AU2017268598B2 - Onset-mitigating high-frequency nerve block - Google Patents

Abstract

Abstract An apparatus is described that comprises an electrode, a waveform generator connected to the electrode, and a 5 controller. The controller is configured to control the waveform generator to deliver a high frequency alternating current (HFAC) waveform to a nerve for nerve conduction block. The HFAC waveform comprises a non-zero amplitude nrloe s block threshold for a time period, after the time 10 period, the amplitude is ramped to an amplitude value that is above the block threshold, and after the amplitude is ramped up, the HFAC waveform continues with the amplitude value that is above the block threshold. The ramped amplitude of the HFAC waveform prevents a secondary onset 15 response reaction. 9736045_1 (GHMatter) P83987.AU.4

Description

ONSET-MITIGATING HIGH-FREQUENCY NERVE BLOCK

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of United States

Provisional Application the same

Frequency

COPYRIGHT

60/983,420 inventors, titled System Nerve Block.

NOTICE

A portion of contains material the disclosure of filed 10-29-2007, by and Method For High copyright owner reproduction disclosure as of it file this patent document subject to copyright protection. The has no objection to the facsimile document or the patent Patent and Trademark the patent appears in or records, the

Office patent copyright rights whatsoever.

BACKGROUND but otherwise reserves all generation of nerve impulses may be a disabling factor in some medical conditions. For example, uncoordinated motor signals may cerebral palsy, multiple uncoordinated

Unwanted and/or uncoordinated produce spasticity in sclerosis, and other signals may result in functional stroke, conditions .

The conditions unwanted make desired movements .

motor signals in so on, may produce unwanted sensory have the inability to Involuntary including tics, choreas, and movements. Additionally, signals can cause pain. Conventional approaches attempted to intercept unwanted or uncoordinated nerve impulses along the nerves on which they travel to attempt to reduce and/or eliminate the disabling condition.

Conventional these conditions

For example, drug approaches associated with have produced unsatisfactory treatments may have produced treating results .

unwanted

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2017268598 19 Feb 2019 side-effects, may have acted globally on the body rather than specifically on a specific nerve, and may have been neither quick acting nor quickly reversible. While chemical treatments (e.g., Botox, phenol blocks), may be 5 applied more specifically, they may have been destructive to the nerve, may have required reapplication, and may not have been quickly reversible. Other conventional treatments for pain (e.g., transcutaneous electrical nerve stimulation (TENS), implantable pain stimulators) have 10 also produced sub-optimal results.

Both alternating current (AC) and direct current (DC) nerve stimulation are known in the art. The inhibitory effect of high-frequency alternating current (HFAC) on nerves has been reported since the early 1900' s.

Additionally, DC electrical nerve stimulation has been illustrated to produce a nearly complete block of nerve activity. However, conventional DC stimulation has damaged both body tissues and/or electrodes when delivered over prolonged periods of time. Thus conventional DC 20 stimulation has been unsuitable for certain applications.

The damage caused by a DC nerve block is due, at least in part, to unbalanced charge applied to the nerve. HFAC, which delivers a zero net charge to the tissue is likely to be safer as a method for nerve block. However, when

2 5 HFAC is	delivered to a	nerve, it causes	a burst	of
activity	in	the nerve that	is undesirable and	likely to	be
painful.		The burst of	activity produced	by HFAC	is
referred	to	as the onset activity.
SUMMARY

In accordance with a first aspect of the present invention, there is provided a system, comprising: at least one sensor to detect a signal from a biological component, wherein the signal is indicative of a biological process;

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2017268598 19 Feb 2019 a controller coupled to the at least one sensor to receive an indication of the signal from the at least one sensor and comprising a processor to determine whether nerve block is required by the biological process based on 5 the indication of the signal from the at least one sensor;

a waveform generator coupled to the controller to configure a nerve block signal when the controller sends instructions indicating that the nerve block is required by the biological process; and an electrode coupled to the waveform generator to apply the nerve block signal to a nerve associated with the biological process, wherein the electrode comprises at least two electrode contacts, wherein the nerve block signal comprises a first waveform delivered to one of the at least two electrode contacts and a second waveform delivered to another of the at least two electrode contacts, and wherein the first waveform is the at least two electrode the first waveform is the at least two electrode applied through the one of contacts for a first time; applied through the one of contacts and the second waveform is applied through the other of the at least two electrode contacts together for a second time, wherein the second time is sufficient for the first waveform to block an onset response associated with application of the second waveform; and the second waveform is applied through the other of the at least two electrode contacts for a third time.

In accordance with a second aspect of the present invention, there is provided a method comprising:

detecting, by a sensor, a signal from a biological component, wherein the signal is indicative of a biological process;

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2017268598 19 Feb 2019 receiving, by a controller, an indication of the signal from the at least one sensor;

determining whether nerve block is required by the biological process based on the indication of the signal 5 from the at least one sensor;

configuring, by a waveform generator, a nerve block signal in response to instructions from the controller indicating that the nerve block is required by the biological process; and applying, by an electrode, the nerve block signal to a nerve associated with the biological process, wherein the electrode comprises at least two electrode contacts, wherein the nerve block signal comprises a first waveform delivered to one of the at least two electrode contacts and a second waveform delivered to another of the at least two electrode contacts, and wherein the first waveform is the at least two electrode the first waveform is the at least two electrode applied through the one of contacts for a first time; applied through the one of contacts and the second waveform is applied through the other of the at least two electrode contacts together for a second time, wherein the second time is sufficient for the first waveform to block an onset response associated with application of the second waveform; and the second waveform is applied through the other of the at least two electrode contacts for a third time.

Also disclosed is an apparatus, comprising:

an electrode;

a waveform generator connected to the electrode; and a controller configured to control the waveform generator to deliver a high frequency alternating current (HFAC) waveform to a nerve for nerve conduction block, wherein the HFAC waveform comprises:

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	a non-zero amplitude below a block threshold for a time period; after the time period, the amplitude is ramped to an amplitude value that is above the
5	block threshold; after the amplitude is ramped up, the HFAC waveform continues with the amplitude value that is above the block threshold; wherein the ramped amplitude of the HFAC waveform
10	prevents a secondary onset response reaction. A method is described that comprises: providing one or more transition waveforms to a nerve to manage an onset activity in the nerve; and
15	providing at least one steady-state waveform to block nerve signal transmission in the nerve. An apparatus is described that comprises: an electrode;
20	a waveform generator connected to the electrode; and a controller configured to: first control the waveform generator to generate a DC ramp and to apply the DC ramp to a nerve through the electrode;
25	then control the waveform generator to generate a first alternating waveform and to apply the first alternating waveform to the nerve through the electrode, where the first alternating waveform has an increasing amplitude, and where the first
30	alternating waveform has one of, a cathodic offset, and an anodic offset; then control the waveform generator to generate a second alternating waveform and to apply the second alternating waveform to the nerve through the
35	electrode, where the second alternating waveform has one of, a cathodic offset that ramps to zero, and an anodic offset that ramps to zero;

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2017268598 19 Feb 2019 then control the waveform generator to generate a steady state, HFAC waveform and to apply the steady state HFAC waveform to the nerve through the electrode .

An apparatus is described that comprises:

an electrode;

a waveform generator connected to the electrode; and a controller configured to:

control the waveform generator to first apply a first high frequency alternating current (HFAC) to a nerve through the electrode, the first HFAC having a first amplitude and a first frequency, the combination of the first amplitude and the first frequency being configured to produce a conduction block in the nerve, where the conduction block blocks transmission of signals through the nerve;

control the waveform generator to then apply a second HFAC to the nerve, the second HFAC having a second amplitude and a second frequency, the combination of the second amplitude and the second frequency being configured to not produce a nerve conduction block in the nerve, the combination of the second amplitude and the second frequency being configured to prevent the occurrence of an onset condition in the nerve upon the application of a third HFAC sufficient to produce a conduction block in the nerve; and control the waveform generator to then apply the third HFAC to the nerve, the third HFAC having a third amplitude and a third frequency, the combination of the third amplitude and the third frequency being configured to produce a conduction block in the nerve.

An apparatus is described that comprises:

an electrode;

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	a waveform generator connected to the electrode; and a controller configured to: control the waveform generator to first apply a direct current (DC) to an axon of a nerve, the DC
5	having a first DC amplitude, the DC having the first amplitude not being sufficient to produce a nerve block in the axon; then control the waveform generator to alter the DC over a first period of time by changing the first
10	DC amplitude to a second DC amplitude, the DC having the second DC amplitude being sufficient to produce a conduction block in the nerve; then control the waveform generator to apply a high frequency alternating current (HFAC) to the
15	nerve, the HFAC having an HFAC amplitude and an HFAC frequency, the HFAC being configured to produce a conduction block in the nerve; and then, after a second period of time sufficient to block an onset activity in the nerve associated
20	with the HFAC and the DC, control the waveform generator to alter the DC over a third period of time by changing the second DC amplitude to a third DC amplitude, the DC having the third DC amplitude not being sufficient to produce a conduction block in the
25	nerve; wherein the combination of the DC and the HFAC and the order in which the DC and the HFAC are applied reduce an onset activity in the nerve associated with producing a conduction nerve block
30	when compared to the onset activity in the nerve if only the HFAC was applied and wherein the second period of time is short enough so that the DC does not cause damage to the electrode or surrounding tissue.

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BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate various example systems, methods, and other example 5 embodiments of various aspects of the invention. It will be appreciated that the illustrated element boundaries (e.g., boxes, groups of boxes, or other shapes) in the figures represent one example of the boundaries. One of ordinary skill in the art will appreciate that in some 10 examples one element may be designed as multiple elements or that multiple elements may be designed as one element. In some examples, an element shown as an internal component of another element may be implemented as an external component and vice versa. Furthermore, elements 15 may not be drawn to scale.

	Figure 1 associated with	illustrates	an	open	loop	apparatus
a	nerve block.
	Figure 2		illustrates	an	open	loop	apparatus
	associated with	a	nerve block.
20	Figure 3		illustrates	a	closed	loop	apparatus
	associated with	a	nerve block.
	Figure 4		illustrates	a	closed	loop	apparatus
	associated with	a	nerve block.
	Figure 5	illustrates a	combination	of DC	and HFAC
25	associated with	an onset-mitigating nerve	block .
	Figure 6	illustrates a	method associated	with an

onset-mitigating nerve block.

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Figure 7 illustrates	an	HFAC	associated	with	an
onset-mitigating nerve block.
Figure 8 illustrates onset-mitigating nerve block.	an	HFAC	associated	with	an
5 Figure 9 illustrates onset-mitigating nerve block.	an	HFAC	associated	with	an
Figure 10 illustrates	an	HFAC	associated	with	an

onset-mitigating nerve block.

Figure 11 illustrates a method associated with 10 providing a nerve conduction block where an onset response is mitigated.

Figure 12 illustrates a method associated with providing a nerve conduction block where an onset response is mitigated.

Figure 13 illustrates an apparatus associated with providing a nerve conduction block where an onset response is mitigated.

DETAILED DESCRIPTION

Example systems, methods, and apparatus produce a nerve block using HFAC waveforms. The block produced by HFAC waveforms is a conduction block in the nerve, and not simply a fatigue block. The block may be referred to as a nerve conduction block. The block is not a result of the nerve being stimulated until it is too fatigued to respond and can no longer recover before the next pulse. The HFAC waveforms block conduction through the nerves by blocking signal transmission through the axon. Unlike a chemical block, which interrupts the transmission of a

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2017268598 19 Feb 2019 chemical signal from the ends of one nerve to the ends of another, an HFAC nerve conduction block prevents the axon of the nerve from transmitting any signals past the area of the block. The block is based on how electrical 5 currents produce activation or block nerve conduction through their influence on the voltage-gated ion channels in the nerve membrane.

HFAC waveforms depolarize the nerve membrane causing the inactivation gates to close. The biophysical mechanism that produces the onset response is based on the effect of the depolarizing current on the nerve membrane. In general, depolarizing the nerve membrane triggers the opening of the fast sodium ion channels, initiating an action potential. Placing the nerve in an alternating 15 current depolarizing field, however, actually results in conduction failure, because it forces the inactivation sodium ion gate to remain closed. Therefore, depolarization is involved in both activating and blocking nerve conduction. It is this dichotomy of action that 20 produces the onset response.

There are two phases of the onset response. The first phase is a summated twitch response that occurs in those nerve fibers to which an AC near or above the block threshold is being applied. The block threshold is 25 defined as the voltage below which a complete block is not obtained. The block threshold increases with frequency. The block threshold generally varies inversely with axon diameter. In addition, the block threshold varies approximately as the square of the perpendicular distance 30 to the axon from the electrode. When the electrode is closer than one millimeter to the axon, the electrode position along the length of the axon also affects the amplitude of the block threshold.

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Once the initial firing is over, which generally occurs in approximately 20 milliseconds, these axons are blocked. The second phase is a period of repetitive firing that can last many seconds. This second phase is not always present and tends to be significantly reduced with higher amplitudes of HFAC. This second phase may be due to the repetitive firing of axons that are on the fringes of the current spread from the electrode. Eventually, the firing in these fibers comes to a stop.

The amplitude of the electrical signal decreases with distance from the electrode. A decrease in the second phase at higher amplitudes may be related to higher amplitudes placing more of the nerve fiber completely within the region that provides sufficient amplitude to produce the block. Since the current gradients are sharper, fewer fibers are within the amplitude region that produces repetitive firing.

Eliminating the undesired onset entirely involves eliminating both phases of the onset response. The 20 repetitive phase can be reduced by adjusting amplitude and frequency. For example, a 30 kilohertz, 10 volts peak-topeak sinusoidal waveform may eliminate the repetitive phase. Generally it is not possible to eliminate the entire onset response by changing frequency and amplitude 25 alone.

Recall that the damage caused by a DC nerve block is due to the charge imbalance applied to the nerve. Therefore, example systems, methods, and apparatus balance charge using AC. Balancing the charge prevents and/or 30 minimizes damage caused by unbalanced charges. A pure AC nerve block typically produces an onset response from the nerve on start-up. Thus some examples described and claimed herein first apply DC to a nerve and then subsequently apply an HFAC nerve block. The combination 35 of DC and HFAC is crafted to prevent the occurrence of the

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2017268598 19 Feb 2019 onset response in the nerve to be blocked. Conventional approaches conduction typically employing an HFAC waveform as a nerve block produce the onset response unacceptable in the application that is of HFAC waveforms to human patients .

High-frequency, as used herein with reference to alternating current (e.g., HFAC), refers to frequencies above approximately 1 kiloHertz. In some examples, highfrequency refers more specifically to 5 to 50 kiloHertz .

Example systems, methods, and apparatus described herein employ a waveform having an amplitude of approximately 4 to 10 volts per pulse. Example systems, methods, and apparatus described herein employ a waveform having a current of about 1 milliamp to about 12 milliamps. Within 15 these voltage and amperage ranges, a waveform having a higher frequency will generally require a higher amplitude to provide an effective block.

Examples described herein may have application in areas including motor nerve block, sensory nerve block, 20 and autonomic block. Additionally, examples described herein may be applied in an open loop configuration where the block is controlled through a switch and/or in a closed loop configuration where the block is controlled automatically through a sensor (s) .

Figure 1 illustrates an example apparatus 20 associated with blocking transmission in a nerve. Apparatus 20 includes an electrode 22 connected to a controller 24 suitable for delivering HFAC and/or both DC and HFAC signals to a nerve 26. Apparatus 20 has an open 30 loop configuration where the controller 24 includes a switch to control application of the block. This configuration of apparatus 20 may facilitate controlling, for example, muscle spasticity. Apparatus 20 may apply the HFAC through a set of HFAC electrodes 22 on the motor

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2017268598 19 Feb 2019 branches of the nerve 26. This facilitates targeting a specific muscle associated with nerve 26 to facilitate relaxing that muscle. In one example, apparatus 20 may provide a sternocleidomastoid block useful for treating 5 torticollis.

Figure 2 illustrates an apparatus 30 used, for example, to block neuroma pain, pain associated with a missing appendage, pain associated with a damaged appendage, and so on. Apparatus 30 may, therefore, 10 produce a median nerve block. Apparatus 30 comprises an

HFAC blocking electrode 32 and an implantable controller 34. The blocking electrode 32 may be positioned adjacent to a nerve proximal to a neuroma. In this application, the nerve block can be delivered continuously, can be 15 triggered using an external signal device 36, and so on.

Figure 3 illustrates an apparatus 40 that provides a motor block. The motor block may be triggered by a recorded signal. Apparatus 40 is a closed-loop system and is illustrated in an application to block intractable 20 hiccups. Indicia (e.g., biological signals) associated with an impending hiccup may be recorded via a sensor 42. In one example, the indicia may appear as a large signal on the phrenic nerve. This signal may control triggering a controller 44 to apply an HFAC block to the phrenic 25 nerve. The block may be administered using an electrode 46 adjacent to the phrenic nerve. The HFAC block prevents diaphragm contraction for a brief period, which interrupts and/or preempts signals that cause the diaphragm to hiccup .

Signals associated with moving a muscle may be recorded when a user intends to move that muscle. The signals may be propagated along a nerve. These signals may facilitate controlling spastic muscles in stroke patients, patients having multiple sclerosis, patients

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2017268598 19 Feb 2019 having cerebral palsy, and so on. In one example, signals may be recorded from both spastic muscles and non-spastic muscles. Therefore, figure 4 illustrates an apparatus 50 that includes a controller 52. Controller 52 comprises a 5 recorder for recording and processing signals from sensors in muscles 56 and/or nerves that control muscles 56.

The controller 52 controls a signal generator 58 to apply an HFAC waveform to an electrode 60 adjacent a nerve that controls muscles 56.

Spasticity reduces function in muscles. However, improved function may be achieved by producing a partial block of undesired motor activity. Thus, example apparatus, methods, and so on, may be configured to quickly reverse an HFAC block. In one example, improved 15 function may be achieved by combining an HFAC block with an intelligent control system that varies the nerve block based on sensed activity including, for example, nerve activity, muscle activity, and so on.

Example systems, methods, and apparatus may produce 20 at least three categories of no-onset and/or onsetmitigating HFAC block solutions. In a first example, separate onset-blocking electrodes apply a DC block on either side of the HFAC electrodes. In a second example, charge-balanced transitory variations of a HFAC waveform 25 produce a no-onset and/or onset-mitigating HFAC block. In a third example, charge-imbalanced transitory variations of the HFAC waveform produce a no-onset and/or onsetmitigating HFAC block.

Figure 5 illustrates a combination of a DC waveform 30 510 and an HFAC waveform 520 to produce an HFAC block. In one example, the DC waveform 510 and the HFAC waveform 520 are provided using separate electrodes. In one example, DC waveforms and HFAC waveforms are provided through a single set of electrodes. The charge in the DC waveform

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510 is ramped up in region 512 before the HFAC waveform

520 is turned on. The DC waveform 510 in region 514 has amplitude sufficient to provide a DC block, which will block the onset response from the HFAC waveform 520. The

DC waveform 510 is ramped down in region 514 once the onset activity is complete. Unlike the charge-imbalanced waveforms discussed below, this ramped DC waveform 510 allows the onset activity caused by the HFAC waveform 520 to occur, but prevents that onset activity from 10 propagating. Although continuous delivery of DC at this level can damage the electrodes that deliver the DC and nearby tissue, infrequent brief application of the DC block may not cause such damage. In one example, the DC block is delivered for approximately 100 to 200 milliseconds each time the

HFAC block is turned on.

Since a DC block can example the DC combined into

This five-pole electrodes for for HFAC.

three-pole be produced electrodes by monopolar electrodes, and the HFAC electrodes a single five-pole nerve cuff nerve cuff electrode may include direct

A further nerve cuff rn one may be electrode .

two outer current and three inner form of the electrode may electrodes utilize a electrode in which the DC and HFAC are superimposed on the outer electrodes.

Figure 6 illustrates a method associated with onset25 mitigating HFAC. Method 600 includes, at 610, applying a first waveform to a nerve to alter onset activity in that nerve. Method 600 also includes, at 620, applying a second transitory wave to the nerve. Method 600 also includes, at 630, applying a third steady state wave to the nerve to continue the HFAC block in the nerve.

Figure 7 illustrates a charge-balanced approach that includes applying a rapid onset block above the block threshold and accepting the initial onset response. In this approach, the amplitude is then lowered below the 35 block threshold but maintained high enough to avoid the

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2017268598 19 Feb 2019 zone of repetitive firing. The previously blocked nerve can conduct normally through the region of HFAC delivery at this amplitude. Then, when a block is desired, the amplitude is ramped up to the block threshold. In this 5 example, the block can be achieved without further firing and thus with no additional onset response. This method maintains a zero net charge but requires that the waveform be delivered even when a block is not needed. In this example, the onset still occurs when the system is first 10 turned on. This method may be employed, for example, in stroke applications. In this environment there may be periods of rapid modulation of the block during functional tasks. This amplitude-modulation method may be suitable in this environment because it can produce a quick 15 transition between block and no-block conditions. During periods of inactivity, the block can be turned off.

However the block can be re-initiated prior to activity using one of the onset-blocking alternatives.

Figure 8 illustrates applying an HFAC waveform 810 20 with an initial offset charge. The HFAC waveform 810 is then ramped up to a charge-balanced average. This type of charge-imbalanced transitory variation may eliminate the onset response. The HFAC waveform 810 is initially charge-imbalanced, and then transitions to a charge25 balanced waveform over a period of tens of milliseconds or longer. This achieves a brief period of effective direct current. In figure 8, both the amplitude of the HFAC waveform 810 and the amount of offset are ramped toward the charge-balanced waveform.

Figure 9 illustrates another HFAC waveform 910 for producing a nerve block. This is a second example that uses charge-imbalanced waveforms to eliminate and/or mitigate the onset response and relies on the virtual electrode zones that develop during monophasic activation.

For sufficiently large depolarizing monophasic pulses, the

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2017268598 19 Feb 2019 initial action potentials associated with an onset response are blocked in the adjacent virtual anodes. This may be referred to as an anodal surround block. Using this feature, the HFAC block will start with a monophasic 5 waveform that produces an anodal surround block starting with the first pulse delivered. Subsequently, the chargeimbalance is decreased to achieve balance. The steady state condition is a charge-balanced HFAC waveform that maintains the block. The transitory portion of this 10 waveform lasts approximately 100 milliseconds or longer and is robust across axon diameters and electrode distances .

Figure 10 illustrates another waveform 1010 for producing a nerve block. Waveform 1010 starts with a 15 ramped cathodic or anodic direct current. While the term ramped is used herein, one skilled in the art will appreciate that more generally the waveform may include linear and/or non-linear increases in DC and/or HFAC amplitude. Thus, ramped or ramping are not to be 20 interpreted as requiring a linear increase up to some level. An HFAC waveform is started after a period where the ramped direct current is applied. The HFAC waveform has its amplitude increased until it reaches a block threshold. At this point, the DC offset is ramped down 25 until the whole waveform is charge-balanced, thus allowing the HFAC block to be established without onset action potentials. In one example, the DC offset peak is in the range of approximately ten percent of the HFAC amplitude. In one example, the total time during which the DC is 30 applied is about 80 milliseconds. The total time includes the DC ramp-up, the DC plateau, and the DC ramp down.

Some portions of the detailed descriptions that follow are presented in terms of algorithms. These algorithmic descriptions and representations are used by 35 those skilled in the art to convey the substance of their

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2017268598 19 Feb 2019 work to others. An algorithm, here and generally, is conceived to be a sequence of operations that produce a result. The operations may include physical manipulations of physical quantities. The physical manipulations create 5 a concrete, tangible, useful, real-world result.

Example methods may be better appreciated with reference to flow diagrams . For purposes of simplicity of explanation, the illustrated methodologies are shown and described as a series of blocks. However, it is to be 10 appreciated that the methodologies are not limited by the order of the blocks, as some blocks can occur in different orders and/or concurrently with other blocks from that shown and described. Moreover, less than all the illustrated blocks may be required to implement an example 15 methodology. Blocks may be combined or separated into multiple components. Furthermore, additional and/or alternative methodologies can employ additional, not illustrated blocks.

Figure an HFAC nerve

1110, applying illustrates a method 1100 associated with conduction block. Method

1100 includes, at a first

HFAC to an axon of a nerve. The first HFAC will have a first amplitude, a first frequency, and a first current.

The combination of amplitude, frequency, conduction conduction through the and current rs block in the block actually axon .

configured to produce axon .

blocks a nerve

Recall that transmission of a nerve signals

Method 1100 also includes, at 1120, applying a second HFAC to the axon. The second HFAC has a second amplitude, 30 a second frequency, and a second current. This combination of amplitude, frequency, and current will not produce a nerve conduction block in the axon. However, this combination of amplitude, frequency, and current will prevent the occurrence of an onset condition in the axon

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2017268598 19 Feb 2019 upon the application of a third HFAC that is sufficient to produce a nerve conduction block in the axon. One skilled in the art will appreciate that the third HFAC may be similar to or identical to the first HFAC.

Thus, method 1100 also includes, at 1130, applying a third HFAC to the axon. The third HFAC has a third amplitude, a third frequency, and a third current. This combination of the third amplitude, the third frequency, and the third current will produce a nerve conduction 10 block in the axon. However, it will do so with less onset activity than would otherwise be incurred.

In one example, kiloHertz range of the first and third all three frequencies are to 100 kiloHertz. In one in the frequencies are second frequency is different. In one amplitude and the third amplitude are example, and the the same, example, the first in the range of 4 volts peak-to-peak to 10 volts peak-to-peak. In one example, the first current and the third current are in the range of 1 milliamp to 12 milliamps. One skilled in 20 the art will appreciate that various combinations of frequency, amplitude, and current can produce a nerve conduction block. The nerve conduction block may be, for example, a motor nerve block, a sensory nerve block, an autonomic block, and so on. The nerve conduction block may be applied to treat symptoms of torticollis, neuroma pain, hiccups, cerebral palsy, muscular dystrophy, stroke, and so on. The nerve conduction block may be, for example, a sternocleidomastoid block, a median nerve block, a phrenic nerve block, a modulated spasticity 30 block, and so on.

Method 1100 may be controlled to selectively apply the first HFAC, the second HFAC, and/or the third HFAC based, at least in part, on a control signal received from an open loop control apparatus. The control signal may be

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2017268598 19 Feb 2019 received, for example, from a switch. Similarly, method 1100 may be controlled to selectively apply the first HFAC, the second HFAC, and/or the third HFAC based, at least in part, on a control signal received from a closed 5 loop control apparatus. The closed loop control apparatus may be, for example, a sensor. Method 1100 may also be controlled to selectively alter the frequency, voltage, and current of an HFAC based on inputs from an open loop apparatus and/or a closed loop apparatus.

In different examples, the first HFAC, the second

HFAC, and/or the third HFAC may initially be unbalanced with respect to charge. Thus, method 1100 may include balancing, over a period of time, the charge of an initially unbalanced HFAC. In one example, method 1100 15 may include varying the amplitude of the unbalanced HFAC over time while the charge is being balanced.

Figure 12 illustrates a method 1200 associated with an HFAC nerve conduction block. Method 1200 includes, at 1210, first applying a direct current (DC) to an axon of a 20 nerve. This DC will have a first DC amplitude that is not sufficient to produce a nerve block in the axon. Method 1200 then proceeds, at 1220, to increase the first DC amplitude over a period of time. The first DC amplitude is increased to a second DC amplitude that is sufficient 25 to produce a nerve block in the axon.

Method 1200 then proceeds, at 1230, to apply an HFAC to the axon. The HFAC has an HFAC amplitude, an HFAC frequency, and an HFAC current. The combination of frequency, amplitude, and current is designed to produce a 30 nerve conduction block in the axon. Note that the HFAC is applied after the DC has been ramped up to a desired level. Method 1200 then proceeds, at 1240, to decrease the second DC amplitude to a third DC amplitude over a period of time. The DC having the third DC amplitude is

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2017268598 19 Feb 2019 not sufficient to produce a nerve block in the axon. Thus, method 1200 provides a combination of the DC and the HFAC in an order that reduces an onset activity that is observed in the nerve either proximally or distally to the 5 blocking electrode or electrodes .

In one example, the DC offset peak is between five percent and fifteen percent of the HFAC amplitude. In one example, the first period of time and the second period of time during which the DC is ramped up and then ramped down 10 collectively comprise less than 80 milliseconds. In another example, the first period of time is between 100 milliseconds and 200 milliseconds, and the second period of time is between 100 milliseconds and 200 milliseconds.

Figure 13 illustrates an apparatus 1300 associated 15 with an HFAC nerve conduction block. Apparatus 1300 includes an electrode 1310 and a waveform generator 1320 connected to the electrode. Apparatus 1300 also includes a controller 1330. Controller 1330 is to control the

waveform	generator	1320	to	apply DC	and/or HFAC	as
20 described	in connection	with	method	1100 (Figure	11)
and/or method 1200	(Figure	12) .	In one	example, apparatus
1300 may	include a	switch	1340	to selectively control	the

controller 1330 and/or the waveform generator 1320. In another example, apparatus 1300 may include a sensor 1350 25 to selectively control the controller 1330 and/or the waveform generator 1320. In one example, the electrode

1310 may have five nodes. The five nodes may include a set of two inner nodes for applying an HFAC and a set of three outer nodes for applying a DC.

References to one embodiment, an embodiment, one example, an example, and so on, indicate that the embodiment (s) or example (s) so described may include a particular feature, structure, characteristic, property, element, or limitation, but that not every embodiment or

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2017268598 19 Feb 2019 example necessarily includes that particular feature, structure, characteristic, property, element or limitation. Furthermore, repeated use of the phrase in one embodiment does not necessarily refer to the same 5 embodiment, though it may.

While example systems, methods, and so on have been illustrated by describing examples, and while the examples have been described in considerable detail, it is not the intention of the applicants to restrict or in any way 10 limit the scope of the appended claims to such detail. It is, of course, not possible to describe every conceivable combination of components or methodologies for purposes of describing the systems, methods, and so on described herein. Therefore, the invention is not limited to the 15 specific details, the representative apparatus, and illustrative examples shown and described. Thus, this application is intended to embrace alterations, modifications, and variations that fall within the scope of the appended claims.

To the extent that the term or is employed in the detailed description or claims (e.g., A or B) it is intended to mean A or B or both. When the applicants intend to indicate only A or B but not both then the term only A or B but not both will be employed. Thus, use of the term or herein is the inclusive, and not the exclusive use. See, Bryan A. Garner, A Dictionary of Modern Legal Usage 624 (2d. Ed. 1995) .

To the extent that the phrase one or more of, A, B, and C is employed herein, (e.g., a data store configured 30 to store one or more of, A, B, and C) it is intended to convey the set of possibilities A, B, C, AB, AC, BC, ABC, AAA, AAB, AABB, AABBC, AABBCC, and so on (e.g., the data store may store only A, only B, only C, A&B, A&C, B&C, A&B&C, A&A&A, A&A&B, A&A&B&B, A&A&B&B&C, A&A&B&B&C&C, and

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2017268598 19 Feb 2019 so on). It is not intended to require one of A, one of B, and one of C. When the applicants intend to indicate at least one of A, at least one of B, and at least one of C, then the phrasing at least one of A, at least one of B, 5 and at least one of C will be employed.

It is to be understood that, if any prior art publication is referred to herein, such reference does not constitute an admission that the publication forms a part of the common general knowledge in the art, in Australia 10 or any other country.

In the claims which follow and in the preceding description of the invention, except where the context requires otherwise due to express language or necessary implication, the word comprise or variations such as 15 comprises or comprising is used in an inclusive sense,

i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention.

Claims (18)

1. THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS:

   1. A system, comprising:

   at least one sensor to detect a signal from a

   5 biological component, wherein the signal is indicative of a biological process;

   a controller coupled to the at least one sensor to receive an indication of the signal from the at least one sensor and comprising a processor to determine whether

   10 nerve block is required by the biological process based on the indication of the signal from the at least one sensor;

   a waveform generator coupled to the controller to configure a nerve block signal when the controller sends instructions indicating that the nerve block is required 15 by the biological process; and an electrode coupled to the waveform generator to apply the nerve block signal to a nerve associated with the biological process, wherein the electrode comprises at least two electrode contacts,

   20 wherein the nerve block signal comprises a first waveform delivered to one of the at least two electrode contacts and a second waveform delivered to another of the at least two electrode contacts, and wherein the first waveform is the at least two electrode the first waveform is the at least two electrode applied through the one of contacts for a first time; applied through the one of contacts and the second waveform is applied through the other of the at least

   30 two electrode contacts together for a second time, wherein the second time is sufficient for the first waveform to block an onset response associated with application of the second waveform; and the second waveform is applied through the other

   35 of the at least two electrode contacts for a third time .

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   2017268598 19 Feb 2019
2. 2. The system of claim 1, wherein the biological process is related to at least one of torticollis, neuroma

   5 pain, hiccups, muscular dystrophy, cancer pain, postoperative pain, chronic pain, pain, and stroke.
3. 3. The system of claim 1 or claim 2, further comprising at least two sensors, each to detect different

   10 signals from one or more biological components.
4. 4. The system of claim 3, wherein the controller is coupled to the at least two sensors and the processor determines whether nerve block is required by the

   15 biological process based on indications of the different signals from the at least two sensors.
5. 5. The system of claim 4, wherein the electrode comprises at least two contacts, and the controller

   20 instructs a respective one of the at least two contacts to apply the nerve block signal based on the indications of the different signals from the at least two sensors.
6. 6. The system of any one of the preceding claims,

   25 wherein the nerve block is one or more of an efferent neuron block, an afferent neuron block, and an interneuron block.
7. 7. The system of any one of the preceding claims,

   30 wherein the controller signals a switch between the waveform generator and the electrode to close when the controller determines that nerve block is required by the biological process.

   35
8. 8. The system of claim 7, wherein the controller signals the switch to open after expiration of a time for application of the block.

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9. 9. The system of any one of the preceding claims, wherein the first waveform comprises a direct current (DC) waveform and the second waveform comprises a high

   5 frequency alternating current (HFAC) waveform.
10. 10. The system of claim 9, wherein the DC waveform is ramped to a peak, the peak is applied for a time, and ramps down from the peak, wherein the HFAC waveform is

    10 applied during the peak and continued for a time after the DC ramps down.
11. 11. The system of any one of claims 1 to 8, wherein the first waveform and the second waveform comprise at

    15 least two HFAC waveforms, one of the at least two HFAC waveforms comprising an amplitude not sufficient to provide the nerve block and the other HFAC waveform comprising an amplitude sufficient to provide the nerve block.
12. 12. A method comprising:

    detecting, by a sensor, a signal from a biological component, wherein the signal is indicative of a biological process;

    25 receiving, by a controller, an indication of the signal from the at least one sensor;

    determining whether nerve block is required by the biological process based on the indication of the signal from the at least one sensor;

    30 configuring, by a waveform generator, a nerve block signal in response to instructions from the controller indicating that the nerve block is required by the biological process; and applying, by an electrode, the nerve block signal to

    35 a nerve associated with the biological process, wherein the electrode comprises at least two electrode contacts,

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    2017268598 19 Feb 2019 wherein the nerve block signal comprises a first waveform delivered to one of the at least two electrode contacts and a second waveform delivered to another of the at least two electrode contacts, and

    5 wherein the first waveform is the at least two electrode the first waveform is the at least two electrode applied through the one of contacts for a first time; applied through the one of contacts and the second

    10 waveform is applied through the other of the at least two electrode contacts together for a second time, wherein the second time is sufficient for the first waveform to block an onset response associated with application of the second waveform; and

    15 the second waveform is applied through the other of the at least two electrode contacts for a third time .
13. 13. The method of claim 12, wherein the first

    20 waveform comprises a direct current (DC) waveform and the second waveform comprises a high frequency alternating current (HFAC) waveform.
14. 14. The method of claim 12, wherein the first

    25 waveform and the second waveform comprise at least two HFAC waveforms, one of the at least two HFAC waveforms comprising an amplitude not sufficient to provide the nerve block and the other HFAC waveform comprising an amplitude sufficient 30 to provide the nerve block.
15. 15. The method of any one of claims 12 to 14, wherein the biological process is related to at least one of torticollis, neuroma pain, hiccups, muscular dystrophy,

    35 cancer pain, post-operative pain, chronic pain, pain, and stroke .

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16. 16. The method of any one of claims 12 to 15, wherein the nerve block is one or more of an efferent neuron block, an afferent neuron block, and an interneuron block.

    5
17. 17. The method of any one of claims 12 to 16, further comprising signaling, by the controller, a switch between the waveform generator and the electrode to close when the controller determines that nerve block is required by the biological process.
18. 18. The method of claim 17, further comprising signaling, by the controller, the switch to open after expiration of a time for application of the block.