Carpal tunnel syndrome (CTS) is a common hand and wrist condition caused by compression of the median nerve in the wrist. It often affects adults who perform repetitive wrist motions — such as keyboarding or mouse use — but can arise from a combination of factors including anatomy, systemic diseases, and pregnancy. Classic symptoms include tingling, numbness, or burning in the thumb, index, and middle fingers, often worsening at night. Over time, CTS can lead to thumb weakness and difficulty gripping objects due to thenar muscle impairment. Diagnosis is primarily clinical: history and physical examination (including Phalen's and Tinel's tests) guide further testing. Current guidelines strongly recommend using a validated tool like the CTS-6 score to confirm diagnosis rather than routine MRI. Early recognition is key to prevent permanent nerve damage. This article reviews the causes, symptoms, and diagnostic approach to CTS, empowering tech professionals to seek the right evaluation and management when symptoms first arise.

What is Carpal Tunnel Syndrome?

The carpal tunnel is a narrow passageway in the wrist formed by bones and ligaments. The median nerve passes through this tunnel alongside tendons that flex the fingers. When the tunnel becomes narrowed — from inflammation, swelling, or anatomical variation — pressure builds on the median nerve, causing the characteristic symptoms of CTS.

Anatomy of the Carpal Tunnel

The floor and walls of the carpal tunnel are formed by the carpal bones (eight small wrist bones arranged in two rows). The roof is the transverse carpal ligament. The median nerve supplies sensation to the thumb, index finger, middle finger, and the thumb-side half of the ring finger — exactly where CTS symptoms appear.

Common Symptoms and Signs

Hand and Wrist Pain, Tingling, Numbness

The hallmark symptoms are tingling and numbness in the distribution of the median nerve: the thumb, index finger, middle finger, and half the ring finger. Pain may radiate up the forearm or shoulder. Many people first notice symptoms while sleeping, driving, or holding a phone.

Nighttime Symptoms and the "Flick" Sign

Worsening at night is characteristic of CTS. Patients often wake and shake or "flick" their hand to relieve the tingling — a pattern so typical it has its own name, the "flick sign." This happens because during sleep the wrist naturally flexes, increasing pressure in the carpal tunnel.

Physical Findings

Clinical examination may reveal:

Tinel's sign — tapping over the carpal tunnel at the wrist reproduces tingling in the fingers
Phalen's test — holding the wrists flexed for 60 seconds provokes symptoms
Thenar atrophy — wasting of the muscle at the base of the thumb in advanced cases, indicating motor involvement

Causes and Risk Factors

Repetitive Motions and Ergonomic Triggers

Prolonged typing, mouse use, and repetitive gripping increase the risk of CTS. Sustained wrist flexion or extension — common when typing without proper ergonomic setup — elevates pressure in the carpal tunnel. Tech workers who code for many hours daily are particularly exposed.

Medical and Physiological Factors

Several medical conditions raise CTS risk: diabetes, hypothyroidism, rheumatoid arthritis, obesity, kidney disease, and pregnancy (due to fluid retention). These conditions cause swelling or structural changes that compress the median nerve.

Demographics

Women are two to three times more likely to develop CTS than men. Risk peaks between ages 40 and 60. Genetics play a role — a naturally smaller carpal tunnel makes compression more likely regardless of occupation.

Diagnostic Workup

Clinical Tools: The CTS-6 Score

The CTS-6 is a validated six-item scoring tool combining symptoms, signs, and simple provocation tests. A score above a certain threshold predicts CTS with high sensitivity and specificity, guiding appropriate management without requiring invasive or expensive investigations.

Electrophysiology: Nerve Conduction Studies and EMG

Nerve conduction studies (NCS) and electromyography (EMG) are the gold standard for confirming CTS and assessing severity. They measure how fast electrical signals travel along the median nerve and whether the muscles it supplies are affected. NCS/EMG are not needed for every case but are recommended when diagnosis is uncertain or surgery is being considered.

Imaging and Ultrasound

Ultrasound can visualise the median nerve directly and measure its cross-sectional area — an objective marker of compression. MRI is rarely needed for routine CTS diagnosis. Both modalities are reserved for atypical presentations or surgical planning.

When to Seek Help

CTS is progressive if left untreated. Persistent or worsening numbness, hand weakness, or sleep disruption should prompt a consultation with your GP or an occupational health professional. Early diagnosis allows conservative treatment (splints, exercises, injections) before surgery becomes necessary. Tech professionals should pay particular attention — numbness or tingling in the fingertips during or after coding sessions is an early warning sign worth acting on.

Carpal Tunnel vs RSI vs Tendonitis: How to Tell Them Apart

Wrist pain from computer work goes by many names. Understanding which condition you actually have affects treatment specifics, prognosis, and urgency.

RSI Is an Umbrella Term

RSI (Repetitive Strain Injury) isn't a specific diagnosis — it describes any pain or injury caused by repetitive motion. Carpal tunnel syndrome, tendonitis, tennis elbow, and trigger finger are all types of RSI. When someone says "I have RSI," they're describing the cause, not the condition.

Tendonitis: Pain Without Numbness

Tendonitis is inflammation of a tendon. In the context of computer work, the most common types are:

Wrist flexor tendonitis: Pain along the inside of the forearm and wrist, aggravated by gripping and typing.
Wrist extensor tendonitis: Pain on the top of the wrist, worsening when lifting objects or extending the wrist.
De Quervain's tenosynovitis: Pain at the base of the thumb, aggravated by gripping, pinching, or twisting.

The key differentiator: Tendonitis produces aching pain and tenderness localized to the tendon — you can often point to exactly where it hurts. There is no numbness or tingling. CTS, by contrast, produces the characteristic numbness and "electric" sensations in the thumb, index, middle, and half of the ring finger.

Simple Self-Tests

Phalen's test (for CTS): Press the backs of your hands together with wrists flexed at 90 degrees. Hold for 60 seconds. Tingling in the thumb, index, and middle fingers suggests carpal tunnel compression.

Tinel's sign (for CTS): Tap the palm side of your wrist over the carpal tunnel crease. Tingling that radiates into your fingers suggests median nerve irritation.

Finkelstein test (for De Quervain's): Make a fist with your thumb inside your fingers. Bend your wrist toward the pinky side. Sharp pain at the base of the thumb suggests De Quervain's tenosynovitis.

These self-tests provide clues, not diagnoses. A hand specialist and nerve conduction studies give definitive answers.

Why the Distinction Matters

Treatment specifics differ: carpal tunnel responds to night splinting, nerve gliding, and sometimes surgical release. Tendonitis responds to rest and targeted stretching, and rarely requires surgery. Untreated carpal tunnel can cause permanent nerve damage and muscle wasting — a risk that tendonitis alone doesn't carry.

The root cause, however, is the same for computer users: repetitive mechanical loading beyond the tissue's capacity to recover. Reducing total repetitive wrist motion addresses all three conditions simultaneously.

Key Takeaways

Definition: CTS is compression of the median nerve at the wrist, causing sensory and motor symptoms in the hand.
Symptoms: Numbness and tingling in the thumb, index, and middle fingers; often worse at night or with wrist flexion. The "flick sign" at night is characteristic.
Risk Factors: Repetitive wrist movements (coding, mouse use), wrist anatomy, and systemic conditions such as diabetes, thyroid disease, and pregnancy all raise risk.
Diagnosis: Primarily clinical using the CTS-6 scoring tool. Nerve conduction studies confirm moderate-to-severe cases. Routine MRI is not recommended.
When to Act: Persistent or worsening symptoms, hand weakness, or sleep disturbance should prompt early evaluation. Catching CTS early prevents permanent nerve injury.

Sources

AAOS Clinical Practice Guideline on Carpal Tunnel Syndrome
NHS UK — Carpal Tunnel Syndrome overview
Mayo Clinic — Carpal Tunnel Syndrome (symptoms and causes)
AAFP (American Family Physician) review of CTS
OrthoInfo (AAOS patient guide) — CTS description
Cochrane review: Surgical vs Non-surgical treatment for CTS
Benson et al., Journal of Hand Therapy, 2025 — Survey on non-invasive CTS management trends

Understanding Carpal Tunnel Syndrome: Causes, Symptoms & Diagnosis