Surgery – Instruments – Electrical application
Reexamination Certificate
1998-02-27
2002-03-12
Cohen, Lee (Department: 3739)
Surgery
Instruments
Electrical application
C606S041000, C607S099000, C607S105000, C607S113000, C604S114000
Reexamination Certificate
active
06355032
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates generally to the field of electrosurgery, and more particularly to surgical devices and methods which employ high frequency electrical energy to treat tissue in regions of the body adjacent to nerves or other sensitive body structures, such as the head and neck, the spine, the brain and the like.
Many surgical procedures involve the treatment and/or removal of soft tissue closely adjacent to other non-target body structures, such as nerves, bone or cartilage (e.g., articular cartilage). One of the major difficulties with these procedures is discriminating between the target soft tissue and the non-target body structure, and then being capable of removing or otherwise modifying the soft tissue without damaging the non-target structure. Particularly troublesome are those surgical procedures which require the surgeon to remove tissue adjacent to nerves (the cordlike structures which convey impulses between a part of the central nervous system and a region of the body).
Many surgical procedures require the manipulation of surgical instruments in and around important nerves in the body. For example, surgical procedures within the nasal cavity (e.g., FESS procedures) often require the surgeon to remove polyps, turbinates or other sinus tissue adjacent to the optic or olfactory nerves, which are the central processes for sight and smell. Surgical procedures within the mouth often involves ablation or contraction of tissue (e.g., in the tongue or uvula) near the hypoglossal nerve, which controls movements of the tongue. Similarly, in spinal procedures (e.g., treatment of herniated discs or spinal fusion), the surgeon must often remove or modify tissue closely adjacent to the spinal nerves near their roots at the spinal cord. One of the significant problems with these procedures is that conventional surgical instruments generally do not differentiate between the target tissue and the surrounding nerves, which may result in nerve injury of impairment of nerve function. Nerve injury can lead to muscle paralysis, pain, exaggerated reflexes, loss of bladder control, impaired cough reflexes, spasticity and other conditions. Moreover, the neurons within some nerves typically do not regenerate after injury.
In the past several years, powered instrumentation, such as microdebrider devices and lasers, has been used to treat tissue in various procedures, such as removing polyps or other swollen tissue in functional endoscopic sinus surgery. Microdebriders are disposable motorized cutters having a rotating shaft with a serrated distal tip for cutting and resecting tissue. The handle of the microdebrider is typically hollow, and it accommodates a small vacuum, which serves to aspirate debris. In this procedure, the distal tip of the shaft is delivered to the target site, and an external motor rotates the shaft and the serrated tip, allowing the tip to cut tissue at the target site, such as sinus tissue, spinal tissue, or the like. While microdebriders have been promising, they are not very precise, and it is often difficult, during the procedure, to differentiate between the target tissue, and other neighboring body structures, such as cartilage, bone or nerves. Thus, the surgeon must be extremely careful to minimize damage to the cartilage and bone at the target site, and to avoid damaging the nerves that extend through the target site.
Lasers were initially considered ideal for many surgical procedures because lasers ablate or vaporize tissue with heat, which also acts to cauterize and seal the small blood vessels in the tissue. Unfortunately, lasers are both expensive and somewhat tedious to use in these procedures. Another disadvantage with lasers is the difficulty in judging the depth of tissue ablation. Since the surgeon generally points and shoots the laser without contacting the tissue, he or she does not receive any tactile feedback to judge how deeply the laser is cutting. Because healthy tissue, cartilage, bone and/or nerves often lie within close proximity of the target tissue, it is essential to maintain a minimum depth of tissue damage, which cannot always be ensured with a laser.
Recently, RF energy has been used to remove or otherwise treat tissue in open and endoscopic procedures. This procedure typically involves the use of a monopolar electrode that directs RF current into the target tissue to desiccate or destroy tissue in the tongue. Of course, such monopolar devices suffer from the disadvantage that the electric current will flow through undefined paths in the patient's body, thereby increasing the risk of unwanted electrical stimulation to portions of the patient's body. In addition, since the defined path through the patient's body has a relatively high impedance (because of the large distance or resistivity of the patient's body), large voltage differences must typically be applied between the return and active electrodes in order to generate a current suitable for ablation or cutting of the target tissue. This current, however, may inadvertently flow along body paths having less impedance than the defined electrical path, which will substantially increase the current flowing through these paths, possibly causing damage to or destroying surrounding tissue or neighboring peripheral nerves.
SUMMARY OF THE INVENTION
The present invention provides systems, apparatus and methods for selectively applying electrical energy to structures in regions of the patient's body adjacent to non-target body structures, such as nerves, cartilage and bone. The systems and methods of the present invention are particularly useful for ablation, resection, contraction and hemostatis of soft tissue that is closely adjacent to nerves, such as tissue within the head and neck, the spine, the brain and the like.
Methods of the present invention comprise positioning an electrosurgical instrument, such as a probe or catheter, in close proximity to a first body structure adjacent to a second body structure so that one or more electrode terminal(s) are brought into at least partial contact or close proximity with the first and second body structures. High frequency voltage is then applied between the electrode terminal(s) and one or more return electrode(s) to cut, remove, ablate, contract, coagulate, vaporize, desiccate or otherwise modify the first body structure without damaging the second body structure. The first body structure is typically soft tissue, such as sinus, mucosal, spinal, or brain tissue, and the second body structure typically comprises a structure either having different electrical or molecular properties than soft tissue, such as bone, cartilage, adipose tissue, nerves and the like. The present invention provides a method for automatically discriminating between the two body structures such that the soft tissue is removed or otherwise modified, while the second structure is left relatively unaffected by the procedure.
In one aspect of the invention, a method is provided for removing or ablating soft tissue that is adjacent to a nerve structure, such as swollen nasal tissue within the sinuses, disc tissue within the spine, tumor tissue within the brain and the like. In this method, one or more electrode terminal(s) are positioned adjacent to the target tissue, either endoscopically, transluminally, or directly in an open procedure. An electrically conductive fluid, such as isotonic saline, is delivered to the target site to substantially surround the electrode terminal(s) with the fluid. Alternatively, a more viscous fluid, such as an electrically conductive gel, may be applied to the target site such that the electrode terminal(s) are submerged within the gel during the procedure. In both embodiments, high frequency voltage is applied between the electrode terminal(s) and one or more return electrode(s) to remove at least a portion of the tissue. According to the present invention, the electrical energy is selectively applied to soft tissue to ablate this tissue, while minimizing energy delivery to the
Eggers Philip E.
Hovda David C.
Thapliyal Hira V.
ArthroCare Corporation
Cohen Lee
Raffle John T.
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