Radial Nerve Entrapment Workup
- Author: Mark Stern, MD; Chief Editor: Harris Gellman, MD more...
In a suspected entrapment of the radial nerve in the arm, radiography should be performed to detect or rule out a fracture, healing callus, or tumor as the cause of entrapment. In radial tunnel syndrome and posterior interosseous nerve syndrome, radiographs should be obtained to detect or rule out elbow or forearm fractures, dislocations or instabilities, tumors, and arthrosis.
Magnetic resonance imaging
Magnetic resonance imaging (MRI) is useful in detecting tumors such as lipomas and ganglions, as well as aneurysms and rheumatoid synovitis.
A study by Jengojan et al found that magnetic resonance neurography based on diffusion tensor imaging was capable of detecting nerve changes during acute entrapment of the radial nerve at the spiral groove. Compression of the nerve resulted in a transient increase in local radial nerve fractional anisotropy values.
Toros et al, in a study of 26 patients with sensory or motor deficiency of a peripheral nerve from trauma or entrapment, confirmed that high-resolution ultrasonography could show the exact location, extent, and type of lesion, yielding important information that might not be obtained by other modalities. Ultrasonography provided reliable visualization of injured nerves in all 26 patients. Axonal swelling and hypoechogenicity of the nerve was diagnosed in 15 cases, loss of continuity of a nerve bundle in 17, formation of a neuroma of a stump in 6, and partial laceration of a nerve with loss of the normal fascicular pattern in 5. Ultrasonographic findings were confirmed at operation in the 19 patients who underwent surgery.
Lo et al compared ultrasonography with electrophysiologic testing in the diagnosis of entrapment neuropathy of the radial nerve at the spiral groove, which is relatively common but technically challenging to localize. The study included 32 normal controls, to obtain ultrasound parameters of the radial nerve, and 10 patients with suspected radial neuropathy, in whom ultrasound and electrophysiologic techniques were used. Ultrasonography correctly identified all six patients with radial neuropathy; the four patients with other diagnoses did not show ultrasound abnormalities. Ultrasonography also required significantly less time than electrophysiologic testing did.
Electromyography (EMG) and nerve conduction studies yield abnormal results in radial nerve injuries in the middle and distal third of the humerus. EMG helps locate the site of injury and helps the clinician monitor the nerve recovery over time. EMG may not be positive for 3-6 weeks following injury. By 4 months after the injury, nerve recovery should be demonstrable. EMG may be performed initially to provide a baseline, but unless the nerve is severed, no changes will be observed for 3-6 weeks.
All electrodiagnostic test results are within normal limits in radial tunnel syndrome.
In posterior interosseous nerve syndrome, nerve conduction studies and EMG usually yield abnormal results and help determine the site of compression. These findings may not become abnormal for 3-6 weeks after injury. Serial EMG usually is not necessary once the diagnosis is established but can be used to document improved or worsening nerve function.
If the medial branch of the posterior interosseous nerve is compressed, EMG and conduction studies reveal abnormal function of the extensor carpi ulnaris, the extensor digitorum communis, and the extensor digiti quinti. If only the lateral branch is compressed, then abnormal function of the abductor pollicis longus, the extensor pollicis longus and brevis, and the extensor indicis proprius is revealed. The site of compression is localized by all function proximal to the compression being normal and all function distal to the compression being abnormal.
To help differentiate lateral epicondylitis from radial tunnel syndrome, injection of cortisone and lidocaine injection may be performed. An injection into the area of the lateral epicondyle should resolve almost all of the symptoms of lateral epicondylitis, at least temporarily. Injection of cortisone and lidocaine into the area of the radial tunnel usually fails to relieve the discomfort or relieves it only incompletely.
In de Quervain disease, injection of cortisone and lidocaine into the tendon sheath of the extensor pollicis brevis and the abductor pollicis longus relieves the symptoms immediately and sometimes permanently. An injection of cortisone and lidocaine into the area of compression of the superficial radial nerve causes the symptoms to subside; however, numbness in the nerve distribution follows, and when the injection wears off, the symptoms return.
A Tinel sign is present in patients with Wartenberg syndrome but usually not in those with de Quervain disease. The two conditions may be related. The inflammation from de Quervain disease causes an inflammation of the nerve. With resolution of one condition, the other may subside or may be adequately treated with an injection.
Lubahn JD, Cermak MB. Uncommon nerve compression syndromes of the upper extremity. J Am Acad Orthop Surg. 1998 Nov-Dec. 6(6):378-86. [Medline].
Edmonson AS, Crenshaw AH. Peripheral nerve injuries. In: Campbell's Operative Orthopedics. 6th ed. 1980:1678-9.
Ritts GD, Wood MB, Linscheid RL. Radial tunnel syndrome. A ten-year surgical experience. Clin Orthop. 1987 Jun. (219):201-5. [Medline].
Sunderland S. Nerves and Nerve Injuries. 2nd ed. 1978:127.
Robson AJ, See MS, Ellis H. Applied anatomy of the superficial branch of the radial nerve. Clin Anat. 2008 Jan. 21(1):38-45. [Medline].
Thomsen NO, Dahlin LB. Injury to the radial nerve caused by fracture of the humeral shaft: timing and neurobiological aspects related to treatment and diagnosis. Scand J Plast Reconstr Surg Hand Surg. 2007. 41(4):153-7. [Medline].
Mehta V, Suri R, Arora J, Rath G, Das S. Anomalous constitution of the brachioradialis muscle: a potential site of radial nerve entrapment. Clin Ter. 2010. 161(1):59-61. [Medline].
Carter GT, Weiss MD. Diagnosis and Treatment of Work-Related Proximal Median and Radial Nerve Entrapment. Phys Med Rehabil Clin N Am. 2015 Aug. 26 (3):539-49. [Medline].
Spinner M. Injuries to the Major Branches of Peripheral Nerves of the Forearm. 2nd ed. 1978:234.
Clavert P, Lutz JC, Adam P, Wolfram-Gabel R, Liverneaux P, Kahn JL. Frohse's arcade is not the exclusive compression site of the radial nerve in its tunnel. Orthop Traumatol Surg Res. 2009 Apr. 95(2):114-8. [Medline].
Seddon HJ. Surgical Disorders of the Peripheral Nerves. 1972:66-88.
Matsubara Y, Miyasaka Y, Nobuta S, Hasegawa K. Radial nerve palsy at the elbow. Ups J Med Sci. 2006. 111(3):315-20. [Medline].
Yamazaki H, Kato H, Hata Y, Murakami N, Saitoh S. The two locations of ganglions causing radial nerve palsy. J Hand Surg Eur Vol. 2007 Jun. 32(3):341-5. [Medline].
Szekeres M. Tenodesis extension splinting for radial nerve palsy. Tech Hand Up Extrem Surg. 2006 Sep. 10(3):162-5. [Medline].
Gousheh J, Arasteh E. Transfer of a single flexor carpi ulnaris tendon for treatment of radial nerve palsy. J Hand Surg [Br]. 2006 Oct. 31(5):542-6. [Medline].
Shao YC, Harwood P, Grotz MR, Limb D, Giannoudis PV. Radial nerve palsy associated with fractures of the shaft of the humerus: a systematic review. J Bone Joint Surg Br. 2005 Dec. 87(12):1647-52. [Medline].
Henry M, Stutz C. A unified approach to radial tunnel syndrome and lateral tendinosis. Tech Hand Up Extrem Surg. 2006 Dec. 10(4):200-5. [Medline].
Ferdinand BD, Rosenberg ZS, Schweitzer ME, Stuchin SA, Jazrawi LM, Lenzo SR. MR imaging features of radial tunnel syndrome: initial experience. Radiology. 2006 Jul. 240(1):161-8. [Medline].
Stanley J. Radial tunnel syndrome: a surgeon's perspective. J Hand Ther. 2006 Apr-Jun. 19(2):180-4. [Medline].
Li H, Cai QX, Shen PQ, Chen T, Zhang ZM, Zhao L. Posterior interosseous nerve entrapment after Monteggia fracture-dislocation in children. Chin J Traumatol. 2013. 16(3):131-5. [Medline].
Akhtar S, Arenas Prat J, Sinha S. Neuropraxia of the palmar cutaneous branch of the ulnar nerve during carpal tunnel decompression. Ann R Coll Surg Engl. 2005 May. 87(3):W1-2. [Medline].
Zlowodzki M, Chan S, Bhandari M, Kalliainen L, Schubert W. Anterior transposition compared with simple decompression for treatment of cubital tunnel syndrome. A meta-analysis of randomized, controlled trials. J Bone Joint Surg Am. 2007 Dec. 89(12):2591-8. [Medline].
Noaman H, Khalifa AR, El-Deen MA, Shiha A. Early surgical exploration of radial nerve injury associated with fracture shaft humerus. Microsurgery. 2008. 28(8):635-42. [Medline].
Jengojan S, Kovar F, Breitenseher J, Weber M, Prayer D, Kasprian G. Acute radial nerve entrapment at the spiral groove: detection by DTI-based neurography. Eur Radiol. 2015 Jun. 25 (6):1678-83. [Medline].
Toros T, Karabay N, Ozaksar K, Sugun TS, Kayalar M, Bal E. Evaluation of peripheral nerves of the upper limb with ultrasonography: a comparison of ultrasonographic examination and the intra-operative findings. J Bone Joint Surg Br. 2009 Jun. 91(6):762-5. [Medline].
Lo YL, Fook-Chong S, Leoh TH, Dan YF, Tan YE, Lee MP, et al. Rapid ultrasonographic diagnosis of radial entrapment neuropathy at the spiral groove. J Neurol Sci. 2008 Aug 15. 271(1-2):75-9. [Medline].
Ilyas A, Ast M, Schaffer AA, Thoder J. De quervain tenosynovitis of the wrist. J Am Acad Orthop Surg. 2007 Dec. 15(12):757-64. [Medline].
Jacobson JA, Fessell DP, Lobo Lda G, Yang LJ. Entrapment neuropathies I: upper limb (carpal tunnel excluded). Semin Musculoskelet Radiol. 2010 Nov. 14(5):473-86. [Medline].