eMedicine Specialties > Neurology > Electromyography and Nerve Conduction Studies

Median Neuropathy: Differential Diagnoses & Workup

Author: Charles Tuen, MD, Consulting Staff, Department of Internal Medicine, Section of Neurology, Methodist Medical Center
Contributor Information and Disclosures

Updated: Mar 27, 2007

Differential Diagnoses

Alcohol (Ethanol) Related Neuropathy
Chronic Inflammatory Demyelinating Polyradiculoneuropathy
Diabetic Neuropathy
Neuropathy of Leprosy

Other Problems to Be Considered

Brachial plexopathy
C6 radiculopathy
Cervical disk syndromes
De Quervain tenosynovitis syndrome
Interosseous syndrome
Proximal median neuropathy (eg, at the elbow)

Workup

Laboratory Studies

  • Blood tests should be ordered if underlying rheumatologic or inflammatory disease or diabetes is suspected; these include fasting blood glucose, erythrocyte sedimentation rate, and rheumatoid factor.

Imaging Studies

  • Wrist x-ray may be helpful if an old or recent fracture is suspected.
  • Magnetic resonance imaging (MRI) of the cervical spine may be needed if cervical radiculopathy is suspected. Some reports on the usefulness of MRI scan of the wrist have been recorded.
  • CT scan of the chest or chest x-ray should be ordered if brachial plexopathy is suspected.

Other Tests

  • Electrodiagnosis
    • Distal motor latency: Stimulate the median nerve at the wrist and record at the abductor pollicis brevis muscle. A markedly prolonged distal latency may be measured. However, in over 50% of patients with CTS, distal median motor latency is within the normal limit.
    • Distal sensory latency: Orthodromic or antidromic sensory studies are performed by stimulating or recording the second (index) or third (middle) fingers. Another method is to stimulate or record at the palm (8 cm from the wrist). To increase sensitivity, the following internal comparison can be used:
      • Compare the median and ulnar nerves from palm to wrist at a distance of 8 cm. Distal latency difference of >0.4 millisecond is a significant finding.
      • Compare the median and ulnar nerve distal sensory latencies by stimulating at the ring finger and recording at the wrist for each nerve. A difference of >0.5 millisecond is significant.
      • Compare median and radial nerves by stimulating the thumb and recording at the wrist at a distance of 10 cm. Distal latency difference >0.5 millisecond is a significant finding.
  • The benefits of the following diagnostic techniques have yet to be fully established:
    • Carpal tunnel pressure measurements
    • Current perception threshold
    • MRI quantitation of the carpal tunnel
    • Sensory quantitation, including vibrometry
    • Ultrasound of the carpal tunnel
    • Semmes-Weinstein pressure esthesiometer

More on Median Neuropathy

Overview: Median Neuropathy
Differential Diagnoses & Workup: Median Neuropathy
Treatment & Medication: Median Neuropathy
Follow-up: Median Neuropathy
References
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References

  1. Altrocchi PH, Daube JR, Frishberg BM. Practice parameter: carpal tunnel syndrome. Neurology. 1993;43(11):2406-9.

  2. Campbell WW. Diagnosis and management of common compression and entrapment neuropathies. Neurol Clin. Aug 1997;15(3):549-67. [Medline].

  3. Chang MH, Chiang HT, Lee SS, et al. Oral drug of choice in carpal tunnel syndrome. Neurology. Aug 1998;51(2):390-3. [Medline].

  4. Fleckenstein JL, Wolfe GI. MRI vs EMG: which has the upper hand in carpal tunnel syndrome?. Neurology. Jun 11 2002;58(11):1583-4. [Medline].

  5. Gooch CL, Mitten DJ. Treatment of carpal tunnel syndrome: is there a role for local corticosteroidinjection?. Neurology. Jun 28 2005;64(12):2006-7. [Medline].

  6. Gross PT, Tolomeo EA. Proximal median neuropathies. Neurol Clin. Aug 1999;17(3):425-45, v. [Medline].

  7. [Best Evidence] Hui AC, Wong S, Leung CH, et al. A randomized controlled trial of surgery vs steroid injection for carpal tunnelsyndrome. Neurology. Jun 28 2005;64(12):2074-8. [Medline].

  8. Levine BP, Jones JA, Burton RI. Nerve entrapments of the upper extremity: A surgical perspective. Neurol Clin. Aug 1999;17(3):549-65, vii. [Medline].

  9. Morgan G, Wilbourn AJ. Cervical radiculopathy and coexisting distal entrapment neuropathies: double-crush syndromes?. Neurology. Jan 1998;50(1):78-83. [Medline].

  10. Nuber GW, Assenmacher J, Bowen MK. Neurovascular problems in the forearm, wrist, and hand. Clin Sports Med. Jul 1998;17(3):585-610. [Medline].

  11. Preston DC, Shefner JM, Rutkove SB. Electrodiagnosis of carpal tunnel syndrome: too many and too few tests. American Academy of Neurology Annual Meeting. 1999;2PC003.

  12. Preston DC. Distal median neuropathies. Neurol Clin. Aug 1999;17(3):407-24, v. [Medline].

  13. Verdon ME. Overuse syndromes of the hand and wrist. Prim Care. Jun 1996;23(2):305-19. [Medline].

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Further Reading

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Keywords

carpal tunnel syndrome, upper extremity (UE) cumulativetrauma disorders, median neuropathy at the wrist, CTS, entrapment neuropathy, compression of the median nerve

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Contributor Information and Disclosures

Author

Charles Tuen, MD, Consulting Staff, Department of Internal Medicine, Section of Neurology, Methodist Medical Center
Charles Tuen, MD is a member of the following medical societies: American Academy of Neurology, American Medical Association, and Texas Medical Association
Disclosure: Nothing to disclose.

Medical Editor

Stephen A Berman, MD, PhD, Professor, Department of Internal Medicine, Section of Neurology, Dartmouth Medical School; Chief, Neurology Service, White River Junction Veterans Medical Center
Stephen A Berman, MD, PhD is a member of the following medical societies: Alpha Omega Alpha, American Academy of Neurology, and Phi Beta Kappa
Disclosure: Nothing to disclose.

Pharmacy Editor

Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine
Disclosure: Nothing to disclose.

Managing Editor

Neil A Busis, MD, Chief, Division of Neurology, Department of Medicine, University of Pittsburgh Medical Center - Shadyside, Clinical Associate Professor, Department of Neurology, University of Pittsburgh School of Medicine
Neil A Busis, MD is a member of the following medical societies: American Academy of Neurology and American Association of Neuromuscular and Electrodiagnostic Medicine
Disclosure: Nothing to disclose.

CME Editor

Matthew J Baker, MD, Consulting Staff, Collier Neurologic Specialists, Naples Community Hospital
Matthew J Baker, MD is a member of the following medical societies: American Academy of Neurology
Disclosure: Nothing to disclose.

Chief Editor

Nicholas Y Lorenzo, MD, Chief Editor, eMedicine Neurology; Consulting Staff, Neurology Specialists and Consultants
Nicholas Y Lorenzo, MD is a member of the following medical societies: Alpha Omega Alpha and American Academy of Neurology
Disclosure: Nothing to disclose.

 
 
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