What is the initial workup for a patient presenting with numbness in the wrist?

Initial Workup for Numbness in the Wrist

Radiographs are the most appropriate initial imaging study for evaluating numbness in the wrist, as they can establish specific diagnoses in many cases including arthritis, complications of injury, and other structural abnormalities. 1

Clinical Evaluation

• Perform a thorough clinical examination focusing on the pattern of numbness, which can help distinguish between different causes such as carpal tunnel syndrome, ulnar neuropathy, or radial nerve compression 2, 3
• Evaluate for hypalgesia in the median nerve territory (likelihood ratio 3.1), which is one of the best distinguishing findings for carpal tunnel syndrome 2
• Assess thumb abduction strength, as weakness is suggestive of carpal tunnel syndrome (likelihood ratio 1.8) 2
• Perform provocative tests including Tinel's sign, Phalen's test, and compression tests to reproduce symptoms 4
• Document the distribution of numbness using hand diagrams, which can be diagnostic (classic or probable Katz hand diagram has likelihood ratio 2.4) 2

Initial Imaging

• Standard radiographic examination should include posterior-anterior and lateral views in neutral position, supplemented by one or more oblique views 1
• Lateral view is particularly important for demonstrating malalignments and soft-tissue swelling that may contribute to nerve compression 1
• Radiographs can identify bony abnormalities that may cause nerve compression, such as fractures, arthritis, or anatomical variants 5

Advanced Imaging Selection Based on Initial Findings

• If radiographs are normal or nonspecific and symptoms persist, MRI without IV contrast is usually appropriate as the next study 5
• MRI without IV contrast accurately depicts abnormalities of bones, bone marrow, articular cartilage, ligaments, TFCC, synovium, tendons, and neurovascular structures that may contribute to numbness 5
• Ultrasound is particularly useful for examining extra-articular soft tissues and can identify nerve compression, especially for carpal tunnel syndrome 5, 1
• Ultrasound is a validated technique for measuring median nerve size in carpal tunnel syndrome, with increased cross-sectional area being diagnostic 1

Location-Specific Evaluation

• For median nerve distribution numbness (thumb, index, middle fingers, and radial half of ring finger):

  • Consider carpal tunnel syndrome and perform specific tests including wrist flexion test and carpal compression test 2, 6
  • Electrodiagnostic testing should be completed before treatment is begun if carpal tunnel syndrome is suspected 7

• For ulnar nerve distribution numbness (little finger and ulnar half of ring finger):

  • Evaluate for ulnar neuropathy at the wrist, which typically presents with wrist discomfort and sensory changes in the fourth and fifth digits 6
  • Activities involving repetitive or prolonged wrist extension increase risk of ulnar neuropathy 6

• For radial nerve distribution numbness (dorsal aspect of hand and first three fingers):

  • Consider radial nerve compression or De Quervain tenosynovitis 1, 6
  • Perform Finkelstein test for De Quervain tenosynovitis 6

Common Pitfalls to Avoid

• Relying solely on classic provocative tests like Phalen's and Tinel's signs, which have limited diagnostic value for carpal tunnel syndrome 2
• Failing to obtain specialized radiographic views (e.g., posteroanterior in ulnar deviation, pronated oblique) when standard views are normal but clinical suspicion remains high 6
• Overlooking the possibility of proximal nerve compression (e.g., cervical radiculopathy) that may present with wrist and hand numbness 3
• Delaying electrodiagnostic testing when carpal tunnel syndrome is suspected, as this should be completed before initiating treatment 7

By following this systematic approach to evaluating numbness in the wrist, clinicians can efficiently identify the underlying cause and initiate appropriate treatment to improve patient outcomes.