Muscle & joint · Nerve ultrasound guide

Carpal Tunnel Syndrome: Symptoms, Tests & When to Get an Ultrasound

Tingling, numbness or pain in the thumb and first fingers—especially at night—may result from pressure on the median nerve at the wrist. Ultrasound can show the nerve and surrounding structures in real time.

Medically reviewed by Mr Pedram Aghaei19 October 2026Adults aged 18+★★★★★ 4.8 · 1,200+ reviews

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What is carpal tunnel syndrome? It is compression of the median nerve as it passes through the carpal tunnel, a narrow channel on the palm side of the wrist.

If your fingers become numb while holding your phone, or tingling repeatedly wakes you at night, it can disrupt typing, cooking, driving and carrying shopping. This guide explains the symptoms, diagnosis, ultrasound findings and treatment options.

Carpal tunnel syndrome affecting the median nerve at the wrist — Carpal tunnel syndrome compresses the median nerve within a narrow wrist passage.

When tissues inside the tunnel swell, the nerve is squeezed and signals to the hand are disrupted. The median nerve supplies feeling to the thumb, index and middle fingers and half of the ring finger. Symptoms therefore usually spare the little finger.

What Does Carpal Tunnel Feel Like?

Carpal tunnel syndrome commonly causes tingling, pins and needles or numbness, often worse at night. Symptoms may start gradually and come and go.

Tingling or pins and needles in the thumb and first fingers.
Numb hands, especially on waking.
Aching or pain in the fingers, hand or arm.
Weakness of the thumb or difficulty gripping.

Many people wake a few hours after falling asleep and shake or flick the hand to restore sensation. Clinicians call this the “flick sign”.

Woman experiencing night-time wrist and hand symptoms from carpal tunnel syndrome — Night-time tingling and numbness are common early symptoms.

What Causes Carpal Tunnel Syndrome?

Pressure builds within the rigid carpal tunnel and compresses the median nerve. There is often no single cause, but risk is greater if you:

Are overweight.
Are pregnant.
Repeatedly bend the wrist or grip forcefully, including use of vibrating tools.
Have arthritis, diabetes or another associated condition.
Have a parent or sibling with carpal tunnel syndrome.
Have previously injured the wrist.

Carpal tunnel during pregnancy

Fluid retention and hormonal changes can cause wrist swelling. Symptoms are most common in the third trimester and often improve after birth.

Does typing cause carpal tunnel? Current orthopaedic guidance has not found strong evidence that keyboard use alone causes carpal tunnel syndrome, so other contributing factors should also be considered.

How Is Carpal Tunnel Syndrome Diagnosed?

Diagnosis usually starts with a symptom history and hand examination. When the picture is unclear, ultrasound or a nerve conduction study can assess the nerve.

Step 1: Symptoms and examination

The clinician checks which fingers are affected, timing, sensation and thumb strength. Tinel’s test taps over the wrist nerve; Phalen’s test holds the wrist bent for 60 seconds to see whether symptoms appear.

Step 2: Imaging or nerve testing

When symptoms are unusual, weakness is present, or an injection or surgery is being considered, ultrasound or nerve conduction testing can confirm compression and assess severity.

In clear-cut cases, history and examination may be sufficient, but tests provide additional evidence and help exclude other causes.

Ultrasound vs Nerve Conduction Test: Which Is Better?

Neither is universally better. They answer different questions: ultrasound shows the nerve’s structure and surrounding anatomy, while nerve conduction testing measures electrical function.

Swipe sideways to view the full table.

	Ultrasound	Nerve conduction test
What it shows	The nerve and surrounding structures.	How well the nerve carries signals.
How it feels	Gel and a probe on the skin; no needles.	Mild electrical pulses through small electrodes.
Can it show a cyst or swelling?	Yes.	No.

What ultrasound shows

The median nerve often appears swollen just before entering the tunnel. Research reviews identify this as the most reliable ultrasound sign, and greater swelling often corresponds with more severe disease. Ultrasound can also reveal cysts, swollen tendons or other structures pressing on the nerve.

Ultrasound examination of the median nerve at the wrist — Ultrasound visualises median-nerve swelling and structural causes of compression.

What nerve conduction testing shows

Small electrodes and mild electrical pulses measure the speed and strength of nerve signals. The test helps grade severity, and many hand surgeons request it before surgery.

What Condition Is Carpal Tunnel Mistaken For?

Numb or tingling fingers do not always come from the wrist.

Cervical radiculopathy

A compressed nerve root in the neck—often C6 or C7—can send pain, tingling or numbness into the hand. Neck movement, neck pain, shoulder pain or arm pain may provide clues.

Cubital tunnel syndrome

Compression of the ulnar nerve at the elbow usually affects the little finger and outer half of the ring finger. Symptoms may worsen when leaning on a bent elbow or holding a phone.

How Is Carpal Tunnel Syndrome Treated?

Treatment is usually stepped. A night splint or steroid injection may be tried first, while surgery is considered for severe, persistent or worsening symptoms.

Wrist splint

A night splint keeps the wrist neutral and reduces pressure during sleep. Improvement can take several weeks; some guidance suggests a trial of up to 12 weeks.

Steroid injection

An injection reduces swelling around the nerve and may give short-term relief. Ultrasound guidance helps place medication accurately while avoiding the nerve and nearby structures.

Carpal tunnel surgery

Release surgery cuts a wrist ligament to create more room. It usually takes 20–30 minutes under local anaesthetic, and most patients go home the same day.

Recovery

Night-time tingling may improve quickly, while hand strength and scar comfort can take several months. Long-standing severe compression may leave residual numbness or weakness.

Carpal tunnel treatment options including wrist splint, ultrasound-guided injection and surgery — Treatment may include a night splint, image-guided injection or surgical release.

When Should You See a GP About Carpal Tunnel?

Arrange assessment if symptoms are worsening, not settling, or a night splint is not helping. Thumb weakness, difficulty gripping, dropping objects or thinning of the muscle at the thumb base can indicate more significant nerve compression.

Do not wait for symptoms to interfere significantly with work or sleep. Progressive weakness or muscle wasting deserves prompt clinical assessment.

London Private Ultrasound offers private GP and orthopaedic consultations, diagnostic ultrasound and selected image-guided nerve injections under one roof, without a GP referral.

Book a Hand and Wrist Ultrasound in London

A specialist hand and wrist ultrasound can assess the median nerve and other wrist structures, with findings explained on the day and a written report within 24 hours.

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No hidden extras and no GP referral. A combined hand-and-wrist scan costs £299 for one side or £499 for both sides.

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Answers before you leave

Findings are explained in the room, followed by a written report within 24 hours.

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Clinics are open 9am–7pm, with same-day appointments often available.

Evidence for the next step

Your report supports decisions about splinting, injection, surgery or additional testing.

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References

Frequently Asked Questions

Can an ultrasound diagnose carpal tunnel syndrome?

Yes. Ultrasound shows median-nerve swelling and can identify structural causes. Research indicates diagnostic accuracy can be comparable with nerve conduction testing.

Does a carpal tunnel ultrasound hurt?

No. Gel and a small probe are used on the wrist, without needles or electrical pulses. The scan takes around 20–30 minutes and needs no preparation.

How much is a carpal tunnel scan in London?

A hand or wrist ultrasound starts from £199. A combined hand-and-wrist scan costs £299 for one side or £499 for both, including explanation and a written report.

Do I need a GP referral for a carpal tunnel scan?

No. You can book directly and share the report with your GP or specialist afterwards.

What if I am not sure the problem is in my wrist?

A peripheral nerve ultrasound can follow the median, ulnar and radial nerves along the arm. It costs £299 for one arm.

Does carpal tunnel go away on its own?

Sometimes, particularly when related to pregnancy. Persistent, worsening or weakness-producing symptoms should be assessed.

Why is my little finger numb? Is that carpal tunnel?

Probably not. The median nerve does not supply the little finger. Numbness there more often suggests ulnar-nerve compression, commonly at the elbow.

Medical disclaimer: This article provides general information and does not replace individual medical advice. Seek prompt assessment for progressive weakness, muscle wasting, severe pain or sudden neurological symptoms.

Written and medically reviewed by Mr Pedram Aghaei, Co-founder and Medical Writer, London Private Ultrasound. Reviewed against NHS, NICE and professional hand/nerve guidance. Last reviewed 19 October 2026; next review due 19 April 2027.