Carpal tunnel syndrome: hydrodissection & thread release
Carpal tunnel syndrome is the most common nerve compression problem in the body. The median nerve runs through a narrow tunnel at the base of the palm, alongside the flexor tendons. When it gets compressed under the transverse carpal ligament, it causes numbness, tingling, and weakness in the thumb, index, and middle fingers.
Ultrasound has changed both how this is diagnosed and how it’s treated. It lets a clinician see the nerve, the ligament, and everything around them in real time, instead of working blind.
Nerve hydrodissection
Hydrodissection is a simple idea. Under ultrasound guidance, a clinician injects fluid — typically saline, sometimes with a small amount of anesthetic or corticosteroid — directly around the median nerve. This gently separates it from surrounding tissue that may be tethering or compressing it.
It’s used two ways: as a stand-alone treatment for mild-to-moderate carpal tunnel syndrome, and as a preparatory step before more definitive procedures like thread release, since it helps create a safe working plane around the nerve.
For many patients with mild or moderate symptoms, hydrodissection provides meaningful relief without surgery, and it can be repeated if needed. It won’t reverse severe, long-standing nerve compression — which is why grading severity matters before choosing a treatment path.
Thread carpal tunnel release (the Guo technique)
Some patients need the compressive ligament actually divided — the definitive fix for carpal tunnel syndrome. Open surgery has traditionally meant a palm incision. Thread carpal tunnel release, developed by Dr. Danqing Guo and colleagues and often called the Guo technique, does this without any incision at all.
Here’s how it works, under continuous ultrasound guidance:
- A thin needle passes beneath the transverse carpal ligament through two small puncture points — entering at the palm, exiting near the wrist.
- A fine surgical thread is threaded through the needle and looped around the ligament.
- Moving the thread back and forth — much like a wire dividing a block of cheese — gradually and precisely divides the ligament.
The nerve and surrounding structures stay protected under direct ultrasound view throughout. No scalpel touches the skin.
Because the technique separates the fibers under vision rather than cutting blindly, studies report a notably fast return to normal activity — often within about a week, compared to several weeks after open surgery — with a low complication rate. It’s one of several ultrasound-guided approaches to carpal tunnel release; others use small blades or specially shaped needles. Thread release stands out for leaving no sharp cutting instrument in place during the procedure.
What to expect
Both procedures are done in clinic under local anesthesia. They take well under an hour and don’t require general anesthesia or a hospital stay. Recovery typically means light activity restrictions for a short period — most patients return to normal hand use faster than after open surgery.
Candidacy depends on the severity of nerve compression and individual anatomy. That’s why an in-person ultrasound evaluation is the starting point.
This page is educational and general in nature, and describes procedures performed by trained clinicians using specialized ultrasound and instrumentation. It is not a guide to performing these procedures, and does not replace an individualized evaluation — see our medical disclaimer.