Electrosurgical cannulas, systems and methods

Electrosurgical cannulas for use with an electrosurgical generator to thermally treat tissue are disclosed. An electrosurgical cannula for use with an electrosurgical generator to treat tissue is provided. The electrosurgical cannula includes a cylindrical body portion defining a lumen therethrough. The body portion includes a non-coring pointed distal tip which is electrically conductive. The electrosurgical cannula further includes at least one thermocouple having a distal end connected to the conductive distal tip.

BACKGROUND

Technical Field

The present disclosure relates generally to cannulas, systems and methods of using the same and, more particularly, to electrosurgical cannulas, systems and methods of using the same in tissue treatment and pain management procedures for intervertebral discs, the nerves surrounding the spinal column and the like.

Background of Related Art

The use of thermal therapy in and around the spinal column, including intervertebral discs and the nerves surrounding the spinal column, is known. Also, the insertion of a cannula either into the intervertebral discs or into the nerves surrounding the spinal column is commonly done for injection of contrast mediums to implement X-ray discograms and for introduction of needle electrode probes therein. This technique is used to detect or diagnose abnormalities or damage to the intervertebral disc and to thermally treat the intervertebral disc or the nerves surrounding the spinal column.

Pain can be derived from degeneration or compression of the intervertebral disc in its posterior or posterior/lateral portions. There is some innervation of the intervertebral disc near the surface of the disc, within its outer portion known as the annulus fibrosus, as well as around the spinal column.

A concern with the use of a cannula, catheter and the like for performing the thermal treatment is the coring of tissue which occurs upon the insertion of the cannula into the target treatment site. In order to prevent the coring of tissue an obturator or a stylet is positioned within the lumen of the cannula in order to occlude the cannula and thus prevent the coring of the tissue. In so doing, the treatment procedure requires the removal of the obturator or stylet from the cannula and introduction of an electrode probe into the cannula and distally to the target treatment site. As can be appreciated, such a procedure requires numerous steps and thus is relatively time consuming.

SUMMARY

According to one aspect of the present disclosure an electrosurgical cannula for use with an electrosurgical generator to treat tissue is provided. The electrosurgical cannula includes a cylindrical body portion defining a lumen therethrough. The body portion includes a non-coring pointed distal tip that is electrically conductive. The electrosurgical cannula further includes at least one thermocouple having a distal end connected to the conductive distal tip.

According to another aspect of the present disclosure, an electrosurgical system for thermally treating tissue is provided. The electrosurgical system includes an electrosurgical generator for supplying an output voltage and an electrosurgical cannula. The electrosurgical cannula includes a cylindrical body portion defining a lumen therethrough. The body portion includes a non-coring pointed distal tip that is electrically conductive. The electrosurgical system further includes at least one thermocouple having a distal end connected to the conductive distal tip and a proximal end connected to the electrosurgical generator. The electrosurgical system still further includes an electrical connection connecting the conductive distal tip of the cannula to a desired output voltage of the electrosurgical generator.

According to another aspect of the present disclosure, a method of performing a thermal treatment of tissue in a patient is provided. The method includes the step of providing an electrosurgical system. The electrosurgical system includes an electrosurgical generator for supplying an output voltage and an electrosurgical cannula. The electrosurgical cannula includes a cylindrical body portion defining a lumen therethrough. The body portion includes a non-coring pointed distal tip that is electrically conductive. The electrosurgical cannula further includes at least one thermocouple having a distal end connected to the conductive distal tip and a proximal end connected to the electrosurgical generator. The electrosurgical system further includes an electrical connection connecting the conductive distal tip of the cannula to a desired output voltage of the electrosurgical generator.

The method further includes the steps of inserting the conductive distal tip of the cannula into a target region, confirming the location of the conductive distal tip of the cannula by activating the stimulate mode of the electrosurgical generator, and treating the target tissue by activating an RF mode of the electrosurgical generator.

It is an advantage of the present disclosure to provide an electrosurgical cannula having a non-coring distal tip.

It is a further advantage of the present disclosure to provide an electrosurgical cannula that can be introduced percutaneously into a target site without having a stylet or obturator operatively disposed within a lumen thereof to occlude the lumen during introduction of the cannula into the target site.

It is still a further advantage of the present disclosure to provide an electrosurgical cannula that can be used to thermally treat tissue without the need to introduce an electrosurgical needle or probe into the cannula or through the cannula following introduction of the cannula into the target site.

DETAILED DESCRIPTION OF EMBODIMENTS

Referring initially toFIG. 1, an embodiment of an electrosurgical system, in accordance with the present disclosure, is generally designated “E”. Electrosurgical system “E” includes an electrosurgical cannula100, which is to be inserted into an organ “OR” of a human body or any other body tissue. As will be discussed in greater detail below, a distal tip104of cannula100is uninsulated and conductively exposed so that electrical currents induce heating within the tissue or organ “OR”. A targeted volume of tissue “T” is shown in sectional view and may represent, for example, a tumor or other abnormality in a human body, the neurological target ganglion or nerve branch of the spinal cord.

Cannula100is connected by a wire or cable10to an electrosurgical generator16. Electrosurgical generator16may be a radiofrequency or high frequency type generator. Electrosurgical generator16includes control elements, illustrated by block17, which may, for example, increase the radiofrequency power output of cannula100, control temperature when electrosurgical system “E” or satellite sensors (not shown) include temperature sensors, monitor or control impedance, power, current, voltage, or other output parameters. Electrosurgical generator16may include a display or screen, illustrated by block18, within it or as a separate system, for providing a display of heating parameters, such as temperature for cannula100, impedance, power, current, or voltage of the radiofrequency output. Such individual display readings are illustrated by the reference letters R1. . . RN.

Electrosurgical system “E” further includes a reference or return electrode19, which may be placed in contact with the skin of a patient or an external surface of organ “OR” with a connection20to electrosurgical generator16. Return electrode19and connection20serve as a path for return current from electrosurgical generator16through cannula100.

By way of example only and in no way to be considered as limiting, electrosurgical generator16may be a radiofrequency generator with frequency between about 100 kilohertz (kHz) to several hundred megahertz (MHz). Additionally, electrosurgical generator16may have power output ranging from several milliwatts to several hundred watts, depending on the clinical application.

As seen inFIG. 1, by way of illustration only, a targeted region to be thermally treated is represented in sectional view by the line “T”. It may be desired to thermally treat the targeted region “T” by fully engulfing targeted region “T” in a volume of therapeutic heat elevation. For example, CT, MRI, or ultrasonic image scanners may be used, and the image data transferred to a data processor or computer26. As an alternate example, an ultrasonic scanner head15may be disposed in contact with organ “OR” to provide an image illustrated by lines15A. Data processor26may be connected to the display devices18to visualize targeted region “T” and/or treatment zone “T1” in real-time during the thermal treatment procedure.

As seen inFIG. 1, a handswitch140may be electrically disposed between cannula100and generator16. Handswitch140functions to activate and de-activate cannula100. In one embodiment, handswitch140may be supported on cannula100. By placing handswitch140on cannula100or at a location between cannula100and generator16, handswitch140may be manipulated from within the sterile field. Handswitch140may be a button, slide or the like supported on cannula100, disposed along a cord extending between cannula100and generator16, or supported on the end of an electrical tether extending from generator16.

The image representation of the scan may be displayed on display unit21, which may, for example, be a CRT or LCD screen. Slice renderings through organ “OR” may be displayed in window22to represent the size and position of target region “T”. Placement of cannula100may be predetermined based on such image data as interactively determined by real-time scanning of organ “OR”. Cannula100may be inserted into the tissue via any suitable method, such as a freehand technique, by a guide block or introducer14, or by stereotactic frame or frameless guidance, as known by those skilled in the art.

By way of example, inFIG. 1, dashed line “T1” represents the treatment zone isotherm in a sectional view through organ “OR”. Such a treatment zone isotherm may be that of the surface achieving possible temperatures of approximately 98.6° F. or greater for treatment of dorsal root ganglion. At that temperature range, sustained for approximately 30 seconds to approximately several minutes, tissue cells will be thermally treated and branch nerves may be thermally treated or ablated. The shape and size of the treatment volume, as illustrated by dashed line8, may accordingly be controlled by the orientation of cannula100, the geometry of distal tip104, the amount of RF power applied, the time duration that the power is applied, the cooling of cannula100, etc.

Turning now toFIGS. 2 and 3, cannula100includes a rigid body portion102that enables cannula100to be easily urged into the body tissue or organ “OR”. Body portion102of cannula100is desirably substantially cylindrical, defining a lumen102atherethrough. In one embodiment, body portion102is formed from an electronically conductive material, such as, for example, stainless steel and the like.

Body portion102of cannula100terminates in a tapered or pointed distal tip104including a penetration portion104aand a transition portion104b. Penetration portion104aincludes a distal edge105aand a proximal edge105b. It is within the scope of the present disclosure for at least a portion of the external surface of body portion102to be covered with an insulating material106(e.g., silicone rubber, etc.), as indicated by the hatched line area inFIG. 2. In one embodiment, insulating material106terminates at transition portion104bof distal tip104. Distal tip104is connected, through body portion102, to cable10, and thereby to electrosurgical generator16.

In one embodiment, distal tip104of tubular body102may include echogenic surfaces configured to reflect ultrasound. In this manner, during the initial positioning of distal tip104of tubular body102, the echogenic surfaces provide for better visualization of distal tip104of tubular body102relative to surrounding and/or adjacent anatomical structures.

In one embodiment, as best seen inFIGS. 2 and 3, body portion102may include an elongate annular recess108formed in an outer surface thereof. Desirably, recess108is configured to contain insulating material106therein and provide a smooth transmission from transition portion104bof distal tip104to insulating material106. In this manner, during use, as cannula100is pushed through the skin of the patient, the skin slides smoothly over and along the outer surface thereof.

As seen inFIGS. 2 and 3, cannula100further includes at least one thermocouple120extending through at least a portion of lumen102aof body portion102. Thermocouple120includes a distal end120aextending from distal tip104of body portion102. In one embodiment, distal end120aof thermocouple120defines a hook shape such that a portion thereof may be hooked onto proximal edge105bof penetration portion104aof distal tip104. Distal end120aof thermocouple120may be fixedly secured around proximal edge105bof distal tip104by any suitable method including and not limited to welding, soldering, and the like. By hooking distal end120aof thermocouple120around proximal edge105bof distal tip104and securing distal end120athereto, the coring effect typically evidenced by a prior art cannula has been eliminated for cannula100. In addition, the necessity or need to use a stylet or obturator during insertion of cannula100to the target site may be eliminated.

A proximal end120bof thermocouple120extends through lumen102aof body portion102and desirably exits body portion102through a port or aperture112formed near a proximal end thereof. While proximal end120bof thermocouple120desirably exits through port112of body portion102, it is within the scope of the present disclosure for proximal end120bof thermocouple120to extend through an open proximal end of body portion102. Cannula100may include any suitable number of thermocouples120.

Proximal end120bof thermocouple120is connectable to electrosurgical generator16. In this manner, during use, information gathered by distal end120aof thermocouple120is transmitted to electrosurgical generator16for processing and analysis. For example, during a surgical procedure, as will be described in greater detail below, thermocouple120monitors for example, the temperature, etc., at or near distal tip104of tubular body102.

As seen inFIGS. 2 and 3, cannula100further includes at least one wire122electrically connected to distal tip104of body portion102to deliver RF power at least to distal tip104. In one embodiment, wire122may include a distal end122adefining a hook shape such that a portion thereof may be hooked onto proximal edge105bof penetration portion104aof distal tip104, and a proximal end122bextending through lumen102aof body portion102and exiting out of body portion102through aperture112thereof. Proximal end122bof wire122is electrically connected to or connectable to electrosurgical generator16. While distal end122aof wire122is shown and described as being electrically connected to distal tip104of cannula100, it is within the scope of the present disclosure for distal end122aof wire122to be electrically connected to any electrically conductive portion of cannula100, including body portion102, so long as said portion of cannula100is itself electrically conductive and is in electrical communication with distal tip104thereof.

In operation, after distal tip104of cannula100has been suitably positioned at the target tissue site, distal tip104of cannula100may be activated to deliver a therapeutic effect to tissue “T”. By electrically connecting distal tip104of cannula100to electrosurgical generator16, the need for separately introducing an electrosurgical needle or probe into cannula100to therapeutically treat tissue “T” has been eliminated.

As seen inFIG. 2, cannula100may include metrical markers114provided on an outer surface thereof, desirably along an entire length thereof. During use, metrical markers114provide the user with an indication of the depth of distal tip104of tubular body102relative to the outer surface of the patient's skin.

In one embodiment, cannula100may include an articulated distal tip104. In this manner, the insertion of distal tip104of cannula100into target region “T” may be eased.

In one embodiment, cannula100includes a luer hub116connected to a proximal end110of tubular body102. Luer hub116is configured to flare or radially expand in a proximal direction. In particular, luer hub116includes a distal portion116ahaving a diameter substantially equal to a diameter of body portion102and a proximal portion116bhaving a diameter that is larger than the diameter of body portion102.

As seen inFIGS. 2 and 3, a fluid conduit130may be provided that extends through lumen102aof body portion102. Desirably, conduit130provides a passage for transmission of fluid (e.g., air, CO2, water, saline, blood, etc.) through cannula100into and out of the patient's body. Conduit130includes a distal end130apositioned in close proximity to distal tip104of cannula100, and a proximal end130bextending proximally from cannula100. By placing distal end130aof conduit130in close proximity to distal tip104of cannula100the fluid is generally transmitted in a proximal direction out of cannula130.

In one embodiment, as seen inFIG. 4, luer hub116includes a rear wall116cfor closing off lumen102aof cannula100. A venting tube118may be placed in rear wall116cof luer hub116in order to provide a passage through which the fluid delivered to distal tip104of cannula100, by conduit130, may exit. While a venting tube118is shown and described, any suitable configuration enabling passage of fluid through rear wall116cis contemplated, including and not limited to an aperture or the like.

With continued reference toFIG. 4, a luer lock132may be provided on proximal end130bof conduit130. Luer lock132enables syringe or needle “N” to be injected therein to deliver a fluid to conduit130.

In many procedures and applications (e.g., therapeutic thermal tissue treatment procedures), placement of multiple cannulas, e.g., 2, 3 or more cannulas, into the target treatment site is required. Accordingly, use of cannulas100, in accordance with the present disclosure, for the procedure will enable the surgeon to simplify the process by reducing the number of steps required to perform the procedure.

In particular, for example, the procedure requires the steps of: inserting cannula100into a target region “T”, activating a “stimulate mode” on electrosurgical generator16, desirably from a sterile field; precisely locating distal tip104of tubular body102of cannula100in the target region “T”, injecting an anesthetic into the target region “T”, re-activating the “stimulate mode” of electrosurgical generator16to reaffirm the position of distal tip104of body portion102of cannula100, and activating an “RF mode” on electrosurgical generator16to treat the tissue while monitoring the temperature.

In one embodiment, the “RF mode” may be activated from within the sterile field by handswitch140(seeFIG. 1) in the manner described above. In this manner, the operator or surgeon does not have to manipulate generator16that may be located outside of the sterile field or instruct a technician who is outside of the sterile field in order to manipulate generator16.

In one embodiment, the procedure utilizing cannula100does not require the separate introduction of an electrosurgical needle or probe through cannula in order to effectuate the treatment of the target region “T”.

During activation of the “RF mode” on electrosurgical generator16, thermocouple120monitors the temperature at or around distal tip104of tubular body102of cannula100and transmits such temperature readings to electrosurgical generator16and/or to computer26. Electrosurgical generator16and/or computer26includes an algorithm that compares the transmitted temperature readings against threshold levels of temperature and adjusts the output parameters to distal tip104of cannula100accordingly. The threshold levels of temperature have been previously determined and stored in electrosurgical generator16and/or computer26.

In particular, high frequency power from electrosurgical generator16may be applied, via cable10and/or wire122, to distal tip104of cannula100. The level of high frequency power is increased according to empirical or pre-planned parameters. This increase may be done either manually or automatically. The process may be controlled according to a microprocessor control within electrosurgical generator16. The rise in power may be controlled according to measurement, as performed by thermocouple120, of temperature, impedance, or other suitable feedback parameters associated with the radiofrequency lesion process.

An algorithm determines if the applied power to cannula100has exceeded the desired value based on temperature monitoring or a pre-plan. If so, the power may be reduced. If not, other parameters may be monitored, such as, for example, impedance, or direct visualization of the lesion size. If these parameters, such as impedance, are within acceptable limits, power may be increased. As discussed above, the temperature of distal tip104of cannula100is monitored by thermocouple120. If the monitored temperatures remain within acceptable levels or are below a targeted temperature or level, the RF power may be increased or modified as needed and/or desired.

Other suitable criteria or parameter choices may be substituted for power as the controlling parameter. For example, as the controlling parameter, the operator may measure, set, vary, or otherwise moderate the current, voltage, impedance, or temperature delivered to distal tip104of cannula100. The current or power output to distal end104of cannula100may be controlled or held constant. The choice of which generator output parameter is used may vary depending on the clinical need or experience of the surgeon.

The process may be repeated for each cannula100until the necessary and/or desired thermal treatment of organ “OR”, as indicated by treatment zone “T1”, is achieved. While multiple cannulas100simultaneously inserted into target region “T” is desired, it is within the scope of the present disclosure for a single cannula100to be repeatedly inserted, at various locations, into target region “T” in order to achieve the necessary and/or desired thermal treatment or therapeutic effect.

Variations in the placement and geometry of cannula100, such as parallel or non-parallel, may be used to create changes in the shape of the treatment volume and needed and/or desired. Insertion of cannula100from varied directions may help in avoiding critical anatomical structured or obstructions while still increasing the numbers of cannula100inserted in order to achieve the size of the treatment zone.

Variations in the degree or size of distal tip104of cannula100may vary according to the particular target region “T” being affected. Additionally, cannula100may be configured to have any suitable length.

Variations in the choice of electrical output parameters from the electrosurgical generator, to control or monitor the treatment process, may vary widely depending on the operator's experience, technique, or preference. For example, a common RF voltage may be applied to all of cannulas100simultaneously. As an alternate embodiment, in accordance with the present disclosure, the clinician may choose to control the RF current to the individual cannulas100or the total current of all the cannulas100combined. Voltage variations on each cannula100could be applied to achieve constant current output from each cannula100. Alternatively, constant power output from each cannula100may be sought in some clinical settings. Voltage variations or phases between cannulas100may be implemented to achieve desired temperature distribution in the tissue as monitored by temperature sensors (e.g., thermocouples120) in the tissue or by visualization of temperature distribution using thermally sensitive MRI scanning, for example. Accordingly, the choice of electrical output type, sequence, and levels and the distribution of the cannulas100should be considered to have wide variations within the scope of the present disclosure.

In view of the foregoing considerations, as would be apparent by persons skilled in the art, implementations and systems should be considered broadly and with reference to the claims set forth below.