The present invention relates to methods and apparatus for providing treatment for the symptoms of various diseases, such as Parkinson's Disease (tremors), and in particular to improved methods and apparatus for providing deep brain electrical stimulation.
Parkinson's Disease is a neurodegenerative disorder that causes muscular tremors, stiffness, and slowness of movement. The first line of treatment for Parkinson's is the administration of drugs. Over a period of time, these drugs slowly lose their effect to arrest the symptoms associated with Parkinson's. Once a patient enters a refractory stage of the disease in which drugs are not effective, one alternative treatment option to reduce associated tremors is Deep Brain Stimulation (DBS). DBS can also be used as a part of a treatment plan for other diseases, such as Huntington's disease, dystonia, and epilepsy, among others.
In DBS, one or more probes are implanted in the basal ganglia area of the brain to administer electric pulses that curb Parkinson's symptoms (or the symptoms of the other diseases mentioned above). Although not fully understood, DBS is becoming a more and more widely accepted treatment, with various implantable devices currently being on the market. An example of such a device is the Active Therapy System sold by Medtronic, Inc. of Minneapolis, Minn. (www.medtronic.com/physician/activa/implantable.html). These devices, however, require the implantation of a relatively large battery and control pack in the chest with subcutaneous wires threaded up through the neck to the top of the skull and ultimately to the implanted probes (one or more). The control pack and wires are a common source of irritation and infection, sometimes necessitating long periods of antibiotics or even removal of the device. Furthermore, such devices are susceptible to a limited battery life and magnetic interference. After the average 3- to 5-year lifespan of an implant's battery, another surgery is required to replace the device. Thus, it would be advantageous to be able to provide DBS in a manner that eliminates the intrusive battery pack and wires, as well as the health risks commonly associated with them.
The present invention relates to an apparatus for providing electrical stimulation to the brain of a patient for treating, for example, Parkinson's disease. The apparatus includes one or more probes for being implanted in the patient's brain and for providing electrical pulses to the brain. The apparatus also includes an implantable device for being implanted subcutaneously in the patient's head that has: (i) control circuitry adapted to generate the electrical pulses and provide the electrical pulses to the probes, and (ii) power circuitry for providing a DC power signal to the control circuitry. A power supply separate from the implantable device provided at a stationary location separate from the implantable device and external to the patient's body is also provided. The power supply provides power to the implantable device through a near-field technique, such as near-field inductive coupling, between the power supply and the power circuitry when the power circuitry is in proximity with the power supply. In particular, the power supply preferably includes an oscillator and a primary winding, wherein the oscillator generates a first AC signal and provides the first AC signal to the primary winding. The power circuitry includes a secondary winding, and the first AC signal induces a second AC signal in the secondary winding when the secondary winding is in proximity with the primary winding. The power circuitry converts the second AC signal into the DC power signal. The power circuitry also preferably includes an energy storage device for storing energy for subsequent use by the implantable device, particularly when the implantable device is located a certain distance from the power supply.
The control circuitry preferably includes a programmable processor and a wireless communications device. The programmable processor controls the generation of the electrical pulses based upon one or more pulse parameters. In this embodiment, the apparatus further includes a remote programming device external to the patient's body that is adapted to wirelessly transmit programming signals to the wireless communications device which are then provided to the programmable processor for adjusting the one or more pulse parameters. The one of more pulse parameters may specify one or more of a frequency of the electrical pulses, an amplitude of the electrical pulses, a pulse width of the electrical pulses, an on/off state of the electrical pulses, and an application location (i.e., to which electrodes) of the electrical pulses.
A method of providing electrical stimulation to the brain of a patient is also provided that includes steps of implanting one or more probes into the brain, implanting a device subcutaneously in the patient's head, causing the device to generate electrical pulses and provide the electrical pulses to the one or more probes, and providing power to the device from a stationary location external to the patient's body using a near-field technique, such as near-field inductive coupling. The method may further include selectively wirelessly adjusting the one or more pulse parameters from a second location external to the patient's body.
In another embodiment, the invention relates to a method of treating a neurodegenerative disease, such as Parkinson's Disease, including steps of implanting a device in the head of a patient, causing the device to generate and provide electrical pulses to the brain, and providing power to the device from a stationary location separate from the device and external to the patient's body using a near field technique such as near-field inductive coupling.
It is an object of this invention to provide a method and apparatus for providing deep brain stimulation that does not require an onboard power supply that is implanted within the body of the patient.
It is a further object of this invention to provide a method and apparatus for providing deep brain stimulation that eliminates the problems associated with the subcutaneous wires that are associated with prior art devices.
It is still a further object of this invention to provide a method and apparatus for providing deep brain stimulation that eliminates the battery life and replacement problems associated with prior art devices.
It is still a further object of this invention to provide a method and apparatus for providing deep brain stimulation that is powered by a near-field technique, such as near-field inductive coupling.
It is still a further object of this invention to provide a method and apparatus for providing deep brain stimulation that allows the electrical pulse parameters to be readily and non-intrusively adjusted from outside of the body.
It is still a further object of this invention to provide a method of treating a neurodegenerative disease such as Parkinson's Disease.
The accompanying drawings illustrate presently preferred embodiments of the invention, and together with the general description given above and the detailed description given below, serve to explain the principles of the invention. As shown throughout the drawings, like reference numerals designate like or corresponding parts.
As will be appreciated, the electronic components of the implantable device 10 require power in order to operate. The implantable device 10 does not, however, have an onboard power supply such as a battery. Instead, the embodiment of the implantable device 10 shown in
In particular, in an embodiment where near-field inductive coupling is used, the DBS device 5 includes a separate, external power supply 20 that is, in one particular embodiment, provided in headgear, such as a hat or cap, worn by the patient. The power supply 20 includes a battery 25 that is electrically connected to an adjustable oscillator 30 which generates an AC signal. A suitable example of an oscillator that may be used for the oscillator 30 is the LTC6900 precision low power oscillator sold by Linear Technology Corporation of Milpitas, Calif., which is capable of generating 50% duty cycle square waves at frequencies of between 1 KHz and 20 MHz. Other types/shapes of waveforms and/or duty cycles may also be used. The power supply also includes a primary winding 35 that is electrically connected to the oscillator 30 and receives the waveform generated thereby.
The implantable device 10 is provided with power circuitry 40 that provides a DC signal of an appropriate level for powering the control circuitry 45 provided as part of the implantable device 10. As described in greater detail herein, the control circuitry 45 controls the generation of the electrical pulses provided to the probes 15 (and ultimately to the patient's brain). As seen in
Because of losses that occur in the inductive coupling, it is preferred to increase the voltage of the induced AC signal in order to provide a supply voltage of an appropriate level to the control circuitry 45 (as described hereinafter, the highest voltage necessary for the control circuitry 45 is typically 3 V, and the required voltage ranges from 1.5 V to 3 V, although voltages to 5 V may also be desired). In addition, because a DC signal is employed to power the control circuitry 45, the induced AC signal is also converted to DC. Thus, the induced AC signal is provided to the voltage boosting and rectifying circuit 55, which increases the voltage of and rectifies the received AC signal. In one particular embodiment, the voltage boosting and rectifying circuit 55 is a one or more stage charge pump, sometimes referred to as a “voltage multiplier.” Charge pumps are well known in the art. Basically, one stage of a charge pump essentially doubles the amplitude of an AC input voltage and stores the doubled DC voltage on an output capacitor. The voltage could also be stored using a rechargeable battery. Successive stages of a charge pump, if present, will essentially double the voltage from the previous stage. The DC signal that is output by the voltage boosting and rectifying circuit 55 is provided to a voltage regulator 60, which in turn provides a regulated DC voltage signal to the control circuitry 45. The voltage regulator 60 is primarily provided to resist spikes in the DC voltage signal provided to the control circuitry 45 and to resist DC voltage signals that may overdrive the control circuitry 45.
In the particular embodiment of the DBS device 5 shown in
As stated above, the processor 65 (
According to an aspect of the present invention, the implantable device 10 is adapted to preserve power when pulsing is not required. Specifically, the processor 65 includes a watchdog timer, and the watchdog timer timeout, used as the wakeup mechanism, can be scaled down so that the processor 65 enters a sleep mode between pulses. In addition, a low power RC oscillator external to the processor 65 may be used with the processor 65 for clocking purposes such that its internal, high speed oscillator can be turned off to further persevere power.
As noted above, it is preferred to be able to selectively adjust the pulsing parameters within the processor 65. Thus, according to a further aspect of the present invention, the DBS device 5 is provided with a mechanism for remotely and wirelessly programming the processor 65 so that the pulse parameters can be selectively adjusted. For this purpose, the control circuitry 45 includes a wireless communications device 85 having an antenna 90 that is in electronic communication with the processor 65 when it is necessary to perform adjustments. The wireless communications device 85 is adapted to receive programming signals sent from a remote programming device 95 shown in block diagram form in
The DBS device 125 includes an antenna 130, which, in the embodiment shown in
In operation, the antenna 130 receives energy, such as RF energy, that is transmitted in space by an RF source 145. The RF source 145 may be, without limitation, a local radio station. The RF energy received by the antenna 130 is provided, in the form of an AC signal, to the charge pump 140 through the matching network 135. The charge pump 140 amplifies and rectifies the received AC signal and provides the resulting DC signal to the voltage regulator 60. The voltage regulator 60 provides a regulated DC signal to the control circuitry 45 as a power supply. Thus, the DBS device 125 is able to be powered remotely without the need for an onboard power supply or energy storage device such as a capacitor or rechargeable battery.
The matching network 135 matches the impedance of the charge pump 140 to the impedance of the antenna 130 as complex conjugates for optimal antenna performance. In one particular embodiment, the matching network is an LC tank circuit formed by the inherent distributed inductance and inherent distributed capacitance of the conducing elements of the antenna 130. Such an LC tank circuit has a non-zero resistance R which results in the retransmission of some of the incident RF energy. This retransmission of energy may cause the effective area of the antenna 130 to be greater than the physical area of the antenna 130.
While preferred embodiments of the invention have been described and illustrated above, it should be understood that these are exemplary of the invention and are not to be considered as limiting. Additions, deletions, substitutions, and other modifications can be made without departing from the spirit or scope of the present invention. Accordingly, the invention is not to be considered as limited by the foregoing description but is only limited by the scope of the appended claims.
This application is a continuation-in-part of U.S. application Ser. No. ______, entitled “Deep Brain Stimulation Apparatus, And Associated Method,” filed on Dec. 20, 2005, which claims the benefit of U.S. Provisional Application No. 60/638,037, entitled “Deep Brain Stimulation,” which was filed on Dec. 21, 2004, the disclosure of which is incorporated herein by reference.
This work was supported in part by a grant from the National Science Foundation under Contract No. EEC 0203341. The United States government may have certain rights in the invention described herein.