Methods for electrosurgical treatment of spinal tissue

Abstract

Systems, apparatus, and methods for treating spinal tissue and other body structures in open and endoscopic spine surgery to relieve symptoms, such as neck or back pain. In particular, the present invention provides methods for the controlled heating of various tissues in or around the vertebral column, including various interspinous tissues, such that spinal ligaments and cartilage surrounding the vertebrae and the facet joints are shrunk or tightened to stabilize the vertebral column of a patient. Thermal energy is applied to the target tissue in a subablation mode of an electrosurgical system to cause shrinkage of the tissue, thereby stiffening the interspinous tissue and stabilizing the vertebral column. In an exemplary embodiment, a high frequency RF voltage can be applied between one or more active electrode(s) and one or more return electrode(s) to heat a target interspinous tissue to within a temperature range at which irreversible shrinkage of the tissue occurs.

Description

RELATED APPLICATIONS [0001] The present application is a continuation of U.S. patent application Ser. No. 09 / 848,843, filed May 3, 2001, which claims priority from U.S. Provisional Patent Application No. 60 / 201,459 filed May 3, 2000, and is a continuation-in-part of U.S. patent application Ser. No. 09 / 316,472, filed May 21, 1999 (Attorney Docket No. S-5), which is a continuation-in-part of U.S. patent application Ser. No. 09 / 295,687, filed Apr. 21, 1999 (Attorney Docket No. E-7-2) and U.S. patent application Ser. Nos. 09 / 054,323 and 09 / 268,616, filed Apr. 2, 1998 and Mar. 15, 1999, respectively (Attorney Docket Nos. E-5 and E-7-1, respectively), each of which is a continuation-in-part of U.S. patent application Ser. No. 08 / 990,374, filed Dec. 15, 1997 (Attorney Docket E-3), which is a continuation-in-part of U.S. patent application Ser. No. 08 / 485,219, filed on Jun. 7, 1995 (Attorney Docket 16238-000600), the complete disclosures of which are incorporated herein by reference for all...

AI Technical Summary

Benefits of technology

[0015] The present invention provides systems, apparatus, and methods for selectively applying electrical energy to structures within a patient's body, such as support tissue within or around the spinal column. The systems and methods of the present invention are useful for shrinkage, ablation, resection, aspiration, and / or hemostasis of tissue and other body structures in open and less-invasive spine surgery. In particular, the present invention includes apparatus and methods for the controlled shrinking of interspinous tissue, in which such tissue is treated with thermal energy to cause the tissue to shrink, thereby stiffening the interspinous tissue structure and stabilizing the vertebral column.

Problems solved by technology

This results in a weakening of the shock absorption properties of the disc and a narrowing of the nerve openings of the vertebral column which may lead to pinching of the nerve or nerve root.

This disc degeneration can eventually cause back and leg pain.

The mere proximity of the nucleus pulposus or a damaged annulus to a nerve can cause direct pressure against the nerve, resulting in pain and sensory and motor deficit.

In some cases, the disc tissue is irreparably damaged, thereby necessitating removal of a portion of the disc or the entire disc to eliminate the source of inflammation and pressure.

Unfortunately, once such tissue has become stretched, it stays stretched.

The stretched tissues do not hold the adjacent vertebrae in a stable configuration and allow the vertebrae to separate and “float” within the vertebral column.

The unstable vertebrae can impinge on surrounding nerves and cause the patient pain.

Consequently, even if a patient's discs have been surgically repaired, the patient may still feel pain if there is excessive mobility in their vertebral column.

In addition, the risk of increased instability due to ligament and bone removal is generally lower in endoscopic procedures than with open procedures.

Unfortunately, these mechanical instruments greatly lengthen and increase the complexity of the procedure.

In addition, these instruments might sever blood vessels within this tissue, usually causing profuse bleeding that obstructs the surgeon's view of the target site.

In addition to the above problems with mechanical instruments, there are serious concerns because these instruments are not precise, and it is often difficult, during the procedure, to differentiate between the target disc tissue, and other structures within the spine, such as bone, cartilage, ligaments, nerves and non-target 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.

Monopolar devices, however, suffer from the disadvantage that the electric current will flow through undefined paths in the patient's body, thereby increasing the risk of undesirable electrical stimulation to portions of the patient's body.

This current, however, may inadvertently flow along paths within the patient's body 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.

Other disadvantages of conventional RF devices, particularly monopolar devices, is nerve stimulation and interference with nerve monitoring equipment in the operating room.

In addition, these devices typically operate by creating a voltage difference between the active electrode and the target tissue, causing an electrical arc to form across the physical gap between the electrode and tissue.

At the point of contact of the electric arcs with tissue, rapid tissue heating occurs due to high current density between the electrode and tissue.

Thus, the tissue is parted along the pathway of evaporated cellular fluid, inducing undesirable collateral tissue damage in regions surrounding the target tissue site.

This collateral tissue damage often causes indiscriminate destruction of tissue, resulting in the loss of the proper function of the tissue.

In addition, the device does not remove any tissue directly, but rather depends on destroying a zone of tissue and allowing the body to eventually remove the destroyed tissue.

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