Carpal Tunnel Syndrome – When a Nerve in the Wrist Is Compressed

Carpal tunnel syndrome (CTS) is one of the most common causes of tingling, numbness, and hands falling asleep, especially at night. It is caused by compression of the median nerve at the wrist – more precisely, in the so-called carpal tunnel.

What is the carpal tunnel?

The carpal tunnel is a narrow passage between the wrist bones and a firm band on the palm side of the hand (flexor retinaculum). Several flexor tendons of the fingers run through this tunnel, along with the median nerve, which is responsible for sensation and movement in the thumb, index, and middle fingers.

If pressure increases in this area – for example, due to swelling, inflammation of the tendon sheaths, or anatomical variations – the nerve may become irritated or damaged.

Typical symptoms of carpal tunnel syndrome

Symptoms usually develop gradually and tend to worsen over time. Common signs include:

• Tingling in the thumb, index, and middle fingers
• Numbness – especially at night or when reading, using the phone, or driving
• Hands “falling asleep” in the morning

• Weakened grip – for example, when holding keys or coins
• Loss of strength when opening bottles or jars
• In advanced stages: visible muscle wasting at the base of the thumb

Diagnosis: Clinical examination, nerve testing, and imaging

Nerve conduction studies (neurography) are widely used and considered a standard diagnostic tool. They can provide important information on how well the nerve is functioning and are often part of the decision-making process for possible surgery.

However, clinical symptoms – such as night-time tingling, numbness, or weak grip – are more important than test results alone when determining whether treatment is needed.

In everyday clinical practice, the findings are not always clear-cut:

• Symptoms may be sporadic, variable, or difficult to interpret
• Nerve testing may appear normal or borderline
• The underlying cause may not be at the wrist, but instead:
  – in the cervical spine (e.g. nerve root irritation)
  – in the brachial plexus
  – or due to a non-compressive neuropathy (e.g. in diabetes or after infection)

Even in cases of persistent or recurrent symptoms after carpal tunnel surgery, further evaluation may be necessary – for example, if nerve decompression was incomplete, scar tissue is present, or other causes are involved.

Modern imaging: High-resolution ultrasound as an additional tool

• Localizing the site of compression
• Identifying the underlying cause (e.g. tendon swelling, ganglion, scarring)
• Dynamic assessment during movement
• Evaluation of postoperative changes

Ultrasound is generally well tolerated, involves no radiation, and can be performed directly in the medical office. The imaging findings support the decision for individualized treatment, whether non-operative (e.g. splinting, modification of activity) or – if necessary – surgical decompression.

Early detection allows for targeted treatment

If carpal tunnel syndrome is diagnosed early, there is often a good chance of relieving pressure on the nerve before permanent damage occurs. In early stages, only the myelin sheath (the insulating layer) may be affected. With prolonged compression, the axons (nerve fibers) can be damaged, which may delay or limit recovery.

Precise diagnostics help identify the most appropriate treatment strategy and may help avoid unnecessary procedures.

Frequently Asked Questions about Carpal Tunnel Syndrome

What causes carpal tunnel syndrome?

Carpal tunnel syndrome occurs when the median nerve in the wrist is compressed – most often due to swollen tendons, inflammation of tendon sheaths, overuse, or anatomical factors.
Other contributing conditions include age-related changes (degeneration), pregnancy, rheumatic diseases, diabetes mellitus, chronic kidney disease, or scar tissue from previous injuries.
The condition often develops gradually over time. Many people report worsening symptoms in colder seasons.

What are typical symptoms?

The most common symptoms include tingling, numbness, or hands falling asleep – especially at night or during activities like reading, holding a phone, or driving.
Other reported signs:

• Weakened grip, especially when holding small objects
• Loss of strength when opening bottles
• In more advanced cases: muscle wasting at the base of the thumb

Symptoms can affect one or both hands.

How is carpal tunnel syndrome diagnosed?

Diagnosis is based on a comprehensive clinical examination along with additional testing, such as:

• Nerve conduction studies (e.g. to assess the speed and quality of nerve signals)
• Imaging, such as high-resolution ultrasound, to assess the median nerve and possible compression points

Especially in unclear or changing symptoms, imaging can provide valuable clues – for example, regarding the location of compression or associated changes such as swelling.

Can carpal tunnel syndrome be treated without surgery?

In certain cases, non-surgical treatment may be possible – particularly if symptoms are recent and there are no signs of significant nerve damage.
Whether non-operative or surgical treatment is more appropriate can only be determined through a thorough medical examination and consultation, taking into account the clinical symptoms, physical findings, and – if needed – nerve testing and imaging results.

When should surgery be considered?

Whether surgery may be helpful depends on how advanced the condition is and the extent of functional limitations.
In a medical consultation, the following are typically considered:

• The clinical symptoms
• The results of nerve testing
• The findings from imaging (e.g. ultrasound)

On this basis, an individualized treatment plan can be developed in consultation with the patient.

What if symptoms persist after carpal tunnel surgery?

If symptoms continue or return after surgery, a more detailed evaluation may be necessary.
Possible reasons include:

• Scar tissue
• Incomplete nerve release
• A different source of the problem – such as the cervical spine, the brachial plexus, or a non-compressive neuropathy

Dynamic ultrasound can help further clarify the cause.

Is the ultrasound examination painful?

Ultrasound is generally well tolerated. No needles are used, and the procedure involves no exposure to radiation.
It can be performed directly in the practise, and results are usually available without delay to assist in further treatment planning.

Disclaimer: The information provided on this page is for general informational purposes only and does not constitute medical advice. It is not a substitute for personal consultation, examination, or treatment by a physician or other qualified healthcare professional. No guarantees of healing or cure are made. While we strive for accuracy and completeness, we cannot guarantee that all content is up to date or free from errors, and we accept no liability for any inaccuracies.