Carpal Tunnel Syndrome
Carpal tunnel syndrome causes tingling and numbness in the thumb and fingers. UK guide to median nerve anatomy, diagnosis, splinting, injection and surgery.
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Carpal Tunnel Syndrome UK: Symptoms, Causes & Diagnosis
A clinically reviewed UK conditions guide to carpal tunnel syndrome — median nerve anatomy, causes, characteristic symptoms, nerve conduction studies, wrist splinting, steroid injection, and surgical decompression.
Carpal tunnel syndrome (CTS) is the most common peripheral nerve entrapment in the UK — analogous in mechanism to sciatica in the lower limb, where a different nerve is compressed, affecting around 3–6% of the population. It is caused by compression of the median nerve as it passes through the carpal tunnel in the wrist, producing characteristic pain, tingling, and numbness in the thumb, index, middle, and half of the ring finger. It is highly treatable — from wrist splinting and corticosteroid injection through to surgical decompression.
What Is Carpal Tunnel Syndrome?
Carpal tunnel syndrome is a peripheral neuropathy caused by compression of the median nerve as it passes through the carpal tunnel — a narrow bony passage in the wrist formed by the carpal bones and the transverse carpal ligament. Increased pressure within this confined space compresses the median nerve, impairing its conduction and producing the characteristic symptoms of CTS.
The Carpal Tunnel: Anatomy
The carpal tunnel is a rigid channel at the base of the palm, approximately 2.5cm long and 2cm wide at its narrowest. Its floor and sides are formed by the carpal bones; its roof by the tough transverse carpal ligament (flexor retinaculum). Through it pass nine flexor tendons and the median nerve. Because the walls are rigid, any process that increases the volume of contents — or causes the tissue to swell — raises the pressure within the tunnel and compresses the median nerve.
The median nerve supplies sensation to the thumb, index finger, middle finger, and the radial (thumb-side) half of the ring finger, and motor supply to the thenar muscles at the base of the thumb. CTS produces symptoms in exactly this distribution.
Causes and Risk Factors
- Idiopathic — in the majority of cases no specific cause is identified; likely multifactorial
- Fluid retention — pregnancy (particularly the third trimester), hypothyroidism, and chronic kidney disease cause increased carpal tunnel contents, precipitating CTS; pregnancy-related CTS often resolves post-partum
- Obesity — associated with CTS; mechanism includes increased adipose tissue in the tunnel and metabolic effects
- Diabetes mellitus — peripheral nerve vulnerability; diabetic neuropathy and CTS frequently coexist and may be difficult to distinguish clinically
- Repetitive wrist use — occupational exposure to repetitive wrist flexion and extension, particularly with vibrating tools
- Inflammatory arthritis — rheumatoid arthritis; tenosynovitis within the carpal tunnel increases pressure
- Previous wrist fracture — particularly Colles fracture; altered carpal tunnel anatomy or callus formation
- Acromegaly and other endocrine disorders — cause soft tissue enlargement
Symptoms
- Tingling and numbness — in the thumb, index, middle, and radial half of ring finger; the characteristic distribution corresponds to the median nerve’s sensory territory
- Pain in the hand and wrist — aching, burning, or shooting pain; often radiates up the forearm
- Night symptoms — waking from sleep with tingling, numbness, or pain is highly characteristic; wrist flexion during sleep increases carpal tunnel pressure; relieved by hanging the hand out of bed or shaking it (“flick sign”)
- Weakness of grip — difficulty with fine motor tasks: turning keys, doing up buttons, holding cups; weakness is in the thenar muscles (thumb opposition and abduction)
- Dropped objects — in more severe CTS; reduced grip strength and proprioception
- Thenar muscle wasting — visible wasting at the base of the thumb in severe, longstanding CTS; indicates significant ongoing nerve damage
Thenar muscle wasting is a sign of severe, longstanding nerve compression. If you have visible loss of muscle bulk at the base of your thumb, seek assessment promptly — prolonged nerve compression without decompression can cause irreversible deficit.
Diagnosis
CTS is primarily a clinical diagnosis based on the characteristic symptom pattern. Two clinical tests are commonly used:
- Tinel’s sign — percussion over the carpal tunnel at the wrist produces tingling in the median nerve distribution; moderately sensitive
- Phalen’s test — sustained wrist flexion for 60 seconds reproduces symptoms; sensitive and specific
Nerve conduction studies (NCS) are the definitive diagnostic test — they can confirm median nerve entrapment at the wrist, grade severity, and exclude other conditions such as cervical radiculopathy or peripheral neuropathy. NICE recommends NCS to confirm diagnosis before surgical decompression.
Treatment Overview
| Treatment | Appropriate for | Evidence |
|---|---|---|
| Wrist splint at night | Mild to moderate; first-line; particularly in pregnancy | Keeps wrist in neutral position overnight; reduces tunnel pressure; very effective for nocturnal symptoms; benefit may take 4–6 weeks |
| Corticosteroid injection | Moderate; when splinting insufficient | Short-to-medium term relief; reduces inflammation and oedema in the tunnel; GP or specialist administered; may need repeating |
| NSAIDs | Mild; symptom relief only | Limited evidence for CTS specifically; may provide short-term pain relief; do not treat nerve compression; not appropriate long-term |
| Treat underlying cause | Where applicable | Treating hypothyroidism, diabetes, or inflammatory arthritis can resolve CTS; discontinuing precipitating medication |
| Surgical decompression | Moderate to severe; failed conservative treatment; thenar wasting or significant weakness | Division of transverse carpal ligament; >90% success rate; day surgery; rapid return to function |
Prescription NSAIDs for wrist and hand pain: Prescription pain relief at Access Doctor → — note that NSAIDs address pain but do not treat the nerve compression underlying CTS.
See Your GP About Carpal Tunnel Syndrome
A GP can assess, confirm the diagnosis clinically, and arrange nerve conduction studies, wrist splint prescription, corticosteroid injection, or surgical referral as appropriate. Early assessment prevents unnecessary progression.
Find Your GP →Surgery: Carpal Tunnel Release
Carpal tunnel release (CTR) involves dividing the transverse carpal ligament to decompress the median nerve. It is performed under local anaesthetic as a day case procedure, either by open surgery or endoscopically. It is one of the most common surgical procedures performed in the UK and has a success rate of 75–90% for long-term symptom relief.
Indications for surgery include: failure to respond to conservative management after 3–6 months; significant weakness or thenar wasting; severe NCS findings; patient preference after informed discussion. Most patients experience significant symptomatic improvement within weeks. Sensory recovery precedes motor recovery; severe muscle wasting may only partially recover.
When to Seek Help
- Persistent tingling or numbness in the thumb, index, and middle fingers — especially if waking you at night
- Weakness of grip or difficulty with fine motor tasks
- Visible muscle wasting at the base of the thumb — seek prompt assessment
- Symptoms not improving with splinting after 6–8 weeks
- CTS in pregnancy — usually managed conservatively; seek GP advice
Frequently Asked Questions
What causes carpal tunnel syndrome?
CTS is caused by compression of the median nerve as it passes through the carpal tunnel in the wrist. In most cases the cause is idiopathic. Known risk factors include pregnancy, hypothyroidism, obesity, diabetes, repetitive wrist use, inflammatory arthritis, and previous wrist fracture.
What does carpal tunnel syndrome feel like?
The characteristic symptoms are tingling, numbness, and pain in the thumb, index, middle, and half of the ring finger — the distribution of the median nerve. Symptoms are typically worst at night, waking people from sleep. Shaking the hand often provides relief. Grip weakness and dropping objects occur in more severe cases.
How is carpal tunnel syndrome diagnosed?
CTS is primarily diagnosed clinically from the characteristic symptom pattern. Phalen’s test (sustained wrist flexion reproducing symptoms) and Tinel’s sign (percussion producing tingling) support the diagnosis. Nerve conduction studies confirm the diagnosis and grade severity, and are recommended before surgical decompression.
What is the treatment for carpal tunnel syndrome?
First-line treatment is a wrist splint worn at night, keeping the wrist in neutral to reduce tunnel pressure. If this is insufficient, a corticosteroid injection into the carpal tunnel provides short-to-medium term relief. Surgery (carpal tunnel release) is highly effective (>90% success) for moderate to severe cases or those failing conservative management.
Does carpal tunnel syndrome go away on its own?
Mild CTS, particularly in pregnancy, may improve spontaneously — pregnancy-related CTS often resolves after delivery. In most adults, CTS does not resolve without treatment. Untreated moderate-to-severe CTS can lead to permanent muscle wasting and irreversible sensory loss. Early assessment and appropriate treatment are recommended.
References
- NICE CKS. Carpal tunnel syndrome. Updated 2023. cks.nice.org.uk
- NHS. Carpal tunnel syndrome. nhs.uk/conditions/carpal-tunnel-syndrome
- Bland JDP. Carpal tunnel syndrome. BMJ. 2007.
- NICE. Carpal tunnel syndrome. IPG43. 2004 (updated 2020).
Medical disclaimer: This article is for informational purposes only and does not constitute medical advice. Always consult a qualified healthcare professional. In a medical emergency, call 999.
