Carpal Tunnel Syndrome (CTS)

What is carpal tunnel syndrome?

It is an entrapment of the median nerve at the wrist, presenting with sensory symptoms and, in advanced stages, weakness.

The carpal tunnel is a narrow passage on the palmar aspect of the wrist. Its “floor” is formed by the carpal bones, while the “roof” is the transverse carpal ligament. Passing through the tunnel are:

• the median nerve,
• the flexor tendons of the fingers.

When pressure within the tunnel increases (due to edema, tenosynovitis, fluid retention, or anatomical narrowing), the median nerve becomes compressed, leading to functional impairment.

How common is it & who is at higher risk?

It is among the most common neurological conditions of the hand and is more frequent in middle age.

Overall prevalence in the general population is estimated at approximately 2–3%, with a peak between 40–60 years. It may occur at any age when predisposing factors are present.

Risk factors include:

• Pregnancy (often resolves postpartum).
• Diabetes mellitus.
• Hypothyroidism.
• Peripheral neuropathies (especially pressure-sensitive conditions such as HNPP).
• Occupational or functional strain with repetitive movements and prolonged wrist flexion/extension (e.g., typing, assembly-line work, musicians), particularly in cold environments.

How does it develop – what exactly happens at the wrist?

The condition results from increased pressure within a “closed” space, leading to ischemia and irritation of the median nerve.

In early stages, compression mainly causes neurapraxia (functional impairment due to demyelination), resulting in slowed nerve conduction. If compression persists, axonal injury may develop, with clinical weakness and atrophy of the thenar muscles.

In simple terms: initially the hand “goes numb,” and later the thumb may become weak. This is why proper assessment and timely treatment are crucial.

What are the typical symptoms and how can I recognize them?

Classic symptoms involve sensory disturbances in the digits innervated by the median nerve, often worse at night.

Common symptoms:

• Numbness/tingling in the thumb, index, middle, and radial half of the ring finger.
• Nocturnal worsening (awakening due to symptoms).
• Sensations described as “electric,” burning, or dysesthetic.
• Pain in the wrist/palm that may radiate to the forearm or up to the elbow (rarely more proximal).
• Impaired fine motor skills or dropping objects.

Neck pain or symptoms following a clear radicular pattern may suggest cervical radiculopathy or coexisting pathology.

What does the clinical examination show (Phalen, Tinel)?

Clinical testing reproduces symptoms using specific maneuvers that support the diagnosis.

• Tinel’s sign: gentle tapping over the carpal tunnel may elicit an “electric” sensation or tingling in the fingers.
• Phalen’s test: wrist flexion for ~60 seconds may reproduce symptoms.
• Reverse Phalen: wrist extension may also provoke symptoms.
• Direct pressure over the carpal tunnel: immediate reproduction or worsening of paresthesias.

In more advanced cases, muscle weakness (particularly of the abductor pollicis brevis) and, in severe CTS, thenar atrophy may be evident.

When is EMG/NCV or ultrasound/MRI required?

Investigations confirm the diagnosis, assess severity, and are helpful when there is diagnostic uncertainty or suspected coexisting entrapment.

Electrodiagnostic testing (EMG/NCV):

• Documents slowed conduction of the median nerve across the carpal tunnel.
• Helps determine whether there is only demyelination or also axonal loss (more severe disease).
• Aids in distinguishing CTS from cervical radiculopathy or other entrapments when the clinical picture is not clear.

Median nerve ultrasound: useful for assessing nerve enlargement/edema and dynamic evaluation.

Wrist MRI is not routinely required but may be useful in atypical cases or when there is suspicion of a cyst/tumor or other rare anatomical cause.

How is it distinguished from cervical radiculopathy or other nerve entrapments?

Accurate diagnosis relies on symptom “mapping” and evaluating for compression at different levels.

CTS may coexist with more proximal nerve compressions such as cervical radiculopathy, thoracic outlet syndrome, or pronator teres syndrome. A general rule:

• The more peripheral the compression, the more localized the symptom distribution (fingers/palm).
• Central lesions more often produce “spreading” symptoms (neck, shoulder) or a radicular pattern.

Clinical assessment combined with EMG/NCV helps determine whether CTS is isolated or part of a “double-crush” phenomenon.

How is severity classified?

Severity determines the risk of permanent damage and influences treatment planning.

• Mild CTS: intermittent symptoms, mainly nocturnal, without evidence of axonal injury.
• Moderate CTS: more frequent/persistent symptoms, without clear clinical or EMG signs of axonal loss.
• Severe CTS: clinical and/or EMG evidence of axonal loss (e.g., weakness/thenar atrophy, neurogenic changes on EMG).

In severe CTS, the goal is to avoid losing valuable time, as prolonged axonal injury may result in residual deficit.

What is conservative treatment and how long does it last?

In mild to moderate CTS, conservative management is often effective and begins with ergonomics and splinting.

Conservative measures:

• Avoidance of symptom-provoking activities and ergonomic adjustments to maintain the wrist in a neutral position.
• Wrist splinting (especially at night) for several weeks.
• Hand physiotherapy/occupational therapy with a structured mobilization program.
• Anti-inflammatory medications may be used in selected cases, while opioid analgesics should generally be avoided.

Response is typically assessed over several weeks. If symptoms persist or worsen, the treatment strategy is re-evaluated.

When are corticosteroid injections recommended?

Injection may provide temporary relief and assist diagnosis, but it is not always a definitive solution.

Corticosteroid injection into the carpal tunnel (with proper technique to avoid nerve injury) may:

• reduce edema and provide temporary symptom relief,
• serve as a “therapeutic test” in equivocal cases.

In cases with axonal injury or advanced atrophy, injections rarely suffice as definitive treatment and should not delay indicated surgical decompression.

When is surgery necessary and what does the procedure involve?

Surgical decompression is recommended when conservative therapy fails or when there is evidence of more significant nerve damage.

Indications for surgery:

• Severe CTS with clinical/electrodiagnostic signs of axonal loss.
• Persistent symptoms that do not improve with adequate conservative treatment.
• Progressive weakness or thenar atrophy.

The procedure is decompression of the median nerve by dividing the transverse carpal ligament (carpal tunnel release). It can be performed:

• with an open technique, or
• with an endoscopically assisted technique in selected cases.

The goal is complete division of the ligament while protecting the median nerve branches, particularly the recurrent motor branch to the thenar muscles.