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Radial neuropathies

Last updated: March 8, 2021

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Radial neuropathies are conditions caused by acute or chronic injury to the radial nerve. Clinical presentations vary with the mechanism, site, and extent of nerve injury. The radial nerve arises from the posterior cord of the brachial plexus, which comprises cervical roots C5–T1. Within the upper extremity, the radial nerve has lateral cutaneous sensory branches and innervates extensors. When injured, radial neuropathies are therefore characterized by sensory symptoms of pain, paresthesia, and numbness, as well as motor symptoms of weakness of extension at the elbow, wrist (“wrist drop”), and/or fingers. Several risk factors are associated with subtypes of radial neuropathies, including crutch use, intoxication, fracture of the humerus or radius, use of tight watch bands or handcuffs, and repetitive pronation and supination. The patient history and examination, including Tinel's sign, may be sufficient for diagnosis in some cases, but x-ray is necessary in the presence of trauma, and electrodiagnostics, though less useful than in carpal tunnel syndrome, may be considered if symptoms persist. Conservative management, consisting of local corticosteroid injections and counseling to reduce risk factors, is typically the treatment of choice in nontraumatic cases. Surgical decompression, with approach varying by location, may be considered in refractory cases.

References:[1][2][3]

Site of lesion Sensory symptoms Motor symptoms
Axilla
  • All below
Mid-arm
  • All below
  • Wrist drop
    • Paralysis or weakness of the hand and finger extensors, which results in decreased grip strength (wrist extension ensures the optimal action of finger flexors)
    • The patient cannot extend their hand at the wrist joint.
Elbow (radial tunnel)
  • Sometimes weakness of extension and supination, secondary to pain (not to missing innervation!)
Deep forearm (proximal posterior interosseous nerve)
  • None [2]
  • Paralysis of the finger extensors (no true wrist drop)
Superficial forearm and wrist (superficial radial nerve)
  • Deficits on the radial side of the dorsum of the hand (thumb, index finger, and the radial half of the middle finger) [3]
  • None


The higher (more proximal) the lesion, the greater the number of extensor muscles involved!

References:[1][2][3][4]

References:[2][3][5]

References:[2][6]

  1. Loh YC, Lam WL, Stanley JK, Soames RW. A new clinical test for radial tunnel syndrome: the Rule-of-Nine test: a cadaveric study. J Orthop Surg. 2004; 12 (1): p.83-86. doi: 10.1177/230949900401200115 . | Open in Read by QxMD
  2. Donofrio PD. Textbook of Peripheral Neuropathy. Demos Medical ; 2012
  3. Brazis PW, Masdeu JC, José Biller J. Localization in Clinical Neurology. Lippincott Williams & Wilkins ; 2006
  4. Stern M. Radial Nerve Entrapment. Radial Nerve Entrapment. New York, NY: WebMD. http://emedicine.medscape.com/article/1244110. Updated: September 13, 2016. Accessed: April 7, 2017.
  5. Birch R. Surgical Disorders of the Peripheral Nerves. Springer ; 2011
  6. Grinsell D, Keating CP. Peripheral nerve reconstruction after injury: a review of clinical and experimental therapies. Biomed Res Int. 2014; 2014 . doi: 10.1155/2014/698256 . | Open in Read by QxMD
  7. Le T, Bhushan V, Sochat M, Petersen M, Micevic G, Kallianos K. First Aid for the USMLE Step 1 2014. McGraw-Hill Medical ; 2014
  8. Szekeres M. Tenodesis extension splinting for radial nerve palsy. Tech Hand Up Extrem Surg. 2006; 10 (3): p.162-165. doi: 10.1097/01.bth.0000231968.51170.6b . | Open in Read by QxMD
  9. Nanjundaiah K, Jayadevaiah ShM, Chowdapurkar Sh. Long head of triceps supplied by axillary nerve. Int J Anat Var. 2012; 5 : p.35–37.