RU2260452C1 - Production method and small-sized epidural electrode with stiletto - Google Patents

Abstract

FIELD: medical engineering.

SUBSTANCE: device has external insulation polyurethane envelope. Active conductor part like Bowden manufactured from 2-4 anticorrosive steel wires. The wires are coated with insulation enamel and twisted as 2-4-threaded spiral. Internal spiral surface forms canal for guiding mandrin stiletto. Electrode ends have 2-4 contact rings, connected to corresponding spiral wire end. The external insulation envelope covers the whole electrode with the exception of the contact rings. Method involves manufacturing active conductor part from 2-4 anticorrosive steel wires. Insulation enamel layer coats in advance each wire and the wires are twisted into 2-4-threaded spiral. Active conductor part assemblage involves setting and fixing contact rings on the electrode ends and welding spiral wire ends to contact rings with contact welding. Polyurethane coating is applied all over the whole electrode length with the exception of the contact rings.

EFFECT: reduced electrode diameter; increased mechanical strength; improved rigidity properties in operation state.

2 cl, 3 dwg

Description

The invention relates to medicine and can be used for the treatment and diagnosis in spinal surgery, neurosurgery, phthisioorthopedics.

Surgical treatment of diseases with pathology of the spine of inflammatory or traumatic origin gives a positive result. At the same time, in a significant part of patients after surgery there are signs of spinal cord damage, for the diagnosis and treatment of which the method of epidural electrical stimulation by implantation of electrodes is used.

Known epidural electrode containing an active conductor part, the surface of which (with the exception of its fan-shaped part) is covered with an insulating sheath. The active part of the electrode is bifurcated in the form of branches. Each branch is a fan-shaped insulated conductor. Each branch of the active part of the electrode contains at least two conductors (RF patent No. 2145242, A 61 N 1/05, 1997).

The known electrode allows for therapeutic and diagnostic coverage of the lesion area of the spinal cord and provides atraumatic removal of the electrode due to the fan-like displacement of all the conductors of each branch when it is pulled out of the tissues over the cutaneous part of the lead.

The disadvantage of this epidural electrode is the difficulty of its introduction, installation and fixation in the affected area of the spinal cord, which is due to the fan-shaped shape of the active part of the electrode. The implementation of the active part of the electrode in the form of branches, in which each branch is a fan-shaped conductor, leads in practice to significant difficulties in the introduction and installation of the electrode in the affected area of the spinal cord. Fan-shaped conductors cannot be strictly oriented to insert and fix in the desired area of the spinal cord, which significantly reduces the effectiveness of using such an electrode in medical practice. The constructive solution of this electrode and the method of its manufacture do not allow to obtain electrodes characterized by a small diameter, high strength and the required stiffness when installed in the tissue of the spinal cord.

Known epidural electrode described in patent EP 0974376 (A2, 01/26/2001), the applicant of which is the company Medtronics USA. The electrode has an insulating shell, in the cavity of which there is an active conductor part, consisting of 1 or 2-4 conductive cores. The distal and proximal ends of the electrode contain each 1 or 2-4 contact rings connected by a corresponding conductive core. The Medtronix epidural electrode is used for local stimulation of the spinal cord and provides for the sequential stimulation of its individual zones in accordance with a given program and the capabilities of the stimulator.

Significant disadvantages of this electrode are:

- low reliability of conductive conductors of copper conductors with a cross section of 0.1 mm;

- high electrical resistance of the electrode and, accordingly, a small resource of the stimulator, which is associated with a large consumption of electrical energy;

- the disadvantage of the known electrode design is the insufficiently accurate reflection of the electrical impulses of the stimulator;

- the manufacture of this electrode requires special equipment and is laborious, while the manufacture of the electrode does not provide high strength and electrical characteristics.

Also known is the epidural electrode (RF patent No. 2181300, A 61 N 1/05 of 05/10/2001), the closest in technical essence, operational characteristics, method of its manufacture and which is selected as the prototype of patented inventions.

The epidural electrode according to RF patent No. 2181300 has an outer insulating sheath made of radiopaque polyethylene, which contains 1 or 2-4 through channels isolated from each other, in each of which an uninsulated conductive core is placed. Each conductive core is made in the form of a twisted seven-wire stainless steel cord. The distal and proximal ends of the electrode contain each 1 or 2-4 contact rings. The ends of each conductive core are connected by contact welding with the corresponding contact ring of the distal and proximal parts of the electrode.

A method of manufacturing this epidural electrode includes assembling the active conductive part of the electrode in the form of 2-4 conductive cores, placing 2-4 contact rings on the distal and proximal ends of the electrode, connecting each contact ring to the corresponding conductive core, and placing the active conductive part in the outer insulating sheath. In this case, the outer insulating sheath is made of radiopaque polyethylene, which contains 2-4 through channels isolated from each other to accommodate the corresponding conductive core.

Medical practice of using this epidural electrode has proved that the developed design allows doctors to implement a fundamentally improved technique for implanting electrodes into the affected area of the spinal cord, which provides for strictly oriented insertion, fixation and good contact of the electrode with the damaged mass of the spinal cord. The high conductivity and low electrical resistance of the electrode, the multipolarity of electrical stimulation due to the programmed functioning of the stimulator and the increased resource of its operation provide high efficiency of using this epidural electrode in medical practice for the treatment and diagnosis of spinal cord lesions.

At the same time, the generalized results of the use of this electrode during electroneurostimulation of the structures of the spinal cord revealed a number of operational disadvantages that reduce the therapeutic effectiveness of its use and necessitate the implementation of new design solutions in the electrode and the development of optimal technological operations for its manufacture. The disadvantages of this electrode include:

- increased diameter of the electrode (about 1.2-1.3 mm), which significantly complicates the procedure for introducing it into the desired region of the spinal cord through the hollow channel of a special positioning needle;

- insufficient mechanical strength of the active conductor of the electrode, which leads to its termination when removed from the tissues of the spinal cord;

- excessive elasticity of the electrode in the working position when it is inserted into the desired region of the spinal cord complicates the procedure for introducing and fixing the electrode in the tissues;

- the method of manufacturing this electrode provides for the implementation of the outer insulating sheath of radiopaque polyethylene in the form of 2-4 through channels isolated from each other, which leads to increased overall dimensions of the electrode and corresponding significant difficulties for the doctor when introducing it into the tissue of the spinal cord through the channel of the installation needle;

- it should be noted that the manufacture of the active conductive part of the electrode in the form of 2-4 conductive cores, each of which is a twisted seven-wire stainless steel cord, leads to increased overall dimensions of the electrode and the corresponding operational difficulties in its use in medical practice.

The present invention solves the problem of reducing the diameter of the epidural electrode while increasing its mechanical strength and ensuring optimal rigidity in the working position when the electrode is inserted into the tissue of the spinal cord.

The invention also solves the problem of developing a high-tech method for manufacturing small-sized high-strength elastic implantable epidural electrodes with a guiding stylet in the inner cavity of the active conductor part.

The solution of this problem is achieved as follows.

In an epidural electrode containing an outer insulating sheath, in the cavity of which there is an active conductor part, consisting of 2-4 conductive conductors isolated from each other, and the distal and proximal ends of which contain each 2-4 contact rings connected by a corresponding conductive core, according to the first The invention, the active conductor part of the epidural electrode is made in the form of a bowden of 2-4 anticorrosive insulated steel wires coated with insulating enamel and twisted in the form of 2-4-n accurate spiral.

The first invention provides that the inner surface of the 2-4-thread Bowden spiral forms a channel for accommodating a guiding stiletto mandrel, which is used to increase the stiffness of the structure when the electrode is inserted into the tissue of the spinal cord.

According to the first invention, the ends of each conductive steel wire by contact welding are connected to the corresponding contact ring of the distal and proximal parts of the electrode, and the outer insulating sheath is made of polyurethane along the entire length of the electrode except for the surface of the contact rings located on the distal and proximal ends of the electrode. The absence of an external insulating shell on the surface of the contact rings of the distal and proximal parts of the electrode ensures the interaction of the contact rings with the tissue of the spinal cord and the conduct of electrostimulation treatment, as well as the connection of the connector of the electrostimulator.

The solution to this problem is also achieved by a new set of technological operations for the manufacture of a structurally improved epidural electrode.

A method of manufacturing an implantable epidural electrode, including assembling the active conductive part of the electrode in the form of 2-4 conductive cores, placing 2-4 contact rings on the distal and proximal ends of the electrode, connecting each contact ring to a corresponding conductive core and placing the active conductive part in the outer insulating sheath , according to the second invention, 2-4 anticorrosion steel wires are used for the manufacture of the active conductive part of the electrode, each of which x pre-applied layer of insulating enamel and which are twisted in the form of a 2-4-thread spiral. In this case, the inner surface of the 2-4-thread Bowden spiral forms a channel for placement in it with the introduction of an electrode into the tissue of the spinal cord of the guiding stylet-mandrena.

According to the second invention, the active conductive part of the electrode is assembled, which includes mounting and fixing the contact rings on the distal and proximal ends of the electrode and conducting the welding of the ends of each spiral wire with the corresponding contact ring of the distal and proximal parts of the electrode. After that, the insulating outer sheath of polyurethane is applied to the active conductor part of the electrode and the outer insulating sheath is removed from the surface of the contact rings of the distal and proximal parts of the electrode. Removing the outer insulating shell from the surface of the contact rings provides electrical contact of the contact rings with the tissue of the spinal cord during electroneurostimulation and implements the ability to connect the connector of the stimulator.

Patentable inventions (a new structural embodiment of the epidural electrode and a developed method for its manufacture) are interconnected so much that they form a single inventive concept, which is manifested in the fact that their joint use provides a solution to the general task of the invention and the achievement of the claimed technical result.

The technical result of the present inventions is that an implantable epidural electrode made by patented technology:

- differs in small overall dimensions (the diameter of the working part of the electrode is from 0.8-1.1 mm), which allows the doctor to comfortably insert and install the electrode in the desired area of the spinal cord;

- has increased mechanical strength, which virtually eliminates its breakage when removed from the tissue of the spinal cord;

- the implementation of the active conductor part in the form of a bowden of a 2-4-thread spiral of stainless wire, the inner surface of which forms a channel for the introduction of a guiding stylet-mandrel, provides optimal structural rigidity when the electrode is inserted and inserted into the spinal cord tissue.

The invention is illustrated by an example implementation of a patentable implantable epidural electrode, a description of the method of its manufacture and drawings, which show:

figure 1 is a General view of the epidural electrode;

figure 2 is a cross section of an electrode along BB;

figure 3 is a cross section of the electrode along aa.

The implantable epidural electrode (Fig. 1) contains an outer insulating sheath 1 made of polyurethane, in the cavity of which there is an active conductor part, which is made in the form of a bowden of 2-4 anticorrosive steel wires 2, coated with insulating enamel and twisted in the form of a 2-4-thread spiral 3. For the manufacture of bowden, for example, stainless steel wire of the VIS-1 OM grade with a diameter of 0.08 mm to 0.1 mm can be used. The inner surface of the spiral 3 forms a channel 4 for the guiding stylet-mandrel 7, which is used to provide the required structural rigidity when introducing and installing the electrode in the tissue of the spinal cord.

The distal and proximal ends of the electrode each contain 2-4 contact rings 5 and 6, respectively, connected by contact welding with the corresponding end of the spiral wire 2.

The outer insulating shell 1 is made along the entire length of the electrode with the exception of the surface of the contact rings 5 and 6 located respectively at the distal and proximal ends of the electrode. The absence of an outer insulating shell 1 on the surface of the contact rings 5 ensures the interaction of the contact rings 5 with the tissue of the spinal cord and electroneurostimulation treatment, and the absence of the outer shell 1 on the surface of the contact rings 6 ensures the connection of the contact rings 6 with the connector of the electric stimulator (not shown in Fig.).

The conductive spiral 3 provides the transmission of programmed electrical signals from the stimulator to the contact rings 5 and 6 of the electrode.

The contact rings 5 and 6 provide the transmission of electrical impulses from the electric stimulator to the areas of the spinal cord and are made of stainless steel XI 8 HI OT.

Patented epidural electrode can be implemented in various design modifications. To conduct bipolar and quadropolar neurostimulation of the structures of the spinal cord, the electrode contains 2 and 4 spirals 3 of stainless steel wire 2, respectively, located in the outer insulating sheath 1. With this constructive implementation, the distal and proximal ends of the electrode contain 2 and 4 contact rings 5 and 6, respectively. electrically connected by the ends of the conductive wire 2.

The manufacture of a patentable implantable epidural electrode is as follows.

For the manufacture of the active conductive part of the electrode, 2-4 anticorrosive steel wires 2 are used, on each of which a layer of insulating enamel, for example, bakelite varnish, is preliminarily applied. The wires 2 are twisted in the form of a 2-4-thread spiral 3. The twisting of the wire 2 and the manufacture of a bowden in the form of a 2-4-thread spiral 3 are carried out on a special machine developed by the applicant (application for invention No. 2003129458). Then, the active conductive part of the electrode is assembled, which includes the installation and fixation of the contact rings 5 and 6 at the distal and proximal ends of the electrode and the resistance welding of the ends of each spiral wire 2 with the corresponding contact ring of the distal and proximal parts of the electrode. Then carry out the application by extrusion of the insulating outer shell 1 of polyurethane on the active conductor of the electrode. After applying the outer insulating sheath 1 to the entire implantable electrode, the outer insulating sheath is removed from the surface of the contact rings 5 of the distal and 6 proximal parts of the electrode. Removing the outer insulating shell 1 from the surface of the contact rings 5 and 6 provides, respectively, electrical contact of the contact rings 5 with the tissue of the spinal cord during electroneurostimulation and connection of the connector of the electrical stimulator to the contact rings 6.

The epidural electrode is used as follows.

In the channel 4, formed by the inner surface of the spiral 3, set the guide stylet-mandren 7. Insert the guide needle with a hollow channel in the desired area of the spinal cord. Through the hollow channel of the needle, the distal end of the epidural electrode is inserted into the spinal cord zone selected for neurostimulation. The operation of implantation of the electrode is carried out under the control of an x-ray machine. After installing the electrode, the guide needle is removed from the electrode. The electrode is attached to the muscle tissue of the spinal cord and fixed in the corresponding connector of the electrical stimulator, which is sutured subcutaneously. According to the program prescribed by the attending physician, the electrical stimulator carries out the corresponding neurostimulation of the necessary areas of the spinal cord.

Tests of this epidural electrode showed the effectiveness of its use for continuous and trial electroneurostimulation of the structures of the spinal cord. The reduced size of the electrode allows you to painlessly and without complications to carry out the procedure of implantation, treatment, diagnosis and removal of the electrode.

Claims (2)

1. A small implantable epidural electrode with a stylet, containing an outer insulating sheath, in the cavity of which there is an active conductor part, consisting of 2-4 conductive conductors isolated from each other, the distal and proximal ends of the electrode contain each 2-4 contact rings connected by a corresponding conductive residential, characterized in that the active conductive part of the electrode is made in the form of a bowden of 2-4 anticorrosive insulated steel wires coated with insulating enamel and twisted in the form of a 2-4 filament spiral, the inner surface of which forms a channel for placement of a guiding stylet-mandrel in it to increase the rigidity of the structure when the electrode is inserted into the tissue of the spinal cord, the ends of each conductive steel wire by contact welding are connected to the corresponding contact ring of the distal and proximal parts of the electrode, while the outer insulating shell is made of polyurethane along the entire length of the electrode with the exception of the surface of the contact rings located on its distal and proximal ends. 2. A method of manufacturing a small implantable epidural electrode with a stylet, including assembling the active conductive part of the electrode in the form of 2-4 conductive cores, placing 2-4 contact rings on the distal and proximal ends of the electrode, connecting each contact ring to the corresponding conductive core, and placing the active conductive parts in the outer insulating shell, characterized in that for the manufacture of the active conductive part of the electrode using 2-4 anti-corrosion steel wires ki, on each of which a layer of insulating enamel is preliminarily applied and which are twisted in the form of a 2-4 filament spiral, the inner surface of which forms a channel for placement of a guiding stylet-mandren in it, the active conductive part of the electrode is assembled, which includes installation and fixation on and the proximal ends of the contact ring electrode and the resistance welding of the ends of each spiral wire with the corresponding contact ring of the distal and proximal parts of the electrode, after four carried on the outer shell of the insulating coating of polyurethane over the entire length of the active part of the electrode wire surface except the contact rings, which produce the removal of the outer insulating sheath from the surface of the contact rings of the distal and proximal electrode.

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