What are the key components of a comprehensive examination for a patient suspected of having ulnar neuropathy?

Comprehensive Examination for Ulnar Neuropathy

A comprehensive examination for suspected ulnar neuropathy must include specific neurological tests, motor and sensory assessments, provocative maneuvers, and anatomical evaluation focused on the ulnar nerve pathway, particularly at common entrapment sites like the elbow.

Clinical Assessment Components

History Taking (Focused Elements)

• Paresthesia and numbness distribution (particularly little finger and medial half of fourth digit)
• Weakness patterns in hand muscles
• Onset characteristics (sudden vs. gradual)
• Aggravating factors (leaning on elbows, repetitive elbow flexion)
• History of trauma, diabetes, or other systemic conditions
• Occupational activities requiring prolonged elbow flexion

Sensory Examination

• Small-fiber function assessment:
  • Pinprick sensation along ulnar nerve distribution 1
  • Temperature sensation testing 1
• Large-fiber function assessment:
  • Vibration perception using 128-Hz tuning fork 1
  • 10-g monofilament testing along ulnar distribution 1
• Map sensory deficits precisely to determine if pattern matches classic ulnar distribution

Motor Examination

• Assess strength of ulnar-innervated muscles:
  • Intrinsic hand muscles (abductor digiti minimi, first dorsal interosseous)
  • Deep flexor muscles to 4th and 5th digits
  • Adductor pollicis (Froment's sign - paper test between thumb and index finger)
• Look for "ulnar hand" deformity (clawing of 4th and 5th digits) 2
• Assess for muscle atrophy in the hypothenar eminence and first dorsal web space

Reflex Testing

• Assess deep tendon reflexes, particularly at the elbow 1

Provocative Tests

• Tinel's sign at the elbow (cubital tunnel) 3
• Elbow flexion test (holding elbow in maximal flexion for 3-5 minutes)
• Pressure provocation test (direct pressure over cubital tunnel)

Anatomical Assessment

• Inspect for deformities around the elbow 1
• Check for ulnar nerve subluxation during elbow flexion/extension
• Palpate for masses, swelling, or tenderness along the nerve course
• Assess for joint instability or previous trauma

Advanced Diagnostic Considerations

Electrodiagnostic Testing

When clinical findings suggest ulnar neuropathy, electrodiagnostic studies should be performed:

• Motor nerve conduction studies:
  • 2×4 cm segmental study across the elbow (highest sensitivity) 4
  • Record from abductor digiti minimi or first dorsal interosseous
• Sensory nerve conduction:
  • Antidromic sensory study to 5th finger 4
• Compare ulnar/median motor response ratios 2
• Needle electromyography of ulnar-innervated muscles

Imaging Studies

• Ultrasound:
  • High-resolution ultrasound to assess nerve caliber and fascicular pattern 5
  • Dynamic evaluation during elbow flexion/extension 1
  • Assessment of cross-sectional area/nerve thickness 1
• MRI (when indicated):
  • T2-weighted MR neurography (reference standard for ulnar nerve entrapment) 1
  • Evaluate for nerve enlargement and signal intensity changes 1
  • Identify compression points and structural abnormalities 5

Differential Diagnosis Assessment

Always consider other causes of similar symptoms:

• Cervical radiculopathy (C8-T1)
• Thoracic outlet syndrome
• Brachial plexopathy (lower trunk)
• Systemic neuropathies (diabetes, B12 deficiency)
• Other nerve entrapments

Common Pitfalls to Avoid

1. Failing to differentiate between entrapment at the cubital tunnel versus retro-epicondylar groove 6
2. Missing bilateral involvement (present in some cases) 2
3. Not considering systemic causes like diabetes that can cause severe ulnar neuropathy 2
4. Relying solely on electrodiagnostic studies without comprehensive clinical assessment
5. Overlooking dynamic nerve compression that occurs only during certain movements
6. Failing to assess for ulnar nerve subluxation during elbow flexion/extension

By systematically performing these examination components, clinicians can accurately diagnose ulnar neuropathy, determine its severity, localize the site of compression, and guide appropriate treatment decisions to improve patient outcomes.