Carpal tunnel: Saline injection could bring relief up to 6 months

• Carpal tunnel syndrome is a condition where pressure on the median nerve in the wrist causes pain, tingling, and numbness in the hand.
• It often results from repetitive wrist movements, such as using a mouse and keyboard, and can cause permanent damage.
• Current treatments include rest, anti-inflammatories, and, in severe cases, surgery.
• A new study has discovered that a saline injection near the nerve can effectively relieve symptoms of carpal tunnel syndrome for up to 6 months.

Carpal tunnel syndrome (CTS) occurs when the median nerve, which travels down the arm to the thumb, is compressed when it travels through the carpal tunnel in the wrist. When the median nerve is compressed, it becomes inflamed.

Symptoms include pain, tingling, and numbness in the hand, primarily in the thumb and first two fingers. These often start at night, but cause increasing problems during the day, as the condition worsens.

CTS is the most common entrapment neuropathy, affecting up to 5% of people in the United States. The syndrome is 10 times as common in women as in men, and usually starts between the ages of 40 and 60.

Causes and current treatments

Often there is no clear cause of CTS, but it may be brought on by:

• trauma or injury to the wrist that causes swelling, such as a sprain or fracture
• an overactive pituitary gland
• an underactive thyroid gland
• rheumatoid arthritis
• mechanical problems in the wrist joint
• repeated use of vibrating hand tools
• fluid retention during pregnancy or menopause
• the development of a cyst or tumor in the canal.

Milder CTS symptoms can be treated by splinting, rest, non-steroidal anti-inflammatory drugs (NSAIDs), or corticosteroid injection. However, if these treatments are ineffective, surgery may be required to reduce pressure on the median nerve.

Now, a new study led by researchers from the University College of Medical Sciences and Guru Teg Bahadur Hospital in Delhi, India, and presented at the annual meeting of the Radiological Society of North America, has found that hydrodissection — a technique that involves injecting saline or other solution around a nerve to separate it from the surrounding tissue — can provide long-term relief from CTS.

Study make-up

All the participants had refractory CTS, as co-author Dr. Anupama Tandon, professor at the University College of Medical Sciences and Guru Teg Bahadur Hospital, explained to Medical News Today.

“We enrolled patients having carpal tunnel syndrome that had not responded to conservative treatment, including medications, splints, and lifestyle changes. The average duration of symptoms was over 1.5 years in our study group. Most patients were advised [to have] surgery but many were unwilling for the same,” Dr. Tandon told us.

The participants ranged in age from 25 to 62 years, with a mean age of 44 years. The female-to-male ratio was 2:1. Patients with other health conditions likely to produce similar symptoms, such as cervical spondylosis and peripheral neuropathy were excluded from the study.

At the start of the study, the researchers divided the participants randomly into three groups. Two of the groups underwent ultrasound-guided hydrodissection, the third received a corticosteroid injection.

The study was single-blind, meaning that the participants did not know which treatment they had received.

Rapid procedure

In procedures that took only 10–15 minutes to perform, group one had hydrodissection with normal saline, group two had hydrodissection with saline plus corticosteroid, and group three received a guided perineural corticosteroid injection.

The procedure was carried out in an outpatient setting, without any anesthesia or specialist equipment, and participants were able to return to work within an hour of treatment.

The researchers followed up participants at 4, 12, and 24 weeks after the injection.

Marked improvement in symptoms

After 4 weeks, all three groups showed a reduction in pain symptoms. However, by 12 and 24 weeks, the group that had not undergone hydrodissection reported a return of symptoms.

“Most previous studies with steroids have reported good efficacy at 4 weeks and in some up to 12 weeks, though long-term follow-ups are lacking in these studies. In the present study, the efficacy [or corticosteroid injection alone] was good at 4 weeks with about 85% patients showing significant improvement but the effect waned off with time.”

– Dr. Anupama Tandon

In contrast, both groups that had received the ultrasound-guided hydrodissection treatment continued to see an improvement in their symptoms up to 24 weeks.

In CTS, inflammation of the median nerve increases its cross-sectional area, so the researchers measured this using ultrasound.

In both the hydrodissection groups, the cross-sectional area of the median nerve was significantly reduced. In the saline group, it was reduced by 43%, and in the group with the combined treatment, it was reduced by 46%.

In those receiving the corticosteroid injection without hydrodissection, the cross-sectional area of the median nerve was reduced by only 11%.

“Previously, the studies that have been done on ultrasound-guided hydrodissection for carpal tunnel syndrome have used corticosteroids either alone or as a part of the injection, making it difficult to assess whether hydrodissection alone was beneficial, or if it was due to the effect of the steroids,” the study’s lead author, Dr. Anindita Bose, senior resident at the University College of Medical Sciences and Guru Teg Bahadur Hospital, points out.

Encouraging results

The researchers were surprised by how effective the straightforward procedure was.

Dr. Tandon commented that “[t]he procedure is simple, low cost, and does not require high-end interventional setup.”

“It can be mastered easily and be performed even at smaller centres. Also, from the patient’s perspective, minimal discomfort, no requirement of admission and the ability to return to normal activities within an hour’s time makes it really lucrative. It could definitely defer, if not completely alleviate the need for surgery,” he added.

The participants in the study reported no adverse effects from the procedure.

Hydrodissection with saline alone was as effective as hydrodissection with corticosteroid in reducing pain and inflammation of the median nerve. As corticosteroid injections can have some adverse effects, Dr. Tandon advised using just saline for hydrodissection to treat CTS.

There is potential for using the procedure as a repeat treatment. Dr. Tandon told MNT: “Though in our study it was used as a one-off treatment with good results at 6 months. I feel a repeat procedure, if required, would be helpful, though more research needs to be done in this area.”

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