Wartenberg's Syndrome (Cheiralgia Paresthetica)

What happens in Wartenberg's syndrome

The radial nerve splits near the elbow into a deep motor branch, which powers the muscles that straighten the wrist and fingers, and a superficial branch, which carries only sensation. This superficial branch runs down the forearm under the brachioradialis muscle, then emerges between two tendons (the brachioradialis and extensor carpi radialis longus) about 3 to 4 inches (8 to 9 cm) above the wrist, where it becomes superficial.

At that point the nerve is close to the skin and is pinched between the tendons, especially when the forearm turns palm-down (pronation) and the wrist bends toward the little finger. It can also be compressed from the outside by anything tight around the wrist. The nerve was described in 1932 by neurologist Robert Wartenberg, who named the condition cheiralgia paresthetica, meaning "hand pain with abnormal sensation".

Because the nerve has no motor fibers, Wartenberg's syndrome never causes weakness.

Causes and risk factors

• External pressure: tight watch straps, bracelets, wristbands, handcuffs, casts and splints
• Repetitive movements: wringing, twisting, hammering, using screwdrivers, typing with the wrist bent, some sports and crafts
• Injury: wrist fractures, forearm blows, and scar tissue
• Surgery and procedures: IV lines, wrist arthroscopy, de Quervain release and fracture plating near the wrist
• Swelling: pregnancy, fluid retention, nearby tendon inflammation
• Nerve vulnerability: diabetes and other causes of peripheral neuropathy

Symptoms

• burning, shooting or aching pain on the back of the thumb side of the wrist and hand
• numbness, tingling or pins and needles over the back of the thumb, the web space between thumb and index finger, and sometimes the index finger
• symptoms worse with pinching, gripping, twisting the forearm or wearing a watch
• tenderness at a point on the thumb side of the forearm a few inches above the wrist
• normal grip and finger strength

Wartenberg's syndrome vs similar conditions

A note on names: "Wartenberg's sign" is a different finding, an inability to bring the little finger in toward the ring finger, which is a sign of ulnar nerve weakness. "Wartenberg's migrant sensory neuritis" is also a separate, rare condition.

Diagnosis

Wartenberg's syndrome is usually diagnosed from the history and examination:

• Tinel's sign: tapping over the nerve in the forearm reproduces the tingling into the back of the thumb.
• Provocation test: holding the forearm palm-down with the wrist bent toward the little finger for about a minute reproduces symptoms.
• Sensory testing of the back of the hand compared with the other side.
• Strength testing to confirm there is no motor weakness.
• Finkelstein's test may also be positive, which is why it is easily confused with de Quervain's tenosynovitis.

Further tests when the diagnosis is unclear:

• Nerve conduction studies: can show slowed or reduced signals in the superficial radial nerve, although results may be normal in mild cases.
• Ultrasound: shows swelling of the nerve or compression points.
• Diagnostic nerve block: a small local anesthetic injection near the nerve that temporarily relieves pain supports the diagnosis.

Treatment

Non-surgical care (first line)

• Remove the source of pressure: take off or loosen watches, bracelets and tight sleeves. Wear a watch on the other wrist or loosely.
• Activity changes: avoid repetitive twisting, wringing and pinching for a few weeks. Use tools with larger handles.
• Splinting: a thumb spica splint, which keeps the wrist and thumb in a neutral position, can be worn during aggravating activities or at night. Make sure it does not press on the nerve.
• Anti-inflammatory pain relief: ibuprofen or naproxen at the label dose, if suitable, or topical NSAID gels.
• Corticosteroid injection near the nerve to reduce local swelling.
• Hand therapy: nerve gliding exercises, desensitization and ergonomic advice.
• Nerve pain medicines, such as gabapentin, are occasionally used for persistent burning pain.

Most people improve over 6 weeks to 6 months with these measures.

Surgery

Surgery is considered when symptoms persist beyond about 6 months despite non-surgical treatment, or are severe. The surgeon frees the nerve (neurolysis) by releasing the tight fascia between the two tendons. Most patients get good relief, though recovery of sensation can take months. Risks include persistent numbness and painful scar or neuroma formation.

Outlook

The outlook is good, especially when an external cause such as a tight band is identified and removed. Cases caused by injury or scarring can take longer to settle. Because the nerve carries only sensation, there is no risk of lasting weakness.

Frequently asked questions

What is Wartenberg's syndrome?

Wartenberg's syndrome is a compression of the superficial radial nerve in the forearm, a nerve that carries feeling from the back of the thumb and hand. Pressure from tight bands, repetitive wrist twisting or injury irritates it, causing burning pain, numbness and tingling, but not weakness.

What causes numbness on the back of the thumb?

A common cause is irritation of the superficial radial nerve (Wartenberg's syndrome) from a tight watch, bracelet, handcuffs or cast. Other causes include wrist injuries, surgery near the wrist, and nerve root problems in the neck. Numbness on the palm side of the thumb is more often carpal tunnel syndrome.

How long does Wartenberg's syndrome take to heal?

Mild cases caused by external pressure often improve within a few weeks after the pressure is removed. Most other cases settle within 6 weeks to 6 months with splinting, activity changes and anti-inflammatory treatment. Persistent cases may need surgery to release the nerve.

Is Wartenberg's syndrome the same as de Quervain's tenosynovitis?

No. De Quervain's tenosynovitis is inflammation of thumb tendons at the wrist and causes pain with thumb movement, without numbness. Wartenberg's syndrome is a nerve problem causing tingling and numbness on the back of the thumb. They can occur together and are often confused.

What is handcuff neuropathy?

Handcuff neuropathy is nerve injury from tight handcuffs. The superficial radial nerve is the nerve most often affected, causing numbness and tingling over the back of the thumb and hand. Most cases recover over weeks to months once the pressure has been removed.