Wartenberg’s Syndrome

The superficial branch of the radial nerve has 3 or 4 terminal branches and is a purely sensory nerve, as indicated by the blue shade on the image above. Sometimes, the innervation area of the superficial radial nerve can overlap with the innervation of the lateral antebrachial cutaneous nerve. There is a difference between Wartenberg’s Syndrome and Wartenberg’s Sign. The Wartenberg’s Sign occurs due to a low ulnar nerve injury and consists of an abduction of the fifth finger which is caused by an unopposed ulnar insertion of the extensor digiti quinti.

The superficial sensory branch arises from the radial nerve in the proximal forearm. The superficial branch of the radial nerve passes along the front of the radial side of the forearm, beneath the brachioradialis muscle. The superficial branch exits from between the brachioradialis and extensor carpi radialis longus muscles about 9cm proximal to the radial styloid process. Wartenberg’s Syndrome is caused by entrapment of the superficial branch of the radial nerve at this point, where the nerve arises from beneath the muscles. The nerve is likely to become compressed between the brachioradialis and the ECRL tendons, especially during forearm pronation. Wartenberg’s Syndrome most commonly occurs in women and may also be associated with De Quervain’s Syndrome. Entrapment of the superficial branch of the radial nerve occurs where the nerve pierces the antebrachial fascia, approximately 2/3rds of the way down the forearm at the lateral border, between the brachioradialis and the ECRL.

Entrapment of the superficial branch of the radial nerve occurs where the nerve pierces the antebrachial fascia, approximately 2/3rds the way down the forearm at the lateral border between the brachioradialis and ECRL. Entrapment occurs with repetitive pronation of the forearm and the brachioradialis muscle closes the space between these two tendons in a scissor like fashion while rotating the nerve. Pain may be elicited with forced pronation and ulnar deviation of the wrist.

Causes of Wartenberg’s Syndrome

· Tight plaster casts

· Forearm fractures

· Wearing bracelets, watches, handcuffs, etc.

The patient will be unable to tolerate wearing a tight bracelet or wristwatch. Symptoms include: numbness, tingling, and paresthesia on the posterior aspect of the thumb. There will be no weakness associated with this condition. The symptoms of Wartenberg’s syndrome are also aggravated by motion such as repetitive wrist flexion and ulnar deviation.

Physical Examination

The Tinel’s Sign over the area of the superficial radial nerve is the most common finding for Wartenberg’s Syndrome. Additionally, the Finkelstein Test may be positive due to traction on the nerve or associated De Quervain’s syndrome.

Differential Diagnosis

De Quervain’s Syndrome is the inflammation of the sheath or tunnel that surrounds the two tendons that control movement of the thumb. The pain associated with intersection syndrome is felt at the top of the forearm where the two muscles which connect to the thumb cross the underlying wrist tendons. The pain is increased by flexion/extension and is more proximal than the pain associated with De Quervain’s Syndrome.

Treatment

Treatment for Wartenberg’s Syndrome includes activity modification in the form of avoiding tight bands and watches. Conservative treatment usually achieves a positive result 70% of the time. Injections are usually diagnostic. Surgery will be done to decompress the nerve and is usually done if the patient has a positive Tinel’s sign and the symptoms continue despite conservative treatment and injections. Surgery will be performed between the brachioradialis and extensor carpi radialis longus muscles. Knowing that the nerve exits between the brachioradialis and ECRL muscles is important.