A small trial has found that injecting saline around the trapped nerve could ease symptoms of carpal tunnel syndrome for longer than a steroid injection, reports Science Alert.
The condition develops when a nerve supplying the hand becomes squeezed inside a narrow passage at the wrist. Pressure can disrupt the nerve’s signals, causing pain, tingling, numbness and weakness.
In the small trial, led by Anindita Bose from Mahatma Gandhi Medical College and Hospital in India, and published in the journal Radiology, relief persisted for six months after the saline procedure, by which time the initial benefits of steroid injection alone had largely faded.
The saline is used to open up space between tissues. In the procedure, called hydrodissection, a clinician uses ultrasound to guide a fine needle alongside the nerve. The sterile salt solution is injected around it, separating it from tissues that restrict its movement.
This aims to help the nerve move more freely. A steroid injection eases symptoms by reducing inflammation and swelling.
“This relieves the pressure on the nerve and improves patients' symptoms,” radiologist Anupama Tandon, from University College of Medical Sciences and Guru Teg Bahadur Hospital told ScienceAlert.
The researchers had wanted to establish how much benefit came from separating the tissues. Most earlier hydrodissection studies included medication in the injected fluid, so it was hard to tell whether the procedure or the drug deserved the credit.
The team studied 39 adults whose symptoms had persisted for more than three months, despite treatments like medication or wrist splints. Some had the condition in both hands, so the trial included 63 wrists.
Each wrist was randomly assigned to one of three treatments. One group received hydrodissection with saline alone. Another received a steroid injection without the tissue-separating procedure. The third received hydrodissection with steroid added to the saline.
All treatments were guided by ultrasound. The steroid-containing injections also included a local anaesthetic. The researchers then followed changes in pain, numbness, and difficulty using the hand, with ultrasound scans checking nerve swelling during the first three months.
All three treatments helped initially. The difference emerged over the following months: pain returned in the steroid-only group, while relief continued in the saline-only hydrodissection group. Adding steroid to hydrodissection did not clearly improve the results.
Ultrasound images supported the patients’ reports. Nerve swelling decreased more in both hydrodissection groups than in the group given steroid injections alone.
These findings support the researchers’ explanation that separating the nerve from surrounding tissues contributes to relief. However, the trial had no group that received a dummy injection, so the contribution of patients’ treatment expectations could not be assessed separately.
Tandon described a young typist whose pain and numbness had become so disruptive that her job was at risk. Medication and a wrist splint had failed to help.
“Post hydrodissection, she had improvement in her symptoms and was able to resume her work,” Tandon said.
Treatment took around 15 minutes and required no hospital stay. No major complications were observed. Some participants experienced mild pain and swelling that settled within a few days. One experienced tingling during needle placement, with no lasting neurological effects reported.
Larger studies are needed to establish how reliably the procedure works and how long relief lasts. This trial involved a small number of people at one centre, with follow-up ending at six months. It did not directly compare hydrodissection with surgery.
“It is beneficial for mild to moderate CTS [carpal tunnel syndrome],” Tandon said, “while severe cases require surgery.”
The team has begun a longer study comparing saline with dextrose, a type of sugar, to investigate which fluid provides more lasting relief.
Study details
Efficacy of US-guided Hydrodissection for Carpal Tunnel Syndrome: A Prospective Randomised Controlled Trial
Anindita Bose, Anupama Tandon, Gopesh Mehrotra et al.
Published in Radiology on 6 October 2026
Abstract
Background
US-guided hydrodissection is a minimally invasive treatment for nerve entrapment syndromes. However, its independent therapeutic efficacy remains unproven because most studies combine hydrodissection with corticosteroids or dextrose.
Purpose
To evaluate and compare the clinical and sonographic outcomes and complication rates of three US-guided hydrodissection techniques for the treatment of carpal tunnel syndrome (CTS) and to assess the relative efficacy of hydrodissection.
Materials and Methods
Adults with refractory CTS were included in this prospective randomised controlled trial (May 2019 to November 2020). Baseline assessment included the Boston Carpal Tunnel Questionnaire (BCTQ), Visual Analog Scale (VAS), and US measurement of median nerve cross-sectional area (CSA). Participants were randomized into three single-blinded groups: group 1, US-guided hydrodissection with normal saline (NS); group 2, perineural corticosteroid injection; and group 3, US- guided hydrodissection with NS plus corticosteroid. For hydrodissection, injectate was administered around the median nerve until complete nerve separation was achieved. Follow-up was performed at 4, 12, and 24 weeks. A linear mixed-effects model was used to evaluate within-group and between-group changes over time.
Results
Thirty-nine participants (mean age, 42.22 years ± 10.46 [SD]; 20 male; 63 wrists) were included. Persistent improvement in BCTQ and VAS scores was observed in groups 1 and 3. At 24 weeks, minimal clinically important difference for BCTQ Symptom Severity Scale was achieved in 85.7% and 90.5% of wrists in groups 1 and 3, respectively, with no significant intergroup difference (P = .979). Although group 2 demonstrated early clinical improvement, symptoms recurred and outcomes at 24 weeks were not significantly different from baseline. Percentage reduction in median nerve CSA was greater in groups 1 and 3 than in group 2 at 12 weeks (43% and 46%, respectively, vs 11%; P = .0001). No major complications were observed.
Conclusion
US-guided hydrodissection with NS alone resulted in sustained clinical and morphologic improvement in CTS, and the addition of corticosteroid provided no additional benefit.
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