June 23, 2017

Carpal tunnel syndrome (CTS) affects more than 12 million Americans and is often associated with high social and economic costs. Compression or irritation of the median nerve can cause pain, numbness, tingling and sometimes weakness in the hand and arm. Severe or persistent cases may be treated surgically by performing a carpal tunnel release (CTR) during which the transverse carpal ligament (TCL) is transected to relieve pressure on the median nerve. Traditional CTR procedures have included open and endoscopic CTR.

Mini-open CTR

During open CTR, a surgeon typically makes a 1- to 3-centimeter (cm) incision at the base of the palm to expose and transect the TCL. This is the traditional form of surgical treatment performed by many and is reported to result in a smaller risk of nerve injury at the expense of perhaps a more short-term, symptomatic scar.

Endoscopic CTR

This procedure utilizes one or two small incisions (1 to 1.5 cm) at the wrist or at the wrist and palm. An endoscope inserted through one incision allows the surgeon to see the TCL during TCL transection. Endoscopic CTR is less invasive than open CTR, with a slightly higher risk of nerve injury, and may result in a faster postoperative recovery for many patients.

Ultrasound-guided CTR

During ultrasound-guided CTR (USCTR), the skilled operator uses commonly available ultrasound (US) equipment to place a cutting tool into the carpal tunnel and cut the TCL. The concept is similar to endoscopic CTR, but instead of using an endoscope, the operator uses ultrasound to visualize the contents of the carpal tunnel, place the device and cut the TCL.

Since the first description of USCTR in 1997, operators have used relatively unprotected cutting blades and tools to transect the TCL. However, physicians at Mayo Clinic have now developed an innovative, user-friendly surgical device, which is equipped with integrated safety features that enable USCTR through a single 4- to 5-millimeter (mm) wrist incision. Two Mayo Clinic physicians and their orthopedic surgeon partners are now offering patients the option of USCTR using this locally developed, ultralow-profile microknife device.

This device is designed to protect the contents of the carpal tunnel from the knife and enhance visibility during the procedure. Once the microknife is positioned within the carpal tunnel, balloons are deployed to expand and maintain a safe zone between the cutting knife and the at-risk nerve and vascular structures within the carpal tunnel. Following balloon deployment, the physician can activate the retrograde cutting knife and cut the TCL in a distal to proximal direction. The small incision can be closed with adhesive strips or sutures, and patients can move and use the wrist immediately. The incision is approximately half the size of the incision(s) used for endoscopic CTR, and one well-designed study reported that patients treated with USCTR recovered significantly faster than those treated with open CTR.

USCTR has been the focus of more than 18 peer-reviewed publications, including 12 clinical studies reporting on more than 600 patients. These studies have reported no major complications, and the clinical success rate has been greater than 95 percent, similar to the success rate reported for open and endoscopic CTR.

"We are excited to offer USCTR in our practice at Mayo Clinic," says Jay Smith, M.D., vice chair of Physical Medicine and Rehabilitation at Mayo Clinic's campus in Rochester, Minnesota, and co-developer of the surgical device. "We treated our first patient in March, and the patient returned to heavy manual labor in just a few weeks. Over 45 procedures have been performed nationally. There have been no complications, and patient satisfaction to date has been 100 percent so far. We have heard inspirational stories about a patient being able to golf within a few days post-procedure, and others being able to use their wheelchairs and/or crutches immediately post-procedure. We look forward to helping more patients with this innovative procedure."

Disclosure: Mayo Clinic and Jay Smith, M.D., have a financial interest in the technology mentioned in this article or news release.