WO2010113072A2

WO2010113072A2 - Device with an electro-catheter for inducing a reversible epidural-related nerve injury

Info

Publication number: WO2010113072A2
Application number: PCT/IB2010/051265
Authority: WO
Inventors: Claudio Reverberi
Original assignee: Vertical Srl
Priority date: 2009-04-02
Filing date: 2010-03-24
Publication date: 2010-10-07
Also published as: WO2010113072A3; ITMI20090106U1

Abstract

A device to induce a reversible epidural lesion is described. The device comprises an electro-catheter having a distal end, a control unit and two control wires having a first end connected near the distal end of the electro-catheter and a second end connected to the control unit. When the control unit is activated it produces a traction force on one of the two control wires which transmits the traction to the distal end, causing the bending of the distal end of the electro-catheter.

Description

DEVICE WITH AN ELECTRO-CATHETER FOR INDUCING A REVERSIBLE EPIDURAL-RELATED NERVE INJURY

DESCRIPTION The invention generally concerns the field of electrical medical devices. In particular, this invention regards a device equipped with an electro-catheter able to induce a reversible epidural nerve lesion to reduce or eliminate pain of a benign nature. There are already known electrical devices using this technology for treatments aimed at reducing or eliminating the pain caused by benign diseases such as back pain, sciatica, herniated discs, etc.

These electrical devices typically include an electro-catheter, or a catheter equipped with an electrode near its distal end. The distal end of the electro-catheter is typically inserted into the epidural space of the spine (that is the annular space inside the spinal column and outside the dura mater which encloses the spinal cord) of the patient to be treated. To access the epidural space, the electro-catheter may be inserted through anatomical foramina of the spinal column (e.g., through the jactus sacralis, via intraspinal, paraspinal or transforaminal routes), or through laminotomies.

Once the epidural space is reached, the distal end of the electro-catheter is placed near the spinal root and the respective posterior root ganglion at the point in which they come out of the intervertebral foramina in the lateral epidural recesses. During the insertion of the electro-catheter, the patient is typically subjected to radiological vision so as to allow medical personnel to accurately control the movements and the positioning of the distal end of the electro-catheter. Once the electro-catheter is positioned it is connected to an external electric generator capable of supplying an alternating electric current to the electrode of the electro-catheter. The electrical current applied to the spinal cord through the spinal root and the posterior root ganglion induces a reversible epidural nerve lesion, which temporarily stops the transmission of the electrical signals communicating the sensation of pain to the brain.

The inventors have noted that the aforementioned electro-catheter insertion operation is very delicate and must be performed by medical personnel with great dexterity and experience. The wrong movement of the electro-catheter could in fact not only lead to ineffective treatment, but could even provoke permanent damage to the tissues surrounding the electro-catheter, resulting in a serious risk for the patient's health.

Moreover, the inventors have noted that the aforementioned electro-catheter insertion operation is quite long, leading to the disadvantage of rather prolonged exposure to X-rays of both patient and medical personnel.

Therefore the inventors addressed the problem of providing a device with an electro-catheter able to induce a reversible epidural nerve lesion to reduce or eliminate pain of benign origin, which resolves the aforementioned problems, that is, that reduces the complexity and duration of the electro-catheter insertion operation.

According to the embodiments of this invention, a device is provided to induce a reversible epidural lesion, the device comprising:

- an electro-catheter having a distal end;

- a control unit; and - two control wires having one end connected near the distal end of the electro- catheter and the other end connected to the control unit, wherein the control unit, when activated, produces a traction force on one of the two control wires, which transmits the traction to the distal end, causing the bending of the distal end of the electro-catheter.

Preferably the electro-catheter comprises a tubular body featuring a side wall and a central cavity.

Preferably a section of the tubular body near the distal end is made of a first type of plastic material and the remaining extension of the tubular body is made of a second type of plastic material with less flexibility with respect to the first type of plastic material. Preferably the tubular body has within the side wall at least two longitudinal elongated cavities, which terminate in a blind end near the distal end.

Preferably two of the at least two longitudinal elongated cavities are placed in diametrically opposed positions with respect to the longitudinal axis of the tubular body. Preferably each of the two control wires are housed in one of the two cavities and have the first end connected near the blind end of its cavity.

Preferably the catheter also comprises an electro-conductive wire housed in one of the at least two longitudinal elongated cavities.

Preferably the conductive wire is electrically connected to an electrode positioned on the external surface of the side wall of the tubular body near the distal end.

Preferably the electrode has an echogenic coating.

Preferably the electro-catheter also comprises a thermocouple housed in one of the at least two longitudinal elongated cavities. Preferably the electro-catheter also comprises an elongated element which extends substantially along the entire length of the electro-catheter, the elongated element being made of a material able to absorb X-rays. Preferably the control unit includes a casing having a distal recess and a plurality of proximal recesses, part of the electro-catheter is housed in the casing so that its proximal end comes out of one of the proximal recesses and the distal end comes out of the distal recess. Preferably the casing has, on its inner surface, a circular guide and a pin.

Preferably the control unit also comprises an internally toothed crown resting on the edge of the circular guide, the second end of the control wires coming out of the electro-catheter and being connected to the crown. Preferably, the control unit also comprises a gear wheel mounted on the pin. Preferably, the control unit also comprises a knob fastened to the gear wheel, the knob coming out of the casing so that it can be rotated by an operator to bend the electro-catheter.

Preferably, the device also comprises an injection unit which comprises an injection tube being at least partially housed in a sliding manner in a central cavity of the electro-catheter.

Preferably the injection unit also comprises a protective tubular body having the proximal end connected to a haemostasis valve and the distal end housed in the control unit, the injection tube being housed in a sliding manner in the protective tubular body. The invention shall be further clarified by the following description, given by way of non limiting example with reference to the attached drawings in which: -Figure 1 is a top view of a device according to one embodiment of the present invention; -Figure 2 is a longitudinal cross-section of the injection tube of the device in Figure 1;

-Figure 3 is a cross-section of the tubular body of the electro-catheter of the device in Figure 1 ; -Figure 4 is a longitudinal cross-section of the distal end of the electro-catheter according to the A-A plane;

-Figure 5 is an exploded perspective view of the control unit of the device in Figure 1 ; and -Figure 6 is a top view of a part of the device in Figure 1 during assembly.

With reference to the attached Figures, a description of a device in one embodiment of the invention will be presented below. Similar components are indicated with the same reference number in the different figures. The device 1 comprises an electro-catheter 2, a control unit 3 and injection unit 4.

The electro-catheter 2 comprises a tubular body 21 with a central cavity 21a. The tubular body 21 has a proximal end 22 connected to an electrical connector 22a, and a free distal end 23. The central cavity 21a has a substantially circular cross section along the entire tubular body 21 from the proximal end 22 to the distal end 23, at which there is an opening 23 a (Figure 4). The distal end 23 is preferably rounded. The side wall of the tubular body 21 has four longitudinal elongated cavities 25a, 26a, 27a and 27b (visible in the cross-section in Figure 3) preferably having a circular cross section and positioned parallel to the longitudinal axis x of the tubular body 21. The cavities 25a, 26a, 27a and 27b terminate in a blind end near the distal end 23. Preferably, the two cavities 25a and 26a are placed in diametrically opposed positions with respect to the longitudinal axis x of the tubular body 21, with their respective centres placed on a first transverse plane y of the tubular body 21. In addition, preferably, the two cavities 27a and 27b are placed in diametrically opposed positions with respect to the longitudinal axis x of the tubular body 21, with their respective centres placed on a second transverse plane z of the tubular body 21, perpendicular to the first plane y. Planes y and z are outlined in Figure 3.

The tubular body 21 preferably has an outer diameter between about 1.0 mm and 2.0 mm, more preferably between 1.5 mm and 1.9 mm and even more preferably equal to 1.7 mm. The central cavity 21a preferably has a diameter between about 0.4 mm and 0.8 mm, more preferably between about 0.5 mm and 0.7 mm and even more preferably equal to 0.6 mm. The cavities 25a, 26a, 27a and 27b preferably have a diameter between 0.25 mm and 0.45 mm, more preferably between 0.3 mm and 0.4 mm and even more preferably equal to 0.35 mm.

Preferably, the tubular body 21 is made of flexible plastic. More preferably, at the distal end 23, a section of the tubular body 21 is made of a first plastic material, while the remaining length of the tubular body 21 is made of a second plastic material less flexible than the first plastic material. The section realized with the first plastic material has a length preferably between 10 mm and 20 mm, more preferably between 13 mm and 17 mm and even more preferably is equal to 15 mm. For example, the first material could be a polyester (e.g., Pebax™ 5533), while the second could be a polyamide material (e.g., Grilamid™ TR90). The use of two plastic materials with different flexibility advantageously provides the electro-catheter 2 with sufficient rigidity to be inserted into the epidural space without bending, while simultaneously ensuring that its distal end 23 has sufficient flexibility to be bent by operating the control unit 3, as will be explained in greater detail hereinafter. Preferably, the cavity 25a houses a conductive wire 25. Near the distal end 23, the side wall of the tubular body 21 has an opening 25b that provides access to the cavity 25a (and thus to the conductive wire 25). Near said opening 25b, on the outer surface of the side wall of the tubular body 21 there is an electrode 24 electrically connected to the conductive wire 25. The electrode 24 preferably comprises a band made of a suitable conductive material which encircles the portion of the side wall of the tubular body 21 near the opening 25b. Preferably, the electrode 24 has a width between 0.3 mm and 0.7 mm, more preferably between 0.4 mm and 0.6 mm and even more preferably equal to 0.5 mm. In addition, preferably, the electrode 24 is positioned at a distance d2 from the distal end 23. Preferably, the distance d2 is included between about 1.0 mm and about 2.0 mm, more preferably between 1.3 mm and 1.7 mm and even more preferably equal to 1.5 mm. Preferably, both the electrode 24 and the conductive wire 25 are made of stainless steel (e.g., AISI 304). Preferably, the electrode 24 has an echogenic coating. For example, to obtain the echogenic coating, the electrode 24 may be subjected to a suitable caulking process. The echogenic coating can advantageously allow the insertion and placement of the electro-catheter 2 by subjecting the patient to ultrasound vision that, in contrast with radiologic vision, is harmless for the patient and the medical personnel conducting the operation.

Inside the cavity 26a there is a thermocouple 26 comprising a first insulated filament 261 and a second insulated filament 262. Preferably, the first insulated filament 261 is made of constantan and the second insulated filament 262 is made of stainless steel (e.g., AISI 316). Advantageously, the thermocouple 26 enables the detection of the temperature of the area around the distal end 23 of the tubular body 21.

Within each of the cavities 27a and 27b a corresponding control wire 271, 272 is housed. Preferably, each control wire 271, 272 has one end connected by fusion to the blind end of the respective cavities 27a and 27b. As shall be described in greater detail below, the second end of the control wires 271, 272 comes out of the tubular body 21 and is connected inside the control unit 3. The control wires 271, 272 have a substantially circular cross-section with a diameter preferably between about 0.16 mm and 0.20 mm, more preferably between 0.17 mm and 0.19 mm and even more preferably equal to 0.18 mm. Preferably the control wires 271, 272 are made of stainless steel (e.g., AISI 316).

Preferably, inside the side wall of the tubular body 21 there is an elongated element 28, parallel to the longitudinal axis x of the tubular body 21 substantially along its entire length. The elongated element 28 is preferably made of a material able to absorb X-rays. This advantageously allows the electro-catheter 2 to be visible with X-rays. The elongated element may be made of barium sulphate for example.

Preferably, there is a graduated metric scale printed on the external surface of the side wall of the tubular body 21. Preferably, the graduated metric scale is printed (e.g., using an inkjet printer) during the extrusion process of the tubular body 21. The graduated metric scale advantageously allows the easy and quick monitoring of the insertion level of the electro-catheter 2 in the epidural space. With reference to Figure 2, the injection unit 4 preferably comprises an injection tube 41 having a proximal end 42 and a distal end 43. The proximal end 42 is preferably connected to a junction 42a, such as a "Luer Lock" fitting. The injection tube 41 has an outer diameter preferably between about 0.3 mm and 0.7 mm, more preferably between 0.4 mm and 0.6 mm and even more preferably equal to 0.5 mm. In addition, the injection tube 41 has an internal diameter preferably between 0.1 mm and 0.5 mm, more preferably between 0.2 mm and 0.4 mm and even more preferably equal to 0.3 mm. Furthermore, the injection tube 41 preferably has a length L between 58 cm and 78 cm, more preferably between 63 cm and 73 cm and even more preferably equal to 68 cm. The injection tube is preferably made of stainless steel (e.g., AISI 304). Preferably, a section of the injection tube 41 near the proximal end 42 is covered by a reinforcement sheath 41a, partially inserted into the junction 42a. The length Ll of the reinforcement sheath 41a which protrudes from the junction 42a is preferably between about 43.0 mm and about 63.0 mm, more preferably between 48.0 mm and 58.0 mm and even more preferably equal to

53.0 mm. Preferably, the reinforcement sheath 41a is made of stainless steel (e.g., AISI 304). Preferably, on the reinforcement sheath 41a there is a printed reference mark (not shown in the drawings), the function of which shall be described below. The reference mark is positioned at a distance from the junction 42a preferably between about 23.0 mm and about 43.0 mm, more preferably between 28.0 mm and 38.0 mm and even more preferably equal to 33.0 mm.

The injection unit 4 also comprises a protective tubular body 43 having the proximal end connected to a junction 43a (e.g., a "Luer Lock" fitting) and a haemostasis valve 43b. The distal end of the protective tubular body 43 is housed in the control unit 3, as shall be described in greater detail hereinafter. The injection tube 41 is housed in the protective tubular body 43 and is able to slide through it by blocking the junction 43 a and the haemostasis valve 43b with one hand, and moving the junction 42a with the other hand. Preferably, the protective tubular body 43 is made of flexible plastic material (e.g.,

Pebax™ 5533).

With reference to Figure 5, the control unit 3 preferably comprises a casing 30, an internally toothed crown 33, a gear wheel 34 and a knob 35. The casing 30 has a symmetrical shape with respect to an axis of symmetry S. The shape is substantially that of a leaf which is pointed toward the distal direction and rounded toward the proximal direction. The casing 30 is comprised of a lower half-shell 31 and an upper half-shell 32. The lower half-shell 31 has a base and a lateral edge which has a distal recess 301 placed on the axis of symmetry S, and a plurality of proximal recesses 302 (three in the embodiment presented in the Figures) arranged symmetrically with respect to the axis of symmetry S. In addition, the lower half-shell 31 has a circular guide edge 303 and a pin 304. The circular guide edge 303 and the pin 304 are in two sections, arranged symmetrically with respect to the axis of symmetry S. Thus slits are formed in correspondence with the axis of symmetry S. The lower half-shell 31 also comprises the guides 305 placed in front of the proximal recesses 302. Preferably, the base and the edge of the lower half-shell 3.1, the edge of the circular guide 303, the pin 304 and the guides 305 are integral and are made of a rigid plastic material (e.g., ABS Terlux™ 2812).

The upper half-shell 32 has a shape corresponding to that of the lower half- shell 31 and has a hole 321 on its upper side. Preferably on the outer surface of the upper half-shell 32 there is a label with a graduated goniometer scale.

Advantageously the graduated goniometer scale provides an indication of the angle of rotation of the knob 35, as shall be explained in greater detail hereinafter. The crown 33 has teeth facing the inside and has anchoring wings 331 on its outer surface, the function of which shall be described below.

The knob 35 has a butterfly shape and has a protuberance 351 which allows the knob to be fastened to the gear wheel 34.

During the assembly of the device in Figure 1, the electro-catheter 2 is laid on the lower half-shell 31 such that the proximal end 22 of the tubular body 21 comes out of one of the proximal recesses 302 and the distal end 23 comes out of the distal recess 301 (possibly through an adapter 301), passing through the slits of the circular guide 303 and the pin 304, as shown in Figure 6. Preferably the distal portion of electro-catheter 2 which comes out of the control unit 3 has a length between approximately 30.0 cm and 70.0 cm, more preferably between 40.0 cm and 60.0 cm and even more preferably equal to 50.0 cm. The injection unit 4 is also laid on the lower half-shell 31, such that the distal end of the protective tubular body 43 (with the injection tube 41 inside) comes out of one of the proximal recesses 302. In the section in which it is laid on the lower half-shell 31, in the tubular body 21 of the electro-catheter 2 there is an opening through which the part of the injection tube 41 coming out of the protective tubular body 43 is inserted into the central cavity 21a of the tubular body 21. The connection area between the tubular body 21 and the protective tubular body 43 is preferably covered with a band 306.

As shown in Figure 4, the length of the injection tube 41 and its position inside the central cavity 21a are such that the distal end of the injection tube 41 substantially reaches the distal end 23 of the tubular body 21. In this way, advantageously, the injection tube 41 helps to increase the rigidity of the electro-catheter 2, and therefore to minimize the risk that the electro-catheter 2 bends during the insertion in the patient's epidural space. Subsequently, the crown 33 is placed on the edge of the circular guide 303 in such a way that the anchoring wings 331 are in symmetrical positions with respect to the axis of symmetry S. A lateral incision is made to the tubular body 21 of the electro- catheter 2 near the distal recess 301, so as to extract the control wires 271, 272, which, as mentioned above, have a first end connected to the blind end of the cavity 27a, 27b in which they are housed. The second end of the control wires 271, 272, once removed from the tubular body 21 are connected to the anchoring wings 331 of the crown 33. In particular, the second end of each control wire 271, 272 is wrapped around a respective cylinder, which is then coated with adhesive (e.g., Loctite® 401) and inserted into one of the anchoring wings 331.

The gear wheel 34 is then mounted on the pin 304, in such a way that its teeth engage the teeth of the crown 33. The upper half-shell 32 is then positioned on the lower half-shell 31, and the edges of the two halves are welded or glued together. In the case of gluing, the operation is preferably performed using Loctite ® 401. Finally, the protuberance 351 of the knob 35 is inserted into the hole 321 of the upper half-shell 32, in such a way as to fasten the knob 35 to the gear wheel 34. As mentioned above, the device 1 is able to induce reversible epidural neurolesions to reduce or eliminate pain of benign origin. In particular, to induce a reversible epidural neurolesion in a patient, the distal end 23 of the tubular body 21 of the electro-catheter 2 is inserted in the epidural space of the spine of the patient, for example using an insertion device such as a needle. Once the epidural space is reached, a traction force is applied on the junction

42a in the direction indicated by the arrow F in Figure 1 , in such a way as to slide the injection tube 41 with respect to the electro-catheter 2, the control unit 4 and the protective tubular body 43. The injection tube 41 is preferably moved until the reference mark on the reinforcement sheath 42 appears from the haemostasis valve 43b. In this way, advantageously, a portion of the central cavity 21a of the tubular body 21 is no longer engaged by the injection tube 41, thereby increasing the flexibility of the distal end 23.

Therefore, by blocking the casing 30 of the control unit 3 (for this purpose an adhesive strip can be provided on the lower surface of the casing 30), it is possible to adjust the position of the distal end 23 by rotating the knob 35 of the control unit 3. In particular, rotating the knob 35 means rotating the gear wheel 34, which in turn transmits the rotation to the crown 33. As mentioned above, the second end of the control wires 271, 272 are connected to the crown 33 and the first end of the wires are connected near the distal end 23 of the tubular body 21. Therefore a rotation of the crown 33 (e.g., clockwise, as shown by the arrow Fl in Figure 6) produces a traction of the control wire 272, which in turn causes the distal end 23 to bend in the direction of rotation of the crown 33. Thus, by turning the knob 35, it is possible to induce a bending of the distal end 23 of the tubular body 21 of the electro-catheter 2 in the plane on which the control wires 271, 272 are positioned, namely the plane of the longitudinal axis x of the tubular body 21 and the transverse axis z.

This advantageously allows the distal end of the electro-catheter 2 to be placed in a very precise manner, by simply turning the knob 35 of the control unit 3. This mechanism is much more accurate and also much simpler than manual positioning and allows the positioning of the electro-catheter 2 to be completed in much less time.

The treatment is completed by connecting the electro-catheter 2 to a generator through the connector 22a and activating the generator. In this way, the conductor 25 transfers the electricity produced by the generator to the electrode 24, which produces the reversible epidural lesion.

It is possible to use the injection tube 41 to simultaneously inject (through the junction 42a) a liquid in the area surrounding the distal end 23 (e.g., an anaesthetic, a contrast fluid, an analgesic, etc.). Thus the device described above has many advantages. First of all, the ability to bend the distal end of the electro-catheter by operating the control unit enables the positioning of the distal end itself in a simple, fast and accurate manner. In addition, the injection tube sliding in the central cavity of the electro- catheter advantageously enhances the rigidity of the electro-catheter during the insertion phase and subsequently reduces the rigidity of the distal end to facilitate its bending.

In addition, the echogenic treatment applied to the electrode advantageously allows the monitoring of the electro-catheter insertion and positioning operation through ultrasound vision, thus avoiding exposure to radioactive emissions by both patient and medical personnel.

Claims

1. Device (1) to induce a reversible epidural lesion, said device comprising: an electro-catheter (2) having a distal end (23); a control unit (3); and - two control wires (271, 272) having a first end connected near said distal end

(23) of said electro-catheter (2) and a second end connected to said control unit (3), wherein said control unit (3), when activated, exerts a traction force on one of said two control wires (271, 272), which transmits said traction to said distal end (23), inducing a bending of said electro-catheter (2) at said distal end (23).

2. Device (1) according to claim 1, wherein said electro-catheter (2) comprises a tubular body (21) having a side wall and a central cavity (21 a).

3. Device (1) according to claim 2, wherein a section of said tubular body (21) at the distal end (23) is made of a first plastic material and the remaining section of said tubular body (21) is made of a second plastic material with less flexibility with respect to said first plastic material.

4. Device (1) according to claim 2 or 3, wherein said tubular body (21) has, within the thickness of said side wall, at least two longitudinal elongated cavities (25a, 26a, 27a, 27b), which terminate in a blind end near said distal end (23).

5. Device (1) according to claim 4, wherein two cavities (27a, 27b) of the at least two longitudinal elongated cavities (25a, 26a, 27a, 27b) are located in diametrically opposed positions with respect to the longitudinal axis (x) of said tubular body (21).

6. Device (1) according to claim 5, wherein each of said two control wires (271, 272) is housed in one of said two cavities (27a, 27b) and has said first end connected to its blind end.

7. Device (1) according to any of the claims from 4 to 6, wherein said electro-catheter (2) comprises a conductive wire (25) housed in one (25a) of said at least two longitudinal elongated cavities (25a, 26a, 27a, 27b).

8. Device (1) according to claim 7, wherein said conductive wire (25) is electrically connected to an electrode (24) positioned on an outer surface of the side wall of said tubular body (21) near said distal end (23).

9. Device (1) according to claim 8, wherein said electrode (24) has an echogenic coating.

10. Device (1) according to any of the claims from 4 to 9, wherein said electro-catheter (2) also comprises a thermocouple (26) housed in one (26a) of said at least two longitudinal elongated cavities (25a, 26a, 27a, 27b).

11. Device (1) according to any of the preceding claims, wherein said electro-catheter (2)also comprises an elongated element (28) which extends along said electro-catheter (2), substantially along its entire length, said elongated element (28) being made of a material able to absorb X-rays.

12. Device (1) according to any of the preceding claims, wherein said control unit (3) comprises a casing (30) having a distal recess (301) and a plurality of proximal recesses (302), part of said electro-catheter (2) being housed in said casing (30) in such a way that its proximal end comes out of one of said proximal recesses (302), and that said distal end (23) comes out of said distal recess (301).

13. Device (1) according to claim 12, wherein said casing (30) has, on its inner surface, a circular guide edge (303) and a pin (304).

14. Device (1) according to claim 13, wherein said control unit (3) comprises an internally toothed crown (33) laid on said circular guide edge (303), said second end of said control wires (271, 272) coming out of said electro-catheter (2) and being fastened to said crown (33).

15. Device (1) according to claim 13 or 14, wherein said control unit (3) comprises a toothed wheel (34) mounted on said pin (304).

16. Device (1) according to claim 15, wherein said control unit also comprises a ^

knob (35) suitable to be fastened to said gear wheel (34), said knob (35) coming out of said casing (30) so as to be able to be rotated by an operator to bend said electro- catheter (2).

17. Device (1) according to any of the preceding claims, also comprising an injection unit (4), said injection unit (4) having an injection tube (41), said injection tube (41) being at least partially housed in such a way as to be able to slide through the central cavity (21a) of said electro-catheter (2).

18. Device (1) according to claim 17, wherein said injection unit (4) also comprises a protective tubular body (43) having a proximal end connected to a haemostasis valve (43b) and a distal end housed in said control unit (3), said injection tube (41) being housed in such a way as to slide in said protective tubular body (43).