JP2010075401A - Pain relieving apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To stimulate nerves at the most effective timing for pains with a pulsating nature, and to extend a battery life by reducing a necessary energy consumption. <P>SOLUTION: A pain relieving apparatus measures circulatory dynamics such as an electrocardiogram, a pressure pulse wave, and heart sounds, and controls generation or intensity of electrical stimulation signals for stimulating peripheral nerves based on the measurements in order to treat pains with the pulsating nature such as a migraine headache, and a cluster headache. The intensity of the electrical stimulation signals is controlled by varying the frequency or level of the amplitude of the electrical stimulation signal at the timing of the stimulation. The frequency, pulse width, pulse current, pulse voltage, and the like are considered as parameters of the electrical stimulation signal. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a pain relieving apparatus that relieves pain by stimulating nerves, and particularly relates to a pain relieving apparatus capable of adjusting stimulation based on circulatory dynamics for pulsatile pain.

  In pain treatment, when the conventional drug therapy, nerve block therapy, and surgical therapy are not effective, or when the treatment cannot be continued due to side effects, etc., electrical stimulation therapy that relieves pain by electrically stimulating the nerve is effective Cite. Spinal cord electrical stimulation therapy, which is electrical stimulation therapy, is a therapy that performs electrical stimulation by placing an electrode lead outside the spinal dura mater that covers the spinal cord. In addition, the peripheral nerve electrical stimulation therapy is a therapy for performing electrical stimulation by placing an electrode lead directly on the peripheral nerve or subcutaneously near the peripheral nerve. In these spinal cord electrical stimulation therapy and peripheral nerve electrical stimulation therapy, pain can be alleviated by interfering with pain transmission through the spinal cord or peripheral nerve using electrical stimulation.

  Migraine is a chronic headache that occurs on one side (sometimes both sides) of the head, which may be accompanied by nausea, vomiting, photosensitivity, and hypersensitivity, and can often cause serious social problems with unbearable pain. In general, there are many women in their 20s and 50s, and the number of patients is said to be about four times that of men. Cluster headache is more common in men and is the most painful of all chronic headaches. It occurs on one side of the head and is about once or twice a year, but a headache occurs every day continuously for a certain period (often 1-2 months). Migraine and cluster headache are characterized by painful pulsation, and it is known that the heartbeat pulsates with the heartbeat like a pulse. In recent years, trials of peripheral nerve electrical stimulation therapy for migraine and cluster headache have been made. This is intended to relieve the pain by electrically stimulating the occipital nerve, which is a peripheral nerve that exits from the cervical vertebrae Nos. 2 and 3 and travels toward the parietal region of the occipital region. In this trial, electrical stimulation is usually performed by placing electrodes under the neck of the neck where the occipital nerve is running, and the stimulation parameters such as voltage and frequency at the time of stimulation depend on the intensity of pain. Had to be changed manually.

  The technique described in Patent Document 1 intends to relieve a headache with a leadless stimulation device implanted near the occipital nerve. This Patent Document 1 particularly describes a method of adjusting stimulation parameters by a sensor. Is disclosed.

US Pat. No. 6,735,475

However, it is difficult to manually change the intensity of stimulation according to the pulsatility of pain, and in the technique described in Patent Document 1, the pulsation of pain characteristic of migraine or cluster headache Because it is not a specialized stimulation method, pulsatile discomfort remains or in order to remove this discomfort, the stimulation intensity must be set according to the peak of painful pulsation, and always The stimulation intensity must be kept high. Therefore, a high voltage is required and there is a problem of shortening the battery life.

  The present invention has been made in view of the above points, and measures whether circulatory dynamics such as electrocardiogram, pressure pulse wave or heart sound are measured, and is stimulation performed for a certain period in synchronization with detection of ventricular contraction or blood output? Another object of the present invention is to provide a pain relieving device that can relieve pain by increasing the intensity of stimulation over normal time for a certain period.

  The present invention for solving the above-described problems is connected to a stimulation unit that generates a stimulation signal for electrically stimulating a nerve, a circulation dynamics measurement unit that measures circulation dynamics, and a stimulation unit and a circulation dynamics measurement unit A control unit is provided, and the control unit controls generation of an electrical stimulation signal in response to an output from the circulatory dynamic measurement unit in order to relieve pulsating pain.

  Here, the nerve to be stimulated electrically is preferably the spinal cord or a peripheral nerve such as the occipital nerve. The pulsatile pain is a migraine or cluster headache, and the circulatory dynamics measured by the circulatory dynamics measuring unit is any one of electrocardiogram, pressure pulse wave, and heart sound.

  As a preferred embodiment of the present invention, when the control unit detects ventricular contraction or blood output, generation of an electrical stimulation signal may be started, or the control unit may start ventricular contraction or blood. When the output is detected, the intensity of the electrical stimulation signal may be increased. Here, it is desirable that the parameters of the electrical stimulation signal depend on at least one of frequency, pulse width, pulse current, and pulse voltage, or a plurality of combinations selected from these.

  According to the above-described configuration of the present invention, nerves can be stimulated at the timing of heart ventricular contraction or blood pumping out of the heart in synchronization with the pulsatile pain cycle.

  According to the present invention, the nerve can be stimulated for a predetermined stimulation period in synchronization with the pulsation of pain, so that pain having a pulsating surname can be relieved accurately and discomfort given to the patient can be reduced. it can. Since the intensity of the electrical stimulation signal for stimulating the nerve is increased only during the stimulation period, there is also an effect that the battery life can be extended.

Hereinafter, the best mode for carrying out the invention (hereinafter referred to as “embodiment”) will be described. The description will be given in the following order.
1. 1. First embodiment Second embodiment 3. 3. Third embodiment Modified example

<1. First Embodiment>
An example of the first embodiment of the present invention will be described with reference to FIGS.

[Configuration of Pain Relief Device]
The pain relieving device is generally sealed in a biocompatible container and implanted in the body. This container is provided with a connector for exchanging signals with the outside, and is connected to a sensor and an electrode lead. The electrode lead is guided to a nerve site to be stimulated through a subcutaneous tunnel, and nerve stimulation is performed by a stimulation electrode provided on the electrode lead. As a site for implanting the pain relieving device, the chest, abdomen, or neck is generally subcutaneous.
FIG. 1 is a functional block diagram showing a pain alleviating apparatus according to the first embodiment of the present invention.
The pain relieving apparatus 101 according to the first embodiment detects ventricular contraction of the heart or blood output from the heart and performs electrical stimulation on the peripheral nerve at a timing synchronized with the detected ventricular contraction or blood output. Is.

  The pain relieving apparatus 101 includes a circulatory dynamics measurement unit 102 connected to a sensor (not shown), a control unit 103, and a stimulation signal generation unit 104 that applies an electrical stimulation signal to a peripheral nerve via an electrode lead (not shown). .

  The circulatory dynamics measuring unit 102 measures the circulatory dynamics in response to an electrical signal from a sensor (not shown), and mainly includes an amplifier and a filter for removing noise. It is connected to the control unit 103 so that it can be output to. Typical examples of circulatory dynamics include electrocardiograms, pressure pulse waves, or heart sounds. In addition, the sensor which is not illustrated is arrange | positioned in the place (in vivo) according to the kind of circulatory dynamics to measure.

  The control unit 103 controls the stimulation signal generation unit 104 based on an electrical signal indicating the circulation dynamics input from the circulation dynamic measurement unit 102.

  The stimulation signal generation unit 104 generates an electrical stimulation signal based on an instruction from the control unit 103, and this electrical stimulation signal is applied to the peripheral nerve via an electrode lead (not shown).

  More specifically, the control unit 103 includes a ventricular contraction / blood output detection unit 105, a timer 106, a stimulation period set value storage unit 107, and a comparison unit 108.

  The ventricular contraction / blood output detection unit 105 is electrically connected to the circulatory dynamic measurement unit 102 and the stimulation signal generation unit 104. A ventricular contraction / blood output detection unit 105 detects ventricular contraction or blood output based on an electrical signal indicating the circulatory dynamics input from the circulatory dynamics measurement unit 102, and ventricular contraction or blood output. The stimulation signal generation unit 104 generates an electrical stimulation signal at the timing at which the signal is detected. Further, the ventricular contraction / blood output detection unit 105 operates the timer 106 at the timing when the ventricular contraction or blood output is detected. Details of detection of ventricular contraction or blood pumping will be described later with reference to FIG.

  The timer 106 measures an elapsed time from the ventricular contraction or blood output detected by the ventricular contraction / blood output detection unit 105, and inputs the elapsed time to the comparison unit 108. The stimulation period setting value storage unit 107 stores stimulation period setting values in advance. This stimulation period set value is preferably shorter than the interval between successive heartbeats, and ideally about 0.3 seconds.

  The comparison unit 108 is a so-called comparator that compares two inputs and switches the output depending on which is greater. That is, the comparison unit 108 compares the elapsed time from the timer 106 with the stimulation period setting value stored in the stimulation period setting value storage unit 107, and the stage where the elapsed time becomes larger than the stimulation period setting value. Then, the operation of the stimulus signal generation unit 104 is stopped.

[Circulation dynamics]
FIG. 2 is a diagram showing various circulatory dynamic electrical signals measured by the circulatory dynamic measurement unit 102.
FIG. 2A is an electrocardiogram showing a time-series change of an electrocardiographic electric signal. The vertical axis represents the signal level of an electrical signal indicating electrocardiogram. The horizontal axis is the time axis.
When the pain relieving device is implanted under the chest, the electrocardiogram can be measured by arranging an electrocardiographic electrode on a container in which the pain relieving device is sealed. When the pain relief device is implanted in a place away from the chest, connect the ECG lead to the connector of the container and place the ECG electrode at the tip of the ECG lead at a position where the ECG signal level increases. It is also possible to measure by implanting. Alternatively, it is possible to insert an electrocardiogram lead into the heart intravenously and measure the electrocardiogram from within the heart.

  An electrical signal indicating an electrocardiogram is a signal having a predetermined period. The electric signal indicating the electrocardiogram is composed of five waves, P wave, Q wave, R wave, S wave, and T wave, and conspicuous Q wave, R wave, and S wave are collectively called QRS wave. . The ventricular contraction of the heart occurs at the timing when this QRS wave is generated. It is known that this substantially coincides with the timing of blood discharge from the heart.

  That is, when the measurement target of the circulatory dynamic measurement unit 102 is an electrocardiogram, the ventricular contraction / blood output detection unit 105 detects the timing of ventricular contraction of the heart by detecting the QRS wave. In order to detect the QRS wave, for example, a circuit including a filter that passes a frequency range of the QRS wave and a comparator in which a predetermined threshold is set can be used.

FIG. 2B is a diagram illustrating a time-series change in the electrical signal of the pressure pulse wave. The vertical axis represents the signal level of the electrical signal indicating the pressure pulse wave. The horizontal axis is a time axis common to the electrocardiogram in FIG.
When the pain relief device is implanted under the neck of the neck, the pressure pulse wave can be measured on the carotid artery by placing an acceleration sensor on a container in which the pain relief device is sealed. When the pain relief device is implanted in a place away from the neck, an acceleration sensor is placed under the carotid artery, and the lead connected to the acceleration sensor is connected to the connector of the pain relief device via the subcutaneous tunnel. It is also possible to connect to and measure.

  The electric signal indicating the pressure pulse wave is a signal representing a change in blood pressure in the blood vessel. The position where the signal level of the electric signal indicating the pressure pulse wave increases rapidly indicates the timing at which blood is pumped from the heart.

  That is, when the measurement target of the circulatory dynamic measurement unit 102 is a pressure pulse wave, the ventricular contraction / blood output detection unit 105 detects the position where the signal level of the electrical signal indicating the pressure pulse wave increases rapidly, Detect the timing of blood output from the heart. The position where the signal level of the electric signal indicating the pressure pulse wave increases abruptly can also be detected by a circuit comprising a filter and a comparator in which a predetermined threshold is set, as in the case of an electrocardiogram.

FIG.2 (c) is a heart sound diagram which shows the electrical signal of a heart sound. The vertical axis represents the signal level of an electrical signal indicating heart sound, and the horizontal axis represents a time axis common to the electrocardiogram in FIG.
When the pain relieving device is implanted under the chest, the heart sound can be measured by placing an acceleration sensor on a container in which the pain relieving device is sealed. In addition, when the pain relief device is implanted in a place away from the chest, an acceleration sensor is placed under the chest, and the lead connected to the acceleration sensor is connected to the connector of the pain relief device container through the subcutaneous tunnel. It is also possible to measure.

  An electrical signal indicating a heart sound is also a signal having a predetermined period. The electrical signal indicating the heart sound is composed of three waves, a heart sound I sound, a heart sound II sound, and a heart sound III sound.

  Heart sound I is a sound generated when the tricuspid valve between the right and right ventricles and the mitral valve between the left and left ventricles close at the beginning of the ventricular systole. It has the feature that it can be heard in line with the QRS wave. That is, the heart ventricle contracts at the timing when the heart sound I is generated, and this substantially coincides with the timing of blood discharge from the heart.

  The heart sound II sound is generated when the pulmonary valve and the aortic valve close at the beginning of the ventricular diastole. The heart sound II sound is characterized by being generated after the T wave of the electrocardiogram. The heart sound III sound is a sound that fills the ventricle with blood when the ventricle expands. The heart sound III sound is a weak signal compared to the heart sound I sound and the heart sound II sound.

  When the measurement target of the circulatory dynamics measurement unit 102 is a heart sound, the ventricular contraction / blood output detection unit 105 detects the timing of the heart ventricular contraction by detecting the heart sound I sound. Since the heart sound III sound is weaker than the heart sound I sound and the heart sound II sound, only the heart sound I sound and the heart sound II sound can be extracted by a filter and a comparator in which a predetermined threshold is set. Further, since the period from the heart sound I to the heart sound II sound is short compared to the heartbeat cycle, after detecting the heart sound I sound, during a predetermined period corresponding to the period from the heart sound I to the heart sound II sound By ignoring the signal from the circulatory dynamic measurement unit 102, it is possible to prevent erroneous detection of the heart sound II sound as the heart sound I sound.

  In the following description, it is assumed that the circulatory dynamic measurement unit 102 measures an electrocardiogram.

[Electric stimulation signal]
Next, the electrical stimulus signal generated by the stimulus signal generator 104 will be described.
The electrical stimulation signal used for stimulation of the peripheral nerve is generally a burst wave by a rectangular pulse train. FIG. 3 is a waveform diagram showing a time-series change when a burst wave is used as the electrical stimulation signal. The vertical axis represents the signal level of the electrical stimulation signal, that is, the voltage. The horizontal axis is a time axis common to FIGS. In the electrical stimulation signal shown in FIG. 3, each vertical line represents an individual rectangular pulse, and the reciprocal of the interval between adjacent vertical lines represents the frequency.

  The timing at which the stimulation period starts, that is, the timing at which the stimulation signal generator 104 starts generating the electrical stimulation signal coincides with the detection of the QRS wave in the electrocardiogram shown in FIG. The timing at which the stimulation period ends, that is, the timing at which the stimulation signal generation unit 104 stops generating the electrical stimulation signal is stored in the stimulation period setting value storage unit 107 for about 0.3 seconds from the start of the stimulation period. Equal to the stimulation period set value.

  The strength with which the electrical stimulation signal stimulates the peripheral nerve preferably changes the electrical stimulation parameter of the electrical stimulation signal according to the degree of pain of the patient. Actually, the pulse width and pulse voltage (pulse current when using a constant current pulse) or the interval (frequency) of each rectangular pulse of the burst wave used for the electrical stimulation signal is changed. By adjusting the strength of stimulating the peripheral nerve.

[Operation of pain relief device]
Next, the operation of the pain alleviating apparatus 101 will be described.
FIG. 4 is a flowchart showing an operation flow of the pain alleviating apparatus 101 according to the first embodiment of the present invention.

  First, when a sensor (not shown) is implanted at a predetermined position in the living body and the pain alleviating apparatus 101 becomes available (step S401), the electrical stimulation parameters of the stimulation signal generation unit 104 are initialized (step S401). Step S402). That is, the electrical stimulation parameters such as frequency, pulse width, pulse current, and pulse voltage are set to initial values. This initialized state is a state in which the stimulus signal generation unit 104 does not operate.

  Next, the circulatory dynamics measurement unit 102 measures an electrical signal indicating the circulatory dynamics via a sensor installed at a predetermined location of the living body (step S403), and the electrical signal indicating the circulatory dynamics is transmitted to the ventricle of the control unit 103. Output to the contraction / blood output detection unit 105.

  Then, the ventricular contraction / blood output detecting unit 105 checks whether ventricular contraction or blood output is detected based on the electrical signal indicating the circulatory dynamics input from the circulatory dynamics measuring unit 102 (step). S404). If ventricular contraction or blood pumping is not detected (NO in step S404), the ventricular contraction / blood pumping detection unit 105 waits until ventricular contraction or blood pumping is detected.

  When ventricular contraction or blood output is detected (YES in step S404), the ventricular contraction / blood output detection unit 105 stops the measurement of the circulation dynamics by the circulation dynamic measurement unit 102 (step S405). The stimulus signal generation unit 104 is operated (step S406). In step S406, the stimulation signal generation unit 104 generates an electrical stimulation signal, and starts stimulation of the peripheral nerve by the electrical stimulation signal. Furthermore, the ventricular contraction / blood output detection unit 105 starts the timer 106 simultaneously with the start of stimulation of the peripheral nerve, that is, the detection of ventricular contraction or blood output, and counts the time from the ventricular contraction or blood output. Is started (step S407). Then, the counted time is input to the comparison unit 108.

  Here, the comparison unit 108 compares the time from the ventricular contraction or blood pumping input from the timer 106 with the stimulation period setting value stored in the stimulation period setting value storage unit 107 in advance. Which value is larger is confirmed (step S408). If the time from the ventricular contraction or blood pumping is smaller than the stimulation period setting value (NO in step S408), the nerve stimulation from the stimulation signal generation unit 104 is performed until this time reaches the stimulation period setting value. continue.

  When the time from the contraction of the ventricle or the blood pumping reaches the stimulation period setting value (YES in step S408), the comparison unit 108 stops the operation of the stimulation signal generation unit 104. That is, the stimulation signal generation unit 104 stops the stimulation by the electrical stimulation signal for the peripheral nerve (step S409).

  After the above processing is completed, the processing returns to step S403, and the processing from step S403 to step S409 is repeated.

  As described above, in this embodiment, the nerve is stimulated by the electrical stimulation signal in synchronization with the contraction of the ventricle of the heart or the pumping of blood from the heart. Pain occurs in synchronization with the pumping of blood, so stimulating nerves in synchronization with the pulsation of pain can alleviate pain with pulsation and reduce discomfort for the patient. It becomes possible to reduce.

  Further, according to the present invention, an electrical stimulation signal is generated for a predetermined stimulation period from the time when the heart ventricle contracts or the blood is pumped out of the heart. In other words, the stimulus signal is not generated during a period of low necessity. This has the effect of extending the life of the battery compared to the conventional one and reducing the risk of side effects.

<2. Second Embodiment>
Next, an example of the second embodiment of the present invention will be described with reference to FIGS. In the following description, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted or simplified.

[Configuration of Pain Relief Device]
FIG. 5 is a functional block diagram showing a pain alleviating apparatus according to the second embodiment of the present invention.
The pain alleviating apparatus 501 of the present embodiment always stimulates the peripheral nerve at a predetermined frequency f1, and when there is contraction of the ventricle of the heart or blood pumping out of the heart, the pain alleviating device 501 has a frequency f2 higher than the frequency f1. Stimulate peripheral nerves. That is, the pain alleviating apparatus 501 sets the electrical stimulus signal generated by the stimulus signal generation unit 104 to a stimulus having a frequency f1 that is a relatively weak electrical stimulus or a stimulus having a frequency f2 that is a stronger electrical stimulus. In addition, a parameter adjustment unit 502 is added to the pain alleviating apparatus 101 shown in FIG.

  The parameter adjustment unit 502 is electrically connected to the ventricular contraction / blood output detection unit 105 and the comparison unit 108. The parameter adjustment unit 502 changes the frequency of the electrical stimulation signal generated by the stimulation signal generation unit 104 based on the outputs from the ventricular contraction / blood output detection unit 105 and the comparison unit 108. In other words, it is the parameter adjustment unit 502 that serves to give the stimulation signal generation unit 104 a signal for changing the frequency (parameter) of the electrical stimulation signal.

  Specifically, the parameter adjustment unit 502 sets the frequency of the electrical stimulation signal to the normal stimulation at the timing when the ventricular contraction / blood output detection unit 105 detects the contraction of the ventricle of the heart or the output of blood from the heart. A signal for making the frequency f2 higher than the frequency f1 is given to the stimulation signal generator 104. On the contrary, the parameter adjustment unit 502 detects that the ventricular contraction / blood output detection unit 105 detects the contraction of the heart ventricle or the output from the heart for about 0.3 seconds (in the stimulation period setting value storage unit 107). (Corresponding to the stored stimulation period setting value), a signal for returning the frequency of the electrical stimulation signal from the high frequency f2 to the low frequency f1 is supplied to the stimulation signal generation unit 104.

[Electric stimulation signal]
Next, the electrical stimulus signal generated by the stimulus signal generator 104 will be described.
FIG. 6 is a waveform diagram showing a time-series change when a burst wave is used as the electrical stimulation signal.
The vertical axis represents the signal level of the electrical stimulation signal, that is, the voltage. The horizontal axis is a time axis. In the electrical stimulation signal, each vertical line represents an individual rectangular pulse, and the reciprocal of the interval between the adjacent vertical lines represents the frequency of the electrical stimulation signal.

  The timing at which the stimulation period starts, that is, the timing at which the stimulation signal generator 104 starts generating an electrical stimulation signal having a high frequency f2 coincides with the timing at which the QRS wave in the electrocardiogram shown in FIG. 2 is detected. The timing at which the stimulation period ends, that is, the timing at which the stimulation signal generation unit 104 returns to the electrical stimulation signal with the low frequency f1 is about 0.3 seconds from the start of the stimulation period, that is, the stimulation stored in the stimulation period setting value storage unit 107 Make it equal to the period setting value.

  In general, the degree of strength with which an electrical stimulation signal stimulates peripheral nerves depends on the frequency of stimulation, and the higher the frequency, the greater the intensity of stimulation. In the present embodiment example, it is possible to preset the level of the stimulation frequency according to the degree of pain of the patient, for example, the level and depth of the pulsation of pain, which is appropriate for each individual patient. It is possible to perform various treatments.

[Operation of pain relief device]
Next, the operation of the pain alleviating apparatus 501 will be described.
FIG. 7 is a flowchart showing a flow of operations of the pain alleviating apparatus 501 in the second embodiment of the present invention.

  First, when a sensor (not shown) is implanted at a predetermined position in the living body and the pain alleviating apparatus 501 is in a usable state (step S701), the stimulation signal generation unit 104 has a pulse width that is an electrical stimulation parameter. The pulse current and the pulse voltage are set to initial values, and the parameter adjusting unit 502 initializes the frequency of the electrical stimulation parameter by giving the stimulation signal generating unit 104 a signal for setting the frequency of the electrical stimulation signal to f1. This is the initialization of the electrical stimulation parameters (step S702). Then, the stimulation signal generation unit 104 generates an electrical stimulation signal with the frequency f1, and stimulates the peripheral nerve with the electrical stimulation signal with the frequency f1 (step S703).

  Next, the circulatory dynamics measurement unit 102 measures an electrical signal indicating the circulatory dynamics via a sensor installed at a predetermined location of the living body (step S704), and the electrical signal indicating the circulatory dynamics is transmitted to the ventricle of the control unit 103. Output to the contraction / blood output detection unit 105.

  Then, the ventricular contraction / blood output detecting unit 105 confirms whether ventricular contraction or blood output is detected based on the electrical signal indicating the circulatory dynamics input from the circulatory dynamics measuring unit 102 (step S705). ). If no ventricular contraction or blood pumping is detected, the ventricular contraction / blood pumping detection unit 105 waits for ventricular contraction or blood pumping to be detected (NO in step S705). Until then, the stimulation signal generation unit 104 continues the stimulation of the peripheral nerve by the electrical stimulation signal of the low frequency f1.

  When ventricular contraction or blood output is detected (YES in step S705), the ventricular contraction / blood output detection unit 105 stops the measurement of the circulation dynamics by the circulation dynamic measurement unit 102 (step S706). At the same time, the ventricular contraction / blood output detection unit 105 generates a signal that causes the parameter adjustment unit 502 to set the frequency of the electrical stimulation signal generated by the stimulation signal generation unit 104 to f2. Then, this signal is given to the stimulus signal generator 104. As a result, the stimulation signal generation unit 104 generates an electrical stimulation signal having a frequency f2 higher than the frequency f1, and starts stimulation of the peripheral nerve by the electrical stimulation signal having the frequency f2 (step S707).

  Further, the ventricular contraction / blood output detection unit 105 starts the timer 106 simultaneously with the start of stimulation of the peripheral nerve by the electrical stimulation signal of frequency f2, that is, the detection of ventricular contraction or blood output, and the contraction of the ventricle or blood Counting of the time from the start is started (step S708). Then, the counted time is input to the comparison unit 108.

  Here, the comparison unit 108 compares the time from the ventricular contraction or blood pumping input from the timer 106 with the stimulation period setting value stored in the stimulation period setting value storage unit 107 in advance. Which value is larger is confirmed (step S709). While the time from ventricular contraction or blood pumping is smaller than the stimulation period setting value (NO in step S709), stimulation at a high frequency f2 is continuously performed.

  When the time from ventricular contraction or blood pumping reaches the stimulation period set value (YES in step S709), the comparison unit 108 generates the frequency of the electrical stimulation signal generated by the stimulation signal generation unit 104 in the parameter adjustment unit 502. Is generated, and this signal is supplied to the stimulation signal generator 104. As a result, the stimulation signal generation unit 104 generates an electrical stimulation signal having a frequency f1 lower than the frequency f2, and returns to a state in which the peripheral nerve is stimulated by the electrical stimulation signal having the lower frequency f1 (step S710).

  After the above processing is completed, the processing returns to step S704, and the processing from step S704 to step S710 is repeated.

  In the present embodiment described above, the peripheral nerve is always stimulated at a predetermined frequency f1, and the nerve is applied at a frequency f2 higher than the frequency f1 for a predetermined stimulation period from the contraction of the ventricle of the heart or the pumping of blood from the heart. To stimulate. By adopting such a configuration, it is effective for a patient who always feels a relatively strong pain other than a pulsation after a predetermined period of time has passed since the detection of ventricular contraction or blood pumping. That is, for normal pain, the pain is relieved by a stimulus having a frequency f1, which is a relatively weak electrical stimulus, and a frequency f2 which is a stronger electrical stimulus than the stimulus having the frequency f1 is added to the pain caused by pulsation. Deal with the stimulus. This has the effect of extending the life of the battery compared to the conventional one and reducing the risk of side effects.

<3. Third Embodiment>
Next, an example of the third embodiment of the present invention will be described with reference to FIGS. In the following description, the same components as those in the first and second embodiments are denoted by the same reference numerals, and the description thereof is omitted or simplified.

[Configuration of Pain Relief Device]
FIG. 8 is a functional block diagram showing a pain alleviating apparatus according to the third embodiment of the present invention.
The pain relieving apparatus 801 of the third embodiment determines a stimulation period in which the electrical stimulation signal is set to the high frequency f2 based on the heart rate or the heartbeat interval. Therefore, the pain alleviating apparatus 801 includes a heart rate / heart rate interval measuring unit 803 and a stimulation period setting value selecting unit 804 as an alternative to the stimulation period setting value storage unit 107 of the pain reducing apparatus 501 of the second embodiment. It has become.

  The heart rate / heart rate interval measurement unit 803 is electrically connected to the stimulation period setting value selection unit 804. Then, the heart rate or heart rate measured by the heart rate / heart rate interval measurement unit 803 is output to the stimulation period setting value selection unit 804.

The stimulation period setting value selection unit 804 calculates the stimulation period setting value for the heart rate interval input from the heart rate / heart rate interval measurement unit 803, for example, according to the following equation.
(Stimulation period set value) = 0.5 x (Heart rate interval)
Further, the stimulation period setting value selection unit 804 can store a table representing the relationship between the heartbeat interval and the stimulation period in advance, and can select the stimulation period setting value based on the measured heartbeat interval from this correspondence relationship. It is.

  The stimulation period setting value selection unit 804 is electrically connected to the comparison unit 108 so as to output the stimulation period setting value calculated by the above formula or selected from the table to the comparison unit 108. The heart rate / heart rate interval measurement unit 803 may measure a heart rate. However, in that case, the stimulation period setting value selection unit 804 calculates or selects the stimulation period setting value based on the heart rate. The heartbeat interval is calculated by 60 ÷ heart rate.

[Operation of pain relief device]
Next, the operation of the pain alleviating apparatus 801 will be described.
FIG. 9 is a flowchart showing the flow of operation of the pain alleviating apparatus 801 in the third embodiment of the present invention. In FIG. 9, the processing from step S901 to step S906 is completely the same as the processing from step S701 to step S706 shown in FIG. 7, and thus the description up to the processing of steps S901 to S906 is omitted here. The processing after step S907 will be described.

  After the circulatory dynamics measuring unit 102 stops measuring the circulatory dynamics in step S906, the heart rate / heart rate interval measuring unit 803 measures the immediately preceding heart rate or heart rate interval (step S907), and the measured heart rate or heart rate interval. Is output to the stimulation period set value selection unit 804. Then, the stimulation period setting value selection unit 804 derives the stimulation period setting value using the above-described formula or table (step S908), and the derived stimulation period setting value is input to the comparison unit 108. At the same time, the ventricular contraction / blood output detection unit 105 generates a signal for setting the frequency of the electrical stimulation signal generated by the stimulation signal generation unit 104 in the parameter adjustment unit 502 to f2. Then, this signal is given to the stimulus signal generator 104. As a result, the stimulation signal generation unit 104 generates an electrical stimulation signal having a frequency f2 higher than the frequency f1, and starts stimulation of the peripheral nerve with the electrical stimulation signal having the frequency f2 (step S909). Further, the ventricular contraction / blood output detection unit 105 starts the timer 106 simultaneously with the start of stimulation of the peripheral nerve by the electrical stimulation signal of frequency f2, that is, the detection of ventricular contraction or blood output, and the contraction of the ventricle or blood Counting of the time from the start is started (step S910). Then, the counted time is input to the comparison unit 108.

  Here, the comparison unit 108 compares the time from the ventricular contraction or blood pumping input from the timer 106 with the stimulation period setting value derived by the stimulation period setting value selection unit 804, Whether the value of is large is checked (step S911). As long as the time from ventricular contraction or blood pumping is smaller than the stimulation period set value (NO in step S911), stimulation at a high frequency f2 is continuously performed.

  When the time from the ventricular contraction or the blood pumping reaches the stimulation period setting value (YES in step S911), the comparison unit 108 generates the frequency of the electrical stimulation signal generated by the stimulation signal generation unit 104 in the parameter adjustment unit 502. Is generated from a high frequency f 2 to a low frequency f 1, and this signal is supplied to the stimulation signal generator 104. Based on this signal, the stimulation signal generator 104 returns to stimulation of the peripheral nerve by the electrical stimulation signal of the low frequency f1 (step S912).

  After the above processing is completed, the processing returns to step S904, and the processing from step S904 to step S912 is repeated.

  As described above, in the third embodiment, the stimulation period in which the electrical stimulation signal is set to the high frequency f2 is determined based on the heart rate or the heartbeat interval. The time required for pulsation changes depending on the patient's metabolism and mental stress, and becomes shorter as the heart rate increases (beat interval decreases). Along with this, the pulsation of pain felt by the patient also changes. Therefore, by determining the stimulation period based on the heart rate or the heartbeat interval, the optimal stimulation period for the patient can be set. As a result, pain having pulsation can be alleviated more accurately and the battery life can be extended.

<4. Modification>
As described above, the pain alleviating apparatus of the first embodiment is an apparatus that stimulates peripheral nerves for a predetermined period with an electrical stimulation signal having a constant frequency. Moreover, the pain relieving apparatus of 2nd, 3rd embodiment changes the intensity | strength of an electrical stimulation signal by changing the frequency to stimulate. As described above, usually, the electrical stimulation signal is generally adjusted in intensity by changing a predetermined pulse interval (or frequency). On the other hand, as shown in FIG. Instead of changing the voltage, the voltage intensity during the stimulation period may be changed. This is because by changing the magnitude of the pulse voltage, the effect of changing the strength of the electrical stimulation intensity can be obtained in the same way as changing the level of the frequency. Further, in order to adjust the intensity of the electrical stimulation signal, it is possible to adjust the electrical stimulation parameters by a plurality of combinations selected from the frequency, the pulse width, the pulse current, and the pulse voltage.

  Furthermore, as shown in FIGS. 10B and 10C, the voltage or frequency of the electrical stimulation signal during the stimulation period may be gradually changed. As a result, the stimulus is gradually increased when the patient is given a stimulus, and the magnitude of the stimulus is gradually reduced when the stimulus is weakened. Can be relieved. Note that the vertical and horizontal axes in FIG. 10 are the same as those in FIGS.

  By the way, in each embodiment mentioned above, the stimulation object by an electrical stimulation signal was made into the peripheral nerve. Although the occipital nerve is generally used as the peripheral nerve for stimulation, it is also possible to stimulate at least one of the large occipital nerve, the small occipital nerve, and the third occipital nerve, which are branches of the occipital nerve. It is also possible to place an electrode outside the spinal dura to stimulate the spinal cord in the region where the occipital nerve originates. In this case, the spinal cord in the region from the first cervical vertebra to the third cervical vertebra is preferred. Furthermore, it can be applied to stimulation of the vagus nerve, which is known to relieve the pain of migraine or cluster headache by stimulation, or stimulation of the brain region related to migraine or cluster headache.

  In the above-described embodiments, the pain relief device and the sensor have been described as being implanted in the body. Generally, the pain relieving device is implanted with only an electrode lead for a few days to a week, and this is connected to an external pain relieving device to confirm the effect of stimulation. Even in such a case, the same effect can be obtained by placing the sensor on the body surface, measuring electrocardiogram, pressure pulse wave, heart sound, etc., and controlling the electrical stimulation signal with an external pain relief device. Needless to say.

  In addition, the present invention is not limited to the above-described embodiments, and various modifications and changes can be made without departing from the scope of the present invention.

It is a functional block diagram which shows the pain alleviation apparatus which concerns on 1st embodiment of this invention. It is a wave form diagram which shows the electrical signal of a circulatory dynamics. It is a wave form diagram which shows the example of an electrical stimulation signal. It is a flowchart which shows the flow of operation | movement of the pain alleviation apparatus which concerns on 1st embodiment of this invention. It is a functional block diagram which shows the pain alleviation apparatus which concerns on 2nd embodiment of this invention. It is a wave form diagram which shows the example of an electrical stimulation signal. It is a flowchart which shows the flow of operation | movement of the pain alleviation apparatus which concerns on 2nd embodiment of this invention. It is a functional block diagram which shows the pain alleviation apparatus which concerns on 3rd embodiment of this invention. It is a flowchart which shows the flow of operation | movement of the pain alleviation apparatus which concerns on 3rd embodiment of this invention. It is a wave form diagram which shows the example of an electrical stimulation signal.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 101 ... Pain relief apparatus, 102 ... Circulation dynamics measurement part, 103 ... Control part, 104 ... Stimulus signal generation part, 105 ... Ventricular contraction / blood output detection part, 106 ... Timer, 107 ... Stimulation period set value storage part, 108 Reference unit 501 Pain relief device 502 Parameter adjustment unit 801 Pain relief device 802 Control unit 803 Heart rate / beat interval measurement unit 804 Stimulation period setting value selection unit

Claims (13)

A stimulation unit that generates a stimulation signal for electrically stimulating the nerve;
A circulatory dynamics measurement unit for measuring the circulatory dynamics,
A control unit connected to the stimulation unit and the circulatory dynamics measurement unit;
In order to treat pain having pulsation, the control unit controls generation of the electrical stimulation signal in response to an output from the circulatory dynamics measurement unit. The pain relief apparatus according to claim 1, wherein the nerve is a spinal cord. The pain alleviating device according to claim 1, wherein the nerve is a peripheral nerve. The pain relieving apparatus according to claim 3, wherein the peripheral nerve is a occipital nerve. The pain relieving apparatus according to any one of claims 1 to 4, wherein the pulsatile pain is migraine or cluster headache. The pain relieving apparatus according to any one of claims 1 to 5, wherein the circulatory dynamics measured by the circulatory dynamic measuring unit is any one of electrocardiogram, pressure pulse wave, and heart sound. The said control part controls generation | occurrence | production of the said electrical stimulation signal, when the start of a ventricular contraction or a blood pumping is detected from the output from the said circulatory dynamics measurement part. The pain alleviating device described in 1. The pain relieving apparatus according to claim 7, wherein the control unit starts generating the electrical stimulation signal when the ventricular contraction or the blood output is detected. The pain relieving apparatus according to claim 7, wherein the control unit increases the intensity of the electrical stimulation signal when the ventricular contraction or the blood output is detected. The intensity of the electrical stimulation signal is increased by adjusting at least one of frequency, pulse width, pulse current, and pulse voltage, which are parameters of the electrical stimulation signal, or a plurality of combinations selected from these. The pain relieving apparatus according to claim 9. The generation of the electrical stimulation signal is performed for a predetermined period from the start thereof, or the intensity of the electrical stimulation signal is increased for a predetermined period. Pain relief device. The pain relieving apparatus according to claim 11, wherein the predetermined period is a fixed period. The pain relief according to claim 11, wherein a heart rate or a heart rate interval is calculated from detection of the ventricular contraction or blood output, and the predetermined period is adjusted based on the calculated heart rate or heart rate interval. apparatus.

Images