News Column

Patent Application Titled "System and Method for Estimating Lead Configuration from Neighboring Relationship between Electrodes" Published Online

July 14, 2014



By a News Reporter-Staff News Editor at Biotech Business Week -- According to news reporting originating from Washington, D.C., by NewsRx journalists, a patent application by the inventors Zhu, Changfang (Valencia, CA); Peterson, David K.L. (Valencia, CA), filed on February 26, 2014, was made available online on July 3, 2014 (see also Biotechnology Companies).

The assignee for this patent application is Boston Scientific Neuromodulation Corporation.

Reporters obtained the following quote from the background information supplied by the inventors: "Implantable neurostimulation systems have proven therapeutic in a wide variety of diseases and disorders. Pacemakers and Implantable Cardiac Defibrillators (ICDs) have proven highly effective in the treatment of a number of cardiac conditions (e.g., arrhythmias). Spinal Cord Stimulation (SCS) systems have long been accepted as a therapeutic modality for the treatment of chronic pain syndromes, and the application of tissue stimulation has begun to expand to additional applications such as angina pectoralis and incontinence. Deep Brain Stimulation (DBS) has also been applied therapeutically for well over a decade for the treatment of refractory chronic pain syndromes, and DBS has also recently been applied in additional areas such as movement disorders and epilepsy. Further, in recent investigations Peripheral Nerve Stimulation (PNS) systems have demonstrated efficacy in the treatment of chronic pain syndromes and incontinence, and a number of additional applications are currently under investigation. Also, Functional Electrical Stimulation (FES) systems such as the Freehand system by NeuroControl (Cleveland, Ohio) have been applied to restore some functionality to paralyzed extremities in spinal cord injury patients.

"Each of these implantable neurostimulation systems typically includes one or more neurostimulation leads implanted at the desired stimulation site and an implantable neurostimulator, such as an implantable pulse generator (IPG), implanted remotely from the stimulation site, but coupled either directly to the leads or indirectly to the leads via one or more lead extensions in cases where the length of the leads is insufficient to reach the IPG. Thus, electrical pulses can be delivered from the neurostimulator to the leads to stimulate the tissue and provide the desired efficacious therapy to the patient.

"In the context of an SCS procedure, one or more neurostimulation leads are introduced through the patient's back into the epidural space, such that the electrodes carried by the leads are arranged in a desired pattern and spacing to create an electrode array. One type of commercially available neurostimulation lead is a percutaneous lead, which comprises a cylindrical body with ring electrodes, and can be introduced into contact with the affected spinal tissue through a Touhy-like needle, which passes through the skin, between the desired vertebrae, and into the epidural space above the dura layer. For unilateral pain, a percutaneous lead is placed on the corresponding lateral side of the spinal cord. For bilateral pain, a percutaneous lead is placed down the midline of the spinal cord, or two or more percutaneous leads are placed down the respective sides of the midline of the spinal cord, and if a third lead is used, down the midline of the special cord. After proper placement of the neurostimulation leads at the target area of the spinal cord, the leads are anchored in place at an exit site to prevent movement of the leads. To facilitate the location of the neurostimulator away from the exit point of the leads, lead extensions are sometimes used.

"Whether or not lead extensions are used, the proximal ends of the neurostimulation leads exiting the spinal column are passed through a tunnel subcutaneously formed along the torso of the patient to a subcutaneous pocket (typically made in the patient's abdominal or buttock area) where a neurostimulator is implanted. The subcutaneous tunnel can be formed using a tunneling tool over which a tunneling straw may be threaded. The tunneling tool can be removed, the leads threaded through the tunneling straw, and then the tunneling straw removed from the tunnel while maintaining the leads in place within the tunnel.

"The neurostimulation leads are then connected directly to the neurostimulator by inserting the proximal ends of the stimulation leads within one or more connector ports of the IPG or connected to lead extensions, which are then inserted into the connector ports of the IPG. The IPG can then be operated to generate electrical pulses that are delivered, through the electrodes, to the targeted tissue, and in particular, the dorsal column and dorsal root fibers within the spinal cord.

"The stimulation creates the sensation known as paresthesia, which can be characterized as an alternative sensation that replaces the pain signals sensed by the patient. Intra-operatively (i.e., during the surgical procedure), the neurostimulator may be operated to test the effect of stimulation and adjust the parameters of the stimulation (e.g., the electrodes that are acting as anodes or cathodes, as well as the amplitude, duration, and rate of the stimulation pulses). The patient may provide verbal feedback regarding the presence of paresthesia over the pain area, and based on this feedback, the lead positions may be adjusted and re-anchored if necessary. A computerized programming system, such as Bionic Navigator.RTM., available from Boston Scientific Neuromodulation Corporation, can be used to facilitate selection of the stimulation parameters. Any incisions are then closed to fully implant the system. Post-operatively (i.e., after the surgical procedure has been completed), a clinician can adjust the stimulation parameters using the computerized programming system to re-optimize the therapy.

"The efficacy of SCS is related to the ability to stimulate the spinal cord tissue corresponding to evoked paresthesia in the region of the body where the patient experiences pain. Thus, the working clinical paradigm is that achievement of an effective result from SCS depends on the neurostimulation lead or leads being placed in a location (both longitudinal and lateral) relative to the spinal tissue such that the electrical stimulation will induce paresthesia located in approximately the same place in the patient's body as the pain (i.e., the target of treatment). If a lead is not correctly positioned relative to the tissue or relative to another lead, it is possible that the patient will receive little or no benefit from an implanted SCS system. Thus, correct lead placement can mean the difference between effective and ineffective pain therapy.

"Multi-lead configurations have been increasingly used in electrical stimulation applications (e.g., neurostimulation, cardiac resynchronization therapy, etc.). In the neurostimulation application of SCS, the use of multiple leads that are grouped together in close proximity to each other at one general region of the patient (e.g., side-by-side parallel leads along the spinal cord of the patient), increases the stimulation area and penetration depth (therefore coverage), as well as enables more combinations of anodic and cathodic electrodes for stimulation, such as transverse multipolar (bipolar, tripolar, or quadra-polar) stimulation, in addition to any longitudinal single lead configuration. In more advanced applications, multiple leads may be placed in different locations of the patient. For example, in an SCS application, one lead may be placed along the cervical region of the spinal cord, and another lead may be placed along the lumbar region of the spinal cord. As another example, in a combined SCS/PNS application, one lead may be placed along the spinal cord of the patient, and another lead may be placed in a peripheral location of a patient (e.g., an arm or a leg).

"Whether the multiple leads are implanted in the patient in close proximity to each other at a particular location or implanted in the patient at separate locations, selection of cathodes/anodes requires the identification of the electrodes that are positioned close to each other and knowledge of the relative positions of the electrodes that are to be activated as the cathodes or anodes. Conventional electrical field-based techniques, such as those described in U.S. Pat. No. 6,993,384, entitled 'Apparatus and Method for Determining the Relative Position and Orientation of Neurostimulation Leads,' and U.S. patent application Ser. No. 12/623,976, entitled 'Method and Apparatus for Determining Relative Positioning Between Neurostimulation Leads,' which are expressly incorporated herein by reference, have been developed to estimate the positions of the electrodes relative to each other by determining longitudinal offset and/or transverse separation between the leads. These techniques usually assume that the electrodes are arranged in-line along each lead and the arrangement of the electrode array is known so that certain patterns of the induced electrical field can be examined.

"If not already taken into account by the programming system, information related to the arrangement of electrode arrays may be obtained through user input if it is available (e.g., a user can enter the spatial orientation of the leads and/or electrodes obtained from a recent radiographic image into the programming system). However, radiographic imaging may not always be available, and even when it is, the images do not allow for identification of each electrode in the array unless certain prior information is available, e.g., lead type, lead-port mapping and electrode configuration. If such prior information is limited, identifying the electrode arrays may be difficult. This problem may be more complicated when, for example, different types of extensions (e.g., splitters) are used to connect the leads to the neurostimulator, which may result in an electrode array configuration that is different from the physical electrode array arrangement. Furthermore, lead position determination software installed in current neurostimulation systems oftentimes need to be updated to accommodate new or unknown lead designs.

"There, thus, remains an improved generic technique for identifying electrodes that are in proximity to each other, the relative positioning between the electrodes, and the configuration of the electrodes."

In addition to obtaining background information on this patent application, NewsRx editors also obtained the inventors' summary information for this patent application: "In accordance with a first aspect of the present inventions, a neurostimulation control system for use with a plurality of electrodes is provided. The neurostimulation control system comprises a user interface configured for receiving an input from a user, and at least one processor configured for, in response to the user input, (a) generating a fixed spatial grid of electrode positions, which may be uniformly spaced from each other, (b) designating one of the electrodes as a reference electrode to be currently examined, and assigning the reference electrode to one of the electrode grid positions. In one embodiment, only six electrode grid positions may immediately surround the electrode grid position with which the reference electrode is assigned, although the number of electrode grid positions immediately surrounding the electrode grid position may differ depending on the application.

"The processor(s) is further configured for (d) assigning one or more previously unassigned ones of the electrodes neighboring the reference electrode respectively to one or more of the electrode grid positions immediately surrounding the electrode grid position to which the reference electrode is assigned.

"In one embodiment, the electrode grid positions are spatially arranged in columns respectively representing linear arrays of electrodes, and the processor(s) is further configured for assigning different numbers respectively to the electrodes. In this case, the processor(s) may be configured for assigning the neighboring electrodes to the electrode grid positions in accordance with a set of rules comprising determining at least one in-line electrode of the neighboring electrodes having a number sequential to the number of the reference electrode, and assigning the in-line electrode(s) to an electrode grid position within the same column having the electrode grid position to which the reference electrode is assigned. The set of rules may further comprise determining at least one off-line electrode of the neighboring electrodes having a number non-sequential to the number of the reference electrode, and assigning the off-line electrode(s) to an electrode grid position within a column different from the column having the electrode grid position to which the reference electrode is assigned. The set of rules may further comprise determining if the off-line electrode(s) has a number sequential to the number of a neighboring electrode previously assigned to the electrode grid, and assigning the off-line electrode(s) to an electrode grid position within the same column having the electrode grid position to which the previously assigned neighboring electrode is assigned.

"In another embodiment, the processor(s) is further configured for (f) designating one of the previously assigned neighboring electrodes as the reference electrode to be currently examined, and (g) again assigning one or more previously unassigned ones of the electrodes neighboring the reference electrode respectively to one or more of the electrode grid positions immediately surrounding the electrode grid position to which the reference electrode is assigned. In this case, the processor(s) may be further configured for repeating steps (f) and (g) until all the electrodes have been assigned to the electrode grid. The processor(s) may be further configured for determining, for each electrode, neighboring ones of the remaining electrodes, wherein, for the each electrode designated as the reference electrode to be currently examined, the previously unassigned electrodes to be assigned to the electrode grid positions immediately surrounding the electrode grid position to which the reference electrode is assigned are selected from the determined ones of the remaining electrodes that neighbor the respective electrode. The processor(s) may be further configured for iteratively merging each electrode into a single electrode subset in an order dictated by merging the electrode closest in proximity to the single electrode subset for each iteration, wherein the electrodes are designated as the reference electrode in the order in which they are merged into the single electrode subset.

"The neurostimulation control system further comprises a controller configured for programming the electrodes based on the assignment of the electrodes to the electrode grid positions. For example, the controller may select at least one of the electrodes as a cathode and select at least another of the electrodes as an anode based on the identified clustering relationship of the electrodes. As another example, the controller may select a plurality of groups of the electrodes to create a respective plurality of stimulation regions based on the identified clustering relationship of the electrodes. The processor(s) and controller may be contained within an external control device.

"In accordance with a second aspect of the present inventions, a method of programming electrodes disposed adjacent tissue of a patient is provided. The method comprises (a) generating a fixed spatial grid of electrode positions, (b) designating one of the electrodes as a reference electrode to be currently examined, assigning the reference electrode to one of the electrode grid positions, (d) assigning one or more previously unassigned ones of the electrodes neighboring the reference electrode respectively to one or more of the electrode grid positions immediately surrounding the electrode grid position to which the reference electrode is assigned, and (e) programming the electrodes based on the assignment of the electrodes to the electrode grid positions. These steps and any optional steps may be performed in the same manner at that in which the processor(s) and controller performed the steps described above.

"Other and further aspects and features of the invention will be evident from reading the following detailed description of the preferred embodiments, which are intended to illustrate, not limit, the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

"The drawings illustrate the design and utility of preferred embodiments of the present invention, in which similar elements are referred to by common reference numerals. In order to better appreciate how the above-recited and other advantages and objects of the present inventions are obtained, a more particular description of the present inventions briefly described above will be rendered by reference to specific embodiments thereof, which are illustrated in the accompanying drawings. Understanding that these drawings depict only typical embodiments of the invention and are not therefore to be considered limiting of its scope, the invention will be described and explained with additional specificity and detail through the use of the accompanying drawings in which:

"FIG. 1 is plan view of one embodiment of a spinal cord stimulation (SCS) system arranged in accordance with the present inventions;

"FIG. 2 is a plan view of an implantable pulse generator (IPG) and two neurostimulation leads used in the SCS system of FIG. 1;

"FIG. 3 is a plan view of the SCS system of FIG. 1 in use with a patient;

"FIG. 4 is a block diagram of the internal components of the IPG of FIG. 1;

"FIG. 5 is a plan view of a remote control that can be used in the SCS system of FIG. 1;

"FIG. 6 is a block diagram of the internal componentry of the remote control of FIG. 5;

"FIG. 7 is a block diagram of the components of a clinician's programmer that can be used in the SCS system of FIG. 1;

"FIG. 8a is a fluoroscopic image of a clinical case wherein neurostimulation leads are implanted within a patient in a side-by-side relationship;

"FIG. 8b is a fluoroscopic image of a clinical case wherein neurostimulation leads are implanted within a patient in rostro-caudal relationship;

"FIG. 9 is a flow diagram illustrated a generic method implemented by the SCS system of FIG. 1 to perform an electrode clustering analysis and program the electrodes;

"FIG. 10a is a dendrogram of a clustering analysis performed on the electrode arrangement of FIG. 8a using a first specific technique implemented by the SCS system of FIG. 1;

"FIG. 10b is a dendrogram of a clustering analysis performed on the electrode arrangement of FIG. 8b using the first specific technique implemented by the SCS system of FIG. 1;

"FIG. 11a is a partitioned block diagram of a clustering analysis performed on the electrode arrangement of FIG. 8a using the first specific technique implemented by the SCS system of FIG. 1;

"FIG. 11b is a partitioned block diagram of a clustering analysis performed on the electrode arrangement of FIG. 8b using the first specific technique implemented by the SCS system of FIG. 1;

"FIG. 12a is a plot of a clustering analysis performed on the electrode arrangement of FIG. 8a using a second specific technique implemented by the SCS system of FIG. 1;

"FIG. 12b is a plot of a clustering analysis performed on the electrode arrangement of FIG. 8b using the second specific technique implemented by the SCS system of FIG. 1;

"FIG. 13a is an image of illustrating a first configuration of three neurostimulation leads are implanted within a patient in a side-by-side relationship;

"FIG. 13b is an image of illustrating a second configuration of three neurostimulation leads are implanted within a patient in a side-by-side relationship;

"FIG. 14 is a flow diagram illustrated a generic method implemented by the SCS system of FIG. 1 to perform an electrode configuration mapping technique and program the electrodes;

"FIG. 15 is a plan view of a spatial grid of electrode positions generated by the SCS system of FIG. 1 to which electrodes will be assigned in accordance with the electrode configuration mapping technique performed in FIG. 14;

"FIG. 16a is a plan view of an electrode configuration map of the neurostimulation lead configuration of FIG. 13a estimated by the SCS system of FIG. 1 in accordance with the technique performed in FIG. 14;

"FIG. 16b is a plan view of an electrode configuration map of the neurostimulation lead configuration of FIG. 13b estimated by the SCS system of FIG. 1 in accordance with the technique performed in FIG. 14;

"FIGS. 17a-17h are plan views illustrating the iterative assignment of electrodes from the neurostimulation lead configuration of FIG. 13a to the electrode grid of FIG. 15 by the SCS system of FIG. 1 in accordance with the technique performed in FIG. 14; and

"FIGS. 18a-18l are plan views illustrating the iterative assignment of electrodes from the neurostimulation lead configuration of FIG. 13b to the electrode grid of FIG. 15 by the SCS system of FIG. 1 in accordance with the technique performed in FIG. 14."

For more information, see this patent application: Zhu, Changfang; Peterson, David K.L. System and Method for Estimating Lead Configuration from Neighboring Relationship between Electrodes. Filed February 26, 2014 and posted July 3, 2014. Patent URL: http://appft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&u=%2Fnetahtml%2FPTO%2Fsearch-adv.html&r=1675&p=34&f=G&l=50&d=PG01&S1=20140626.PD.&OS=PD/20140626&RS=PD/20140626

Keywords for this news article include: Therapy, Cardiology, Paresthesia, Spinal Cord, Rheumatology, Medical Devices, Neurostimulator, Adolescent Medicine, Sensation Disorders, Chronic Pain Syndrome, Central Nervous System, Biotechnology Companies, Nervous System Diseases, Somatosensory Disorders, Neurologic Manifestations.

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Source: Biotech Business Week


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