JPH0141330B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an intracerebral manometer, and more particularly, the present invention relates to an intracerebral manometer, and more particularly, an inductive coupling method is used to connect a sensor buried under the scalp and an external measuring device without directly communicating with physical means such as electric wires or tubes. This invention relates to an intracerebral manometer that measures changes in intracerebral pressure and a more accurate intracerebral manometer.

Conventionally, intracerebral manometers that continuously measure changes in a patient's intracerebral pressure over a long period of time are devices that directly measure intracerebral pressure by connecting physical communication means such as electric wires or tubes from a sensor buried under the scalp. Various methods are known, but since the communication means of this type penetrate the scalp and are led out, there is a high risk of external infection.

Some solutions to this drawback include a wireless electrical connection between a sensor implanted under the scalp and an external measurement device rather than a physical connection; When a circuit is configured, it becomes complicated and large, drifts are likely to occur, and the components are sensitive to heat, so heat sterilization is not possible, and uncertain and inefficient methods such as gas sterilization must be used. Moreover, the lifespan of the power supply is limited and cannot withstand long-term use.

It should be noted that an internal sensor that does not have a power source is also known (Japanese Patent Laid-Open No. 152580/1983). This intracerebral manometer has a movable magnet displaceably housed in a capsule to constitute an internal sensor, and a pulsed magnetic force is applied to this movable magnet by an external induction generator, and this magnetic force causes static pressure due to intracranial pressure. The aim is to measure intracranial pressure by externally detecting the movement of the movable magnet when the head is moved.

However, since the above-mentioned magnetic force is inversely proportional to the square of the distance, the installation position of the external induction generator, such as the distance between them, the axis line, and the spatial arrangement of the external coil, etc. If it changes, the force acting between the two will change significantly, and this will directly appear as a measurement error. In this type of intracerebral manometer, the sensor embedded under the scalp is naturally not visible from the outside, and since the thickness of hair and skin varies from person to person, an inductive generator is used for the internal sensor. It is nearly impossible to install the coil accurately, keeping the coils at a certain distance, aligning the axes, and without tilting.

In addition, because intracerebral manometers are generally buried under the scalp separately from the shunt duct, the catheters leading into the ventricle overlap, and a separate duct is required to vent air and clean the path inside the sensor. The disadvantage is that the amount of deposits under the scalp increases.

Furthermore, although air is sealed in the pressure sensitive part of the sensor, the air pressure changes due to changes in the temperature of the human body, making it impossible to accurately sense intracerebral pressure.
Although it is possible to compensate the intracerebral pressure in response to changes in the temperature of the human body, the temperature of the human body varies slightly depending on the measurement location, and it is not possible to measure by temperature compensation compared to minute changes in the intracerebral pressure.

In addition, since it measures extremely minute changes in intracerebral pressure compared to atmospheric pressure, it must have high sensitivity, and at the same time must be able to withstand pressures close to atmospheric pressure.

In order to solve the above-mentioned difficulties, the inventor developed a resonance grid dip.
By applying the principle of burying a non-power resonant circuit consisting of a coil and a capacitor under the scalp and inductively coupling it from the outside world, we focused on the fact that it is possible to detect the resonance point with the non-power resonant circuit. As a result, the inductance L of the coil of this unpowered resonant circuit
(hereinafter simply abbreviated as L) or capacitance C of a capacitor (hereinafter simply abbreviated as C) or L,C
By making both L and C variable and associating the resonance frequencies of L and C with changes in intracerebral pressure, we have come up with the idea that it is possible to indirectly measure intracerebral pressure from the outside using the above-mentioned inductive coupling. As a result of further testing and research, we found that by interposing the sensor of the intracerebral pressure gauge in the middle of the shunt conduit, the duplication of conduits was eliminated, and by evacuating the pressure sensitive part of the sensor, the gas pressure of the built-in gas could be adjusted due to temperature changes. The desired objective was achieved by ensuring that the measured pressure was not adversely affected, and by making measurement easier by utilizing the beat phenomenon of the composite wave when detecting minute changes in intracerebral pressure.

That is, an object of the present invention is to configure a passive circuit that does not include a built-in power supply, thereby making it possible to communicate between the sensor and an external measuring device without using physical means.
Therefore, there is no risk of external infection, it can withstand long-term use, the sensor can be heat sterilized before installation, and it is made of extremely high-precision coils and capacitors that can minimize the volume of the sensor. A sensor having a power-free resonant circuit and having a pressure sensitive part buried under the scalp so that at least one of L and C of the coil and capacitor can change in response to changes in intracerebral pressure; The purpose of the present invention is to provide an intracerebral manometer consisting of a grid depth meter that externally measures the displacement of the resonant frequency.Another purpose is to provide an intracerebral manometer that is unaffected by temperature changes and is more reliable. At least one of L and C of the coil and capacitor can change with the expansion and contraction of the bellows, which is buried under the scalp and creates a vacuum inside in response to changes in intracerebral pressure. The purpose of the present invention is to provide an intracerebral manometer consisting of a sensor equipped with a pressure sensitive part and a grid depth meter that externally measures the displacement of this resonant frequency. A sensor that has a resonant circuit and a pressure sensitive part that is buried under the scalp and whose core advances and retreats within the coil to change the L of the coil as the bellows expands and contracts in response to changes in intracerebral pressure. The purpose is to provide an intracerebral manometer consisting of a grid dipmeter that externally measures the displacement of this resonant frequency.Another purpose is to provide an intracerebral manometer consisting of a grid dipmeter that measures the displacement of this resonance frequency from the outside. The cylindrical part of the hat-shaped core, which is buried under the scalp and has a flange part at the bottom of the cylindrical part, responds to changes in intracerebral pressure as the bellows expands and contracts. To provide an intracerebral manometer consisting of a sensor provided with a pressure sensing part that changes the L of the coil by moving back and forth within the coil, and a grid depth meter that externally measures the displacement of the resonance frequency of this sensor. , as other purposes, it has an unpowered resonant circuit consisting of a coil and a capacitor that can reduce the amount of sub-scalp deposits by communicating with the shunt conduit, and allow air venting and cleaning of the sensor.
A pressure sensitive part is provided which is buried under the scalp and at least one of L and C of the coil and the capacitor changes in response to changes in intracerebral pressure, and this pressure sensitive part is used as a shunt for draining cerebrospinal fluid from the ventricles. The object of the present invention is to provide an intracerebral manometer consisting of a sensor interposed in a conduit and a grid depth meter for externally measuring the displacement of the resonant frequency of this sensor. A pressure-sensitive device that is embedded under the scalp and can change at least one of L and C of the coil and capacitor in response to changes in intracerebral pressure transmitted through the brain membrane. The object of the present invention is to provide an intracerebral manometer consisting of a sensor provided with a section and a grid depth meter that externally measures the displacement of the resonant frequency of this sensor. It has an unpowered resonant circuit consisting of a coil and a capacitor that can easily and accurately measure the amount of time.
and C, and a device for synthesizing the resonant frequency signal of a grid dipmeter with a standard frequency signal to externally measure the displacement of the resonant frequency of this sensor. To provide an intracerebral manometer consisting of:

Embodiments of the present invention will be described in detail below with reference to the drawings.

In FIG. 1, 10 is a sensor. The main body 12 is cylindrical and has a flange 14 slightly below the top end.

Reference numeral 16 denotes a bellows, which is housed in the main body 12 with its lower end fixed, and has an auxiliary spring 18 inside.
is provided.

Reference numeral 20 denotes a bellows base, in which the lower edge of the bellows 16 is fixed to the recessed part on the upper surface of the disk.
A communication hole 24 passing through the internal center of the vertical groove 2 on both sides
6, and a screw 28 is provided on the circumferential side of the disc.
is provided, which is screwed into the lower part of the main body 12 to move the disk in the vertical direction, so that the relative positional relationship between the coil and the core can be finely adjusted as described later.

Reference numeral 30 denotes an introduction pipe, which is connected to the center of the bottom of the perose table 20, communicates with the communication hole 24, and connects the main body 1.
The mold part 32 extends through the center of the mold part 32 that closes the lower end of the mold part 2.

A stopper 34 regulates the contraction limit of the bellows 16.

A coil 36 is fixed to the upper end of the main body 12 with its center axis perpendicular. Reference numeral 38 is a ferrite core with a flange 40 provided at the lower end of the cylinder, the entire core being formed into a hat shape, and a bellows 16
It is attached vertically to the center of the free end of the upper surface of the coil 36, and moves back and forth within the coil 36 as the bellows 16 expands and contracts.

A capacitor 42 is combined with a coil 36 to form a power-free resonant circuit. A cap 44 is placed over the coil 36, and sealed with a mold 46 so as to cover the upper surface of the main body 12 from above. ing.

Reference numeral 48 designates a lead-out tube, and the cerebrospinal fluid introduced from the introduction pipe 30 passes through the communication hole 24 and the vertical groove 26 communicating therewith, passes around the bellows 16, wets the core 38 and the coil 36, and passes through the lead-out tube 48. It is discharged to the outside.

FIG. 2 shows a sensor 10a according to another embodiment, in which an introduction pipe 30a hangs down from the center of the bottom of the main body 12a, and the lower end of the bellows 16a is connected to a bellows base 20.
a to the main body 12a, while the coil 36
The coil 36a is fixedly supported by the coil holder 50, and is screwed into the upper part of the main body 12a by a screw 52 provided on the outer peripheral wall of the coil holder 50, so that the coil 36a can be moved in the vertical direction.

In this way, in the sensor 10, the bellows stand 20
The core 38 can be moved up and down within the coil 36 by adjusting the coil holder 50 in the up and down direction, and the coil 36a can be moved up and down with respect to the core 38 by adjusting the coil holder 50 in the sensor 10a in the up and down direction. By setting the relative positional relationship of the cores, L of the coil can be appropriately set to a standard value.

As shown in FIG. 3, the sensor 10 has a recess 64 formed in the skull 62 under the scalp 60, and the sensor body 12 is fitted into the recess 64.
The flange portion 14 is supported and buried in the rim of the surface side of the concave portion 64 of the caput 62.

A catheter 54 is connected to the tip of the introduction pipe 30 and penetrates the cerebral membrane to reach the ventricle 66 of the brain. Further, the outlet tube 48 is connected to a reservoir 56 for draining cerebral spinal fluid which also serves as an air vent, and is interposed in a shunt conduit which will be described later.

Reference numeral 58 denotes an oscillation coil of the grid depth meter, which is inductively coupled to the sensor 10 from outside with the scalp 60 interposed therebetween.

The present invention is constructed as described above, and is assembled by adjusting the bellows base 20 of the sensor 10 to set the relative positional relationship between the coil 36 and the core 38 to a standard position in advance, and mold-sealing the sensor 10 to the scalp 60.
If it is buried below and communicates with the inside of the ventricle 66, if the cerebrospinal fluid in the ventricle 66 increases due to some physiological cause, the overflowing cerebrospinal fluid will be guided into the atrium or abdominal cavity through the shunt conduit. However, when an abnormal failure occurs such as blockage of the shunt conduit, abnormal pressure is generated in the cerebral spinal fluid within the ventricle 66, and this pressure change is transmitted to the sensor 10, causing the bellows 16 to contract. As a result, the core 38 is retracted within the coil 36 and the L of the coil is
is changed, and the resonant frequency of the unpowered resonant circuit within the sensor 10 is changed.

Therefore, if the oscillation frequency of the oscillation coil 58 adjacent to the outside is changed continuously within a certain range,
Resonance occurs at a resonance point with the resonant frequency of the power-free resonant circuit, and if the correspondence between this resonance point and intracerebral pressure is known in advance, intracerebral pressure can be measured indirectly from the outside.

In this way, the sensor 10 can have a pressure sensitive part interposed in the shunt conduit that discharges cerebral spinal fluid from the ventricle, and the same applies to the sensor 10a.

FIG. 4 is an enlarged explanatory diagram of the case where the sensor 10 or 10a is interposed in the shunt pipe, and shows 56
is a reservoir bore, which is provided immediately after the sensor 10 or 10a, and a connection tube 56a is connected between the sensor outlet tube 48 and the reservoir bore 56, and a connection tube 56b is connected after the reservoir bore 56.

The reservoir bobber 56 is a pump chamber, and the connecting tube 5
The rear end of the tube 6a slightly protrudes into the reservoir 56, and when the reservoir 56 is pressed with a finger from outside the scalp, the protrusion of the connecting tube 56a is simultaneously crushed, acting as a check valve and pumping.

Also, if you press the connecting tube 56b with your finger and press the reservoir 56 while avoiding the protruding part of the connecting tube 56a, the cerebral spinal fluid will flow backwards, so if there is an accident where the sensor path is blocked by the feeling of the pressing finger, Since the sensor can be detected, the sensor path can be cleaned by pressing the reservoir bower 56 more forcefully.

Next, as shown in FIG. 5, the sensor 10b is constructed by filling a pressure medium such as silicone oil around the bellows 16b, sealing the open lower end of the sensor body 12b with a diaphragm 70, and connecting the diaphragm 70 with the brain membrane. It is designed to sense pressure by contacting the brain from the outside, so there is no need to insert a pipe through the brain membrane to the ventricle. However, in this configuration, since the sensor 10b is sealed by the diaphragm 70, the sensor 10b cannot be interposed between the shunt conduits like the sensors 10 and 10a.

In the sensors 10, 10a, 10b, the core 3
The reason why the flange 40 is provided at the lower end of the cylinder to form the core 38 into a hat shape as a whole is to continuously strengthen the magnetic path of the oscillation coil 58, and the bellows 16 supporting the core 38 Since airtightness and good spring elasticity are required, a metal such as stainless steel or nickel is used as the material, and this is to prevent the magnetic path of the oscillation coil 58 from being cut and the pressure sensing accuracy to decrease.

Further, since the inside of the bellows 16 of the sensor is kept in a vacuum, there is no problem in which the built-in gas is affected by changes in the temperature of the human body, causing errors in the pressure sensitive section. Furthermore, since the pressure sensing part must sense minute changes in pressure, the bellows 16 must be flexible accordingly.Therefore, a stopper 34 is provided within the bellows 16 to prevent the bellows 16 from being subjected to excessive pressure. It is designed to prevent permanent deformation from occurring in the event of accidental contact.

In general, the brain pressure of a healthy person is 200 mm in gauge pressure.
Aq, and therefore, as an intracerebral manometer, it has a range of (+) 1000mmAq to (-) 500mmAq, with atmospheric pressure as the standard.
Since an extremely narrow measurement range of about mmAq is set, the amount of expansion and contraction of the bellows is small, and the change in L is also small, making measurement difficult.

Therefore, by combining the resonant frequency of the sensor and a fixed frequency close to this resonant frequency, it is possible to detect the change in pressure in an expanded manner as a "beat" whose frequency is the difference between the two.

Since the value obtained by this measurement is an absolute pressure, it is sufficient to subtract and correct the fixed value of the atmospheric pressure transmitter to obtain the gauge pressure.

In the above example, a bellows was used as the pressure sensitive part, and the change was converted into the movement of the core in the coil back and forth, and the change in intraventricular pressure was captured as a change in L of the coil. It may be regarded as a change in C, or both of these may be changed at the same time.

As described above, according to the intracerebral manometer according to the present invention, since the sensor under the scalp and the external measuring device are inductively coupled, there is no risk of external infection, and since there is no power supply inside the sensor, it can withstand long-term use. Since there is no active circuit, it is resistant to heat, and since the sensor can be heat sterilized before being implanted under the scalp, sterilization is complete and efficient, and the volume of the sensor can be minimized.

Furthermore, in the present invention, it is only necessary that the external alternating magnetic field by the external grid depth meter acts as a resonant absorption of the resonance of the unpowered resonant circuit of the internal sensor.
In other words, if the relative spatial position of the sensor and coil is maintained within a range that maintains the electromagnetic inductive coupling, it is theoretically possible to measure with sufficient accuracy. does not require rigor. Therefore, accurate measurement of intracerebral pressure is possible even if the thickness of hair and skin varies somewhat from person to person. Furthermore, since the sensor does not have a mechanical resonance part, the sensor to be buried under the scalp can be constructed simply, with fewer failures and can be used buried for a long period of time, providing an ideal intracerebral pressure meter. It was done.

In addition, by interposing the pressure-sensitive part of the sensor in the shunt conduit, only one catheter is required to be inserted into the ventricle, and the shunt conduit can be used for air removal and cleaning, which increases the amount of material buried under the scalp. If the pressure sensitive part is in a vacuum and no built-in gas exists, there will be no error due to changes in the temperature of the human body.

Furthermore, in cases where changes in the positional relationship between the coil and the core are used, the shape of the core is made into a hat shape to prevent the magnetic path from being cut and to make the sensitivity of the pressure sensitive part more sensitive. The present invention has remarkable effects, such as making an intracerebral manometer, which was conventionally impractical for measuring minute changes in intracerebral pressure, extremely practical and highly reliable.

Although the present invention has been variously explained above with reference to preferred embodiments, the present invention is not limited to these embodiments, and it goes without saying that many modifications can be made without departing from the spirit of the invention. It is.

[Brief explanation of drawings]

The drawings show an embodiment of the intracerebral manometer according to the present invention, and FIGS. 1 and 2 show sensors 10 and 1, respectively.
0a, FIG. 3 is an explanatory view showing the state of use, FIG. 4 is an explanatory cross-sectional view showing the embedded state of the sensors 10 and 10a, and FIG. 5 is an explanatory cross-sectional view of another sensor 10b. 10, 10a, 10b...sensor, 12, 12
a, 12b...main body, 14...flange, 16,
16a, 16b... bellows, 18... auxiliary spring, 20... bellows stand, 24... communicating hole,
26... Vertical groove, 28... Screw, 30, 30a...
...Introduction pipe, 32...Mold part, 34...Stopper, 36, 36a...Coil, 38...Core, 40...Flange, 42...Capacitor, 4
4...cap, 46...mold, 48...lead tube, 50...coil holder, 52...screw, 54...catheter, 56...reservoir,
56a, 56b... Connection tube, 58... Oscillation coil, 60... Scalp, 62... Skull, 64...
... recess, 70... diaphragm, 66... ventricle.

Claims (1)

[Claims] 1. A power-free resonant circuit consisting of a coil and a capacitor, which is buried under the scalp so that at least one of the inductance and capacitance of the coil and capacitor can change in response to changes in intracerebral pressure. An intracerebral manometer consisting of a sensor equipped with a pressure-sensitive section and a grid dipmeter that externally measures the displacement of the sensor's resonance frequency. 2 It has an unpowered resonant circuit consisting of a coil and a capacitor, and as the bellows, which is buried under the scalp and creates a vacuum inside in response to changes in intracerebral pressure, expands and contracts, the inductance and capacitance of the coil and capacitor change. An intracerebral manometer consisting of a sensor equipped with a pressure sensitive part, at least one of which can change, and a grid dipmeter that externally measures the displacement of this resonance frequency. 3 It has a power-free resonant circuit consisting of a coil and a capacitor, and is buried under the scalp, and as the bellows expands and contracts in response to changes in intracerebral pressure, the core advances and retreats within the coil, changing the inductance of the coil. This intracerebral manometer consists of a sensor equipped with a pressure-sensitive part, and a grid dipmeter that externally measures the displacement of this resonance frequency. 4 It has an unpowered resonant circuit consisting of a coil and a capacitor, and is buried under the scalp so that the cylindrical part of the hat-shaped core, which has a flange part at the bottom of the cylindrical part, expands and contracts like a bellows in response to changes in intracerebral pressure. This intracerebral manometer consists of a sensor equipped with a pressure-sensitive part that moves back and forth within the coil to change the inductance of the coil, and a grid dipmeter that externally measures the displacement of the sensor's resonance frequency. 5. A pressure-sensitive section is provided, which has a power-free resonant circuit consisting of a coil and a capacitor, and is buried under the scalp so that at least one of the inductance and capacitance of the coil and capacitor can change in response to changes in intracerebral pressure; This intracerebral manometer consists of a sensor in which this pressure-sensitive part is interposed in a shunt conduit that drains cerebrospinal fluid from the ventricle, and a grid depth meter that externally measures the displacement of the resonance frequency of this sensor. 6. It has an unpowered resonant circuit consisting of a coil and a capacitor, and at least one of the inductance and capacitance of the coil and capacitor changes in response to changes in intracerebral pressure that is buried under the scalp and transmitted through the brain membrane. This intracerebral manometer consists of a sensor equipped with a pressure-sensitive section that can be used to detect pressure, and a grid dipmeter that externally measures the displacement of the resonance frequency of this sensor. 7. It has a power-free resonant circuit consisting of a coil and a capacitor, and is provided with a pressure-sensitive part that is buried under the scalp and can change at least one of the inductance and capacitance of the coil and capacitor in response to changes in intracerebral pressure. An intracerebral manometer consisting of a sensor, a grid dipmeter that externally measures the displacement of the resonance frequency of the sensor, and a device that synthesizes the resonance frequency signal of the grid dipmeter with a standard frequency signal.