A 45 percent reduction in nerve swelling separates a new treatment for carpal tunnel syndrome from traditional steroid injections, according to a prospective randomized controlled trial published October 6, 2026, in Radiology. While standard steroid shots offer temporary relief that often fades, a minimally invasive procedure using plain salt water provides lasting symptom reduction for up to six months.
Hydrodissection With Normal Saline Versus Steroid Injections
Carpal tunnel syndrome develops when the median nerve becomes compressed inside a narrow passage at the wrist, triggering pain, tingling, numbness, and weakness that can disrupt everyday activities like typing or writing. To combat persistent cases, researchers examined a technique called hydrodissection. During this 15-minute outpatient procedure, a clinician uses ultrasound guidance to guide a fine needle alongside the trapped nerve and injects fluid to separate it from surrounding restrictive tissues.
The trial evaluated 39 adult participants with refractory carpal tunnel syndrome whose symptoms had lasted more than three months despite trying medications and wrist splints. Because some individuals had the condition in both hands, the study tracked a total of 63 wrists divided into three treatment groups: hydrodissection with normal saline alone, a perineural corticosteroid injection without tissue separation, and hydrodissection using a mixture of saline and corticosteroids.
All three groups experienced initial symptom relief during the first four weeks. However, a distinct divergence emerged over the subsequent months. Patients who received steroid injections alone experienced a return of symptoms by the 12-week mark. In contrast, participants who underwent hydrodissection with normal saline maintained significant clinical improvement and pain reduction through the six-month follow-up period.
“Traditional steroid injection for carpal tunnel syndrome often provides only temporary relief, thus requiring repeats of the procedure,” study co-author Anupama Tandon, a professor in the Department of Radiodiagnosis and Imaging at University College of Medical Sciences and Guru Teg Bahadur Hospital in Delhi, said in a statement. “Further, steroids carry risk of localized skin changes, fat thinning and tendon weakening.”
Ultrasound Scans Reveal Greater Reduction in Median Nerve Swelling
Objective measurements from ultrasound scans backed up the patients’ reported symptom scores. The cross-sectional area of the median nerve decreased by approximately 43 percent to 46 percent in both hydrodissection groups after three months. Meanwhile, wrists treated with steroid injections alone saw nerve swelling decrease by about 11 percent to 15 percent.
At 24 weeks, 85.7 percent of wrists treated with saline hydrodissection achieved a minimal clinically important difference for the Boston Carpal Tunnel Questionnaire Symptom Severity Scale. The group receiving saline combined with a corticosteroid reached 90.5 percent on the same scale, showing no statistically significant difference from the saline-only group. This finding indicates that adding steroids to the fluid did not provide any meaningful long-term advantage over plain salt water.
The procedure required no anesthesia, carried no major complications, and allowed patients to return to their daily routines shortly after treatment. Mild side effects reported by some participants included temporary pain and swelling that resolved within a few days.
Researchers note trial limitations including small sample size
Despite the promising six-month outcomes, researchers pointed out several limitations in the current trial. The study involved a small cohort of 39 participants at a single medical center, and the trial lacked a placebo or dummy injection group, meaning the researchers could not entirely rule out the psychological contribution of patients’ treatment expectations.
Larger analyses with follow-ups are needed to establish how reliable the procedure performs, especially since some severe cases of carpal tunnel syndrome require surgery.
Frequently Asked Questions About Carpal Tunnel Hydrodissection
What is nerve hydrodissection and how does it work?
Hydrodissection is a minimally invasive procedure where a clinician uses ultrasound guidance to inject fluid—such as sterile normal saline—around a compressed nerve. The liquid physically opens up space between surrounding tissues, allowing the median nerve to move freely and relieving internal pressure.
How long does the pain relief from saline hydrodissection last?
In the 2026 trial published in Radiology, symptom relief and functional improvements persisted for six months following a single saline hydrodissection procedure. By comparison, the benefits of traditional steroid injections largely faded, with symptoms recurring.
Is the hydrodissection procedure painful or complicated?
The 15-minute procedure requires no hospital stay or general anesthesia. Researchers observed no major complications, though some patients experienced mild, short-lived pain and swelling at the injection site that settled within a few days.
Does hydrodissection replace surgery for severe carpal tunnel syndrome?
No. Study authors note that while ultrasound-guided saline hydrodissection is beneficial, some severe cases of carpal tunnel syndrome require surgery.
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