METHOD OF TREATING MENIERE'S DISEASE AND CORRESPONDING APPARATUS

Abstract: In a method of treating Ménière's disease intermittent air pressure pulse trains are administred to an outwardly sealed external ear volume bordering to a surgically perforated tympanic membrane. In a pulse train air pressure is increased from ambient (p0) to a first level (p1) and from there repeatedly to a second level (p2) and repeatedly decreased to the first level (p1), and finally decreased to ambient (p0). P1 is from 4 to 16 cm H2O, p2 is from 8 to 16 cm H2O, with the proviso that p1 > p2, the pressure increase rate is from 0 to 4 mm H2O per millisecond, the pressure decrease rate is from 0 to 2 mm H2O per millisecond, the modulation frequency is from 3 to 9 Hz, the intermittent time period is from 3 to 10 seconds. Also disclosed is an apparatus for carrying out the method.

Description: METHOD OF TREATING MENIERE'S DISEASE AND CORRESPONDING APPARATUS FIELD OF THE INVENTION The present invention relates to a method for treatment of Meniere's disease by producing variations in positive air pressure, which are transmitted to one of the ears of a patient, and to an apparatus for carrying out the method. BACKGROUND OF THE INVENTION Meniere's disease can be treated by affecting the pressure in the internal ear, in particular the endolymphatic system. WO 83/02556 teaches the treatment of Meniere's disease by a particular kind of air pressure pulses and an apparatus for their generation. Pulse trains of a low frequency, that is, short time periods of raised pressure interrupted by similarly short time periods of 'normal' (ambient) pressure, are administered to the external ear of a patient that has been put in communication with the middle ear by means of a transmyringeal passage. The pulse trains resemble to a square wave and are separated by periods of ambient pressure. Modulation pulses of a higher frequency are superimposed on the low frequency pulses. Via the middle ear the pressure pulses are transmitted to the internal ear where they reduce the excessive volume of liquid in the endolymphatic space. EP 266 474 Al discloses a total pulse amplitude of from 10 to 30 cm H ≥ O, a modulation amplitude of from 25 to 0 cm H0, a modulation frequency of from 3 to 15 Hz, a pulse length of from 0.5 to 5 seconds, the pulse train frequency of 4.5 -1 Hz = 0.22 Hz, the length of a treatment session to be from 5 to 10 minutes. Until a clinical effect is seen the treatment is repeated every second hour: Thereafter the frequency of treatment is lowered to 3.4 per day. WO 93/08775 discloses an air pressure generator for the treatment of Meniere's disease by pressure pulses of the following parameters: a minimum pressure which is 33 % of the maximum pressure; a maximum pressure of from 10 to 30 cm H 2 0; intervals between pulses of 5 seconds; a number of pulses per treatment from 1 to 18; a modulation frequency of from 1 to 10 Hz; a pulse length of from 0.1 to 2 seconds. When applying square wave pulses to the internal ear in cats with a patent cochlear aqueduct a pronounced rebound effect could be noted (Transmission of Square Wave Pressure Pulses through the Perilymphatic Fluids in Cats, B Densert et al . , Act Otolaryngol . Stockholm 1986). In humans the situation might be similar. The pressure changes in the internal ear caused by the application of square wave pulses according to methods disclosed in the prior art thus could lead to results substantially differing from what was endeavoured. This provides a possible explanation of the fact that, in spite of various apparatus for the production and transmission of such air pressure pulses having been devised over the past fifteen years, none of them has been put into practical use at a commercial scale. This delay in the implementation of an interesting therapeutic principle seems to be due not only to these apparatus having certain drawbacks from a constructional point of view making them insufficiently adapted to the need of most outdoor patients but also to methodical shortcomings in regard of how to vary the pressure during a treatment such as to make it applicable to a large group of patients. OBJECTS OF THE INVENTION The present invention seeks to overcome these drawbacks and problems, and to provide an improved method of treating Meniere's disease and a corresponding apparatus. Other objects of the invention will become apparent from the following short description of the invention and a preferred embodiment of it, as well as of the appended claims. SUMMARY OF THE INVENTION According to the present invention is provided a method of treatment of Meniere's disease by intermittent administration of air pressure pulse trains to an outwardly sealed external ear volume bordering to the tympanic membrane brought into communication with the inner ear by means of surgery, a pulse train comprising increasing air (gas) pressure from ambient pressure (p 0 ) to a first level (pi) above ambient pressure and from the first level (pi) repeatedly increasing the pressure to a second level (p 2 ) and decreasing it to the first level (pi) and, upon said repeated increase and decrease, decreasing the pressure from the first level (pi) to ambient pressure (p 0 ) , wherein pi is from 4 to 16 cm H 2 0, p 2 is from 8 to 16 cm H 2 0, with the proviso that pi 3= p 2 , the pressure increase rate is from 0 to 4 mm H 2 0 per millisecond, the pressure decrease rate is from 0 to 2 mm H 2 0 per millisecond, the modulation frequency is from 3 to 9 Hz, preferably from 5 to 7 Hz, the intermittent time period being from 3 to 10 seconds, preferably about 5 seconds. It is preferred for the number of pulse trains to be from about 10 to about 50, more preferred of about 25 to about 35. It is preferred to administer, during a treatment session, two to four treatments, in particular three treatments separated by from about 25 seconds to about 80 seconds. In the method according to the invention the pressure pulses are formed in an apparatus comprising an air (gas) pressure chamber being in sealing communication with said outwardly sealed external ear volume. It is preferred to vary the pressure by applying an electromagnetic force to a diaphragm forming a wall of the pressure chamber. It is preferred for the electromagnetic force to be controlled by a control circuit comprising a microprocessor, power control means, and pressure monitoring means. It is preferred for the power supply means to provide the coil with pulse modulated DC. According to the present invention is also disclosed an apparatus for treatment of Meniere's disease by intermittently increasing, in an air (gas) pressure chamber being in communication with an outwardly sealed external ear volume bordering to the tympanic membrane, air (gas) pressure from ambient pressure (po) to a first level (pi) above ambient pressure and from that (pi) repeatedly increasing the pressure to a second level (p 2 ) and decreasing it to the first level (pi) and, upon said repeated increase and decrease, decreasing the pressure from the first level (pi) to ambient pressure (po) , comprising: a flexible diaphragm (membrane) forming a wall of the chamber; actuating means for displacing the diaphragm; pressure sensing means for monitoring the gas pressure in the chamber; pressure equalising means for equalising the air pressure in the chamber with ambient air pressure; control means comprising a microprocessor, for controlling the displacement of the diaphragm and the pressure equalising means by signal input from the pressure sensing means . It is preferred for the pressure equalising means to comprise valve means. It is preferred for the valve means to be in an open (equalising) position except during the generation of pulse trains. It is preferred for the diaphragm actuating means to comprise an elongate actuating member having an axis and being fixed to the diaphragm at its one end and to an electromagnet, an electric coil for displacement of the magnet along said axis in the direction of the chamber; means for providing the coil with electric power controlled by the control means; means for displacement of the diaphragm in a direction away from the chamber. It is preferred for the means for displacement of the diaphragm in a direction away from the chamber to comprise resilient means not controlled by the control means; it is even more preferred for these displacement means to essentially consist of compressed air contained in the chamber, the conduit, and the sealed external ear volume (the compressed air in the middle ear being disregarded from in this context) . To prevent the pressure to raise excessively in case of a software failure the inclusion of an hardware controlled extra safety means is preferred, breaking the current to the pressure equalising means and the pressure actuating means if the chamber pressure is excess of 25 cm H 2 0 in regard of ambient pressure. On the other hand it is important not to apply a pressure which would expose inner ear structures to suction, that is, negative pressure. It is therefore preferred to provide the apparatus of the invention with a mechanical safety valve for protection of the patient against negative pressure opening at a pressure of about - 1 cm H 2 0; the acceptance of a slightly negative pressure is due to design requirements for such a mechanical safety valve. It is also preferred to provide the apparatus of the invention with a safety valve for protection of the patient against positive pressure opening at a pressure of about + 35 cm H 2 0. The safety valves are purely mechanical and not controlled by the control means. The pressure equalising means preferentially comprise on/off electromagnetic silent valve means working below a hearing level of 20 DB, in particular valve means provided with sealing faces comprising a resilient polymer. The combined volume of the chamber and the conduit can be varied within a broad range but considerations of design and conditions of use suggest the combined volume to be preferably from about 20 ccm 2 to about 50 ccm 2 . According to a preferred aspect of the invention it is preferred to store, in an E^PROM (electrically erasable and programmable read-only memory) or an equivalent media coupled to the microprocessor, the information for control of the apparatus in form of parameter sets, each set comprising all parameters necessary to carry out a treatment, that is, the variation of pressure in the chamber with time during treatment. It is preferred to provide the apparatus of the invention with input means to allow a parameter set to be replaced by another set. Input means not requiring an electrical connection, such as infrared (IR) input means, are preferred. The various parameter sets then are stored in PC or similar and transferred therefrom to the apparatus of the invention. It is also preferred to store several parameter sets in the E 2 PROM, and to provide the apparatus with means for their individual selection. The apparatus of the invention thus comprises a fixed basic program stored in the PROM memory of the microprocessor and an exchangeable supplementary program stored in the E 2 PROM. It is, of course, possible to chose functionally equivalent storage media for the fixed and/or the exchangeable software for controlling the apparatus of the invention. In the following the invention will be explained in more detail by reference to a preferred embodiment illustrated in drawing. The embodiment is however only described to exemplify the invention but not to limit it in any way. SHORT DESCRIPTION OF THE DRAWING Fig. 1 is a schematic function diagram of an apparatus according to the invention; Fig. 2 is a schematic pulse diagram with a non-linear time axis. The preferred embodiment of the apparatus according to the present invention illustrated schematically in Fig. 1 comprises an about cylindrical chamber 1 for generating pressure pulses by displacement of a flexible circular rubber diaphragm 4 forming one base of the chamber 1 wall, a piston 2 centrally fixed to the diaphragm 4 at its one end and at a ferromagnetic alloy core 22 at its other end, the core 22 being partially inserted into an field coil 3. The chamber 1 has a terminal section 5 provided with a λ silent' (hearing level <20 DB) on/off electromagnetic equalising valve 12 which puts it in communication with the atmosphere when in an open position. Via a flexible plastic tube 10 (of polystyrene, polypropene or a similar material) the chamber 1 is put into communication with an air volume in the external ear bordering to the tympanic membrane of a patient sealed off by an ear plug 11. The tympanic membrane is penetrated by a microtube which has been applied by surgery; thereby the external and middle ear of the patient is put into communication. The pressure in the chamber 1 is monitored by a pressure sensor 8, the signal 20 of which is processed in a control unit comprising a microprocessor 16 and software 14. By input of sets of data 15 software parameters relating to pressure and time can be changed. Input is via an IR-link 17 from data stored in a personal computer. One output signal 18 from the microprocessor 16 controls the power supplied to the field coil 3 while another output signal 13 controls the equalising valve 12 by switching it between an open and a closed position. If, for some reason the chamber 1 pressure cannot be maintained within the physiologically acceptable interval the equalising valve is opened. If the chamber pressure exceeds the maximum treatment pressure by 25 cm H 2 0 a hardware controlled safety function breaks the power both to the equalising valve 12 and the field coil 3. As a further safety precaution mechanical safety valves 7,9 against negative pressure (opening pressure - 1 cm H 2 0) excess positive pressure, respectively, are provided in addition. The treatment data are stored in the microprocessor in form of one or several parameter sets. A parameter set contains all information in regard of pulse amplitude, frequency, pressure increase and decrease rate, etc. In addition each parameter set comprises data for the software controlled safety functions. In Fig. 2 a typical treatment sequence is shown, except for the number of pulse trains being reduced to two for the sake of simplicity. The chamber pressure (lowermost section of the diagram, the chamber volume (central section of the diagram) and the mode of the equalising valve 12 (uppermost section of the diagram; 12' = open; 12'' = closed) are set off against time. The various phases of the treatment sequence are identified by capital letters. During phase A the pressure sensor 8 is brought to a working temperature, the equilibrating valve 12 is in an open position, and the chamber 1 is at ambient pressure. Then follows a leak test in phase B during which the valve 12 is kept closed while the pressure is gradually increased to a test pressure p of about 1 cm H 2 0, and then again decreased to zero. In test phase C an openness test is carried during which the chamber 1 volume V c is varied in the same way as in phase B but with valve 12 in an open position. If the test pressure p t deviates from the expected values the program will stop the apparatus from proceeding to the treatment sequence proper. During the first treatment phase D the chamber pressure p is gradually raised to an intermediate pressure i and from there to the maximum pressure p, followed by a decrease to the intermediate pressure pi; the pi — > p 2 — > pi cycle is repeated trice, followed by lowering the pressure to ambient pressure po. After an interval E of about 5 seconds a second pulse train (phase F) similar to the one in phase D is generated. This is followed by a second interval at po (phase G) and 10 to 30 further pulse trains (not shown) with corresponding intervals. This first treatment section of equally spaced 12 - 32 pulse trains is followed by a rest period of about 40 seconds, and second and third treatment sections also spaced by a corresponding rest period. For optimal effect the treatment should be repeated several times a day.

Claims: C l a i m s 1. A method of treating Meniere's disease by intermittent administration of air pressure pulse trains to an outwardly sealed external ear volume bordering to the tympanic membrane brought into communication with the inner ear by means of surgery, a pulse train comprising increasing air pressure from ambient pressure (po) to a first level (pi) above ambient pressure and from the first level (pi) repeatedly increasing the pressure to a second level (p 2 ) and decreasing it to the first level (pi) and, upon said repeated increase and decrease, decreasing the pressure from the first level (pi) to ambient pressure (p 0 ) , wherein pi is from 4 to 16 cm H 2 0, p 2 is from 8 to 16 cm H 2 0, with the proviso that pi > p 2 , the pressure increase rate is from 0 to 4 mm H 2 0 per millisecond, the pressure decrease rate is from 0 to 2 mm H 2 0 per millisecond, the modulation frequency is from 3 to 9 Hz, the intermittent time period being from 3 to 10 seconds, preferably about 5 seconds. 2. The method of claim 1, wherein the modulation frequency is from 5 to 7 Hz. 3. The method of claim 1 or 2, comprising administering, during a treatment session, two to four treatments, in particular three treatments, separated by from about 25 seconds to about 90 seconds. 4. The method of any of claims 1-3, wherein the pulse trains are formed in an apparatus comprising an air (gas) pressure chamber being in sealing communication with said outwardly sealed external ear volume and provided with an electromagnetic force actuated diaphragm and an equilibration valve controlled by a microprocessor. 5. An apparatus for treatment of Meniere's disease by intermittently increasing, in an air (gas) pressure chamber being in communication with an outwardly sealed external ear volume bordering to the tympanic membrane, air (gas) pressure from ambient pressure (p 0 ) to a first level (pi) above ambient pressure and from that (pi) repeatedly increasing the pressure to a second level (p 2 ) and decreasing it to the first level (pi) and, upon said repeated increase and decrease, decreasing the pressure from the first level (pi) to ambient pressure (po) , comprising: a flexible diaphragm forming a wall of the chamber; actuating means for displacing the diaphragm; pressure sensing means for monitoring the gas pressure in the chamber; pressure equalising means for equalising the air pressure in the chamber with ambient air pressure; control means comprising a microprocessor, for controlling the displacement of the diaphragm and the pressure equalising means by signal input from the pressure sensing means, wherein pi is from 4 to 16 cm H 2 0, p 2 is from 8 to 16 cm H 2 0, with the proviso that pi > p 2 , the pressure increase rate is from 0 to 4 mm H 2 0 per millisecond, the pressure decrease rate is from 0 to 2 mm H 2 0 per millisecond, the modulation frequency is from 3 to 9 Hz, the intermittent time period is from 3 to 10 seconds. 6. The apparatus of claim 5, wherein the modulation frequency is from 5 to 7 Hz. 7. The apparatus of claim 5 or 6, wherein the pressure equalising means comprise on/off electromagnetic silent valve means working below a hearing level of 20 DB provided with sealing faces comprising a resilient polymer. 8. The apparatus of any of claims 5 to 7, wherein the valve means are controlled to be in an open position except during the generation of pulse trains. 9. The apparatus of any of claims 5 to 8, wherein the means for displacement of the diaphragm in a direction away from the chamber essentially consist of compressed air contained in the chamber, the conduit, and the sealed external ear volume . 10. The apparatus of any of claims 5 to 9, comprising safety means for breaking the current to the pressure equalising means and the pressure actuating means if the chamber pressure is excess of 25 cm H 2 0 in regard of ambient pressure. 11. The apparatus of any of claims 5 to 10, comprising a mechanical safety valve for protection of the patient against negative pressure. 12. The apparatus of any of claims 5 to 11, wherein the information for control of the apparatus is stored in form of parameter sets in an E 2 PR0M coupled to the microprocessor or an equivalent media. 13. The apparatus of claim 12, wherein a parameter set is replaceable by another parameter set. 14. The apparatus of claim 13, wherein replacement is by IR input means.

Inventors: DENSERT BARBARA, ENGVALL DANIEL, NILSSON ANDERS, DENSERT, BARBARA, ENGVALL, DANIEL, NILSSON, ANDERS
Applicants: DENSERT BARBARA, ENGVALL DANIEL, NILSSON ANDERS, PASCAL MEDICAL AB, DENSERT, BARBARA, ENGVALL, DANIEL, NILSSON, ANDERS
Application year: 1999
Main classification: A61F11
IPC codes: A61F11