Ultrasound Guided Carpal Tunnel Steroid Injection

What is Carpal Tunnel Syndrome?

Carpal Tunnel Syndrome (CTS) is a condition characterised by pain, pins-and-needles and numbness in the hand and wrist in the median nerve distribution. It is secondary to pressure upon the median nerve as it passes through a special space within the wrist (the carpal tunnel). A study found that carpal tunnel syndrome affects approx. 16% of the UK population, and it is more prevalent in women.

Relevant anatomy

The carpal tunnel is a canal or small space within the wrist. It contains several important anatomical structures like the flexor tendons and the median nerve. The wrist bones form the tunnel's floor, while the tunnel's roof is formed by a special thick fibrous structure (the flexor retinaculum). The median nervous is the main structure affected by carpal tunnel syndrome.

What are the causes of carpal tunnel syndrome?

The median nerve can get irritated within the carpal tunnel due to a variety of causes:

Tendon inflammation- inflammatory conditions (like tenosynovitis) can predispose to carpal tunnel syndrome.
Wrist/flexor tendons overuse. This can be seen in manual workers or people who use a keyboard/computer for prolonged periods.
Wrist arthritis
Carpal tunnel syndrome is higher in diabetics, pregnant women, and people with underactive thyroid (hypothyroidism).

How do I know if I have carpal tunnel syndrome (CTS)?

The clinical features of carpal tunnel syndrome include:

Numbness (pins and needles) in the wrist and hand in the median nerve distribution (see photo) mainly involves the thumb, index, middle fingers, and palm.
Weakness of hand movements like gripping.
Symptoms can be worse at night and can awaken you from sleep. You may feel the need to shake your hand to get rid of the symptoms.

What other conditions can be confused with carpal Tunnel Syndrome?

Other conditions that can cause hand/wrist pain and be confused for carpal tunnel include:

The above conditions usually result in pain that can be felt in the thumb or the adjacent wrist, but there is usually no numbness, which is characteristic of nerve compression.

Pressure on the ulnar nerve or triangular fibrocartilage complex (TFCC) injury can result in wrist pain. However, this is usually felt in the region of the little finger and adjacent wrist joint, which is different from carpal tunnel syndrome distribution.

Pinching of the nerves in the neck (usually due to neck arthritis) can result in symptoms similar to carpal tunnel syndrome. Careful clinical assessment, MRI imaging of the cervical spine (neck) and nerve conduction studies are all useful tests to differentiate the two conditions.

A diagram illustrating the difference in sensory symptoms (numbness) experienced from the pressure of the median nerve vs other nerves in the hand/wrist (the ulnar and radial nerves).

Wrist osteoarthritis vs carpal Tunnel Syndrome

Wrist osteoarthritis will result in pain, swelling and joint stiffness. The joint movement might also be restricted. These symptoms are not usually seen in carpal tunnel syndrome.

How to diagnose Carpal Tunnel Syndrome?

The condition is usually suspected after clinical assessment by a hand specialist. The "Tinnel test" might be performed. This refers to pain sensation in the median nerve distribution on tapping over the carpal tunnel. A nerve conduction study is very useful for the assessment. It is a special test to measure the speed of movement of an electric impulse through the median nerve. Ultrasound assessment is also very useful for the diagnosis. Ultrasound will directly visualise the median nerve to assess for any swelling or nerve changes indicative of nerve compression. It can also assess for the cause of increased pressure within the carpal tunnel (for example, tendon inflammation). Ultrasound also allows for direct comparison with the median nerve on the other side (if no symptoms exist). Ultrasound can rule out other causes of wrist pain, like wrist or thumb arthritis.

What is the treatment for Carpal Tunnel Syndrome?

Management of carpal tunnel usually starts with physiotherapy and lifestyle modification (like ensuring correct posture at work or when using a computer). Over-the-counter medications can be useful. Supporting the wrist using a wrist brace to ensure correct positioning and help relieve the pressure of the median nerve can be helpful. These can be trialled, particularly at night. A hand specialist will be the best person to advise you about this.

What if conservative management is not helping with carpal tunnel syndrome?

If the above treatment options are not helpful, then an ultrasound-guided steroid injection can be considered. This is a recognised treatment option for carpal tunnel. In addition, a positive response from the injection will help confirm the diagnosis. Ultrasound guidance ensures the procedure is performed with extreme accuracy minimising adverse effects.

Are steroid injections useful in treating Carpal Tunnel Syndrome?

Cortisone/steroid injections are well-recognised treatment options for the management of carpal tunnel syndrome. Using ultrasound guidance ensures accuracy, safety and efficacy. The National Institute for Health & Care Excellence (NICE) recommendations for Carpal Tunnel syndrome includes corticosteroid injections. The treatment is also recommended by other specialised bodies, like The American Academy of Orthopaedic Surgeons (AAOS).

What is a steroid injection?

The clinical features of carpal tunnel syndrome include:

Corticosteroid (cortisone) is a potent anti-inflammatory medicine routinely used to manage inflammatory conditions (like bursitis, arthritis, and tendinosis). A cortisone injection will reduce the inflammation in the injected area. In Carpal Tunnel Syndrome, ultrasound guidance ensures that the medicine is accurately injected around the median nerve as it passes through the carpal tunnel to reduce inflammation effectively.

Weakness of hand movements like gripping.
Symptoms can be worse at night and can awaken you from sleep. You may feel the need to shake your hand to get rid of the symptoms.

Should carpal tunnel injections be done under ultrasound guidance?

Ultrasound guidance increases accuracy therefore, this is our routine practice. Ultrasound guidance results in less pain and faster procedures, with better outcomes than these injections without guidance. Ultrasound guidance ensures avoidance of sensitive structures (like median nerves and vessels) during the procedure.

Are carpal tunnel cortisone injections safe?

These injections are generally very safe and routinely done in our practice. There is a very small risk of infection (about 1:10.000). The procedure will be explained to you in detail during your appointment, and all your questions will be addressed. To find out more about cortisone injections in general, please see our FAQs.

What are the risks of a carpal tunnel injection?

Our practice routinely performs these injections with very few adverse effects. There is a very small risk of infection (about 1:10.000). This is very small as a strict aseptic (clean) technique is used during the procedure. The area could feel sore for a few days after the injection. This is referred to as a steroid flare and is reported in some patients. The risk of injury to the median nerve is very small as the procedure is done under ultrasound guidance, allowing for direct visualisation of the needle and the nerve.

How long will carpal tunnel steroid injection last?

It is difficult to answer this question and predict the duration of carpal tunnel injections, as this depends on many factors. Generally, Injections can be effective for a few months, but their effect can last up to a year, especially if combined with other measures like activity modification and physiotherapy. In some cases, a single injection can settle carpal tunnel syndrome for a very long period without further treatment.

Can I have repeated steroid injections for Carpal Tunnel Syndrome?

This depends on the cause of the carpal tunnel. The aim is to minimise the need for these injections by combining injection therapy with other measures mentioned earlier. If repeated injections are needed, then surgical treatment might be an option.

What are other treatment options for Carpal Tunnel Syndrome?

One ultrasound technique referred to as “hydroneurolysis or hydrodissection” is being increasingly used to treat Carpal Tunnel Syndrome. In this procedure, a mixture of medicine (usually containing a steroid and normal saline) is accurately injected around the median nerve to release it from surrounding scar tissue and thickened flexor retinaculum. The results of the procedure are encouraging.

Surgical treatment may be recommended in severe cases that do not respond to conservative treatments or when the response from the steroid injections is suboptimal.

The surgical treatment involves cutting the ligament overlying the median nerve to release the pressure within the carpal tunnel. Surgery is usually done using a keyhole technique and lasts around 30 minutes only. Post-operative rehabilitation usually involves multiple physiotherapy sessions and usually last for 6 weeks. Carpal Tunnel syndrome can reoccur even after surgical treatment.

Steroid Injection vs carpal tunnel surgery

Overall, evidence shows carpal tunnel surgery is more effective in the long term than injection therapy. However, an ultrasound-guided steroid injection is a much simpler and cheaper procedure and is often done first when simple conservative measures are not working. This will aim to treat the condition and confirm the diagnosis.

Can carpal tunnel syndrome lead to neck or shoulder pain?

It is not common for carpal tunnel syndrome to cause neck or shoulder pain, although this can be seen in severe cases. On the other hand, neck, or shoulder problems (like cervical spine osteoarthritis) can cause symptoms mistaken for Carpal Tunnel Syndrome. The median nerve roots start high up in the neck, so the nerve can be irritated in the neck or shoulder for various reasons, resulting in symptoms mimicking Carpal Tunnel Syndrome. Shoulder and neck MRI would be useful to assess the median nerve for any higher.

Can inflammatory conditions like Rheumatoid arthritis or Lupus cause Carpal Tunnel Syndrome?

Yes. Lupus and rheumatoid arthritis can cause inflammation and swelling to the wrist tendons, which could cause pressure upon the median nerve, especially since the carpal tunnel is a small and tight space. Other risk factors include diabetes, underactive thyroid and pregnancy.