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[Conditions](https://durgical.com/en/conditions/) · [Upper limb](https://durgical.com/en/anatomy/region/upper-limb/)

# Carpal tunnel syndrome

Carpal tunnel syndrome is pressure on the median nerve at the wrist; it causes numbness and tingling in the thumb, index and middle fingers.

Updated 2026-10-29

## Structures involved

Tap one to see what it is and open it in 3D.

- [Median nerve](https://durgical.com/en/anatomy/median-nerve/)
- [Flexor retinaculum](https://durgical.com/en/anatomy/flexor-retinaculum/)
- [FDS tendons](https://durgical.com/en/anatomy/flexor-digitorum-superficialis-tendons/)
- [FDP tendons](https://durgical.com/en/anatomy/flexor-digitorum-profundus-tendons/)
- [FPL](https://durgical.com/en/anatomy/flexor-pollicis-longus/)
- [APB](https://durgical.com/en/anatomy/abductor-pollicis-brevis/)
- [Opponens pollicis](https://durgical.com/en/anatomy/opponens-pollicis/)
- [Recurrent motor branch](https://durgical.com/en/anatomy/recurrent-motor-branch-of-the-median-nerve/)

## In biochemistry

- [Transthyretin (prealbumin)](https://durgical.com/en/biochemistry/enzymes/transthyretin/)

## In histology

- [Peripheral nerve: endoneurium, perineurium, epineurium; myelin](https://durgical.com/en/histology/peripheral-nerve-endoneurium-perineurium-epineurium-myelin/)
- [Nerve injury and regeneration (Wallerian degeneration)](https://durgical.com/en/histology/nerve-injury-and-regeneration/)
- [Skin receptors: Meissner, Pacinian, Merkel, Ruffini and free nerve endings](https://durgical.com/en/histology/skin-receptors-meissner-pacinian-merkel-ruffini-and-free-nerve-endings/)

## In the clinical exam

- [Phalen and Tinel signs](https://durgical.com/en/clinical-exam/phalen-and-tinel-signs/)

## What it is

Compression of the median nerve as it passes under the flexor retinaculum (transverse carpal ligament) at the wrist. It is the most common entrapment neuropathy of the [upper limb](https://durgical.com/en/anatomy/region/upper-limb/).

## Who gets it

Common in adults of working age, more often in women. In Latin America it is frequently seen in occupational health clinics among people doing repetitive manual work.

## Causes

- Usually idiopathic
- Anything that raises pressure in the tunnel: tenosynovitis of the flexor tendons, fluid retention, wrist fracture or arthritis
- Space-occupying lesions such as a ganglion or tumour (rare)

## Risk factors

- Female sex and middle age
- Pregnancy
- Diabetes mellitus
- Hypothyroidism
- Obesity
- Rheumatoid arthritis
- Repetitive forceful wrist flexion or vibrating tools

## Pathophysiology

The carpal tunnel is a rigid space bounded by the carpal bones and the flexor retinaculum, holding nine flexor tendons and the median nerve. Raised pressure impairs blood flow in the nerve, causing focal demyelination first and, if it persists, axonal loss. Sensory fibres are affected early; motor loss in the thenar muscles comes later.

## Classification

- Mild: intermittent sensory symptoms
- Moderate: constant sensory loss or weakness
- Severe: thenar atrophy and axonal loss on nerve studies (grading schemes vary)

## Symptoms and signs

- Numbness and tingling in the thumb, index, middle and radial half of the ring finger
- Symptoms worse at night, often waking the patient; shaking the hand gives relief
- Clumsiness and dropping objects
- Weak thumb abduction and opposition
- Thenar atrophy in advanced cases

## Red flags

- Thenar atrophy or constant numbness, which suggest axonal loss
- Rapid onset after a wrist fracture or crush injury (acute carpal tunnel syndrome needs urgent release)

## Diagnosis

**Clinical**
Typical sensory distribution with sparing of the thenar eminence [skin](https://durgical.com/en/anatomy/skin/) ([palmar cutaneous branch](https://durgical.com/en/anatomy/palmar-cutaneous-branch-of-the-median-nerve/) runs above the retinaculum). Tinel sign over the tunnel, Phalen test (sustained wrist flexion) and the carpal compression test.

**Tests**
Nerve conduction studies and electromyography confirm the diagnosis and grade severity; they are especially useful before surgery. Glucose and thyroid tests can look for associated conditions.

**Imaging**
Not routine. Ultrasound can show an enlarged [median nerve](https://durgical.com/en/anatomy/median-nerve/); X-ray if bony deformity is suspected.

## Differential diagnosis

- Cervical radiculopathy (C6–C7)
- [Pronator teres](https://durgical.com/en/anatomy/pronator-teres/) syndrome
- Peripheral polyneuropathy
- Thoracic outlet syndrome
- Thumb base (CMC) osteoarthritis

## Goal of treatment

Relieve pressure on the median nerve, control symptoms and prevent permanent sensory loss and thenar weakness.

## Treatment

**Conservative**
Night splint holding the wrist in neutral, plus modification of repetitive or forceful activity.

**Medical**
Corticosteroid injection into the [carpal tunnel](https://durgical.com/en/anatomy/carpal-tunnel/) can give relief, often temporary; oral corticosteroids are used less. NSAIDs have limited evidence.

**Surgical**
Carpal tunnel release (open or endoscopic) divides the flexor retinaculum; indicated for failed conservative care, constant numbness or thenar atrophy.

**Rehabilitation**
Hand therapy and nerve and tendon gliding exercises after release.

## Drugs for this condition

- [Lidocaine](https://durgical.com/en/pharmacology/lidocaine/)

## Complications

- Permanent numbness
- Thenar muscle atrophy and weak pinch
- Pillar pain or scar tenderness after surgery
- Rarely, injury to the recurrent motor or palmar cutaneous branch during release

## Prognosis

Mild cases often improve with splinting. Surgical release relieves symptoms in most patients, though recovery of sensation and strength is slower and may be incomplete when there was long-standing axonal loss.

## Prevention

- Ergonomic adjustments and breaks during repetitive hand work
- Control of diabetes, thyroid disease and weight

## Test yourself

Think of the answer, then tap the question to see it.

## Which nerve is compressed in carpal tunnel syndrome, and under which structure?

The median nerve, under the flexor retinaculum (transverse carpal ligament) at the wrist.

## Why is skin sensation over the thenar eminence usually spared in carpal tunnel syndrome?

That skin is supplied by the palmar cutaneous branch of the median nerve, which runs superficial to the flexor retinaculum.

## What are the Tinel and Phalen tests in carpal tunnel syndrome?

Tinel: tapping over the tunnel causes tingling in the median nerve fingers. Phalen: holding the wrist in full flexion reproduces the symptoms.

## Which test confirms carpal tunnel syndrome and grades its severity?

Nerve conduction studies with electromyography.

## What sign of advanced carpal tunnel syndrome is a common indication for surgical release?

Thenar muscle atrophy (or constant numbness), which suggests axonal loss.

[Add to my cards (5)](https://durgical.app/estudiar/?add=/en/conditions/carpal-tunnel-syndrome/)

## Related conditions

- [Cervical Spondylosis](https://durgical.com/en/conditions/cervical-spondylosis/)
- [De Quervain tenosynovitis](https://durgical.com/en/conditions/de-quervain-tenosynovitis/)
- [Trigger finger](https://durgical.com/en/conditions/trigger-finger/)
- [Cervical radiculopathy](https://durgical.com/en/conditions/cervical-radiculopathy/)
- [Thoracic outlet syndrome](https://durgical.com/en/conditions/thoracic-outlet-syndrome/)
- [Degenerative cervical myelopathy](https://durgical.com/en/conditions/degenerative-cervical-myelopathy/)
- [Distal radius fracture (Colles)](https://durgical.com/en/conditions/distal-radius-fracture/)
- [Cubital tunnel syndrome (ulnar neuropathy at the elbow)](https://durgical.com/en/conditions/cubital-tunnel-syndrome/)

Educational information, not medical advice. For any symptom, see a health professional.

Sources: [Carpal Tunnel Syndrome](https://www.ncbi.nlm.nih.gov/books/NBK448179/) (StatPearls (NCBI Bookshelf), 2023).

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Representative model, for educational purposes only.

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Source: https://durgical.com/en/conditions/carpal-tunnel-syndrome/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/conditions/carpal-tunnel-syndrome/