WO2006108638A1

WO2006108638A1 - Device and method for measuring the pressure in the middle ear

Info

Publication number: WO2006108638A1
Application number: PCT/EP2006/003378
Authority: WO
Inventors: Detlef Behrend; Wolfram Schmidt; Thorsten Zehlicke; Klaus-Peter Schmitz; Hans Wilhelm Pau
Original assignee: Universität Rostock
Priority date: 2005-04-13
Filing date: 2006-04-12
Publication date: 2006-10-19
Also published as: DE102005017091A1; DE102005017091B4

Abstract

The invention relates to a device and method for measuring the pressure in the middle ear. The device comprises an elastically flexible diaphragm (2), which is pre-shaped into the natural shape of a human eardrum (12) in a corresponding funnel-shaped curved manner so that is rests against the eardrum (12) of a human while conforming thereto and can be removeably attached thereto. The device also comprises signal generating means (3a, 3b, 4), which are connected to the diaphragm (2) and furnish signals representative of a deformation of the membrane (2). The middle ear pressure can be determined by virtue of the fact that the inventive device (1) is attached to at least a portion of the eardrum (12) of a human while conforming to this portion, and that the device receives signals generated by the signal generating means (3a, 3b, 4), and values are stored or recorded for a multitude of different points in time, these values being characteristic of the received signals. The values are stored or recorded as pairs of values and measurement points in time. The diaphragm (2) is subsequently removed from the eardrum (12).

Description

Apparatus and method for measuring the pressure in the middle ear

The present invention relates to an apparatus and a method for measuring the pressure in the middle ear.

The human ear can be subdivided from the outside inwards into the adjoining sections outer ear, middle ear and inner ear. The outer ear covers the pinna and the external auditory canal. The latter is bounded on the inside by the eardrum, to which the tympanic cavity adjoins. In the medial wall of the tympanic cavity, which closes it to the inner ear, there are two closed connective tissue windows (the round and the oval window). In the air-filled tympanic cavity three ossicles (hammer, anvil and stirrup) are arranged. The inner surface of the eardrum, the tympanic cavity with the ossicles and the adjacent parts of the Eustachian tube and the air-containing cells of the mastoid belong to the middle ear. The inner ear finally includes the fluid-filled cochlea and the semaphore apparatus.

Sound waves conducted through the outer ear reach the eardrum through the external auditory canal and cause it to vibrate. The three auditory ossicles transmit the vibrations of the eardrum to the oval window of the inner ear, which generates in the fluid of the cochlea sound vibrations that pass through the liquid. These sound vibrations cause moving hair cells in motion in the liquid, and the movement of the hair cells triggers nerve impulses, which are finally forwarded to the generation of an auditory impression to the brain.

In the human ear also plays the so-called Eustachian tube, which is also known as a tube or Eustachian tube, an important role. It is a tubular connection between the middle ear and the nasopharynx (and thus the outer space) and usually opens when swallowing and yawning. In this way, on the one hand, the pressure in the middle ear to the external pressure can be equalized via the Eustachian tube, which is required at regular intervals, as in the middle ear gases are continuously absorbed, which must be replaced to prevent the formation of a negative pressure. This is of great importance, as over or under pressure in the middle ear leads to a limitation of the eardrum mobility and a concomitant deterioration of the hearing. On the other hand, the Eustachian tube is used to drain secretions from the middle ear.

In this system, a variety of different malfunctions can occur, which leads to an impairment or prevention of the perception of sound. A number of these dysfunctions are related to the middle ear and the eustachian tube. Thus, in some people, the ear trumpet does not open or not properly because of anatomical dispositions or pathological changes, which can lead to a permanent pressure difference between the middle ear and the outer space associated with a deterioration of hearing and possibly pain. Furthermore, especially in the absence of tympanic ventilation, inflammation and suppuration may also occur in the middle ear. These often create an overpressure in the middle ear, because the Eustachian tube swells and the inflammatory products can not drain. The pressure of the secretion can then bulge the eardrum painfully. Due to poor drainage of the inflammatory products or insufficient air supply, the healing of an inflammation can be impaired. Persistent inflammation can eventually attack and destroy the ossicles. In addition, both overpressure and vacuum not only restrict eardrum mobility but can also lead to a painful stretching of the eardrum.

After early childhood middle ear suppurations, no more healing perforations of the eardrum can form. Eardrum perforations can also be caused by injuries with hard objects and the effect of a high sound pressure (explosion trauma). In contrast to the perforations caused by chronic inflammatory relapses, traumatic perforations often close spontaneously. If the eardrum is damaged and not completely closed, the hearing will be impaired and the middle ear will lose the protection provided by the intact eardrum against the ingress of dirt and pathogens.

For these reasons, it is very important to be able to measure the pressure in the middle ear and the function of the Eustachian tube. So must be ensured, for example, before the operative closure of a tympanic membrane perforation that the Eustachian tube works well, otherwise can very quickly build a tympanus destructive pressure difference again.

For this purpose, a number of methods are known in the art. In the so-called tympanometry, for example, the stiffness of the eardrum is measured, which allows conclusions about the middle ear pressure and the vibratory ability of the eardrum. For this purpose, a special probe is inserted into the external auditory canal, which seals the external auditory canal, so that the pressure prevailing there can be manipulated. Subsequently, sound signals are emitted by the probe for a short period of time, typically a few seconds, while the pressure in the external auditory canal is varied. At the same time, the probe reflects the portion of the sound signals reflected by the eardrum as a function of the pressure in the outer ear. -A -

The ear canal is measured (the corresponding plot is called the tympanogram). Since the maximum eardrum mobility at pressure identity is between the external auditory canal and the middle ear, the sound reflection is lowest when the pressure generated by the probe in the external auditory canal corresponds to the pressure in the middle ear. For normal middle ear function, this should be about normal pressure. Negative pressure in the middle ear (e.g., due to venting of the eustachian tube) results in a shift of the maximum into the negative pressure range, while middle ear suppuration is typically characterized by a flat tympanogram.

This method has the disadvantage that only the effect on the middle ear spaces can be measured, but not the opening of the Eustachian tube can be detected. Thus, it is not possible and the patient is not expected to extend the measurement to a large period of time, because the introduced into the ear probe is unpleasant in the long run. Furthermore, the probe, which must contain a sound generator and a sound detector, complicated and expensive to manufacture. In addition, always a pressure generating device is required, which can produce both negative pressure and pressure in the external auditory canal. A continuous pressure measurement is not possible, it can always only - staggered - take individual measurements.

The same disadvantages exist in other known methods, such as the blowing of the Eustachian tube by blowing air into the middle ear via an existing eardrum perforation or the arbitrary application of negative pressure, which must be eliminated by swallowing (so-called tube manometry). The latter methods are only applicable to perforated eardrums, while tympanometry can only be used on intact eardrums. Furthermore, the tube manometry - as well as tube burst experiments of the nasopharynx her (pressure injection while holding her nose or a balloon in the nose while talking a "K-sound") - always snapshots or yes-no answers to the question of the actual tube opening. In addition, methods which measure the pressure development by hoses introduced airtight into auditory canal perforations regularly have the disadvantage that a very small volume having a very large volume has to be measured. For these and other reasons, known methods allow only indirect conclusions about the middle ear pressure and the function of the Eustachian tube.

It is an object of the present invention, an apparatus and a method for measuring the pressure in the middle ear in such a way that the middle ear pressure under physiological conditions can be measured continuously, and the disadvantages mentioned are eliminated. Furthermore, it should also be possible to determine the rigidity of the eardrum.

To achieve this object are the features of claim 1 and of the claims 16 and 20. Advantageous embodiments of the device and the method are the subject of the respective dependent claims.

According to the present invention, it is provided that a device for measuring the pressure in the middle ear or the deformation of the eardrum comprises an elastic flexible membrane, which is preformed in the manner of a natural shape of a human eardrum in a funnel-shaped bulge that it conforms to the eardrum created and releasably attached to this can be attached to a man. Further, the apparatus includes signal generating means connected to the membrane and providing representative signals for deformation of the membrane. By this configuration, the deformation of the eardrum and in this way the middle ear pressure can be followed in a simple manner as follows. First, the membrane is placed on the eardrum and releasably attached to this. Since the eardrum, like the membrane, is not planed but funnel-shaped inward, the membrane can cling to the eardrum. Ideally, the membrane may conform to the eardrum without altering its predetermined shape or without significantly altering its predetermined shape. In this case, the membrane can be attached to the eardrum in such a way that a large area, and preferably a substantially full-surface connection between a surface of the membrane and the eardrum is produced. Thus, on the one hand, the membrane interferes as little as possible with the physiological conditions in the ear. On the other hand, the membrane makes or follows any deformation of the eardrum, so that the deformation of the membrane directly reflects the deformation of the eardrum. Fastening the membrane in a state snuggled against the eardrum causes the membrane and the eardrum to have an identical shape in the covering area. In this case, the membrane is preferably made sufficiently pliable to ensure that the mobility and elasticity of the eardrum are not significantly affected and, ideally, not affected, so as not to disturb the physiological conditions.

Thus, the signals generated by the signal generating means are representative not only of the deformation of the membrane, but also immediately of the deformation of the eardrum. Furthermore, as the eardrum deforms in the middle ear as a function of pressure, the signals are also representative of the pressure in the middle ear. In this way, the ear is advantageously used practically as its own pressure measuring chamber. The signals can be used to determine pressure changes in the middle ear. With appropriate calibration, for example, with With the aid of a pressure measuring catheter inserted into the middle ear through the Eustachian tube, absolute values of the pressure in the middle ear can also be determined.

With the invention, the middle ear pressure associated with the function of the Eustachian tube can be registered over a longer period of time. On this basis, a physician can decide whether the openings of the Eustachian tube are functionally sufficient to bring about pressure equalization. It also measurements over several hours are possible because the device does not disturb the patient or only slightly and no complicated and often large facilities are required to produce an over or under pressure. The middle ear pressure is measured with the greatest possible consideration of the physiological conditions. In addition, the device is simple and can be manufactured very inexpensively. Thus, the device can also be used advantageously as a disposable product.

The signal generating means may advantageously comprise at least one piezoelectric element and / or at least one strain gauge. It is possible that only one or more piezoelectric elements or only one or more strain gauges are provided. It. But it is also possible that both piezoelectric elements and strain gauges are provided.

In a preferred embodiment, the signal generating means are at least partially attached to a surface of the membrane. This means, for example, that in the case of several piezoelectric elements at least one of these elements is fastened to the surface of the membrane. Similarly, with multiple strain gauges, at least one of them is attached to a surface of the membrane. In a further preferred embodiment, the signal generating means are at least partially embedded in the membrane. This means, for example, that with several piezoelectric elements at least one of these elements is embedded in the membrane. Similarly, with multiple strain gauges, at least one of them is embedded in the membrane.

It is preferred if the membrane is designed in such a way that, upon contact, adhesion forces act between it and a human eardrum, through which the membrane conforms to and is fastened to the eardrum. In this way, the application of the membrane to the eardrum and ensuring a snug contact is particularly easy to implement. Furthermore, the physiological conditions are not disturbed by fasteners such as adhesives. The membrane can also be designed in an advantageous manner so that it can be attached to the eardrum by means of an incompressible adhesion aid. As an incompressible adhesion aid, an isotonic NaCl solution (0.9%) or ultrasound gel may preferably be used.

It is further preferred if the membrane is designed and dimensioned such that it can be applied to the remains of the eardrum in a perforated eardrum and releasably attached thereto, that the perforation is sealed airtight in the eardrum. The unit of eardrum and membrane then has the shape of an intact tympanic membrane. Due to this configuration, the middle ear pressure can be followed even without any limitations in perforated eardrum. The doctor is thus given a meaningful basis on which he can decide whether the function of the Eustachian tube is sufficient for an operative closure of the eardrum perforation. If this is not the case, additional measures can be taken in good time. Thus, the middle ear pressure can be measured with a single device both intact eardrum and perforated eardrum. It is not necessary to have different measuring devices available for these two cases.

The membrane is advantageously made of a biocompatible material. It is preferred that the membrane is made of a polyurethane or a silicone elastomer or comprises such a material. Further, it is preferable that the membrane has a modulus of elasticity in the range of 7 to 20 MPa and / or a Shore A hardness of 60 to 80.

In a preferred embodiment, a memory device is provided which stores characteristic values for a plurality of different times for the signals of the signal generating means.

In a further preferred embodiment, a converter is provided which receives the ^'signals from the signal generating means and converts it into printing signals representative (stand ie to this in a unique context) for the pressure in the middle ear, and preferably to the pressure in the middle ear are proportional. ^1, this way signals are supplied directly, that are in a simple connection with the middle ear pressure. It is particularly advantageous if a memory device is provided which stores characteristic values for the printing signals for a large number of different times. These values can be values proportional to the pressure in the middle ear. With appropriate calibration, the values may also correspond directly to the mean ear pressure in a given pressure unit.

The middle ear pressure or the deformation of the eardrum can be measured advantageously by a method, in which a device according to the invention is first provided and its membrane is placed on at least part of the eardrum in such a way that it conforms to the eardrum. In this position, the membrane is attached to the eardrum, and then the signals generated by the signal generating means are received. In this case, values are stored or recorded for a large number of different times which are characteristic of the received signals. The storage or recording is done in such a way that pairs of values and associated times are stored or recorded. The recording can be done for example by a printer or on an electronic storage medium. Thus, the middle ear pressure can be evaluated time-resolved. After completion of the measurement, the membrane is removed from the eardrum.

This method can be used advantageously in a perforated eardrum by the membrane is placed on the eardrum in such a way that an existing therein perforation is closed airtight.

In a preferred embodiment, the signals generated by the signal generating means are converted into pressure signals which are representative of the pressure in the middle ear and preferably proportional to the pressure in the middle ear. Then it is also advantageous if the stored or recorded values for the pressure signals are characteristic. The values are then preferably also proportional to the pressure in the middle ear. With appropriate calibration, the values preferably indicate directly the pressure in the middle ear in a predetermined pressure unit.

Furthermore, it is also possible in an advantageous manner, the deformation of the eardrum as a function of the pressure in the external auditory canal and / or in the middle ear and in this way the increase To measure the elasticity or the elasticity of the eardrum by a method in which initially provided a device according to the invention and its membrane is placed on at least part of the eardrum in such a way that it conforms to the eardrum. In this position, the membrane is attached to the eardrum, and then the signals generated by the signal generating means are received. In this case, the pressure in the external auditory canal and / or in the middle ear is manipulated selectively and the change in the received signals is determined as a function of the pressure set by the manipulation by storing or recording values for a number of pressure values of the pressure in the external auditory canal or in the middle ear which are characteristic of the received signals, wherein the recording takes place in the form of pairs of associated values and pressure values (ie, pressures in the external auditory canal or in the middle ear, respectively). The recording can be done for example by a printer or on an electronic storage medium. The deformation or deformation of the eardrum as a function of the pressure in the external auditory canal and / or in the middle ear and, in turn, the rigidity or elasticity of the eardrum can be determined from the stored measured values. After completion of the measurement, the membrane is removed from the eardrum. The manipulation of the pressure can be accomplished, for example, by catheters which are introduced into the external auditory canal or through the ear trumpet into the middle ear.

The invention will be explained in more detail below with reference to an embodiment with reference to the drawings.

Figure 1 shows a schematic plan view of an embodiment of the device according to the invention. FIG. 2 shows a cross section of the device shown in FIG. 1 in the state fastened to an eardrum.

Figure 3 shows a section through the middle ear and a part of the adjacent external auditory canal, wherein the device shown in Figures 1 and 2 is mounted on a perforated eardrum.

FIG. 4a shows, by way of example, a diagram in which the time profile of the measured middle ear pressure for an ear with a disturbed function of the eustachian tube is plotted.

FIG. 4b shows by way of example a diagram in which the time course of the measured middle ear pressure for an ear with a normal function of the Eustachian tube is plotted.

The device 1 shown in Figure 1 has a thin, flexible and elastic membrane 2, which has a generally round shape, but is spatially bulging (see Figures 2 and 3). The transverse extent of the membrane 2 is about 8 mm. As can be seen in Figure 2, which shows a cross-section of a device 1 according to the invention, the membrane 2 is attached over its entire surface conforming to an unperforated eardrum, on a surface of the membrane 2, a strain gauge 3a is fixed, and on the opposite surface of the membrane 2 attached in the direction of the transverse extent of the membrane 2 of the strain gauge 3a and spaced parallel to this second strain gauge 3b. These two strain gauges 3a and 3b can also be completely or partially embedded in the membrane 2. Each of the strain gauges 3a and 3b is provided with two electrical connected lines 4, which have a diameter of, for example, 120 to 150 microns.

FIG. 3 shows a section through a middle ear 5 and a part of the adjoining external auditory canal 6. The middle ear 5 and the external auditory canal 6 are located in the cranial bone 7. On the right in FIG. 3, the middle ear 5 passes through the so-called oval window 8 limited, which is associated with the stapes called ossicles 9. The stirrup 9 is connected to one end of the ossicle 10 designated as anvil, the other end of which is in turn connected to the ossicle 11 designated as a hammer. The hammer 11 is finally connected to the eardrum 12.

In FIG. 3, the eardrum 12 has a perforation 13. The membrane 2 of the device 1 of Figures 1 and 2 is attached to the remaining remnants of the eardrum 12 in such a way that the perforation 13 is hermetically sealed. Furthermore, the membrane 2 hugs the remainder of the eardrum 12. For this purpose, the membrane 2 is formed in a funnel-shaped bulging in the manner that their shape corresponds to the natural shape of a tympanic membrane. Thus it is achieved that the unit of the remaining remnants of the eardrum 12 and the membrane 2 substantially corresponds in shape to an intact eardrum. Thus, in the middle ear 5 shown in FIG. 3, substantially natural physiological conditions prevail. The electrical lines 4 extend from the membrane 2 through the outer Gehόrgang 6 to the outside.

In order to follow the deformation of the diaphragm 2, the change in the electrical resistance of the strain gauges 3a and 3b is tracked. Their electrical resistance changes under mechanical loads, such as during stretching and compression. The change in the resistance can be detected, for example, by incorporating the strain gauges 3a and 3b in an electrical circuit containing a Wheatstone measuring bridge or a half or quarter bridge.

From the electrical resistance of the strain gauges 3a and 3b, pressure changes in the middle ear 5 or, if the gauge is suitably calibrated, the pressure in the middle ear 5 can be determined. Figures 4a and 4b show typical temporal pressure curves in the middle ear 5, wherein on the y-axis, the pressure and on the x-axis, the time is plotted. In FIG. 4 a, a rising negative pressure builds up in the middle ear 5 over time. This suggests that the function of the Eustachian tube is disturbed. In contrast, the negative pressure in Figure 4b is suddenly reduced at regular intervals. These regularly occurring, sudden reductions show that the Eustachian opens when swallowing. From Figure 4b is also apparent that an initially existing, relatively high negative pressure is completely reduced over time. This shows that the function of the Eustachian tube is functionally sufficient to effect a pressure equalization required for proper middle ear function.

Claims

claims

Device for measuring the pressure in the middle ear (5), comprising: an elastically flexible membrane (2) preformed in the manner of a funnel shape in the natural shape of a human eardrum (12) in such a way that it conforms to the eardrum (12) and a signal generating means (3a, 3b, 4) connected to the membrane (2) and providing representative signals for deformation of the membrane (2).

2. Device according to claim 1, wherein the signal generating means (3a, 3b, 4) comprise at least one piezoelectric element.

A device according to claim 1 or claim 2, wherein the signal generating means (3a, 3b, 4) comprises at least one strain gauge (3a, 3b).

4. Device according to one of the preceding claims, wherein the signal generating means (3a, 3b, 4) are at least partially fixed on a surface of the membrane (2).

5. Device according to one of the preceding claims, wherein the signal generating means (3a, 3b, 4) are at least partially embedded in the membrane (2).

6. Device according to one of the preceding claims, wherein the membrane (2) is designed such that act between her and a human eardrum (12) in contact adhesion forces through which the membrane (2) conforms to the eardrum (12) and attached to this.

7. Device according to one of claims 1 to 5, wherein the membrane (2) is designed such that it can be attached to a fitting with a film of isotonic NaCl solution or ultrasound gel as an adhesion aid to the eardrum (12)

8. Device according to one of the preceding claims, wherein the membrane (2) is designed and dimensioned so that they in a perforated eardrum (12) so conforming to the perforation (13) surrounding remnants of the eardrum (12) placed and releasably can be attached to this, that the perforation (13) in the eardrum (12) is hermetically sealed.

9. Device according to one of the preceding claims, wherein the membrane (2) is made of a biocompatible material.

10. Device according to one of the preceding claims, wherein the membrane (2) is made of a polyurethane or a silicone elastomer.

11. Device according to one of the preceding claims, wherein the membrane (2) has a modulus of elasticity in the range of 7 to 20 MPa.

12. Device according to one of the preceding claims, wherein the membrane (2) has a Shore A hardness of 60 to 80.

13. Device according to one of the preceding claims, wherein a memory device is provided which for a plurality of different times for the signals of Signal generating means (3, 4) stores characteristic values.

14. Device according to one of the preceding claims, wherein a transducer is provided, which receives the signals from the signal generating means (3, 4) and converts into pressure signals representative of the pressure in the middle ear (5).

15. The apparatus of claim 14, wherein a memory device is provided which stores characteristic values for a plurality of different times for the pressure signals.

16. A method of measuring pressure in the middle ear, comprising: providing a device (1) according to any one of claims 1 to 15, applying the elastically flexible membrane (2) to at least part of a human's eardrum (12) in that it mates with the tympanic membrane (12), affixes the elastic membrane (2) to the eardrum (12) and receives the signals generated by the signal generating means (3, 4), stores or stores values for a plurality of different times which are characteristic of the received signals, the values being stored or recorded as pairs of values and measurement times, and the membrane (2) being removed from the eardrum (12).

17. The method according to claim 16, wherein the membrane (2) is placed on the eardrum (12) in such a way that a in This existing perforation (13) is closed airtight.

A method according to claim 16 or claim 17, wherein the signals generated by the signal generating means (3, 4) are converted into pressure signals representative of the pressure in the middle ear (5).

A method according to claim 18, wherein the stored or recorded values for the pressure signals are characteristic.

A method of measuring the rigidity of the eardrum, comprising: providing a device (1) according to any one of claims 1 to 15, applying the elastically flexible membrane (2) to at least a portion of a human's eardrum (12) is that it conforms to the eardrum (12), the elastic membrane (2) is attached to the eardrum (12), the signals generated by the signal generating means (3, 4) are received, the pressure in the external auditory canal and / or in the middle ear (5) is manipulated, for a number of pressure values of the pressure in the external auditory canal or in the middle ear (5) values are stored or recorded, which are characteristic of the received signals, wherein the recording or in the form of pairs each other stored or recorded associated pairs of values and pressure values in the external auditory canal or in the middle ear (5), and the membrane (2) is removed from the eardrum (12).