JP6460457B2 - VEP pad and visual function monitoring device - Google Patents

Description

The present invention relates to a photostimulation pad (hereinafter referred to as “VEP pad”) that dramatically improves the evaluation accuracy of visual evoked potential (hereinafter referred to as “VEP”), which is one of intraoperative monitoring in neurosurgery. is there.
VEP is an abbreviation for Visual Evoked Potential.

Intraoperative monitoring in neurosurgery has been actively used in recent years in order to suppress surgical precision and postoperative complications, and is now an indispensable surgical technique.
Various techniques and methods are used for this intraoperative monitoring, but in the operation of brain tumors near the visual tract and internal carotid artery aneurysms near the branches of the ophthalmic artery, visual function is used to suppress the occurrence of postoperative complications such as blindness. Monitoring will be conducted.
In order to monitor visual function, it is necessary to give a light stimulus to the retina and measure VEP.

  VEP is an evaluation method that is susceptible to anesthetics because it reflects long-latency cortical activity via multiple synapses, and it has been said that stable electrical recording is difficult, but in recent years it has little impact on VEP. Monitoring accuracy has been improved with the introduction of propofol, an anesthetic, and the appearance of high-brightness LEDs.

At present, there are roughly two types of photostimulation devices used for intraoperative monitoring. A goggle type that has been used as a neurological function test and a sheet type in which a plurality of light emitting points are provided on a flexible sheet such as a silicon sheet.
For example, Patent Document 1 (Japanese Patent Laid-Open No. 2007-185326) describes a light-stimulated goggle as a background art (see paragraphs 0005 to 0007 and FIG. 3). As an example, a waveguide 20 is formed on a plastic resin plate. Optical stimulation glasses 11 are described that are embedded and provided with a reflective surface 130 that directs light 201 emitted from the waveguide 20 in the direction of the eyeball (see, in particular, paragraphs 0014 to 0015 and FIG. 1).

  However, since the goggles completely cover the eyelids, light leakage is small and it is easy to make a difference between light and dark, but as described in Patent Document 1 (paragraphs 0006 to 0007), consciousness is lost due to anesthesia. In patients with disabilities, it may be difficult to place them in the eyes properly, and if the optical axis shifts during surgery, the intensity of stimulation may be greatly attenuated or the eyelids may remain open. Nevertheless, doctors and nurses have difficulty in noticing that their eyes are open.

In addition, the optical stimulation glasses of the embodiment described in Patent Document 1 are devices that are premised on reuse, and light emitted from an LED or laser is guided to a waveguide and is emitted from the end of the waveguide. Is directed in the direction of the eyeball, the light emission intensity cannot be increased so much and the irradiation range is narrow.
Furthermore, Patent Document 1 (paragraph 0020) also describes controlling the light emission interval, light emission intensity, light frequency, and the like by digital operation of the control unit. Is not considered at all.

JP 2007-185326 A

The present invention uses an inexpensive flexible printed circuit board, and connects and arranges a plurality of LEDs so that they can be driven independently to the printed wiring portion of the flexible printed circuit board, and attaches the plurality of LEDs to the end of the flexible printed circuit board. The first object is to provide not only a reuse but also a single use by providing a connector for connecting to the conversion board for controlling the power supply to constitute a VEP pad and making the VEP pad detachable from the conversion board. It is said.
In addition, by providing a reflector that reflects light emitted from a plurality of LEDs on the back side or the front side of the VEP pad, it is possible to minimize waste of LED light and irradiate more light to the retina. The second object of the present invention is to create a clear contrast between light and dark like a goggle type without requiring a shading operation at the time of attachment.
Furthermore, by providing a light intensity adjustment mechanism for each LED on the conversion board, it is possible to provide a visual function monitoring device that enables various controls such as the light emission period and light emission intensity of each LED, and to identify the position of the pupil. It is a third object of the present invention to provide a possible visual function monitoring device.

The visual function monitoring device of the invention according to claim 1 is a flexible printed circuit board having a flat pad portion, a line lead portion, and a printed wiring portion extending from the pad portion to an end portion of the line lead portion, and the pad portion. A plurality of LEDs arranged and connected to the printed wiring portion so as to be independently driven, and capable of emitting light from the surface side of the pad portion; provided at an end of the line lead portion; A conversion board for controlling power supply to a plurality of LEDs, a VEP pad having a connector for electrically connecting the printed wiring portion , the conversion board, and light emitted from the VEP pad is the eyelid of the subject. A VEP measuring device for measuring VEP generated when the retina is irradiated through
The conversion board can individually control power supply to the plurality of LEDs, and one or the same number of adjacent LED groups installed near the center of the pad portion. Divided into a plurality of groups composed of LEDs, power can be sequentially supplied to the LEDs constituting each group,
Recording means for sequentially supplying power to the LEDs constituting each group to emit light, and recording each VEP waveform, inter-vertex amplitude calculating means for determining the amplitude between the vertices for each VEP waveform, and between the vertices It is characterized by comprising a central LED specifying means for specifying the LED constituting the group corresponding to the largest among all the amplitudes between the vertices obtained by the amplitude calculating means as the LED directly above the pupil center. To do.

The visual function monitoring device of the invention according to claim 1 is directed to a conversion board capable of individually controlling power supply to a plurality of LEDs, and light emitted from a VEP pad is applied to the retina through the eyelid of the subject. Since a VEP measuring device that measures the VEP generated when the LED is emitted is provided, the VEP can be measured while performing various controls such as the light emission period and light emission intensity of each LED.
Further, in a medical institution that already has a medical neurological function monitoring device, it is necessary to replace the goggle-type or sheet-type photostimulation device attached to the device with the conversion board and the VEP pad of the present invention. Monitoring can be implemented.
Furthermore, the conversion board can individually control power supply for a plurality of LEDs, and one or a group of LEDs adjacent to the LED group installed near the center of the pad portion. Can be divided into a plurality of groups, and power can be sequentially supplied to the LEDs constituting each group.
Recording means for sequentially supplying power to the LEDs constituting each group to emit light, and recording each VEP waveform, inter-vertex amplitude calculating means for obtaining the inter-vertex amplitude for each VEP waveform, and inter-vertex amplitude Since the center LED specifying means for specifying the LED constituting the group corresponding to the largest one among all the amplitudes between the vertices obtained by the calculating means as the LED directly above the center of the pupil, the left of the retina is provided. It is possible to easily perform half-side visual field stimulation that applies light stimulation only to the half or right half.

The schematic diagram of the visual function monitoring device concerning an example. The top view of the VEP pad which concerns on an Example. The figure which shows the installation position of a needle electrode. Explanatory drawing of the amplitude between vertices. The figure which shows the visual pathway in a human eyeball. The figure which shows the principle which pinpoints LED directly on the pupil center.

  Hereinafter, embodiments of the present invention will be described by way of examples.

  FIG. 1 is a schematic diagram of a visual function monitoring apparatus 1 according to the embodiment. As shown in FIG. 1, the visual function monitoring device 1 of the embodiment includes a VEP pad 2, a conversion substrate 3, and a VEP measurement device 4.

FIG. 2 is a plan view of the VEP pad 2 according to the embodiment. As shown in FIGS. 1 and 2, the VEP pad 2 of the embodiment is a flat printed board having a printed wiring portion 5, a light-transmissive and flexible polyimide flexible printed board 6, and 12 LEDs 7. A connector 8 for electrically connecting the conversion board 3 and the printed wiring part 5 is provided.
The flexible printed circuit board 6 has a rectangular pad portion 9 having a length of 3 to 5 cm and a width of 5 to 8 cm, and a width of 0.5 to 1.5 cm and a length of 10 which can completely cover the eyelid. The printed wiring portion 5 has 15 elongated wiring patterns having a thickness of about 10 μm and a width of about 20 μm extending from the pad portion 9 to the end of the line leading portion 10.
Further, the connector 8 is provided at the end of the line lead-out portion 10, and 15 wiring patterns and the extension cord 11 are connected using the connection terminals 12 provided at the tip of the extension cord 11 extending from the conversion board 3. The 15 electric wires which comprise are each electrically connected.

The twelve LEDs 7 are arranged and fixed to the pad portion 9 in a matrix of three in the vertical direction and four in the horizontal direction, and are electrically connected to the printed wiring portion 5 and fed through the conversion board 3. As a result, light of a predetermined wavelength is emitted from the surface side of the pad portion 9.
As can be seen from FIG. 2, the four LEDs 7 arranged in the horizontal direction are electrically connected to one common wiring pattern and are also electrically connected to the four wiring patterns separately. The light emission can be individually controlled.

Each LED 7 has a wide emission angle of about 120 degrees, a high emission luminance of about 1800 mcd, and a visible light wavelength band (single wavelength or a combination of a plurality of wavelengths). 4 are arranged and fixed in a matrix, and are electrically connected to the printed wiring portion 5 as described above, so that each of the pad portions 9 can be individually received by receiving power supply from the conversion board 3. The intensity of light emitted from the surface side can be controlled.
Further, although not shown, the back side of the pad portion 5 is coated with aluminum.
Therefore, it is possible to create a clear light / dark difference like a goggle type without performing a light shielding operation such as attaching a light shielding member when attaching the VEP pad 2, and it is emitted from the LED 7 and reflected on the surface of the eyelid. Since the reflected light is reflected again to the surface side of the pad portion 9, more light can be incident on the retina.

The measurement of VEP using the visual function monitoring device 1 of the embodiment is performed according to the following procedure.
(1) The pad portion 9 is placed so that the surface side is in contact with the surface of the closed eyelid so that the subject's eyelid is completely covered.
(2) An eye patch is stuck on the pad portion 9 to fix the pad portion 9.
(3) As shown in FIG. 3, needle electrodes (cathodes) are provided at two points (cathode installation points 14 and 15) 4 cm above and 4 cm outside the outer occipital ridge 13 as electrodes for measuring VEP. Needle electrodes (anodes) are installed at two points (anode installation points 16 and 17) of the mastoid process, and body earth is taken from an appropriate location (usually subcutaneous in the frontal region).
(4) Gradually lower the light emission intensity of the LED from a sufficiently high value, and search for the light emission intensity (maximum stimulation) immediately before the VEP amplitude starts to decrease.
One stimulation time is about 20 milliseconds, and the stimulation frequency is about once per second.
(5) Measure and record the VEP while repeating the stimulation with the maximum stimulation.

While monitoring the VEP waveform obtained in the above procedure, the brain tumor near the visual tract and the internal carotid artery aneurysm near the branch of the ophthalmic artery are operated. However, in monitoring, the maximum appearing around 100 milliseconds from the start of stimulation. Focusing on the apex of the negative wave (18 in FIG. 4), the larger amplitude (hereinafter referred to as “inter-vertex amplitude”) of the amplitudes of the positive wave vertices (19 and 20 in FIG. 4) before and after that is used as an index. As an evaluation.
Based on the amplitude between the vertices obtained before the operation, the case where the amplitude between the vertices obtained during the operation is increased by 50% or more is improved, and the case where the amplitude is decreased by 50% or more is defined as the deterioration.

Next, half side visual field stimulation using the VEP pad of the embodiment will be described.
In the human eyeball, as shown in FIG. 5, the light stimulus on the left side of the retina is transmitted via the visual path 21 to the left brain, and the light stimulus on the right side of the retina is transmitted via the visual path 22 to the right brain. .
Therefore, for example, as shown in FIG. 5, if only the LED group in the pad portion 9 on the right side of the pupil is blinked and light stimulation is applied only to the left side of the retina, VEP appears on the left brain side, VEP does not appear on the right brain side.
In this way, the half-side visual field stimulation means that light stimulation is applied only to the left side or only the right side of the retina, and the visual path and site-selective VEP can be evaluated by the half-side visual field stimulation.

By the way, in order to realize the half-side visual field stimulation, it is necessary to confirm where the center portion of the pupil is, but the center of the pad portion 9 is not always fixed directly above the center of the pupil. After fixing the pad portion 9, the LED located immediately above the center of the pupil must be specified.
FIG. 6 is a diagram illustrating the principle of specifying the LED directly above the center of the pupil.
Here, the symbols (ai) and numerals (1-8) attached to the top and the left of the pad portion 9 in FIG. 6 are for explaining the LEDs fixed to the pad portion 9. For example, the LED emitting light in FIG. 6A is referred to as c4.
FIG. 6A shows a state in which the LED (c4) on the left side of the pupil emits light and a VEP waveform appearing at that time. FIG. 6B shows a state in which the LED on the right side of the pupil (f4) emits light and at that time. The VEP waveform that appears, FIG. 6C shows the state in which the LED (e4) directly above the center of the pupil emits light and the VEP waveform that appears at that time.
As can be seen from these figures, the largest VEP is obtained when the LED (e4) immediately above the center of the pupil is caused to emit light, and the amplitude of the VEP decreases with increasing distance from the center of the retina. Become. The reason for this is that the density of cone photoreceptors that sense light and color on the retina is higher as it is closer to the fovea.

If this principle is used, the LED immediately above the center of the pupil can be specified by the following procedure.
(1) One LED in the LED group (for example, c3 to c6, d3 to d6, e3 to e6, f3 to f6, and g3 to g6 in FIG. 6) installed near the center of the pad portion 9 On the other hand, power is sequentially supplied to emit light, and VEP waveforms are recorded respectively.
(2) When all the VEP waveforms are recorded, the amplitude between the vertices is obtained.
(3) The LED corresponding to the maximum amplitude among all the obtained inter-vertex amplitudes is identified as the LED directly above the center of the pupil.

For example, when the LED of e4 is identified as an LED directly above the center of the pupil, in order to give a light stimulus only to the right side of the retina, a1 to a8, b1 to b8, c1 to c8, and d1 to d8 In order to emit light by supplying electric power to the left side of the retina, light is supplied by supplying power to f1 to f8, g1 to g8, h1 to h8, and i1 to i8. You can do it.
For example, when the LED of f4 is identified as an LED directly above the center of the pupil, power is applied to c1 to c8, d1 to d8, and e1 to e8 in order to apply light stimulation only to the right side of the retina. What is necessary is just to supply and light-emit, and in order to give a light stimulus only to the left side of a retina, it should just light-emit by supplying electric power with respect to g1-g8, h1-h8, and i1-i8.

The modification regarding the VEP pad of an Example is listed.
(1) In the embodiment, the flexible printed circuit board 6 is made of polyimide having high light transmittance and flexibility, but may be made of other materials having light transmittance and flexibility, and the light transmittance is good. It can also be made of a flexible material.
(2) In the embodiment, the back side of the pad portion 5 is coated with aluminum, but it is not necessary. Instead of the aluminum coating, a metal coating other than aluminum or a coating based on silicon dioxide or barium sulfate is used. A material may be applied.
Further, when the flexible printed circuit board 6 is made of a material that does not transmit light, a non-conductive state is formed between a portion other than the printed wiring section 5 on the surface side of the pad section 5 or between the printed wiring section 5 and the substrate surface. It is preferable to provide a reflective material. In short, a reflector that reflects light emitted from a plurality of LEDs may be provided on the back side or the front side of the pad portion.
Non-conductive reflectors include coating materials based on any of silicon dioxide, titanium dioxide, aluminum oxide, calcium carbonate, and barium sulfate.
(3) In the embodiment, three LEDs 7 are arranged in a matrix in the vertical direction and four in the horizontal direction on the pad portion 9, but any number may be arranged, and the number is not limited to a matrix, but a staggered pattern Or may be arranged radially.
Furthermore, in order to be able to more accurately identify the LED directly above the center of the pupil, the LED group arrangement density in the vicinity of the center part of the pad portion 9 may be made higher than the LED group arrangement density in the vicinity thereof. good.
(4) As a method of evaluation in monitoring of the VEP waveform, based on the amplitude between the vertices obtained before the operation, the case where the amplitude between the vertices obtained during the operation was increased by 50% or more was improved, and it was decreased by 50% or more. Although an example in which the case is defined as worsening has been shown, the rate of increase in the case of improvement in consideration of the surgical site and the like, and the rate of decrease in the case of deterioration may be changed as appropriate.
Further, the function of determining the amplitude between vertices is added to the VEP measuring device 4 to store the amplitude between vertices obtained before the operation (hereinafter referred to as “reference amplitude”), and the amplitude between the vertices obtained during the operation. The reference amplitude is compared, and it is determined whether it exceeds the rate of increase when it is improved, and whether it is below the rate of decrease when it is deteriorated, and the determination result is notified by sound, light, display, etc. If this is possible, the visual function monitoring device is easy to use.
As an algorithm for determining the amplitude between vertices, the following procedure is given as an example.
a. VEP is sampled as appropriate over 80-120 milliseconds from the start of stimulation.
b. From the sampled VEP, a minimum value (approximating to the apex of a positive wave) and a maximum value (approximating to the apex of a negative wave) are sequentially obtained.
c. The difference value between the adjacent minimum value and maximum value is calculated and recorded.
d. The largest one of the plurality of difference values recorded at the end of sampling is determined as the amplitude between vertices.
(5) In the procedure for specifying the LED immediately above the center of the pupil, one LED in the LED group installed near the center of the pad 9 is sequentially supplied with power to emit light. However, the LED group installed near the center of the pad portion 9 is divided into a plurality of groups composed of the same number of adjacent LEDs, and power is sequentially supplied to the LEDs constituting each group. You may make it light-emit.
In such a case, since a plurality of LEDs can emit light and the amount of light can be increased, the difference in amplitude between the vertices is increased, and the LED directly above the center of the pupil can be specified more accurately.
Further, if a function for determining the amplitude between the vertices is added to the VEP measuring device 4, the center of the pupil is simply determined by determining the light emitting LED when the maximum amplitude between the vertices is obtained by paying attention to the sequentially obtained amplitude between the vertices. Since the LED directly above can be identified, the visual function monitoring device is easy to use.
Furthermore, if a function for extracting the maximum peak-to-vertex amplitude from all the peak-to-vertex amplitudes determined by the VEP measuring device 4 and a function for notifying the light-emitting LED when the maximum peak-to-vertex amplitude is obtained by display, voice, or the like are added. Furthermore, the visual function monitoring device is more convenient to use.

DESCRIPTION OF SYMBOLS 1 Visual function monitoring apparatus 2 VEP pad 3 Conversion board 4 VEP measuring apparatus 5 Printed wiring part 6 Flexible printed circuit board 7 LED 8 Connector 9 Pad part 10 Line drawing part 11 Extension cord 12 Connection terminal 13 Outer occipital uplift 14,15 Cathode installation point 16, 17 Anode installation point 18 Maximum negative wave peak 19, 20 Positive wave peak

Claims (1)

A flexible printed board having a flat pad portion, a line lead portion, and a printed wiring portion extending from the pad portion to the end of the line lead portion;
A plurality of LEDs arranged on the pad portion and connected to the printed wiring portion so as to be driven independently, and capable of emitting light from the surface side of the pad portion,
A VEP pad that is provided at an end of the line lead-out portion and includes a connector for electrically connecting the printed wiring portion and a conversion board that controls power supply to the plurality of LEDs ;
The conversion substrate;
A VEP measuring device for measuring VEP generated when the light emitted from the VEP pad is irradiated on the retina through the eyelid of the subject;
The conversion board can individually control power supply to the plurality of LEDs, and one or the same number of adjacent LED groups installed near the center of the pad portion. Divided into a plurality of groups composed of LEDs, power can be sequentially supplied to the LEDs constituting each group,
Recording means for sequentially supplying power to the LEDs constituting each group to emit light and recording each VEP waveform;
For each VEP waveform, an inter-vertex amplitude calculating means for obtaining an inter-vertex amplitude;
Center LED specifying means for specifying the LED constituting the group corresponding to the maximum amplitude among all the amplitudes between the vertices obtained by the intervertex amplitude calculating means as the LED directly above the pupil center. Visual function monitoring device characterized by.