- 2014-12-01 (x)
- Mortimer, J. Thomas (x)
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Show moreBackgroun of the invention: The present invention relates to the biomedical arts for introducing electrical signals on nerve trunks. The present invention finds particular application in introducing a string of artifically generated antidromic pulses on the nerve trunk for collision blocking orthodromic pulses moving in the opposite direction along the nerve trunk and will be described with particular reference thereto. It is to be appreciated that the invention may have broader applications and may apply electrical signals on nerve trunks for other purposes. Heretofore, various techniques have been used to block nerve pulses passing along a nerve trunk. A common blocking technique was the application of DC currents on the nerve trunk. However, it has been found that the application of DC currents can be expected to cause nerve damage. To eliminate the DC current induced nerve damage, others have suggested using an oscillating current such that the induced electrical current flowed alternately in both directions along the nerve trunk. It has been found that the application of high frequency stimulation blocks the passage of nerve signals therethrough. It appears that high frequency stimulation may, in effect, be overdriving neuromuscular junctions and depleting the neurotransmitter at the terminal end. That is, rather than blocking the passage of nerve stimuli on the nerve fiber or axon, the high frequency stimulation techniques may be overworking the nerve terminal to the point of exhaustion causing a failure of proper functioning. Yet another blocking technique utilized a three electrode cuff which included a dielectric sleeve having a passage through which the nerve trunk passes. Three annular electrodes were arranged within the sleeve. A cathode was positioned near the center of the passage and a pair of anodes were positioned to either side. A signal generator was connected with the electrodes to apply an electrical pulse train that induced antidromic pulses on the nerve trunk. Each pulse of the pulse train included a rapid rise to a preselected amplitude, a 100 to 3000 microsecond plateau, and an exponential decay back to zero. This pulse train induced artifically generated antidromic pulses on the nerve trunk which traveled unidirectionally in the opposite direction to the normal pulse flow. The artificially generated antidromic pulses collided with and blocked further propagation of natural orthodromic pulses moving in the other direction on the nerve trunk. The application of a series of pulses of common polarity, again has been found to cause damage to neural tissues. To eliminate this nerve damage, others have suggested applying a low amplitude, relatively long duration rectangular wave pulse of opposite polarity between each pulse of the above-described pulse train. The opposite polarity of the rectangular wave pulse balanced the net charge flow caused by the primary pulse.
http://www.google.com/patents?vid=USPAT4608985
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Show moreBackground of the invention: The present invention relates to biomedical electrodes. It finds particular application in electrodes for surrounding a nerve trunk to introduce electrical stimuli thereon for the purpose of generating action potentials that propagate in only one direction from the cuff. The present invention may find other utility. Heretofore, others have used electrical stimuli to create action potentials that in turn cause the release of a neurotransmitter that may result in a measurable physiological response. Many of these prior art stimulation techniques applied the electrical stimuli to peripheral nerves subserving muscle or peripheral sense organs, bypassing the higher levels of the nervous system. It has also been found that electrical signals can be applied to other excitable tissue directly, such as muscle. Although the applied electrical signals can cause the nervous system to activate appropriate muscles or other organ responses, another potentially important use is to block the naturally generated action potentials traveling along a nerve fiber. Specifically, the proper application of electrical signals can block nerve impulses traveling up the nerve trunk toward the brain to arrest pain signals, phantom limb signals in amputees, and the like. Analogously, appropriately generated action potentials can block nerve impulses traveling on the nerve trunk to eliminate nerve impulses which cause unwanted physiological activity. For example, the stimuli can block signals which cause spasmodic behavior, hiccups, and the like. A potential application is to cause the controlled relaxation of the external urinary bladder or sphincter in paralyzed patients who have lost this control. With proper application of electrical signals, a paraplegic with a loss of voluntary bladder control can void the contents of the bladder. Various electrical potentials have been applied between a cathode and an anode to suppress the transmission of unwanted nerve action potentials. Some researches have used DC currents flowing from the anode to the cathode to block natural nerve impulses. Others have used high frequency sinusoidal stimulation to block natural nerve impulses. In the past, electrical stimuli have been applied to the nerves for the purpose of generating unidirectional propagating action potentials with cuffs containing three electrodes. The prior art electrode cuff included a dielectric, i.e., electrically non-conductive, cylindrical tube or sleeve. Three annular electrodes were disposed along the inner surface of the sleeve. A cathode electrode was commonly positioned centrally in the sleeve and a pair of anode electrodes were positioned to either side thereof and displaced from the ends of the sleeve. The electrodes have been utilized to introduce a string of artificially generated antidromic pulses which propagate unidirectionally in the opposite direction to the normal orthodromic pulse flow.
http://www.google.com/patents?vid=USPAT4628942
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Show moreBackground of the invention: The present invention relates to the biomedical arts for introducing electrical signals on nerve trunks. The present invention finds particular application in inducing a stream of artifically generated antidromic pulses on the nerve trunk for collision blocking orthodromic pulses moving in the opposite direction on the nerve trunk and will be described with particular reference thereto. The invention may have broader applications including generating action potentials on nerve trunks for other purposes and monitoring naturally occuring nerve impulses. Various techniques have been used to block nerve pulses passing along a nerve trunk. Commonly, an electrode cuff including a dielectric sleeve and three symmetric electrodes were positioned around a nerve trunk. The three electrodes were arranged symmetrically within the sleeve, with an annular cathode positioned in the center and a pair of annular anodes were positioned to either side. A signal generator was connected with the electrodes to apply an electrical pulse train that induced action potentials on the nerve trunk. One blocking technique was the application of DC currents on the nerve trunk. However, it has been found that the application of DC and unidirectionally pulsed currents induced nerve damage. To eliminate the DC current induced nerve damage, others have used a bipolar current wave forms such that the average electrical charge passed through an electrode is approximately zero. In one technique, a train of pulses was applied to the cuff electrodes. Each pulse of an exemplary pulse train included a rapid rise to a preselected amplitude, a 200 to 1000 microsecond plateau, and an exponential decay back to zero. The ends of the cuff have been defined as the "arrest" end and the "escape" end. No action potential was intended to emerge from the "arrest" end and the colliding pulse emerges from the "escape" end. This pulse train induced artifically generated antidromic pulses traveling unidirectionally on the nerve trunk. The antidromic pulses collided with and blocked orthodromic pulses traveling in the other direction. To eliminate nerve damage that may result from monopolar stimulation, a relatively long duration, low amplitude rectangular pulse of opposite polarity was applied between each pulse of the first polarity pulse train. Although it was intended that current should flow within the cuff from the anodes to the cathode, some current (secondary current) also flowed outside the cuff in the body tissue, creating a virtual cathode along the nerve outside the cuff. This secondary current tended to generate unwanted action potentials near the arrest end of the cuff that traveled along the nerve trunk in the orthodromic or undesired direction.
http://www.google.com/patents?vid=USPAT4649936
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Show moreBackground: The present invention is directed to the art of educational systems. It finds particular application in conjunction with interactive systems which control and facilitate the comprehension of a subject to a student user in dynamically changeable sequences, dynamically changeable knowledge levels, and dynamically customizable authoring of subjects to ensure an up-to-date status of material and will be described with particular reference thereto. The invention will also find application in other educational area in which information is to be presented to a student for comprehension and includes interconnection with directly or indirectly related subject matter. A classroom typically includes a professor, a number of students and a selected textbook containing information that the students are attempting to learn. The professor verbally presents the information to the students in a lecture and uses visual aids such as a blackboard or projector when needed. The lecture is typically limited to a one or two hour time period thus requiring the professor to proceed at a continuous pace in order to cover the subject matter for the day. Students experience a number of problems with the lecture-based form of education. For example, while trying to write down notes, the student fails to hear what is currently being said by the professor and consequently fails to make notes on the material which was not heard. The student may also fail to see a visual aid which is displayed but quickly removed. Information is missed due to the pace of the class and students are not given sufficient time for copying and personalizing notes as desired. The pace of the class also reduces the time students have to ponder and absorb what is being discussed and prohibits students from enhancing their notes by adding more information about their own understanding of what is being discussed. Overall, comprehension of the discussion is often far less than optimal. Another problem exists in most lecture-based classrooms, namely each student has a different level of understanding based on past course work or experiences. Due to the limited time period of a lecture, a professor conducts the discussion at a fairly consistent pace. It is difficult, if not impossible, to accommodate each student's understanding of the discussed topic. For those students who understand the topic, the lecture pace is too slow causing a loss of interest. For those students who do not understand, the lecture pace is too fast causing confusion and eventually frustration. The selected textbook offers no solution for these students because it is written for one narrow range of knowledge. A different textbook must be found and consulted in order for a student to obtain background or elementary information for a selected topic. Likewise, a different textbook must be found and consulted if advanced information is desired.
http://www.google.com/patents?vid=USPAT6091930
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Show moreBackground of the invention: The present invention relates to the electrode art. It finds particular application in conjunction with electrodes for stimulating skeletal muscles and will be described with particular reference thereto. Functional restoration of a paralyzed limb can be achieved through the application of technique known as functional electrical stimulation (FES). In this technique, an electrode is implanted at an appropriate point in one of the patients skeletal muscles. The electrode must be positioned accurately, generally with a tolerance of a couple of millimeters. Once the electrode is implanted, its lead wire is run under tile skin to an exit site or connected to an implanted stimulator or other similar device. Physiological movements are relatively complex, frequently requiring the coordinated operation of numerous muscles. To achieve full functional control, a patient may need as many as 50 or more implanted electrodes. The leads from the plurality of electrodes run through the tissue and the muscles to an exit site or are connected to an implanted stimulator or other similar device. The skeletal muscle tissue environment is much more severe than the environment for brain electrodes, skin surface electrodes, heart electrodes, or the like. The stimulated skeletal muscle is continually contracting and expanding. The implanted electrode moves a relatively large distance with each expansion and contraction relative to movement which brain, skin, or heart electrodes undergo. One problem with the prior art electrodes has been a loosening of the electrodes due to the muscle contraction and expansion. Another significant problem with the prior art electrodes has been failure of the electrode leads attributable in large part to the flexing and stress which they undergo during muscle contraction and expansion. Once the electrodes are implanted and the leads are run under the skin, it is difficult to tell when a lead or electrode has failed. More specifically, electrical continuity of the lead is commonly checked by placing a current into the electrode lead at the interface and completing the circuit with an electrode on the surface of the patient's skin. The patient's muscle, skin, and other tissue between the surface electrode and the implanted electrode has a relatively high impedance. Frequently, it is difficult to distinguish between the high impedance attributable to an electrical break in the lead from the high impedance of the patient tissue. The present invention contemplates a new electrode and lead combination which overcomes the above-referenced problems and others. Summary of the invention: In accordance with the present invention, an FES electrode and lead are formed with a double helix lead. More specifically, the lead includes an insulated conductor which is wrapped spirally around a polymeric core. The polymeric core with spiral wrapped conductor is wrapped into an open helix.
http://www.google.com/patents?vid=USPAT5366493
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Show moreBackground of the invention: The present invention relates to the biomedical arts, particularly implantable cuffs. The present invention finds application in electrodes disposed around nerve trunks and other small tissue strands and will be described with reference thereto. It is to be appreciated that the invention is also applicable to medicinal infusers and other implanted biomedical devices for introducing, monitoring, or removing matter or energy. Functional electrical stimulation of the nervous system has been shown in recent years to offer great hope in restoring some degree of lost sensory and motor function in stroke victims and individuals with spinal cord lesions. Ways in which functional electrical stimulation can be utilized to restore a particular function include: (1) the use of surface electrodes to activate the nerves in the general region of interest; (2) the use of intramuscular electrodes, also to activate the nerves in a general region; and (3) the use of nerve cuff electrodes placed around specific nerves of interest and used to activate them specifically. The third alternative offers advantages over the first two in that it requires the least amount of stimulating current and hence charge injected into the tissue. In addition, it allows easy excitation of entire muscles rather than parts of muscles, a common situation for the first two categories. Because the use of nerve cuff electrodes requires delicate surgery, they are usually contemplated only when: (1) excitation of specific, isolated muscles is desired; or (2) the generation of unidirectional action potentials is required. The prior art cuff electrodes included a cylinder of dielectric material defining a bore therethrough of sufficient diameter to receive the nerve trunk to be electrically stimulated. The cylinder had a longitudinal split or opening for receiving a nerve. During installation, the longitudinal split was sutured or otherwise held closed. Although suturing held the cuff in place, an electric current path was defined through the split which permitted current leakage. Two or three annular electrodes were positioned on the inner surface of the bore for use in applying the electrical stimuli. The electric stimuli, for example, may provide functional electrical stimulation, may block natural nerve pulses traveling along the nerve trunk, or the like. The present invention contemplates a new and improved cuff which is readily installed and removed without damaging the nerve trunk or other tissue. Summary of the invention: In accordance with the present invention, a cuff is provided for encircling a nerve trunk or other body tissue with at least one medication or electrical energy conductive member and a non-conductive sleeve extending to either side of the conductive member. The cuff includes a self-curling sheet of non-conductive material which is self-biased to curl into a tight spiral or roll.
http://www.google.com/patents?vid=USPAT4602624
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Show moreBackground of the invention: The present invention relates to the art of electrical activation of the diaphragm using epimysial electrodes. It is to be appreciated that the invention is also applicable to control other nerve groups through electrical activation using epimysial electrodes. It is possible to support ventilation in patients with chronic ventilatory insufficiency using a diaphragm pacer device. In broad terms, these devices pass a small amount of electric current through a pair of electrodes placed on the diaphragm muscle itself. The current passes through the diaphragm muscle thereby activating the phrenic nerves which are proximate the placement of the electrode pair, on the opposite side of the muscle. A proportion of the current may also pass through tissues other than the phrenic nerve and thus have no effect on the phrenic nerves. Since the proportion of current affecting phrenic nerve activation depends on the distance between the electrode and the phrenic nerves, electrode placement is critical. In any case, by passing the small amount of electric current through the pair of properly placed electrodes on the diaphragm muscle, the phrenic nerves are activated in turn causing a contraction of the diaphragm muscle, the primary muscle used for breathing. The diaphragm muscle contraction draws air into the lungs and the patient is ventilated. Although the above approach appears to be simple, past attempts at diaphragm pacing have met with limited success for a variety of reasons. The general idea of stimulating the phrenic nerve for ventilation was investigated by Sarnoff in the late 1940's (Sarnoff 1948). Sarnoff's work was made a clinical reality by Glenn in the 1960's (Glenn 1973, Glenn 1988). In those systems, the electrodes are "cuffs" made of silicon rubber with platinum stimulating surfaces which are placed directly on the nerve in the neck or thorax. The electrodes themselves may be unipolar or bipolar but the current trend is to implant electrodes of the unipolar type. FIG. 1A illustrates a unipolar electrode 10 for diaphragm pacing. FIG. 1B illustrates a bipolar electrode 20 also for diaphragm pacing. The unipolar electrode 10 includes a first electrode 12 for placement around the phrenic nerve and an anode 14 located somewhere in the body of the patient. A pulse of current is applied to a first connector 16, through the first electrode 12. The current passes through the body tissues into the anode 14 and out of the diaphragm pacing system 10 through a second connector 18. A reversal of the above-described flow occurs for a second current pulse immediately following the first. After a short delay, the pair of current pulses is repeated. This repetition continues as long as diaphragm muscle contraction is desired. Current flowing from the first electrode 12 to the anode 14 or from the anode 14 and to the first electrode 12 stimulates the phrenic nerves inbetween.
http://www.google.com/patents?vid=USPAT5472438
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Show moreBackground of the invention: The present invention relates to the art of selective nerve stimulation. The invention finds particular application in conjunction with urination control and will be described with particular reference thereto. The invention is also applicable to control systems for fecal incontinence, penile erection, and others. The organs involved in bladder, bowel, and sexual function receive much of their control via the second, third, and fourth sacral nerves (S.sub.2, S.sub.3, and S.sub.4). While one level of roots usually predominates for a particular function, there is considerable overlap. For example, the S.sub.3 sacral nerve is the main stimulus for both bladder and rectal wall contraction. Bladder and rectal wall both receive some control also from S.sub.4 and/or S.sub.2 sacral nerves. Sphincters are probably mainly innervated by S.sub.4, although the urethral sphincter has significant contributions from S.sub.3. Hence, there is difficulty in applying artificial stimulus to contract the bladder without contracting the urethral sphincter and to contract the rectum without contracting the anal sphincter. The external urethral sphincter receives stimulation on the sacral ventral roots to cause contraction to block urine flow. To discharge the bladder, in a healthy person, the bladder detrusor muscles are contracted to expel urine simultaneously with relaxing the urethral sphincter to allow the passage of the urine. The contraction of the bladder is also controlled by the sacral ventral roots. More specifically, contraction of the bladder detrusor muscles is caused by smaller diameter S.sub.3 nerves and contraction of the urethral sphincter is controlled by predominantly larger diameter S.sub.3 nerves as well as by S.sub.2 and S.sub.4 nerves which are intermixed in same roots. Previously, electrical stimulation has been applied to control the bladder and bowel. The previous attempts have focused on three techniques: direct stimulation of the detrusor muscle, activation of the detrusor by stimulation of the conus medullaris, and activation of the detrusor by sacral root or nerve stimulation with extensive dorsal rhizotomy. All three of these methods suffer from the same problem. They all cause contraction of the bladder to expel urine concurrently with contraction of the external urethral sphincter blocking urine flow. The rhizotomy technique also results in the loss of erection for the male. It would be advantageous if contraction of the sphincter could be selectively blocked. Techniques that are available for blocking nerve impulses are discussed, for example, in "A Technique for Collision Block of Peripheral Nerve: Single Stimulation Analysis", van den Honert and Mortimer, IEEE Transactions on Biomedical Engineering, Vol. BME-28, No. 5, May 1981, pages 373-378 and "Generation of Unidirectionally Propagated Action Potentials in a Peripheral Nerve by Brief Stimuli".
http://www.google.com/patents?vid=USPAT5199430
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Show moreBackground of the invention: The present invention relates to the biomedical arts, particularly implantable electrodes. The present invention finds particular application in conjunction with cuff electrodes which are self-biased to curl around and snugly engage a nerve trunk, and will be described with particular reference thereto. The invention is also applicable to other types of implanted electrodes and biomedical devices. Many types of nerve tissue damage do not heal. Such injuries leave a patient permanently without an appropriate nerve path for electrical signals or action potentials which travel from the brain to muscles or other biological tissue to cause a biological response. Similarly, such a discontinuity prevents action potentials from carrying sensory information or other biological feedback from the tissues to the brain. Moreover, there is also a tendency for action potentials to commence propagating naturally from below the injury site to the biological tissue causing an unconscious and unwanted biological response. Analogously, action potentials can propagate from above the injury site to the brain causing pain and erroneous sensory feedback. Electrical potentials can be applied to nerve trunks and fibers to block the propagation of action potentials and for controllably initiating the propagation of action potentials in an upstream direction, a downstream direction, or both. Cuff electrodes, such as illustrated in U.S. Pat. No. 4,602,624 to Naples, Sweeney, and Mortimer controllably initiate and/or block action potentials in the nerves. Such cuff electrodes are self-biased to wrap around a nerve trunk in a spiral providing close contact. Because the electrode can be opened flat, it is surgically installed around the nerve fiber without cutting or damaging the nerve. Although these prior art cuff electrodes have proven effective, they do have drawbacks. Primarily, the prior art cuff electrodes are labor intensive to manufacture. Metal foil strips are mounted and adhered to an elastomeric sheet. A second elastomeric sheet is stretched and laminated to the first elastomeric sheet. Apertures are provided in the second, stretched sheet to provide communication with the foil electrodes. Electrical leads are spot welded to the foil electrodes. Interconnecting the leads with the electrodes at the cuff has drawbacks. First, the interconnection tends to increase the bulk of the electrode. Second, a failure of the spot weld requires removal of the electrode and the implantation of a new electrode. Another drawback is that flat and annular sheet surface electrodes do not provide a uniform current density across their entire face. Rather, there tends to be a higher current flux adjacent the edges causing more rapid electrolytic degradation of the electrode edges. This concentration of the electrical flux at the edges accelerates edge degradation and corrosively reduces the size of the electrode.
http://www.google.com/patents?vid=USPAT5324322
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