What is the workup to determine a brachial plexus injury?

Workup for Brachial Plexus Injury

MRI of the brachial plexus is the gold standard first-line imaging test for evaluating brachial plexus injuries due to its superior soft-tissue contrast and spatial resolution. 1, 2

Initial Evaluation

• A thorough clinical assessment should identify the mechanism of injury (blunt force, penetrating, compression), distribution of weakness, sensory changes, and Tinel's sign to help localize the injury 3, 4
• Electrodiagnostic studies (EMG/NCS) should be performed to assess the severity and location of nerve injury, with correlation between abnormal intraneural signal on MRI and active radiculopathy on EMG 5
• Imaging should ideally be delayed until approximately 1 month after trauma to allow for resolution of hemorrhage and edema, and for pseudomeningocele formation 5, 2

Imaging Protocol

• MRI brachial plexus with dedicated protocol is the preferred initial imaging modality 5, 1, 2

  • Should include orthogonal views through the oblique planes of the plexus 2
  • T1-weighted, T2-weighted, fat-saturated T2-weighted sequences, STIR sequences 2
  • Fat-saturated T1-weighted postcontrast sequences may be added but usually don't provide significant additional information for traumatic injuries 5, 2

• CT myelography of the cervical spine is indicated when:

  • MRI is contraindicated 5
  • There is suspicion of preganglionic nerve root avulsion requiring high-resolution imaging of the nerve roots 5
  • CT myelography provides excellent visualization of traumatic cervical nerve root avulsions and pseudomeningocele formation 5

Critical Diagnostic Determinations

• Determine if the injury is preganglionic (involving intraspinal nerve roots) or postganglionic (involving plexus lateral to dorsal root ganglion) as prognosis and reconstruction approaches differ 5
• Assess whether the nerve is completely ruptured (requiring early operative management) or stretched but intact 5
• Identify associated findings such as 5:
  • Pseudomeningocele (indicator of root avulsion)
  • Spinal cord edema or hemorrhage
  • Nerve edema, fibrosis, or neuroma formation
  • Soft-tissue hematoma or displaced fracture causing extrinsic compression

Management Considerations

• Penetrating and open injuries typically require early surgical exploration 5, 1
• Blunt and closed injuries may be managed operatively or non-operatively depending on severity 5, 1
• Complete nerve ruptures generally have worse prognosis and often require early operative intervention 5, 1

Common Pitfalls to Avoid

• Standard MRI protocols for the neck, chest, or spine are inadequate for proper evaluation of the brachial plexus; specialized brachial plexus protocols are required 1, 2
• CT of the cervical spine alone cannot fully visualize the preganglionic nerve roots and has limited soft-tissue contrast resolution compared to MRI 5
• Imaging in the acute post-traumatic setting can be challenging due to subarachnoid hemorrhage and soft-tissue edema obscuring the nerve roots and plexus 5
• Clinical overlap between radiculopathy and plexopathy can be challenging; in cases of diagnostic uncertainty, cervical spine MRI may be complementary to brachial plexus MRI 2