Neurostimulation system

Abstract

Neurostimulation system (10) comprising at least one electrode (120) configured to stimulate tissue, preferably brain tissue, an implantable pulse generator unit (IPG), storage means for storing at least one first and second set of electrophysiological data, wherein the first set of data is formed by the intraoperatively obtained data and wherein the second set of data is formed by the postoperatively obtained data, comparison means configured to compare the first set of data and the second set of data to obtain a set of comparison data, and analysis means configured to at least partially compare the set of comparison data to determine the position of the at least one electrode (120) or to determine data from which the position of the at least one electrode (120) can be determined.wherein the neurostimulation system (10) comprises at least one chronic probe (100), wherein the chronic probe (100) includes the at least one electrode (120) and is connected to the implantable pulse generator unit (IPG), wherein the at least one chronic probe (100) is configured to perform an intraoperative measurement on which the intraoperatively obtained data are based and a postoperative measurement on which the postoperatively obtained data are based, and wherein the implantable pulse generator unit (IPG) is configured to receive signals from the chronic probe (100).

Description

[0001] The present invention relates to a neurostimulation system.

[0002] During the implantation of neurostimulation probes (see, for example, US 2005 / 0 070 781 A1 or US 2007 / 0 129 770 A1), the surgical team often performs so-called electrophysiological mapping. Furthermore, US 2009 / 0 149 898 A1 describes systems and methods for delivering targeted neural stimulation treatment for neurological disorders, including neuropsychiatric and neuropsychological disorders. Using acutely implanted test probes, the functional properties of neural tissue are measured at various positions along a planned surgical trajectory toward the target area. This mapping is performed with the goal of precisely determining the spatial conditions of the functional target tissue region. The functional conditions are identified through certain characteristic patterns in the recorded signals and further through the analysis of the responses to the test stimulation.Based on the identification of functional conditions, the team can decide on the best location for positioning the final chronic tube.

[0003] New neurostimulation probes under development will have a large number (10) of electrodes distributed around their surface. Through these electrodes, the neurostimulation system can measure electrical neural activity and observe the effects of the test stimulation delivered by these electrodes. Such information can be helpful in the postoperative period to identify electrodes close to the target region.

[0004] It is inevitable that the relative position of the chronic lead in relation to the target region will change during the postoperative period. This may be due to various reasons, such as surgical manipulation (e.g., fixation) immediately following lead implantation exerting certain mechanical forces on the lead, resulting in displacement; tissue deformation during the postoperative recovery period (recovering from a brain displacement), resulting in tissue displacement relative to the lead; or displacement of the lead over time, particularly after strong forces have been applied to the guide (cable) or the head.

[0005] As a result of the mechanisms described above, an implanted probe will generally not be in the predetermined position expected based on the coordinates where the surgical team implanted the probe. This makes it even more difficult to find the optimal stimulation settings (because the target position relative to the probe is not reliably determined).

[0006] It is therefore the object of the present invention to advantageously further develop a neurostimulation system of the type mentioned at the outset, in particular to the effect that the best possible stimulation settings can be found more easily and with greater accuracy and that, furthermore, the position of an implanted chronic probe of a neurostimulation system can be determined with high accuracy.

[0007] This object is achieved according to the invention by the subject matter of claim 1.

[0008] This has the advantage of placing the intraoperatively acquired information into the correct context, for example, of an implanted electrode within the brain, and of precisely determining the position of the implanted electrode in relation to the target area. Consequently, a neurostimulation system can be improved, particularly in that the optimal stimulation settings can be found more easily and with greater accuracy. In particular, functional limits determined during the implantation of the probe, especially during surgery, can be related to the chronic situation of the implanted electrode, especially at a later time, and thus the target position in relation to the chronic electrode can be determined.Over time, the electrode may shift in position and may have a different or unknown orientation relative to the target region. By comparing the first and second data sets, the new electrode position can be determined.

[0009] In particular, the comparison of the first data set and the second data set to derive a new electrode position can be performed as follows: The intra-operative measurement and the post-operative measurement are performed using the same (chronic) probe carrying the at least one electrode. In this case, the chronic probe is measured during surgical implantation with the aim of creating an electrophysiological map (EP map) of the target area. In the post-operative phase, signals are recorded from the same probe, e.g., using the implantable pulse generator (IPG) unit, and a post-operative EP map is created. By comparing the intra-operative map with the post-operative map, corrections to the target localization towards the probe can be made, e.g., to compensate for brain displacement in the post-operative phase.

[0010] It is possible that the data on the basis of which the position of the at least one electrode is determined is raw data comprising coordinates, angles, and electrophysiological data. It is also possible that the data on the basis of which the position of the at least one electrode can be determined also includes recordings of neural activity, e.g., local field potentials (LFP) and / or microelectrode recordings (MER), and that, based on these data, a so-called map of intraoperative electrophysiological data and a map of postoperative electrophysiological data are provided and can be compared with each other.

[0011] The comparison means may be implemented at least in part by a software program product, which is installed, for example, on a workstation, which is part of the neurostimulation system and which is connectable to the neurostimulation system.

[0012] Additionally, in a preferred embodiment, it is possible for the probe to be equipped with a plurality of electrodes, wherein the plurality of electrodes are arranged in a predetermined geometric relationship, and wherein the electrodes are designed such that the electrodes are suitable for delivering electrical stimulation to tissue and that each of the electrodes is suitable for detecting electrical signals. This results in the advantage that customized stimulation can be carried out using the probe equipped with a plurality of electrodes, and that the brain tissue to be stimulated can thereby be stimulated with high precision. Additionally, the advantage is achieved that electrical signals can also be determined, and that this determination process can be carried out with high precision.

[0013] Furthermore, the probe may be a chronic probe, which is designed in such a way that the probe is a long-term implantable probe.

[0014] It is also possible for the neurostimulation system to include a test probe that can be implanted intraoperatively. This allows the data obtained intraoperatively to be recorded.

[0015] The intra-operative acute implantable leads are used only during the surgical operation and the implantation process of e.g. the chronic lead or the chronic leads and is removed after the recording of the intra-operative electrophysiological data.

[0016] Preferably, the data obtained intra-operatively by the at least one electrode comprise recordings of electrical brain activity, in particular by the electrode of the probe, in particular by the plurality of electrodes and / or stimulation effects caused by the stimulation of the at least one electrode, preferably by the plurality of electrodes, in particular by a group of preselected electrodes.

[0017] In a preferred embodiment, the plurality of electrodes are arranged on a chronic probe, with the electrodes arranged in a predetermined geometric manner to form an array on the probe. Additionally, the intraoperatively acquired data can be acquired either through the acutely implanted test probe, through the chronic probe, through chronic probes during implantation, or both.

[0018] Further preferably, the postoperatively acquired data comprise recordings of the at least one electrode of electrical brain activity, preferably the electrode of the probe, in particular of a plurality of electrodes, and / or stimulation effects induced by the stimulation of the at least one electrode, preferably by the plurality of electrodes, in particular by a group of preselected electrodes. In particular, the plurality of electrodes can be arranged on the chronic probe.

[0019] In addition, the neurostimulation system may comprise control means configured to control the neurostimulation system to acquire the at least one first and second set of electrophysiological data.

[0020] In a further advantageous embodiment, it is possible for the neurostimulation system to comprise intra-operative electrophysiology system means designed such that intra-operative electrophysiological tissue characteristics can be recorded at different positions in the brain.

[0021] Preferably, the intra-operative electrophysiology system means may comprise connection means configured such that the intra-operative electrophysiology system means can be connected to the at least one electrode. This allows the intra-operative electrophysiology system means to receive data collected by the at least one electrode.

[0022] In a further advantageous embodiment, it is possible for the neurostimulation system to comprise data processing means configured to analyze data acquired by the intra-operative electrophysiology system means and for at least some of the first set of data to be provided by the data processing means.

[0023] Further preferably, it is possible that the first set of data, which is a set of intra-operatively acquired electrophysiological data, is a first spatial 3D map of local field potential beta activity and that the second set of data, which is a set of post-operatively acquired electrophysiological data, is a second spatial 3D map of local field potential beta activity.

[0024] In addition, it is also possible that the neurostimulation system is such that the first spatial 3D map and the second spatial 3D map are compared by the comparison means and that the analysis means use a spatial translation to determine the position of the at least one electrode or to determine data by which the position of the at least one electrode can be determined.

[0025] In a further advantageous embodiment, it is possible for the analysis means to be designed in such a way that, through spatial translation, functional limits determined intraoperatively are placed in context with the chronic situation of at least one electrode. This provides the advantage that the new position of the implanted chronic lead can be determined, since it is possible for the implanted chronic lead to shift over time.

[0026] Furthermore, it is possible for the analysis means to be configured such that the analysis means use spatial translation to process additional patient data, in particular an intraoperative image, preferably an image acquired by magnetic resonance imaging. This allows additional data to be used to improve the accuracy of the process of determining the position of the chronic probe.

[0027] Furthermore, in connection with the present invention as described above, a method for determining a position of at least one electrode of a neurostimulation system is explicitly disclosed, wherein the at least one electrode is configured such that tissue, preferably brain tissue, can be stimulated, wherein at least a first and a second set of electrophysiological data is stored, wherein the first set of data is the set of data acquired intraoperatively and wherein the second set of data is the set of data acquired postoperatively, wherein the first set of data and the second set of data are compared to obtain a set of comparison data, and wherein the set of comparison data can be at least partially compared to determine the position of the at least one electrode or to determine data on the basis of which the position of the at least one electrode can be determined.

[0028] As already disclosed above in connection with the neurostimulation system according to the invention, it is possible that the data on the basis of which the position of the at least one electrode can be determined are raw data comprising coordinates, angles, and electrophysiological data. It is also possible that the data on the basis of which the position of the at least one electrode can be determined also comprise recordings of neural activity, e.g., local field potential (LFP) and / or microelectrode recordings (MER), and that, based on these data, a so-called map of intraoperative electrophysiological data and a map of postoperative electrophysiological data can be created and compared with each other.

[0029] In a first step of the procedure, at least one measuring probe may be moved toward the target area and various position measurements may be performed. The target area may be an area in the brain that is to be stimulated by a chronic probe of a neurostimulation system. This first step may be performed intraoperatively.

[0030] In a second step of the process, it is possible to create a spatial map with certain signal characteristics from the different position measurements.

[0031] In a third step of the method, it is possible for a chronic probe, e.g., a probe as defined above, having a plurality of electrodes arranged on the chronic probe, wherein the electrodes are arranged in a predetermined geometric manner and form an array on the probe, to be implanted at a predetermined location in the target area of ​​the brain. The target area is the area to be stimulated by the chronic probe in order to perform a neurostimulation treatment.

[0032] Because it is possible that over time the chronic probe may change its position and may have a different or unknown orientation with respect to the target area, in a fourth step a number of measurements are performed and a new map of signal characteristics is created.

[0033] In a fifth step, a transformation matrix can be calculated by comparing both maps. This transformation matrix can then be used to transform other data, allowing the new probe position to be derived.

[0034] This method can be carried out using the neurostimulation system according to the present invention, in particular with a neurostimulation system according to any one of claims 1 to 14.

[0035] Further details and advantages of the present invention will now be described with reference to the drawings: Fig. 1 : the step of acquiring the first set of data performed with a neurostimulation system according to the present invention; Fig. 2 : the step of creating a spatial map performed with the neurostimulation system according to the present invention; Fig. 3 : the step of implanting the chronic probe of the neurostimulation system according to the present invention; Fig. 4 : a possible displacement of the chronic probe of the neurostimulation system according to the present invention; Fig. 5 : the step of creating a further spatial map performed with the neurostimulation system according to the present invention; and Fig. 6 : the step of calculating a transformation map by comparing the two spatial maps performed with the neurostimulation system according to the present invention.

[0036] Fig. Figure 1 schematically shows that a number of measuring probes 12 are moved towards the target area 20 of brain tissue and that different position measurements are taken.

[0037] The neurostimulation system 10 according to the present invention may consist of a computer program, an intra-operative electrophysiology (ioEP) system, and an implanted neurostimulation probe 100 connected to a unit suitable for stimulation and signal acquisition.

[0038] The measuring probes are part of the ioEP system and are acutely implanted test probes 12. The intra-operatively acquired data can be recorded either by acutely implanted test probes or by the chronic probe 100 (as in Fig. 3) during implantation or by both, and may include recordings of electrical brain activity by the electrodes 120 of the probe 100 and / or stimulation effects elicited by stimulation of a single electrode(s) or a group of electrodes.

[0039] The ioEP system is used during surgery to record electrophysiological tissue characteristics at different locations in the brain. The computer program analyzes this data and can compile a set of intraoperatively acquired electrophysiological data, which is a "map" of certain characteristic signal features.

[0040] For example, the ioEP could have measured LFP signals and constructed a 3D spatial map of LFP beta activity (beta activity is a measure of the oscillatory energy in the "beta band", i.e., the 15-30 Hz frequency band). This map allows the boundaries of the functional target (target = high beta) to be identified. In a later (post-op) phase, LFP can be recorded from the chronically implanted probe 100. This allows a second spatial map 50 of LFP beta activity (see Fig. 5) to create.

[0041] As in Fig. 2, on the basis of this intra-operatively acquired first set of data, a spatial map 40 of certain signal characteristics with respect to the target region 20 is created and stored in the storage means of the neurostimulation system.

[0042] Furthermore, as in Fig. As shown in Figure 3, a chronic probe 100 of the neurostimulation system 10 is implanted at a predetermined position 110 in the target area 20. A plurality of electrodes 120 are arranged on the chronic probe 100, with the electrodes 120 forming an array on the probe 100 in a predetermined geometric manner.

[0043] As in Fig. 4, the position of the probe 100 may change over time and may have a different, unknown orientation with respect to the target region 20 and a new probe position 110' that differs from the previous position 110. It should always be borne in mind that in the postoperative phase, the relative position of the chronic probe 100 and its electrodes may change with respect to the target region 20. This may have various reasons, e.g., that surgical handling (e.g.,) Fixation exerts mechanical forces on the chronic probe 100 resulting in displacements, or that in the post-surgical recovery phase the tissue deforms (when recovering from the brain displacement), resulting in a displacement of the tissue with respect to the chronic probe 100, or that the probe displacements occur over time, especially after large forces have been applied to the guide (cable) or the head.

[0044] As in Fig. As shown in Figure 5, by performing numerous measurements, a new map 50 (also called post-operative (feature) map 50) of signal characteristics is created. The post-operatively acquired data from the chronic probe 100 may include recordings of electrical brain activity from the electrodes 120 of the probe 100 and / or stimulation effects elicited by stimulating a single electrode(s) or group(s) of electrodes.

[0045] Furthermore, as in Fig. 6, a transformation matrix 200 is calculated by comparing both maps 40, 50. This transformation matrix 200 can be used to transform other data so that the new probe position 110' (see Fig. 4) can be derived.

[0046] The two maps can be compared and through spatial transformation (e.g. translation, rotation) the ioEP map 40 (see Fig. 2 ; also the so-called intra-OP (feature) card 40) into the chronic card 50 (see Fig. 5 ; also called post-op (feature) map). Then, the functional boundaries determined during the surgical operation are put into context with the chronic situation, and the target region 20 in relation to the chronic probe 100 is thus known.

[0047] It is possible that the same transformation matrix 200 can also be applied to other patient information (e.g., an intra-operative image).

[0048] In an improved and / or alternative embodiment of the present invention, the intra-operative measurement and the post-operative measurement are performed using the same (chronic) probe 100. In this case, the chronic probe 100 is measured during surgical implantation with the aim of creating an electrophysiological map (EP map) of the target region 20. The probe 100 is then connected to an implantable pulse generator unit (IPG), the patient is closed, and the surgical operation is completed. In the post-operative phase, signals are recorded from the same probe 100 (using the IPG), and a post-operative EP map is created. By comparing the intra-operative and post-operative maps, corrections can be made regarding the target localization towards the probe, e.g., to compensate for brain displacement in the post-operative phase.

Claims

[1] Neurostimulation system (10) comprising at least one electrode (120) configured such that tissue, preferably brain tissue, can be stimulated, an implantable pulse generator unit (IPG), storage means for storing at least a first and second set of electrophysiological data, wherein the first set of data is formed by the data obtained intraoperatively and wherein the second set of data is formed by the data obtained postoperatively, comparison means configured such that the first set of data and the second set of data can be compared to obtain a set of comparison data, and analysis means configured such that the set of comparison data can be at least partially compared to determine the position of the at least one electrode (120) or to determine data from which the position of the at least one electrode (120) can be determined,wherein the neurostimulation system (10) comprises at least one chronic probe (100), wherein the chronic probe (100) comprises the at least one electrode (120) and is connected to the implantable pulse generator unit (IPG), wherein the at least one chronic probe (100) is configured to perform an intra-operative measurement on which the intra-operatively obtained data is based and a post-operative measurement on which the post-operatively obtained data is based, and wherein the implantable pulse generator unit (IPG) is configured to receive signals from the chronic probe (100). [2] Neurostimulation system (10) according to claim 1, characterized bythat the probe (100) is equipped with a plurality of electrodes (120), wherein the plurality of electrodes (120) are arranged in a predetermined geometric relationship and wherein the electrodes (120) are such that the electrodes (120) are suitable for delivering electrical stimulation to tissue and that each of the electrodes (120) is suitable for detecting electrical signals. [3] Neurostimulation system (10) according to claim 1 or 2, characterized by that the probe (100) is a chronic probe (100) which is designed such that the probe (100) is a long-term implantable probe (100). [4] Neurostimulation system (10) according to one of claims 1 to 3, characterized by that the neurostimulation system (10) has a test probe (12) which can be acutely implanted intraoperatively. [5] Neurostimulation system (10) according to one of the preceding claims, characterized bythat the data obtained intra-operatively by the at least one electrode (120) comprise recordings of electrical brain activity, in particular by the electrode (120) of the probe (100), in particular by the plurality of electrodes (120) and / or stimulation effects caused by the stimulation of the at least one electrode (120), preferably by the plurality of electrodes, in particular by a group of preselected electrodes (120). [6] Neurostimulation system (10) according to one of the preceding claims, characterized bythat the post-operatively obtained data comprise recordings of the at least one electrode (120) of electrical brain activity, preferably the electrode (120) of the probe (100), in particular of a plurality of electrodes (120) and / or stimulation effects caused by the stimulation of the at least one electrode (120), preferably by the plurality of electrodes, in particular by a group of preselected electrodes (120). [7] Neurostimulation system (10) according to one of the preceding claims, characterized by that the neurostimulation system (10) has control means designed such that the neurostimulation system (10) can be controlled such that the at least one first and second set of electrophysiological data can be acquired. [8] Neurostimulation system (10) according to one of the preceding claims, characterized bythat the neurostimulation system (10) comprises intra-operative electrophysiology system means designed such that intra-operative electrophysiological tissue characteristics can be recorded at different positions in the brain. [9] Neurostimulation system (10) according to claim 8, characterized by that the intra-operative electrophysiology system means comprise connecting means which are such that the intra-operative electrophysiology system means can be connected to the at least one electrode (120). [10] Neurostimulation system (10) according to claim 8 or 9, characterized by that the neurostimulation system (10) comprises data processing means arranged such that data acquired by the intra-operative electrophysiology system means are analyzed and that at least part of the first set of data can be provided by the data processing means. [11] Neurostimulation system (10) according to one of the preceding claims, characterized by that the first set of data, which is a set of intraoperatively acquired electrophysiological data, is a first spatial 3D map of local field potential beta activity and that the second set of data, which is a set of postoperatively acquired electrophysiological data, is a second spatial 3D map of local field potential beta activity. [12] Neurostimulation system (10) according to claim 11, characterized by that the neurostimulation system (10) is such that the first spatial 3D map and the second spatial 3D map are compared by the comparison means and that the analysis means use a spatial translation to determine the position of the at least one electrode or to determine data by which the position of the at least one electrode can be determined. [13] Neurostimulation system (10) according to claim 12, characterized by that the analysis means are designed in such a way that, through spatial translation, functional limits determined intraoperatively are put into context with the chronic situation of at least one electrode (120). [14] Neurostimulation system (10) according to claims 12 and 13, characterized by that the analysis means are such that the analysis means use spatial translation to process additional patient data, in particular an intra-operative image, preferably an image acquired by magnetic resonance imaging.

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