Examination of Radial, Ulnar, and Median Nerves

Patient Positioning

• The American College of Rheumatology recommends a sitting position with the hand placed on top of the thigh or on an examining table for a systematic examination of the radial, ulnar, and median nerves 1, 2, 3
• For dynamic examination, the American College of Rheumatology suggests performing active flexion/extension of the fingers 1, 3
• The American College of Rheumatology advises using full extension with supination for ventral scans and 90° flexion for dorsal scans for elbow examination 2, 3
• The Anesthesiology society recommends avoiding excessive elbow flexion beyond 90° as this increases risk of ulnar neuropathy 5

Standardized Scanning Approach

Wrist Examination

• The American College of Rheumatology recommends a volar transverse scan at the carpal tunnel to visualize the median nerve 1, 2
• The American College of Rheumatology suggests a volar longitudinal scan 1, 3
• The American College of Rheumatology advises dorsal transverse and longitudinal scans (radial and ulnar) 1, 3
• The American College of Rheumatology recommends a dorsal longitudinal scan of median nerve 1, 3

Elbow Examination

• The American College of Rheumatology suggests an anterior transverse scan at distal humeral epiphysis 2, 3
• The American College of Rheumatology advises an anterior humeroradial longitudinal scan 2, 3
• The American College of Rheumatology recommends a posterior transverse scan at distal humeral epiphysis 2, 3
• The Anesthesiology society recommends avoiding pressure on the postcondylar groove of the humerus (ulnar groove) 5

Nerve-Specific Assessment

Median Nerve

• The American College of Radiology recommends motor testing: Thumb opposition, abduction, and flexion of the thumb and index finger 6
• The American College of Radiology advises ultrasound assessment: Volar transverse scan at carpal tunnel (sensitivity 77-79%, specificity 94-98%) 6
• The American College of Radiology suggests looking for nerve enlargement and high signal intensity on imaging 6

Ulnar Nerve

• The American College of Radiology recommends motor testing: Finger abduction/adduction, thumb adduction, and flexion of 4th and 5th digits 6
• The American College of Radiology advises ultrasound assessment: Cross-sectional area at the elbow 6
• The American College of Radiology suggests checking for nerve dislocation with dynamic ultrasound 6

Radial Nerve

• The American College of Radiology recommends motor testing: Wrist and finger extension 6
• The American College of Radiology advises ultrasound assessment: Best visualized at the elbow 6

Advanced Diagnostic Techniques

• The American College of Radiology recommends MRI with T2-weighted neurography as the reference standard for nerve entrapment imaging 6
• The American College of Radiology advises ultrasound has high accuracy for detecting nerve abnormalities (sensitivity 77-79%, specificity 94-98%) 6
• The American College of Radiology suggests shear-wave elastography shows 100% specificity and sensitivity for ulnar neuropathy at the elbow 6

Common Pitfalls and Considerations

• The Anesthesiology society recommends avoiding prolonged pressure on the ulnar groove during examination 5
• The Praxis Medical Insights society advises maintaining neutral forearm position when the arm is at the patient's side 4