endolymphatic sac.
In accordance with practical embodiments of the invention, the coupling elements of the catheter are made of carbon material or titanium oxide ceramic. The other parts of the catheter can be made of silicon. These materials have proven to be particularly suitable for implantation into the human body without affecting the surrounding tissue.
BRIEF DESCRIPTION OF THE DRAWINGS
Other objects and features of the present invention will become apparent from the following detailed description considered in connection with the accompanying drawings. It is to be understood, however, that the drawings are designed as an illustration only and not as a definition of the limits of the invention.