WO2008012398A1

WO2008012398A1 - Method and equipment for controlling the measurement of nerve response wirelessly

Info

Publication number: WO2008012398A1
Application number: PCT/FI2007/050427
Authority: WO
Inventors: Pentti Manninen
Original assignee: Mediracer Ltd.
Priority date: 2006-07-25
Filing date: 2007-07-12
Publication date: 2008-01-31
Also published as: FI20065500A0

Abstract

Nerve response measurement arrangement (10) comprises a central unit (11), a stimulator (12, 12a) and a measurement unit (13, 13a) wirelessly communicating with the central unit, and, optionally, a separate display unit (14). The person carrying out the measurement can control the measurement arrangement at the side of the object (1) being measured and find a suitable place for the stimulation or the measurement sensors. The intensity, frequency, and shape of the stimulation and the measurement amplification can be controlled in real time, and the results of the last two measurements are presented in the display device for determining a place of stimulation or measurement which gives a better neurophysiological measurement result. Independent claims also describe a wireless stimulator and a wireless measurement unit in which the load on the fastening point of the electrode is reduced by connecting the electrode to the stimulation source or the A/D converter using a cable.

Description

METHOD AND EQUIPMENT FOR CONTROLLING THE MEASUREMENT OF NERVE RESPONSE WIRELESSLY

The invention relates to a method and equipment for controlling the measurement of nerve function wirelessly at a patient.

The measurement of nerve response is a conventional way of examining the functioning of a nerve. The matters to be examined in the nerve response are the response time, from which the conductive speed of the nerve, as well as the size and shape of the amplitude of the response can be calculated. This information can be utilized when making assessments of the entrapment of a nerve or general damage suffered by the nerve. However, the stimulation of the nerve and the measurement of the response are very place-sensitive, and for succeeding they require following the response signal on the display in real time, at the same time as the point of registration, point of stimulation and the stimulation strength required for achieving the maximum nervous response are being looked for. In the traditional ENMG (electroneuromyography), the actual measurement device, stimulator and display device constitute one entity, and the patient is connected directly to the device by relatively short conductors. An advantage is a large display device, by which real-time control of the stimulation strength is achieved, and the best point of stimulation and measurement can be found by moving the electrodes. A disadvantage is the fact that the working area is limited because of the short conductors, poor ergonomy caused by that, and the conductors becoming frequently tangled with each other. The display is generally at a different side from the patient, and the same applies to the controllers and buttons required for the measurement control, and during the measurement the person performing it must frequently turn away from the patient to the measurement device and back.

The published application US 2005/0262559 describes wirelessly operating equipment for the measurement of nerve response, by which an attempt is made to avoid the problems caused by the cabling described above. The equipment includes a central unit, a wireless stimulation unit and a wireless sensor unit. The two last mentioned may also be in the same unit. The units exchange information with each other via a Bluetooth connection. The central unit of the device arrangement controls the measurement event. The user of the device can control the level of stimulation and the moment of stimulation by means of switches in the stimulation unit. The nerve response signals measured are transmitted in almost real time wirelessly to the central unit and saved for processing and displaying. It is the objective of the invention to provide an new method and measurement arrangement, by which the measurement of nerve response can be managed wirelessly at the patient as an interactive process with the central unit. By using the device arrangement, the person performing the measurement of nerve response can determine the places of the electrodes and adjust the level of stimulation to the optimum and perform the measurement of nerve response by the side of the person being examined, without turning at times to operate the central unit and without the limitations caused by conductors between the central unit and the patient.

The objectives of the invention are achieved by a device arrangement, which comprises at least one wireless nerve stimulation unit, or stimulator, which is connected by means of separate stimulation electrodes to the patient, a wireless measurement unit, which is connected by means of separate measurement electrodes to the patient, and a central unit with a suitable display device and possibly a large auxiliary display placed in the field of vision of the person performing the measurement. The person performing the measurement starts looking for the response of the nerve by sending a stimulus from a wireless stimulator via separate electrodes to the patient. The response caused by the stimulation and measured from the nerve of the patient is viewed in real time on the display device. The strength of the stimulation or the place of the electrodes is changed when required for finding the best nerve response. Although the person carrying out the measurement knows the points of measurement and stimulation relatively accurately in advance, by changing their places slightly it is often possible to get an optimum response with regard to the actual nerve measurement.

The invention has the advantage that the point of stimulation of the nerve measurement and the points of connection of the measurement unit, as well as the stimulation strength required can be determined and the measurement carried out directly on the side of the person being examined, and it is not necessary to turn to the display or control devices of the central unit at times for performing the measurement.

In addition, the invention has the advantage that the measurement is not made more difficult by cables connected between the central unit, which is difficult to move, and the person being examined, which largely restrict the working area and adversely affect the ergonomy. In addition, the invention has the advantage that by using electrodes that are connected by cables to the stimulation device and measurement unit belonging to the measurement arrangement, the electrodes and measurement devices can be connected to the patient in as user-friendly manner as possible, and the weight of the device itself does not burden the fastening point of the electrode on the patient.

In addition, the invention has the advantage that the signal coming to the measurement unit from the electrodes connected to it can be amplified already at the point of connection of the electrodes, and therefore the weak analogue signals that are susceptible to interference need not be transferred in the measurement arrangement.

Yet another advantage of the invention is the fact that it is possible to connect a separate, large auxiliary display behind the patient in the field of vision of the examiner, in which case the examiner need not turn away from the patient, but only looking up is enough to follow the display.

The method, measurement arrangement and computer program product according to the invention are characterized in what is set forth in the independent claims.

Some advantageous embodiments of the invention are presented in the dependent claims.

The basic idea of the invention is the following: Wireless data transfer is used in a neurophysiological measurement between the components belonging to the measurement arrangement. In the device arrangement according to the invention, a stimulator, a measurement unit and a possible auxiliary display device are connected by means of a wireless radio network to the central unit of the measurement arrangement.

In an advantageous embodiment of the invention, the electrodes belonging to the measurement arrangement are connected by using cables both to the stimulator and the measurement unit.

A program application controlling the operation of the measurement arrangement has been installed in the central unit. The wireless radio network can be a Bluetooth or ZigBee radio network, for example. The central unit can be a personal computer, for example. The wireless stimulation unit according to the invention has means for producing a stimulus of the desired strength and for conducting it to the patient at the moment desired by the person performing the stimulation. The result of the stimulation is transmitted to the central unit from a wireless measurement unit connected to the patient. The central unit may comprise a display device, by which the nerve response of the stimulation given is presented almost in real time. Alternatively, the central unit transmits the measurement result by wireless/wired means to a separate display device, which is located in the vicinity of the object being examined, in which case the measurement result is in the field of vision of the person performing the measurement. By following the nerve response caused by the stimulation and measured, it is possible to find and optimize the places of both the stimulation electrodes and the measurement electrodes and the stimulation strength for achieving the best measurement result, and perform the actual measurement event after that.

In the following, the invention will be described in more detail. Reference will be made to the accompanying figures, in which

Figure 1 shows a measurement arrangement according to the invention by way of example,

Figure 2a shows an example of a stimulator according to the invention,

Figure 2b shows an example of a measurement unit according to the invention,

Fig. 2c shows an example of another stimulator according to the invention,

Fig. 2d shows an example of another measurement unit according to the invention, and

Figure 3 shows, by way of example, a flow chart of the main steps of the positioning method according to the invention.

Fig. 1 shows an example of a nerve response measurement arrangement 10, in which the invention can be applied. In the example of Fig. 1 , the object of the examination of nerve response is the nerve 2 in the hand of a person 1 , the state of operation of which is wanted to be measured. The nerve response to be measured can be optimized by a device arrangement and method according to the invention by positioning the places of the electrodes connected to the stimulator 12 and the measurement unit 13, which are optimal for the measurement.

In an alternative embodiment of the invention, it is also possible to utilize a stimulator 12a and a measurement unit 13a according to the second embodiment of the invention.

The operation of the measurement arrangement 10 is controlled by a central unit 11. It can be either a special device designed for performing a nerve measurement, or, for example, a personal computer, in which computer programs enabling the measurement according to the invention have been installed. The central unit 11 may comprise a display unit, by which the result of the nerve measurement can be presented either as a real-time or non-real-time record. The nerve measurement according to the invention is activated in the central unit 11 by starting the measurement program utilized in the realization of the invention. The measurement program guides the other components 12, 13 and 14 belonging to the measurement arrangement 10 to the readiness state preceding the measurement.

Nerve stimulation is achieved by a wireless stimulator 12. It communicates with the central unit 11 by means of a wireless radio connection 121. Via the radio connection 121, the stimulator 12 can both receive messages from the central unit

11 and transmit messages to the central unit 11. In Fig. 1 , the stimulator 12 is shown only schematically. Arrow B indicates that in the measurement situation of a nerve of the hand according to Fig. 1, the stimulator 12 has at least an indirect skin contact with the hand of the person 1 being measured. The skin contact can advantageously be formed by a separate prior art stimulation sensor, well known as such, which is placed on the skin and can be connected to a wireless stimulator

12 according to the invention for performing the measurement. When the best place of stimulation is being looked for, the stimulation sensor is moved when required. The stimulation can be started either by an instruction transmitted by the central unit or by an instruction given by the person performing the measurement directly to the stimulator 12 via its user interface. The starting time and strength of the stimulation can advantageously be transmitted to the central unit 11.

The nerve response caused by stimulation is measured by a wireless measurement unit 13 according to the invention. It processes and transmits the nerve response measured by it via a wireless radio connection 131 to the central unit 11. Arrow A indicates that in the measurement situation, when a nerve of the hand is being measured according to Fig. 1, the measurement unit 13 has at least an indirect skin contact with the hand of the person 1 who is the object of measurement. The skin contact can be realized by a prior art measurement sensor, for example, which can be connected to the measurement unit 13 for performing the measurement.

When required, a separate display unit 14 can also be connected to the measurement arrangement 10. It is also connected to the central unit 11 via a wireless radio connection 141 or directly connected as an auxiliary display to the central unit with a cable. The display unit 14 can be located in a place where it is in the field of vision of the person performing the measurement.

The wireless radio connection 121 , 131 or 141 can be implemented as a Bluetooth network or a ZigBee network, for example. It is also possible to use some other prior art radio network without changing the inventive idea. In the radio network, the messages are advantageously transferred as digital messages, whereby the noise and interference problems related to analogue data transfer can be avoided.

Fig. 2a shows an example of a stimulator 12 according to the first embodiment of the invention. The stimulator 12 comprises a power source 127, a processing unit 124, a transceiver 122 and a stimulation pulse source 125 for satisfying the power requirement. The power source 127 can be a rechargeable or non-rechargeable battery. The stimulator 12 also comprises a suitable antenna 123, by using which the transceiver 122 of the stimulator 12 can receive or transmit messages in the radio network being used. The stimulator 12 may also comprise a user interface 128, by which the strength of the stimulation used and its moment of occurrence can be determined. Reference no. 126 indicates an interface, to which a suitable prior art stimulation sensor (not shown in Fig. 2a) can advantageously be connected.

The processing unit 124 of the stimulator 12 advantageously comprises a suitable processor or programmable logic and a memory connected to it. The processing unit 121 receives the control messages obtained from the user interface 128. These messages control the operation of the stimulation pulse source 125. The processing unit 124 can also receive the control messages transmitted over the air 121 by the central unit 11 of the measurement arrangement by means of the transceiver 122. The processing unit 124 can also send to the central unit 11 via the transceiver 122 information on when the stimulation was performed and what kind of stimulation it was.

The stimulation pulse source 125 is capable of producing a stimulus according to the instruction received from the central unit 124. It can modify the shape of the stimulation pulse(s) created, the number of the pulses, the repetition frequency of the pulses and/or the voltage of the pulses. Having received either an instruction from the central unit 11 of the measurement arrangement or an instruction given by the user through the user interface 128, the stimulation pulse source 125 transmits the stimulus produced by it through the interface 126 to the object being measured.

Fig. 2b shows the wireless measurement unit 13 according to the first embodiment of the invention by way of example. The measurement unit 13 comprises a power source 137, a processing unit 134, a transceiver 132 and an operational block 135. The power source 137 can be a rechargeable or non-rechargeable battery. The operational block 135 advantageously comprises an amplifier for amplifying the signal received, a filter for filtering the amplified signal, and an A/D converter for converting the filtered signal into digital form for data transfer. The measurement unit 13 also comprises a suitable antenna 133, by using which the transceiver 132 of the measurement unit 13 can receive or transmit messages in the radio network 131 being used. Ref. no. 136 indicates an interface to which a suitable, prior art measurement sensor used in nerve measurement (not shown in Fig. 2b), which has been placed on the object being measured, can advantageously be connected. The signal obtained from the measurement sensor is amplified, filtered and converted into digital in the operational block 135.

The processing unit 134 advantageously comprises a suitable processor or programmable logic and a memory connected to it. The processing unit 134 can receive the control messages 121 transmitted by the central unit 11 of the measurement arrangement by means of the transceiver 132. The control messages can, for example, set the measurement unit 13 in the readiness state preceding the measurement. In the measurement state, the processing unit 134 also transmits to the central unit 11 of the measurement arrangement 10 the measurement messages indicating the response of the nerve stimulus, received from the A/D converter 135 through the transceiver 132. Fig. 2c shows an example of a stimulator 12a according to the second embodiment of the invention. The stimulator 12a comprises a power source 127a, a processing unit 124, a transceiver 122 and a stimulation pulse source 125 for satisfying the power requirement. The power source 127a advantageously comprises a rechargeable battery. The power source 127a also comprises means for charging the battery from an external source via a connection 127b. The stimulator 12a also comprises a suitable antenna 123, by using which the transceiver 122 of the stimulator 12a can receive or transmit messages in the radio network being used. The stimulator 12a may also comprise a user interface 128, by which the strength, pulse form and pulse duration of the stimulation used and its moment of occurrence can be determined.

Ref. 126a advantageously denotes a protected connection cable, which connects the stimulator 12a to the junction box 129a. The junction box 129a comprises means for electrically connecting the conductors of the cable 126a and the stimulation electrodes 129b to each other. The electrical connection is advantageously detachable. The stimulation electrodes 129b can be advantageously either planar, conductive electrodes or needle-shaped electrodes.

For its other structural and functional parts, the stimulator 12a corresponds to the stimulator 12 according to the first embodiment.

Fig. 2d shows the wireless measurement unit 13a according to the second embodiment of the invention by way of example. The measurement unit 13a comprises a power source 137a, a processing unit 134, a transceiver 132, and an A/D converter and a filter 135. The power source 137a is advantageously a rechargeable battery. The power source 137a also comprises means for charging the battery from an external source via a connection 137b. The operational block 135 advantageously comprises a filter for filtering the signal, and an A/D converter for converting the filtered signal to digital form for data transfer. The measurement unit 13a also comprises a suitable antenna 133, by using which the transceiver 132 of the measurement unit 13 can receive or transmit messages in the radio network 131 being used.

The measurement unit 13a can also comprise a user interface 130.

Ref. 136 denotes a connection cable, by which the measurement electrodes 139 are connected to the measurement unit 13a. The connection cable 136 is connected to the measurement electrodes 139 in the junction box 138. The junction box 138 comprises means for electrically connecting the conductors of the cable 136 and the measurement electrodes 139 used to each other, and an amplifier unit, by which the analogue signal obtained from the electrodes is amplified to a volt-level signal. The electrical connection between the junction box and the electrodes is advantageously detachable. Either planar, conductive electrodes or needle-shaped electrodes can be advantageously used as measurement electrodes 139.

The junction box 138 comprises an analogue pre-amplifier (not shown in Fig. 2d) for amplifying the microvolt signal coming from the measurement electrodes 139 to a volt-level signal. After amplification, the measurement signal is transferred via a cable 136 to the measurement unit 13a. The length of the cable 136 can be selected according to the object being measured.

In block 135, the signal is first filtered, and an A/D conversion is performed after filtering. The transformed digital signal is conducted to the processing unit 134.

The processing unit 134 advantageously comprises a suitable processor or programmable logic and a memory connected to it. The processing unit 134 can receive the control messages 121 transmitted over the air by the central unit 11 of the measurement arrangement by means of the transceiver 132. The control messages can, for example, set the measurement unit 13 in the readiness state preceding the measurement. In the measurement state, the processing unit 134 also transmits to the central unit 11 of the measurement arrangement 10 the measurement messages indicating the response of the nerve stimulus, received from the A/D converter 135 through the transceiver 132.

Cables are used in the embodiments of the invention shown by Figs. 2c and 2d, so that the load on the point of fastening of the electrode on the patient can be eliminated. Using cables makes it possible to locate the devices containing the actual electronics and operating wirelessly in such a manner that they do not disturb the user.

Fig. 3 is an exemplary flow chart of the main steps of the method according to the invention. The reference numbers used in the previous figures 1-2d are also used in connection with the description of the flow chart. In step 30, the measurement arrangement is activated by starting the measurement program according to the invention in the central unit 11. After starting, the central unit 11 sends a "ready" command to the devices connected to the measurement arrangement 10 through the radio links 121 , 131 and 141. Having received the "ready" command, both the stimulator 12 or 12a and the measurement unit 13 or 13a are ready for measurement. If the measurement arrangement 10 includes an optional display device 14, it is also set in the operation mode. The electrodes connected to the stimulator 12 or 12a and the measurement unit 13 or 13a are placed on the assumed places of measurement on the body of the person 1. The person performing the measurement can also set the form and intensity of the nerve stimulation to the assumed level of measurement.

In step 31 , the person performing the measurement produces the first nerve stimulus to a nerve, such as nerve 2 in the example of Fig. 1. The nerve stimulus produced may be a single voltage pulse or a string of pulses. The shape of the pulse of the nerve stimulus and the amplitude of the voltage of the pulse can be determined from the stimulator 12 or 12a before giving the nerve stimulus. When the nerve stimulus is given, information about it is advantageously transmitted through the wireless link 121 to the central unit of the measurement arrangement 10.

The electric response signal caused by the nerve stimulation is received by the measurement unit 13 or 13a from another place of the body of the person 1. The signal is advantageously amplified and filtered before the A/D conversion performed on it. The filtering and amplification parameters can be adjusted, when required. The measurement unit 13 or 13a transmits the received nerve signal data as a digital message to the central unit 11 via the wireless link 131.

In step 32, the central unit 11 saves the measurement message it has received and guides either its own display unit and/or a separate display device 14 to present the signal received by the measurement unit 13.

The measurement of nerve response is very place-sensitive. Therefore, finding optimal places for measurement often requires experimenting with points of connection for measuring stimulation and response. Hence it is sensible to experiment and optimize the places of both within certain limits, if the response signal is weak. In the example of Fig. 3, the place of stimulation is first changed in step 33. Without changing the idea of the invention, the place of connection for the measurement unit 13 or 13a could also be changed first. In step 34, it can be read from the display shown by the central unit 11 whether the response signal received became stronger after changing the place or not. This can be done advantageously, if at least the measurement result of the previous measurement is displayed simultaneously. If the response signal became stronger compared to the previous place of stimulation, the place of stimulation can be changed again, which brings the process back to step 33. The measurement result of the response signal can advantageously be shown either as a graph or as a characteristic, which can be calculated or concluded from the graph. One possible characteristic is the peak value of the nerve response signal measured.

In some measurement event, the received response signal does not increase any more. In that case, the place of stimulation can be returned to the previous place of stimulation in step 35. Step 35 may include an additional checking stimulation (not shown in Fig. 3) in order to be sure that the best possible place of stimulation has been found. In addition, it is possible to test in step 35 how the amplitude of the pulse used as a nerve stimulus affects the result of the measurement. When required, the amplitude of the voltage of the stimulus can be increased within certain limits, until the response signal received from the measurement unit 13 does not increase any more.

In the exemplary flow chart shown in Fig. 3, the place of connection of the measurement unit 13 or 13a is changed after the place of stimulation has been found. In step 37, a new stimulus is produced, and its measurement result is judged against the previous measurement result. If the nerve response increased, the place of connection of the measurement unit 13 or 13a is changed again in step 36, and a new measurement is performed. In some measurement event, the signal received does not increase any more. In that case, the point of connection of the measurement unit 13 or 13a can be returned to the previous place of measurement in step 38. Step 38 may include an additional checking stimulation (not shown in Fig. 3) in order to be sure that the best possible point of connection for the measurement unit 13 or 13a has been found.

After this, the place determination of the nerve measurement ends in step 39, after which the measurement arrangement 10 is ready for the actual neurophysiological measurement.

In the measurement method according to the invention, a measurement program can be utilized in the central unit 11 to manage the neurophysiological measurement, receive messages wirelessly from the stimulator 12 or 12a and the measurement unit 13 or 13a and to transmit control messages or measurement data to the devices 12, 12a, 13, 13a tai 14 connected to the measurement arrangement 10. In addition, the measurement program advantageously comprises means for presenting the measurement results of two or more consecutive measurement results of nerve stimulation simultaneously. The measurement program may also comprise program means for controlling the measurement event. In that case, the measurement program will suggest to the person carrying out the measurement which measurement parameter or place related to the measurement should be changed in order to increase the nerve response signal.

Some advantageous embodiments of the method and device arrangement according to the invention have been described above. The invention is not limited to the above described solutions only, but the inventive idea can be applied in many ways within the limits defined by the claims.

Claims

1. A method for determining places of stimulation and measurement of nerve response by utilizing measurement devices (11, 12, 13, 14), which communicate with each other wirelessly, in which method:

- nerve stimulation is caused in a nerve (2) being examined by a stimulator (12)

- a nerve response evoked by the stimulation is received and measured by a measurement unit (13)

- the nerve response measured by the measurement unit (13) is received and saved in a central unit (11 )

- the measurement result last received is presented on a display device (14), characterized in that the measurement results of at least the measurement last received and the one preceding it are presented on the display device for determining a place of stimulation or measurement which gives a better measurement result.

2. The method according to Claim 1 , characterized in that the strength of the nerve stimulation given is determined by a user interface (124) of the stimulator (12).

3. The method according to Claim 1, characterized in that the number and shape of the pulses belonging to the nerve stimulation given are determined by a user interface belonging to the stimulator (12).

4. The method according to Claim 1 , characterized in that the measurement results are shown as graphs.

5. A measurement arrangement (10) for measuring nerve response, the measuring arrangement comprising: - a wireless stimulator (12) for causing nerve stimulation in a nerve (2) being examined

- a wireless measurement unit (13) for receiving and measuring a nerve response caused by the stimulation

- a central unit (11) for receiving and saving the nerve response measured by the measurement unit (13), and

- a wireless/wired display device (14) for presenting the measurement result, characterized in that the measurement results of at least the measurement last received and the one preceding it are arranged to be presented on the display device (14) for determining a place of stimulation or measurement which gives a better measurement result.

6. The measurement arrangement according to Claim 5, characterized in that the strength of the nerve stimulation given is arranged to be determined by a user interface (124) of the stimulator (12).

7. The measurement arrangement according to Claim 5, characterized in that the number and shape of the pulses belonging to the nerve stimulation given is arranged to be determined by the user interface of the stimulator (12).

δ. The measurement arrangement according to Claim 5, characterised in that the measurement results are arranged to be shown as graphs.

9. A wireless stimulator (12, 12a), which comprises:

- a power source (127, 127a)

- a user interface (128) - a transceiver (122)

- a processing unit (124), and

- a stimulation pulse source (125), characterized in that stimulation electrodes (129b) have been connected with a cable (126a) to the stimulation pulse source (125) for reducing the load on the fastening point of the electrode.

10. The stimulator according to Claim 9, characterized in that the stimulation electrodes (129b) have been arranged to be fastened to the cable (126a) and to be detached from the cable (126a) in a junction box (129a).

11. The stimulator according to Claim 10, characterized in that the stimulation electrodes (129b) are either planar electrodes or needle-shaped electrodes.

12. A wireless nerve response measurement unit (13, 13a), which comprises: - a power source (137, 137a)

- a transceiver (132), and

- a processing unit (134), characterized in that the measurement electrodes (139) have been connected with a cable (136) to an A/D converter (135) in the measurement unit.

13. The measurement unit according to Claim 12, characterized in that the measurement electrodes (139) have been arranged to be fastened to the cable

(136) and to be detached from the cable (136) in a junction box (138).

14. The measurement unit according to Claim 13, characterized in that the junction box (138) comprises a pre-amplifier for amplifying the signal received from the measurement electrodes (139).

15. The measurement unit according to Claim 14, characterized in that the measurement electrodes (139) are either planar electrodes or needle-shaped electrodes.

16. The measurement unit according to Claim 12, characterized in that it also comprises a user interface (130).

17. A computer program product, which comprises computer program means saved on a computer-readable medium for implementing the determination of the places of stimulation and measurement of nerve response, which computer program product comprises:

- computer program means for setting a measurement arrangement in the measuring state - computer program means for receiving a message including a measurement result of the nerve response signal wirelessly from the measurement unit

- computer program means for saving the received measurement message, and

- computer program means for presenting the saved measurement message on a display device, characterized in that the computer program product also comprises computer program means for presenting the measurement results of at least the measurement last received and the one preceding it for determining a place of stimulation or measurement which gives a better measurement result.

18. The computer program product according to Claim 17, characterized in that it comprises computer program means for presenting the measurement result as a graph.