WARTENBERG'S SYNDROME

Wartenberg syndrome, which is entrapment of the superficial (ie, sensory) branch of the radial nerve (SRN), was first described by Dr. Wartenberg in 1932. At the time, he suggested the name “cheiralgia paraesthetica,” because he observed a similarity to the isolated involvement of the thigh’s lateral cutaneous nerve. Wartenberg syndrome is a compressive neuropathy associated with sensory manifestations such as painful paresthesias on the dorsum of the thumb and radial hand.  Wartenberg syndrome is not associated with any motor deficits.

Pathophysiology

• Due to its anatomic location, the SRN is highly vulnerable to compression from trauma, masses, and constriction from the fascia connecting the brachioradialis and extensor carpi radialis longus (ECRL).  
• Although the SRN can be compressed anywhere along its course in the forearm, the point of greatest vulnerability is at the posterior border of the brachioradialis as the nerve transitions from a deep to a subcutaneous location.
• The syndrome can be caused by:
  • Bony spurs
  • Colles’ fracture
  • Nerve tumors (eg, hemangioma, ganglion cyst)
  • Overexertion of the hand
  • Repetitive movements
  • Severe cold
  • Stretch injury to the SRN (eg, closed reduction of forearm fracture)
  • Trauma such as nail gun injuries
  • Tight fascial bands

Related Anatomy

• The radial nerve bifurcates into the SRN and posterior interosseous nerve (PIN).
• The SRN courses distally into the forearm deep to the brachioradialis. Approximately 9 cm proximal to the radial styloid, the SRN becomes a subcutaneous structure by traveling between the brachioradialis and ECRL tendons.
• The SRN continues subcutaneously and branches out into dorsal digital nerves responsible for afferent sensory input from the dorsum of the thumb, index, and middle fingers proximal to the proximal interphalangeal (PIP) joints.

Incidence and Related Conditions

• Wartenberg syndrome is rare.
• Although Wartenberg syndrome often is confused with de Quervain’s tenosynovitis, the two disorders can present simultaneously occassionally.

Differential Diagnosis

• de Quervain’s tenosynovitis (pain is not aggravated by wrist pronation)
• Intersection syndrome
• Lateral antebrachial cutaneous nerve (LACN) neuritis (positive Tinel’s sign over LACN can be mistaken for positive Tinel’s sign over SRN) This extremely rare.

The patient usually reports pain over the distal radial forearm radiating to the thumb and index finger and associated with paresthesia over the dorsal radial hand. Symptom location can vary slightly due to anatomic differences. Weakness is unlikely (may be present with rare lipoma).  Grip strength is reduced only if the patient presents with chronically untreated symptoms that cause pain that interferes with use. Questioning may elicit a history previous surgery of the hand or wrist, or a fracture, or work activities involving repetitive supination and pronation, but a variety of other causes are possible. Patients who smoke or abuse alcohol are at increased risk of nerve entrapment syndromes.

• Failed decompression
• Infection
• Nerve damage
  • Intraneural lipoma/lipofibromatous hamartoma: in most cases, can be enucleated without damage to nerve fibers
• Persistent pain and numbness
• Wound dehiscence

• Conservative treatment: 71% success rate was reported for 29 patients who underwent removal of external sources of compression and underwent splinting
• Surgical treatment: 74% success rate was reported for 23 patients who had failed conservative therapy and underwent surgical decompression  
• Maximum medical improvement: typically 60–90 days post-surgery 

• Wartenberg syndrome is extremely rare.
• Radial neuropathy is twice as likely to occur in men as in women.
• Even handcuffs or a tight wristwatch can cause Wartenberg syndrome.
• Wartenberg syndrome should not be confused with Wartenberg sign, which is slightly greater abduction of the fifth digit, due to paralysis of the abducting palmar interosseous muscle and unopposed action of the radial innervated extensor muscles. 
• Spontaneous resolution of Wartenberg syndrome is common.

New Articles

1. Amadei F. Wartenberg’s syndrome: an unusual bilateral case. Ortho Rheumatol Open Access J 2016;2(4): Accessed October 24, 2016 at https://www.juniperpublishers.com/oroaj/pdf/OROAJ.MS.ID.555595.pdf
2. Patel A, Pierce P, Chiu DT. A fascial band implicated in Wartenberg syndrome. Plast Reconstr Surg 2014;133(3):440e-2e. PMID: 24572905

Review

1. Kowalska B, Sudol-Szopinska I. Ultrasound assessment on selected peripheral nerve pathologies. Part I: Entrapment neuropathies of the upper limb – excluding carpal tunnel syndrome. J Ultrason 2012;12(50):307-18. PMID: 26674101

Classic

1. Braidwood AS. Superficial radial neuropathy. J Bone Joint Surg Br 1975;57(3):380-3. PMID: 1158953