JPS60194933A - Multifunctional nerve examination apparatus during operation - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an intraoperative nerve multifunctional testing device that makes it possible to easily test continuity of damaged nerves during surgery.

[Background of the invention]

Damage to peripheral nerves or their junctions with the spinal cord results in severe motor and sensory paralysis of the innervating muscles and skin, respectively. However, recent advances in microsurgical techniques have made it possible to surgically repair these damaged peripheral nerves. It is based on the introduction of surgical microscopes, advances in microsurgical tools, and the development of small imitative sutures. Despite the results of peripheral nerve surgery using these techniques, the rate of complete recovery is still quite low.

From the perspective of surgical technology, microsurgical techniques and the tools and materials required for them have been developed primarily around microvascular anastomosis surgery, which has a more complex internal structure and function than blood vessels. This can be said to be due to the delay in the development of tools specific to peripheral nerve surgery and intraoperative nerve function testing equipment that can be used to repair peripheral nerves.

Up until now, surgeons have made decisions regarding various types of peripheral nerve repair surgery based primarily on macroscopic findings of nerve damage during surgery. However, even if nerve continuity is recognized macroscopically or microscopically, functionally the nerve fibers may undergo Wallerian degeneration (even if the membrane covering the nerve fibers remains, the nerve fibers themselves may degenerate due to damage). In many cases, the condition is such that the patient is unable to perform any neurological functions at all due to the condition being depressed, or the condition is simply a continuation of scar tissue.

In such cases, if it were possible to easily determine the functional continuity of the nerve and the degree of damage during surgery, it would be possible to perform nerve ablation (removal of scar tissue around the nerve while preserving nerve continuity). (Surgical removal method to encourage nerve fiber regeneration)
or nerve suturing (resecting the scarred part of the nerve and creating a new
This provides a powerful clue for deciding whether to perform a surgery in which the C-shaped nerve stumps are microsurgically sutured together and the regenerated nerve is passed to the peripheral side to recover from paralysis.

Conventionally, for this purpose, tests and measurements such as nerve trunk conduction tests, motor nerve conduction velocities, and sensory nerve conduction velocities have been performed. However, all of these methods rely on responses or potentials obtained via muscle and skin sensory receptors, and are only applicable when there are two or more nerve damage sites in one nerve trunk (
double narν1nlX.

In cases where the regenerated nerve fibers are peripheral to the injured area and have not yet reached the muscles or sensory receptors, there may be no conduction or no potential measurement even though the nerves have passed through the injured area. It will be judged as impossible. Therefore, such determination results are not directly useful for diagnosing the degree of nerve damage limited to the injured site. For this reason, testing the nerve conductivity in segments of the nerve trunk centered around the injured area is an effective means of directly determining the presence or absence of continuity of nerve fibers in the injured area and the degree of damage.

There have already been a few reports on methods of electrically stimulating nerves across the injured nerve trunk and deriving the resulting electric potential from the nerves.

However, since conventional testing machines of this type were originally designed for preoperative non-invasive diagnosis, they are too large and difficult to handle for use during surgery, making it difficult for the surgeon to operate them himself. Met.

Next, we will discuss the intraoperative nerve function tests required for nerve suturing or nerve grafting when there is no continuity of nerve fibers at the peripheral nerve injury site or when the nerve is clearly ruptured macroscopically. state

Inside the peripheral nerve trunk runs a bundle of nerve fibers called a nerve bundle covered by several nerve membranes. In actual surgery, nerve suturing is performed using a microscope for each nerve bundle (nerve bundle suturing method). An essential issue in this nerve bundle suturing is that the nerve bundles at both stumps are correctly sutured, the sensory nerve bundle to the sensory nerve bundle, and the motor nerve bundle to the motor nerve bundle.

If this junction is made incorrectly, there is a misinnervation (misd-innervation).
It is known that this can cause severe hindrance to post-operative nerve regeneration. Therefore, the function of each nerve bundle in both stumps is identified (nerve bundle identification, fun
icular orientation) is required prior to nerve bundle suturing.

Each nerve bundle is anatomically characterized by running in a complex plexus structure while exchanging nerve fibers with each other within the nerve trunk, and the pattern of the nerve bundles at each cut plane varies depending on the level. In addition, there are differences between left and right and individual differences in the running, and the 1ntraneural to
- Although it is possible to know a certain tendency of the course of each nerve bundle using a pographic atlas, it cannot be used for each example of an actual surgical operation.

Therefore, we developed a method for identifying severed nerve bundles using electrophysiological techniques. That is, the surgery is performed under epidural paralysis, and the position of the sensory nerve bundles in the stump is known by the patient's sensory response to electrical stimulation given to each nerve bundle in the central nerve stump, while the patient's voluntary motor awareness Derive motor nerve impulses from the stump and confirm the position of the motor nerve bundle.

In the peripheral stump, in cases of fresh rupture (within approximately 3 days after injury), electrical stimulation of the nerve bundle can be used to stimulate the motor nerve bundle using myoelectric potential from the innervating muscles, and mechanical stimulation of the skin (e.g., brushing, etc.) It was found that the location of sensory nerve bundles can be identified by the sensory nerve action potentials evoked by compression. It was also found that when nerve bundle suturing was performed based on the results of this identification, the post-operative nerve recovery was better than when conventional identification was not performed. Although this identification method is effective, one of the reasons why it is still used only in some facilities is that nerve bundle identification devices based on this identification method have not yet become generally easy to use. This can be said to be because it is not commercially available.

Recently, however, surgical repair techniques for brachial plexus injuries have begun to be performed. That is, damage near the junction of peripheral nerves with the spinal cord (nerve roots) is repaired by nerve ablation or free nerve grafting. However, this repair technique is also ineffective if the injury is torn or pulled out centrally to the ganglion, and is only effective if the injury is peripheral to the ganglion.

Therefore, it is important to determine whether the injury is a postganglionic nerve root injury, which can be expected to be surgically repaired, or a nodal type injury, which is not. Therefore, Vlfi due to peripheral nerve stimulation
It is extremely useful to determine the presence or absence of functional continuity at the junction of the spinal cord and nerve roots by measuring electric potentials or somatosensory evoked potentials. Furthermore, if the injury is in the nodal area, the motor nerves in the periphery are affected by Wallerian degeneration, but the sensory nerves are not. It can be used to determine if there is a subsequent injury.

The conventional method for measuring sensory nerve action potentials, which is induced by electrical stimulation of the skin and obtained by averaging them, takes time to add the averages, and the skin that can be electrically stimulated is limited, so the nerves that can be tested are limited. There were two drawbacks.

[Key points of the invention]

We can detect sensory nerve action potentials in a very short period of time during surgery.
Moreover, they investigated a method that can test any nerve, and considered that the measurement of sensory nerve action potentials induced by the mechanical stimulation described above could be used to determine whether the injury is in the nodal or postganglionic region. In other words, if mechanical stimulation of the skin produces a sensory nerve action potential from the torn nerve root despite complete motor paralysis, the injury is of the nodal type and surgical nerve repair is impossible. It turns out. If there is nerve root damage, first confirm the continuity of functional peripheral nerves with the spinal cord by measuring somatosensory evoked potentials.

Next, once a functional disruption has been diagnosed, it is determined whether it is a nodal type or a postganglionic type based on the presence or absence of sensory nerve action potentials caused by mechanical stimulation.

In accordance with the above principles, the intraoperative nerve multifunctional testing device of the present invention can perform (1) peripheral nerve or spinal cord conduction testing, (2)
) Nerve bundle identification test on peripheral nerve section, (3) Peripheral nerve/
The basic function is to test the function of the medullary junction, and it is configured so that it can be selected by switching modes.

[Embodiments of the invention]

The details of the present invention will be explained below based on examples.

FIG. 1 schematically shows an embodiment of the intraoperative nerve multifunctional testing device according to the present invention. In the figure, 2 Tet 1 is the nerve bundle to be tested, 2 is the stimulation probe, and 3 is the nerve bundle to be tested. Detection probe; 4, intraoperative operation unit/display unit (hereinafter referred to as the operation unit) for setting various parameters and usage modes; 5, connection cable; 6, multifunctional testing device main body for testing control and signal processing; Reference numeral 7 represents a signal line for connecting the probe, 8 represents a stimulation electrode integrated into the stimulation probe, and 9 represents a bipolar electrode for detecting nerve impulses integrated into the detection probe.

FIG. 2 shows the configuration of FIG. 1 in more detail.

In the figure, reference numeral 10 is a stimulation pulse isolator, 11 is a low-noise differential amplifier, 12 is an isolation amplifier, and 13
is a bandpass filter for noise suppression, 14 is an AD converter,
15 is a microcomputer, 16 is a control circuit, 17 is a stimulation pulse generation circuit, 18 is a key operation section, 19 is a display device, 20 is a DA converter, and 21 and 22 are output terminals.

Next, the operation of the apparatus will be explained for each inspection function.

(1) Peripheral nerve or spinal cord continuity test Stimulation pulse generation circuit 17 inside the multifunctional testing device main body 6
The stimulation pulses generated by the cable 5 and the operating part 4
, is applied to the nerve bundle via the stimulation electrode 8 which is electrically insulated by the isolator 10 in the stimulation probe 2 via the signal line 7.

This electrical stimulation pulse generates impulsive action potentials (hereinafter referred to as nerve impulses) in the normal nerve fibers in the nerve bundle 1, which propagate in two directions along the length of the nerve fibers. This propagating nerve impulse is detected by the low-noise differential amplifier 11 built into the nerve impulse detection probe 3 via the detection bipolar electrode 9 that is in contact with the outside of the nerve bundle. After being electrically isolated by an isolation amplifier 12 built into the probe 3, it is led to the main body 6 via the operating section 4.

Degeneration or damage to the nerve fibers within a nerve bundle slows the propagation of nerve impulses, or sometimes causes them to go undetected. Even when a nerve impulse propagates through normal nerve fibers, when detected outside the nerve bundle, the amplitude is extremely weak, on the order of several μV (microvolts) at most. Therefore, the first-stage differential amplifier 11 of the amplifier used for amplifying nerve impulses is particularly sensitive to low iπ sounds (100H
.

In the band of ~10H2, the input equivalent noise voltage is 1μ■ peak
At the same time, it is essential that the common mode suppression ratio be sufficiently large (80 dB or more at low frequencies) to remove external common mode noise. In addition, the detection bipolar electrode 9 has as low an impedance as possible,
Use a differential amplifier with a noise level comparable to that of the differential amplifier described in "-."

The nerve impulse detected by the low noise differential amplifier 11 is
After passing through an isolation amplifier 12 and a bandpass filter 13, the signal is converted into a digital signal by an AD converter 14, and then input into a microcomputer 15. The signal detected in this way contains a lot of various noises, and the signal-to-noise ratio (S/N ratio) is not necessarily good. Clearance is being performed to reduce irregular noise.

FIG. 3 schematically shows a stimulation pulse waveform (a), a detected nerve impulse waveform (b), and their temporal relationship. The stimulation pulse generation circuit 17 generates a pulse with a repetition period T, and sends a 1 to RIGA signal to the control circuit 16 at the moment of generation.

As a result, the nerve impulse waveforms can be averaged by adding sequential AD-converted periodic waveforms N times in the memory based on the stimulation time. Especially when there is a lot of noise, high frequency noise can be suppressed by calculating a moving average (number of moving samples M).

As shown in FIG. 3, the propagation delay time TP from the application of the stimulation pulse until the nerve impulse is detected is:
When the distance between the stimulation electrode and the detection electrode is L and the propagation velocity of the nerve impulse is υ, it is given by T P -L /υ. Since the propagation velocity and waveform change depending on the degree of nerve damage, the observed waveform or Propagation delay time T
The operator needs to change it depending on p.

Further, the number N of addition averages and the number M of moving averages must be selected by the operator according to the S/N ratio of the signal.

After these processes, the nerve impulse waveform and propagation delay time T must be continuously monitored closely during the intraoperative continuity test. For this reason, the operation unit 4 has a small display device 19 such as a liquid crystal graph ink display, and several key operations for setting the parameters T, N, M and for setting the mode of use. Part 18 is provided.

There are three modes of use: ■ nerve continuity test mode, ■ nerve bundle identification test mode, and ■ nerve/medullary junction test mode, and the microcomputer 15 performs processing functions and parameters according to the set use mode. etc.

The results of the signal processing as described above are output to the display device 19 of the operation unit 4 as well as to the DA converter 20.
It is also output to the output terminal 21 via the , and can be recorded (in two types: waveform and print).

In addition to this, another output terminal 22 can be used to directly monitor the output from the bandpass filter 13.

By connecting this output terminal 22 to a speaker, it is possible to obtain an effective acoustic monitor for detecting nerve impulses buried in 'ltt sounds during surgery.

Note that when this device is used for testing continuity of the spinal cord, the nerve bundle 1 in Fig. 1 can be replaced with the spinal cord, and the electrodes 8 and 9
Basically, the same operation as in the case described above is performed, except that the shape of is slightly changed.

(2) Nerve bundle identification test at the peripheral nerve section (detection at the center of motor nerve impulses generated by the patient's voluntary motor awareness (detection at the Qq section, and sensory nerve impulses stimulated by peripheral skin stimulation) In either case of detection at the distal cut plane, either Fig. 1 or Fig. 2
A part of the apparatus having the configuration shown in the figure is used as is. That is, in the diagram of FIG.
The signal is amplified by the isolation amplifier 12, passed through the bandpass filter 13, and shifted from the output terminal 22 by /ll. In this case, only the presence or absence of reception of nerve impulses is detected without using the stimulation pulse generation circuit 17.

An effective method for investigating peripheral sensory nerves is to apply repeated mechanical stimulation and detect the evoked nerve impulses. In this case, the 212th
1 isolator 10 and stimulation electrode 8, a mechanical stimulation probe 25 comprising a power amplifier 23 and a solenoid type vibrator 24 as shown in FIG. Either a mechanical stimulation probe 28 consisting of a high-voltage power amplifier 26 and a piezoelectric element 27 as shown in the figure is used. Note that the nerve impulse induced by this repeated mechanical stimulation has a constant propagation delay time TP, as in the above (]) test.
The signal processing mechanism can be used as is, although the effect of the averaging is not so great because the FP has a certain distribution.

(3) Functional testing of peripheral nerve and medullary junctions In terms of wood, the only differences are the shape of the electrodes and parameters such as time and amplitude, and the basic circuit functions are shown in Figures 1 and 2. It is the same as what is there. In other words, a stimulation electrode is placed on the +1g side of the damaged nerve to give stimulation pulses, and a detection coil is placed on the scalp above the cerebral sensory cortex on the opposite side of the damaged nerve. to perform signal detection.

By the way, the electrodes used in the present invention may be any conventionally available commercially available electrodes, but in that case it is necessary to hold and operate two sets of electrodes separately. This is quite complicated during surgery.

Therefore, good results can be obtained by using a probe 29 as shown in FIG. 6 for testing four peripheral nerves. Probe 29
is equipped with a fixed bipolar electrode 30 and a movable bipolar electrode 31 at its tip.

The movable bipolar electrode 31 is connected to the sliding potentiometer 3
2, and the distance between the electrodes can be interpreted as a change in electrical resistance. This results in bipolar electrodes 30.31
Among them, when stimulating one side and detecting nerve impulses on the other side, the nerve impulse conduction velocity can be automatically calculated by the microcombi 15 in Fig. 2, and the operating unit 4 is displayed on the display device 19 of.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to perform highly reliable nerve tests and other tests with simple operations on arbitrary nerve sites that are damaged in various ways. This makes it possible to quickly obtain data that is useful in determining surgical procedures.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram of a device according to an embodiment of the present invention, FIG. 2 is a detailed diagram thereof, FIG. 3 is a signal waveform diagram of stimulation pulses and nerve impulses, and FIGS. 4 and 5 are mechanical stimulation FIG. 6 is a block diagram of an embodiment of a probe having a structure in which a stimulation probe and a detection probe are integrated. In the figure, ■ is a nerve bundle, 2 is a stimulation probe, 3 is a detection probe, 6 is the main body of the multifunctional testing device, 13 is an i:・area filter, 15 is a microcomputer, and 16 is a control 11
circuit, 17 is a stimulation pulse generation circuit, 18 is a key operation section,
19 indicates a display device. Patent applicant Fumihiro Hase, patent attorney, New Technology Development Corporation, 28 Figure 6

Claims (1)

[Claims] A nerve bundle stimulation probe, a nerve impulse detection probe, an examination section to which each of the probes is connected, an operation section for setting the operation mode and operation parameters of the examination section, and a display of the waveform of the detected nerve impulse. When the first operation mode is set, the testing section periodically generates and applies stimulation pulses to the nerve bundle stimulation probe, and outputs them from the nerve impulse detection probe. When the second operation mode is set, the probe for detecting nerve impulses can be used to detect nerve impulses without generating stimulation pulses. a function of monitoring the output signal of the controller and detecting the presence or absence of reception of nerve impulses, and when a third operation mode is set, the operation parameters of the period and amplitude of the stimulation pulse are set as the operation parameters in the first operation mode. An intraoperative neurological multifunctional testing device characterized by having a function of changing to a preset value different from the first operating mode and operating in the same manner as in the first operating mode.