Method and system for neural tissue modification

Abstract

A method and apparatus for altering a function of neural tissue in a patient. An electromagnetic signal is applied to the neural tissue through an electrode. The electromagnetic signal has a frequency component above the physiological stimulation frequency range and an intensity sufficient to produce an alteration of the neural tissue, the alteration causing the patient to experience a reduction in pain, and a waveform that prevents lethal temperature elevation of the neural tissue during application of the electromagnetic signal to the neural tissue.

Description

FIELD OF THE INVENTION[0001]This invention relates generally to technological advances in the medical field and systems and procedures for prolonging and improving human life. More particularly, this invention relates to a method and system for altering or modifying neural tissue in a human body by using a modulated radiofrequency generator coupled to a signal applicator system that is strategically located in tissue near a patient's neural system to relieve pain without heating it to lethal levels.BACKGROUND OF THE INVENTION[0002]In the past, radiofrequency (RF) generators and electrodes have been applied near or in neural tissue, for relieving pain or modifying its function. By way of one example, a lesion generator identified by Model No. RFG-3C RF, available from a company named Radionics, Inc., located in Burlington, Mass., has electrodes, which may be placed near a desired neural tissue area. The desired neural tissue area is heated by radiofrequency (RF) resistive power dissi...

AI Technical Summary

Benefits of technology

[0007]The present invention is directed to a modulated high frequency system for use with a signal applicator such as an electrode, conductive plate, or structure, which is applied to a patient's body to modify its neural function. The present system advantageously relieves pain or modifies a patient's neural system without average heating the patient's tissue above 45° C. to 50° C., without stimulating it at frequencies in the range of 0 to about 300 Hertz, and without burning or cauterizing it. Thus, the present system avoids the painful effects of forming radiofrequency (RF) lesions at high temperatures and circumvents the need for chronic stimulation of the tissue.

[0008]In accordance with one preferred embodiment, the system generates an RF waveform output, which is coupled to an electrode inserted into a patient's body, near or in the neural tissue. The system, by interrupting the RF waveform with bursts of RF power interposed with periods of off-time, accomplishes a pain relieving effect or other neural modulating effect in a patient, without exceeding the tissue temperature beyond approximately 45° C. on average. With this system, the painful heat lesions formed near the electrode, with temperatures substantially greater than 45° C. are avoided. The modulated RF system of the present invention may be used painlessly and easily, avoiding usual discomforts inflicted by standard RF heating procedures. Yet relief from pain or neural disfunctions such as motor disfunctions, spasticity, Parkinsonism, tremors, mood disorders, incontinence, etc., are long lasting, yielding results in many cases that are comparable to, if not superior than, results from RF heat lesions formed at much higher temperatures.

[0009]Some applications of the system and method in accordance with this invention may include relied from back, head, or facial pain, by procedures such as dorsal root ganglion or trigeminal ganglion treatments, spinal cord application for relief of intractable pain, spacicity, or motor control, treatment of the basal ganglia in the brain for relief of Parkinsonism, loss of motor control, tremors, or intractable pain. This pain relief or control of eliminator of motor or other neural disfunction is comparable if not more effective than relief from long-term stimulators with implanted electrodes. Besides, the need for permanent implants, expensive implanted devices an circuits, battery changes, involving repeated surgery and expense, and repeated application of simulation energy over long periods (months and years) is avoided.

[0010]Advantageously, unlike electrosurgical systems, the present system accomplishes pain relief or neural modification in patients in a non-violent, painless manner, avoiding average tissue temperature elevations into the lethal range and violent macroscope tissue separations.

[0011]Different embodiments of the present modulated frequency generator and its output waveforms are disclosed in this application. Some embedments with temperature monitors and thermal sensing electrodes are disclosed, which serve to control the modulated system and its use in some applications. For example, by using a temperature monitor in the tissue, to which the modulated radiofrequency output is applied, a surgeon may monitor the temperature of the tissue and thus, avoid RF voltage or current levels, which would raise the tissue to lethal thermal levels (which are generally beyond 40° C.-50° C.).

Problems solved by technology

Tissue generally dies when heated to about 45° C. to 50° C., which causes the patient to suffer severe, if not, unbearable pain.

Use of local or general anesthetic exposes a patient to undesired risks, and the destructive nature of and unpleasant side effects of the radiofrequency (RF) heat lesions are limitations of this technique, which is well known.

Chronologically or permanently implanted stimulators of the type discussed above, require frequent battery changes or long-term maintenance and patient follow-up, which is expensive and inconvenient, often requiring repeated surgery.

Thus, their output controls, power ranges, duty cycles, waveforms, and monitoring capabilities are not designed for gentle, therapeutic, neuro-modulating, sub-lethal temperature applications.

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