WO2010035203A1

WO2010035203A1 - Electrode for intraoperative nerve stimulation

Info

Publication number: WO2010035203A1
Application number: PCT/IB2009/054122
Authority: WO
Inventors: Andreas Langer
Original assignee: Dr. Langer Medical Gmbh
Priority date: 2008-09-24
Filing date: 2009-09-21
Publication date: 2010-04-01
Also published as: DE102008048788A1; DE102008048788B4; EP2328651A1

Abstract

The invention proposes an electrode (10) for intraoperative nerve stimulation of the nervus vagus, said electrode being suitable for continuous neuromonitoring during an operation, in particular for the neuromonitoring of the nervus laryngeus recurrens during thyroid operations. The electrode is characterized by an electrode body (11) that is designed with an approximately T- or anchor-shaped cross-section, and that comprises an electrode shaft (12) and at least one support bracket (13) that protrudes out on both sides thereof, wherein the contact surface (16) is disposed on the side of the support bracket (13) opposite the electrode shaft (12). Through this especially advantageous electrode configuration, the electrode can be placed between the vena jugularis (22) and the arteria carotis (23) such that the electrode shaft lies in the intermediate space (24) between these two blood vessels and such that one side (14a) of the support bracket (13) reaches beneath the vein and the other side (14b) thereof reaches beneath the artery and such that the front side of the bracket facing away from the electrode shaft, on which side the contact surface (16) is located, presses against the nervus vagus (21) to be stimulated.

Description

Description Title of Invention: Electrode for intraoperative nerve stimulation

[1] The invention relates to an electrode for intraoperative stimulation of the nerve

Vagus, essentially consisting of an electrode body with at least one electrically conductive contact surface, which is connectable by means of a signal transmission means with a signal generator and / or a signal receiver.

[2] Intraoperative neuromonitoring has been used for several decades in operations to verify during surgery that potentially damaged nerve structures in the surgical site are being violated. The technique of neuromonitoring is used in many surgical procedures, for example in neurosurgery, ENT, vascular or thyroid surgery. In this case, the nerve to be monitored is electrically stimulated and it comes to the formation of an action potential, which can then be derived and analyzed, for example in the form of electromyography signals on the successful organ of the affected nerve, for example a muscle via electrodes. The Ables signal indicates the functional state of the nerve.

Of particular importance is intraoperative neuromonitoring, inter alia, in thyroid surgery, where there may be an injury to the recurrent laryngeal nerve leading to voice disorders, loss of voice and / or respiratory or swallowing discomfort in the patient. In the case of a bilateral injury of the branching off of the vagus nerve laryngeal nerve in Strumaoperationen exists for the patient even mortal danger.

By the use of functional monitoring of nerves in the operation was also in thyroid surgery, the most common and most dangerous complication, namely the recurrent nerve injury of the recurrent laryngeal nerve significantly reduced. As far as can be seen, however, intermittent methods are used so far in which a functional control of the nerve can be performed only before and after a dangerous operation of the surgeon by the nerve by means of a hand-held electrode before or after a cut or the like , is stimulated. The stimulation is carried out via stimulation probes whose structural design varies depending on the manufacturer. For example, monopolar probes with spherical tips or bipolar designs with concentric pole tips or fork tips or even hook probes with either straight or bayonet-shaped handpieces are used. Naturally, with all these stimulation probes stimulation of the nerve is only possible if it is applied by the surgeon by hand to the nerve to be stimulated. Although intermittent neuromonitoring for both

Thyroid surgery as well as other surgical procedures such as neurosurgery assists the surgeon in the identification of a vulnerable nerve as well as the verification of nerve function, this intermittent procedure does not provide safe protection for the vulnerable nerves, since only before and after the per se risky surgical activity, a functional monitoring takes place. Intermittent monitoring does not prevent the surgeon from injuring or even severing a nerve. Therefore, a continuous monitoring method is sought, which can be regarded as a kind of early warning system for nerve damage. The term 'continuous' in this context is to be understood as a continuous or at short intervals independently, ie without manual operation of the surgeon stimulation of the corresponding nerve and the derivative of the response signal on successful muscle and the present invention is concerned with an electrode, with which enables such continuous monitoring.

With the older, unpublished DE 10 2007 036 862 Al the Applicant an electrode with a lockable around the nerve to be stimulated, can be closed to a closed loop contact strip of elastic, biocompatible material has been proposed which at least one nerve facing , electrically conductive contact surface, which is connectable by means of a signal transmission means with a signal generator and / or a signal sensor. This earlier development of the Applicant can be much easier and faster to create the nerve to be monitored of the patient as previously known electrodes for permanent nerve stimulation, which are intended for permanent retention in the human body. Such permanent electrodes are all relatively difficult to apply and in particular to remove again, which is possible only in relatively time-consuming operations. They are therefore not suitable for monitoring the functional control of a nerve during surgery. However, it has also been shown that the application of the contact strip on the vagus nerve similar to a cable tie around the nerve requires a great deal of practice and skill in a gland surgery and its removal from the surgeon at the end of the operation, because the vagus nerve lies concealed in the surgical field behind the surgeon The jugular vein and the carotid artery immediately adjacent to it, which, of course, must not be injured when exposing the nerve required to apply the electrode loop. In addition, the noose around the nerve should not be pulled too tight to avoid nerve squeezing.

[7] The object of the invention is to provide an electrode for the intraoperative neuromonitoring of the vagus nerve, which is fast and at the beginning of the operation can reliably apply, so that their contact surface reliably remains in contact with the nerve to be stimulated vagus during surgery, and can be removed in a similar simple manner again. It should be reliably avoided with the electrode and a pinch of the nerve.

This object is achieved with the invention in that the electrode body in

Section is designed approximately T- or anchor-shaped and has an electrode shaft and at least one of this on both sides projecting headband, wherein the contact surface is disposed on the side opposite the electrode shaft side of the retaining clip.

By this particularly advantageous embodiment of the electrode, this can be placed between the jugular vein and the carotid artery so that the electrode shaft in the space between these two blood vessels and the retaining bracket with its one side of the vein and with its other side, the artery grasped and presses with his on the side facing away from the electrode shaft front, where the contact surface is located against the nerve to be stimulated vagus. In doing so, the electrode remains 'open', i. it does not surround the nerve in the applied state, but lies with its contact surface only on this. The invention thus concerns the application of the electrode to the nerve, i. for an electrical contact between the contact surface of the electrode and the nerve which is to be ensured during the duration of the operation, exploiting the special anatomical conditions in the operating area where the two blood vessels and the nerve to be stimulated at regular intervals are in close proximity to one another, which is the case previously available means the surgeon regularly has been a major challenge. The new, inventive electrode can be easily introduced with their headband between the closely juxtaposed blood vessels, which have to be spread apart by the surgeon to form a sufficiently wide for the electrode passage only slightly apart. In the applied state of the electrode, the jugular vein on one side of the electrode shaft and the carotid artery on the other side of the electrode shaft press against the retaining bracket from behind, which, due to the pressing force exerted by the blood vessels, has its contact surface on the vagus nerve at its front invests. The electrode is thus securely clamped in the triangle between the vein, the artery and the nerve during the operation and reliably maintains its position throughout the operation.

Preferably, the arrangement is such that the retaining clip is essentially formed by two webs projecting laterally from the electrode shaft. The headband or the webs forming this is / are preferably concavely curved in the direction of the electrode shaft and thus to the curved outer surface of the Blood vessels behind which they are fitted. It is also advantageous if, in the region of the contact surface formed thereon, the retaining clip has a concave or approximately V-shaped indentation or depression, into which the nerve to be monitored inserts, so that it receives a lateral guidance.

[11] If the contact surface is striped over at least part of the width of the

Even if the nerve should slip laterally relative to the electrode clamped between the blood vessels during the operation, a reliable electrical contact between the nerve and the electrode is always ensured. It is recommended that the contact surface is in the area of confiscation.

[12] If several, preferably stripe-like juxtaposed

Contact surfaces are provided on the electrode, the electrode is thus designed bipolar or multipolar, can be dispensed with a remotely located reference electrode, because supply and discharge of the electrical signals can be carried out in such a configuration on one and the same electrode.

Preferably, at least one plug connection is provided at the rear end of the electrode shaft, which is conductively connected to the at least one contact surface via a line running in isolation through the electrode shaft. The connection of the electrode to a signal transmitter and / or a Signalwertaufnehmer can then easily be done via a cable that is plugged into the easily accessible on the electrode shaft even after the application of the electrode plug connection.

The electrode shaft and the headband can in a preferred

Embodiment of the invention consist of a flexible material. Due to the flexibility of the electrode, this varying from patient to patient local conditions in the surgical field can optimally adapt; the flexible design also facilitates the application of the electrode and in particular their removal after the operation by bending the two webs or wings of the retaining bracket upwards or forwards into an approximately parallel position to the electrode shaft and so on due to a force exerted on the electrode tensile force simply withdraw from the space between the two blood vessels. Depending on the anatomical conditions of the patient to be operated on, however, it may also be expedient if the electrode is essentially rigid or at least stiff. A suitable material for the electrode body is, for example, polyphenylene sulfone or another biocompatible material. For a substantially rigid electrode, the contact surface may be on a medical grade stainless steel insert embedded in the electrode body; In particular, in a flexible embodiment of the electrode of course, the contact surface is flexible, for example, by an electrically conductive HTV silicone rubber insert is formed.

Further features and advantages of the invention will become apparent from the following

Description and the drawing, wherein a preferred embodiment of the invention is explained in more detail by way of example. It shows:

FIG. 1 shows an electrode according to the invention for intraoperative nerve stimulation of the

Nervus vagus in its applied position in a perspective view; and

[17] Fig. 2 shows the subject matter of Fig. 1 in longitudinal section.

The electrode designated in the drawing in its entirety by 10 is used for intraoperative nerve stimulation of the vagus nerve for continuous monitoring of nerve functions, especially in thyroid surgery, whereby the stimulation of the vagus nerve and the function of the laryngeal nerve particularly endangered in thyroid operations recurrens can be monitored, which is acted upon as a side branch of the vagus nerve during its stimulation.

With the electrode according to the invention, the intermittent monitoring method usually used in such operations can be superseded, in which the surgeon has to apply stimulation electrodes to the nerve by hand and thus can not directly point out to the surgeon a danger to the nerve while the surgeon does a nerve-damaging act. The electrode according to the invention is applied to the nerve to be stimulated and remains in place during the operation. By means of a suitable signal transmitter, the nerve is then stimulated continuously or at short, constant intervals, wherein triggered by the stimulation reaction of the body, namely an identifiable to the vocal folds or the voice muscle EMG signal - recorded there by suitable electrodes and after appropriate signal processing visualized on a screen for the surgeon. Changes in the representation of the recorded signals are then a warning to the surgeon that the nerve is affected by actions during the operation, for example temperature, tension or pressure, squeezed or even (partially) severed. This technique of intraoperative nerve stimulation is known as such and should not be reproduced here in depth.

[20] As the drawing clearly shows, the electrode 10 has an approximately T-shaped or armature-shaped electrode body 11, which consists essentially of an electrode shaft 12 and a retaining clip 13 protruding on both sides at its lower or front end. The two laterally projecting webs 13a, 13b of the retaining clip 13 are each curved concavely in the direction of the intermediate electrode shaft, so that they are two approximately circular segment-shaped running Form holding surfaces 14a, b.

[21] At the lower or front side of the electrode shaft 12 opposite the electrode shaft 12

Holding bracket 13 is provided in its central region with a recess or recess 15, so that the headband has in section (Figure 2) has an approximately w-shaped shape with rounded transitions. On this lower or front side of the headband has two strip-like over approximately two-thirds of the width of the retaining clip extending contact surfaces 16 which are formed by electrically conductive HTV silicone rubber inserts 17, which are embedded in the otherwise non-electrically conductive material from the electrode body 11 consists. For example, this material may be a medically acceptable silicone rubber based material. The inserts 17 are connected via extending through the electrode shaft 12 lines 18 with provided at the upper and rear end of the electrode body 11 connector plugs 19 to which supply or discharge cable 20 are connected.

The thus configured electrode is the surgeon at the beginning of surgery on

Nervus Vagus 21 is created by being inserted with its front bracket 13 between the two lying in front of the nerve 21 blood vessels, namely the jugular vein 22 and the carotid artery 23, so that the nerve 21 lies in the recess 15 and the front - Or on the underside of the retaining bracket 13 arranged contact surfaces 16 touch the nerve 20. In this case, the electrode is initially held rotated by 90 ° for easier passage through the narrow gap 24 between the vein 22 and the artery 23, so that the headband 13 is aligned approximately parallel to the two blood vessels 22,23. Subsequently, the electrode is rotated by 90 ° in the position shown, so that the two blood vessels to the holding surfaces 14a, b of the two webs 13a, b create and thereby press the headband 13 with the contact surfaces 16 disposed therein against the nerve 21, the through the recess 15 receives a lateral guide. Trapped in the interstice between the two blood vessels and the nerve, the electrode attached to the nerve remains 'open', ie does not surround it, as is the case with many other electrodes, especially those intended for permanent retention. Despite its 'open' position, the electrode keeps its position generally unchanged during the operation. However, even if there should be a displacement of the electrode during the operation, an electrically conductive contact between the electrode and nerve is ensured even if the nerve should shift laterally relative to the position shown due to the relatively long contact surfaces. The constriction or depression 15 in conjunction with the trapping force prevailing between the blood vessels and the nerve generally causes the nerve to return to the position shown in the deepest place of the depression 15 by itself. [23] After the operation has been completed, the electrode can easily be removed again. For this purpose, due to the inherent flexibility of the electrode in the described embodiment, it is not even absolutely necessary to first turn the electrode body by 90 ° as in the case of the application; simply pulling the electrode upwards from the blood vessels and the nerve, the flexible bars of the headband will bend down and then protrude downwards approximately parallel to the electrode shaft so that they can be pulled up between them without damaging the vessels.

[24] The invention is not limited to the illustrated embodiment, but there are various changes or additions, without departing from the scope of the invention. Thus, for example, it is readily possible to provide only one contact strip instead of two contact surfaces for forming a bipolar electrode, if the neuromonitoring is to take place with a monopolar electrode. Likewise, of course, electrodes with three or more contact surfaces are conceivable. The electrode may also consist of a substantially rigid material. For example, the electrode body may be made of an electrically nonconductive plastic, e.g.

[25] Polyphenylene sulfone (PPSU) in which at least one insert made of medical grade stainless steel, which forms the contact surface, is embedded on the front side of the retaining clip. It is also conceivable, flexible design only the headband or the webs forming these, while the electrode shaft is rigid or at least rigid, so that a particularly simple handling is guaranteed.

Claims

[0008] 1. Electrode for intraoperative stimulation of the vagus nerve, essentially consisting of an electrode body (11) with at least one electrically conductive contact surface (16) which is connected to a signal transmitter and / or by means of a signal transmission means (18, 19, 20) a signal receiver is connectable, characterized in that the electrode body (11) is configured approximately T- or anchor-shaped in section and an electrode shank (12) and at least one on both sides projecting headband (13), wherein the contact surface (16) on the the electrode shaft (12) opposite side of the retaining clip (13) is arranged.

[Claim 2] 2. Electrode according to claim 1, characterized in that the retaining clip (13) is essentially formed by two laterally projecting from the electrode shaft (12) webs (13a, b).

[Claim 3] 3. Electrode according to claim 1 or 2, characterized in that the retaining clip (13) or the webs forming therefrom (13a, b) in the direction of the electrode shaft (12) is concavely curved / are.

4. Electrode according to one of claims 1 to 3, characterized in that the retaining bracket (13) in the region of the contact surface formed thereon (16) has a concave or approximately V-shaped Einzeihung or depression (15).

[Claim 5] 5. Electrode according to one of claims 1 to 4, characterized in that the contact surface (16) extends in strip form over at least part of the width of the retaining clip (13).

[Claim 6] 6. An electrode according to claim 4 or 5, characterized in that the contact surface (16) in the region of the recess (15).

7. Electrode according to one of claims 1 to 6, characterized by a plurality of, preferably strip-like juxtaposed contact surfaces (16).

8. Electrode according to one of Claims 1 to 7, characterized by at least one plug connection (19) provided at the rear end of the electrode shaft (12) and connected via a line (18) extending in isolation through the electrode shaft (12) at least one contact surface (16) is conductively connected.

[Claim 9] 9. Electrode according to one of claims 1 to 8, characterized in that the electrode shaft (12) and / or the retaining clip (13) consist of a flexible material.

10. The electrode according to claim 1, wherein the at least one electrode shank consists of a rigid or rigid material.

[Claim 11] 11. An electrode according to any one of claims 1 to 10, characterized in that the electrode body (11) consists at least partly of polyphenylene sulfone.