What is the Carpal Tunnel?
The carpal tunnel is a narrow passageway on the palm-side of your hand. It’s made up of the transverse carpal ligament (TCL) on the top, carpal bones that connect the hand to the fingers, at the bottom, blood vessels, muscles and a prominent nerve called the median nerve. The median nerve provides sensation to the palm side of the thumb and all fingers except the little finger. It is also responsible for movement of the muscles near the base of the thumb by carrying signals back and forth the Central Nervous system.
What is Carpal Tunnel Syndrome?
In some people, the median nerve gets compressed or squeezed causing a lot of numbness, pain and tingling sensation in the hands and palms. This condition is called the Carpal Tunnel Syndrome (CTS). The medico-technical term is entrapment mono-neuropathy of the median nerve. CTS is quite common and affects nearly 4 percent of the general population causing billions of dollars in healthcare annually, around the world.
Wrist fracture, dislocation of the wrist, being a woman, rheumatoid arthritis, diabetes, obesity and certain medications all increase the risk for CTS. People who perform some repetitive actions of the palm are also at risk, hence the prevalence of CTS in people who type long hours on a keyboard. It’s quite common in the working age-group of 25 to 60 years, causing millions of hours of lost work-hours and hence revenue from the same.
What is Carpal Tunnel Release?
In people with CTS, the transverse carpal ligament or TCL presses down on the carpal tunnel and compresses the median nerve in the process. Treating CTS will require releasing this pressure or compression. This is done by dividing or cutting the TCL into two segments, which makes more room for the median nerve and tendons passing through the tunnel. The procedure is called Carpal Tunnel Release (CTR), Carpal Tunnel Surgery and Carpal Tunnel Decompression Surgery.
Till date, the most common techniques for CTR have been:
- Open carpal tunnel release (OCTR): As the name implies, this is an open, incisional surgery of the hand. A long incision is made on the palm running up to the wrist and the TCL is divided by a surgeon who is looking at it directly. Needless to say, an open surgery has various disadvantages which is why minimally invasive options are preferred.
- Endoscopic carpal tunnel release (ECTR): This is one such minimally invasive procedure. Here, an endoscope, which is a thin, flexible narrow tube, fitted with a camera and cutting instruments are threaded through the palm or wrist. Images from the camera are relayed on to a monitor screen in the OR. Looking at that, the surgeon moves the endoscope and cuts the TCL as desired.
ECTR is a better option than open surgery as there is less post-operative pillar pain, or pain around the incisional area in the palm, that’s common with open surgery. However, ECTR comes with its own risks. The median nerve may get damaged during the procedure, the release may be incomplete, and the patient may have a steep learning curve during post-operative rehabilitation.
Incisionless, ultrasound-guided approach
Ultrasound-guided procedure is one approach. Here, the orthopedic surgeon uses a needle with cutting instruments at the tip. These could be a hook knife, a guided angle blade, a trocar-led blade, retractable blade, saw blade or an arthroscopic meniscotome. The doctor may also use what is called a fenestration technique along with a corticosteroid injection. The doctor uses ultrasound imaging on a screen to guide his movements.
Around 2015, a new procedure emerged, which is neither open, incisional, nor does it use an endoscope. It also uses an ultrasound-guided approach like the ones described above.
In this procedure, a specialized, contoured (specially-shaped), cannulated (tubular) needle called a Tuohy needle is used. This is pushed through an entry point in lower palm and through an exit point in the wrist in two back and forth passes. The needle carries an abrasive surgical thread. The back and forth passes of the needle aim to loop the TCL so that the surgical thread can be used like a saw to cut the TCL in a technique called as hydro-dissection.
Before insertion of the needle, the entry and exit points are identified carefully using an ultrasound probe. The probe is passed over the inlet of the carpal tunnel, the median nerve, the ulnar neurovascular structures, and then longitudinally to identify the superficial palmar arterial-arch. All these help establish a ‘safe zone’ so that movements of the needle and thread do not damage the median nerve or any blood vessels in the area.
Advantages of Incisionless, Ultrasound-Guided Approach
While local anesthesia may be used, the nature of the procedure is painless. Its quick, lasting 10 to 15 minutes. The entry and exit points of the needle are covered using adhesive bandages and changed a few days later. The wounds heal very quickly and no scars are visible.
The best part of this incisionless, ultrasound-guided procedure is that the person can get back to work and resume a normal life in 24 hours’ time. In contrast, OCTR and ECTR require anywhere from 2 to 8 weeks for complete recuperation and rehabilitation. The procedure has a high successrate of 90% of the cases, the carpal tunnel release is complete and no repeat procedure is required in the future.