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Carpal tunnel syndrome occurs when the median nerve in the wrist becomes compressed. MarsBars/Getty Images
  • Researchers say hydrodissection injections may help relieve pain caused by carpal tunnel syndrome.
  • However, not all experts agree it is the best option for this common wrist ailment.
  • They say a wrist splint worn at night or ergonomic aids such as wrist rests can be effective.

A minimally invasive procedure called hydrodissection might help millions of people living with carpal tunnel syndrome, according to a new study presented today at the annual meeting of the Radiological Society of North America.

Hydrodissection is an injection of a liquid, typically saline, into a nerve to separate it from the surrounding tissue. Medical practitioners use ultrasound to identify nerves and guide the injection.

In their study, which hasn’t been published yet in a peer-reviewed journal, researchers divided 63 participants into three groups.

  • Group 1 had a hydrodissection injection with saline
  • Group 2 received saline and corticosteroid in the hydrodissection injection
  • Group 3 received a corticosteroid injection without hydrodissection

The scientists completed follow-ups at 4 and 12 weeks and six months.

At four weeks, all participants reported a reduction in their pain. At the 12-week and 6-month follow-ups, groups one and two reported improvements while group three reported a recurrence of symptoms.

The hydrodissection procedure usually takes 10 to 15 minutes and does not require any high-end equipment.

“Hydrodissection is a relatively new technique in the musculoskeletal ultrasound sphere, so there is a natural interest in what this can mean for nerve entrapment syndromes like carpal tunnel,” said Dr. Joanne Zhang, a hand, wrist, and elbow surgeon at the Hoag Orthopedic Institute in Southern California who treats people with carpal tunnel syndrome.

“Physicians must rely on strong, consistent, and time-tested data to guide decisions when offering treatment options to patients,” Zhang told Healthline. “Although the results of this study are thought-provoking, the application is still very new and more research is required.”

“This is a small study with a follow-up of only six months, so we don’t have long-term data on how patients fared. I would need to see additional information before including this in my recommended treatments,” Zhang noted.

Carpal tunnel syndrome is entrapment neuropathy.

This happens when a nerve becomes compressed between two other structures in the body, often between a ligament and a bone, according to the National Library of Medicine.

In carpal tunnel syndrome, the median nerve, which goes through a passageway in the wrist called the carpal tunnel, becomes compressed. It is the most common type of entrapment neuropathy.

Approximately 3% to 6% of adults in the United States have carpal tunnel syndrome, according to the American Academy of Family Physicians.

Symptoms include:

  • Pain and numbness typically in the thumb, index finger, and middle finger
  • Fingers feeling swollen when they’re not
  • Loss of strength when gripping an item or performing some tasks
  • Pain radiating up the arm

The symptoms usually worsen at night, often waking the person up. Moving the wrist, or flicking it, can sometimes relieve the discomfort.

Symptoms typically worsen over time.

Not all doctors embrace hydrodissection for their patients.

“I am not convinced this is the leading cause of nerve symptoms in idiopathic carpal tunnel syndrome and therefore I am uncertain it is a ‘cure’ for most patients who have carpal tunnel syndrome,” said Dr. Kanu Goyal, an orthopedic hand surgeon at Ohio State Wexner Medical Center.

“Though I find hydrodissection of nerves an interesting idea, I am not prepared to recommend this treatment for my patients,” Goyal told Healthline. “I feel there is still insufficient data to support hydrodissection (with or without steroids) as an effective long-term solution for carpal tunnel syndrome, particularly in the scenario where a nighttime splint or a simple steroid injection hasn’t worked.”

“I find a carpal tunnel release to be the most logical next option for these patients,” he added.

For people with mild to moderate symptoms, non-surgical treatments may help, according to the American Academy of Family Physicians.

These include:

  • Wrist splints, often worn while sleeping
  • Oral corticosteroids
  • Corticosteroid injections

Some people reported decreased pain by using ergonomic aids, such as a wrist rest, mouse pad, digital pen, or using speech-to-text programs, while using a computer.

Surgery, however, could be a viable solution for more severe symptoms.

“Typically, we recommend surgery for carpal tunnel syndrome in a few situations,” said Zhang, “One, if patients are waking up in the middle of the night with hand pain, numbness, or tingling and bracing has not helped resolve this. Two, if the carpal tunnel syndrome is leading to muscle weakness in the hands. Or three, if the patient has undergone a nerve conduction study that shows severe carpal tunnel syndrome.”

The carpal tunnel is a small passageway formed by the bones in the wrist. Swelling in this passageway causes compression of the median nerve. During surgery, the ligament pressing on the carpal tunnel is cut, making more room for the nerve and tendons and relieving pain.

“Oftentimes, the first step in determining the severity of carpal tunnel syndrome is by performing a nerve conduction study,” said Dr. Ilan Donan, a sports neurologist and pain management specialist at the Center for Sports Neurology and Pain Medicine at Cedars-Sinai Kerlan-Jobe Institute in Los Angeles.

“Depending on the severity, and a patient’s symptoms, we determine the best course of treatment. Common conservative forms of treatment may include wrist bracing and occupational therapy,” he told Healthline.

“I have been performing ultrasound-guided median nerve hydrodissections for several years with considerable success,” Donan added. “Having said that, when patients display loss of motor function consistent with muscle atrophy and severe median nerve compression across the wrist, the discussion will include a consultation with a hand and wrist surgeon.”