Brachial Plexus Lesions: Evaluation and Management
MRI of the brachial plexus is the first-line imaging modality for suspected brachial plexus lesions, with timing and additional studies determined by whether the injury is traumatic or non-traumatic. 1
Initial Clinical Evaluation
Begin by determining the mechanism and timing of injury through focused history:
- Traumatic: Motor vehicle collision (especially motorcycle), fall, sports injury, penetrating trauma
- Non-traumatic: Malignancy, radiation therapy, inflammatory/immune processes (Parsonage-Turner syndrome), infection
Perform a detailed motor examination testing individual muscle groups innervated by C5-T1 nerve roots to localize the lesion pattern (upper trunk, lower trunk, or total plexus involvement). 2, 3
Imaging Strategy
For Traumatic Brachial Plexopathy
Critical timing consideration: Delay imaging for approximately 1 month post-trauma to allow subarachnoid hemorrhage and soft-tissue edema to resolve, and for pseudomeningoceles to develop—these are key markers of nerve root avulsion. 1
Primary imaging: MRI brachial plexus without contrast is superior to all other modalities, with 84% sensitivity and 91% specificity for detecting nerve injuries. 1 MRI distinguishes:
- Preganglionic (nerve root avulsion) vs postganglionic injuries—this differentiation is crucial as it determines surgical approach and prognosis
- Complete nerve rupture vs stretching injuries with maintained continuity
- Associated findings: pseudomeningocele (68% accuracy for root avulsion), hematoma, fracture fragments causing compression, traumatic neuromas
Secondary imaging: CT myelography of cervical spine is reserved for cases where preganglionic injury assessment is needed but MRI is contraindicated. However, it only evaluates preganglionic injuries and misses postganglionic plexus pathology. 1
For Non-Traumatic Brachial Plexopathy
Primary imaging: MRI brachial plexus with and without IV contrast provides 81% sensitivity and 91% specificity for detecting pathology. 1 Contrast enhancement is essential here (unlike traumatic cases) to:
- Detect and characterize tumors (schwannomas, neurofibromas, malignant peripheral nerve sheath tumors, metastases)
- Identify inflammatory/infectious processes
- Distinguish tumor from surrounding structures
Avoid: CT myelography, CT cervical spine, and FDG-PET/CT have no established role in non-traumatic plexopathy evaluation unless malignancy staging is needed. 1
Electrodiagnostic Studies
Obtain nerve conduction studies and electromyography (EMG) 3-4 weeks post-injury to:
- Confirm clinical localization
- Assess severity of denervation
- Differentiate plexopathy from radiculopathy or peripheral nerve injury
- Provide prognostic information
These studies complement but do not replace imaging, as they cannot reliably distinguish preganglionic from postganglionic lesions. 1, 3, 4
Management Algorithm
Traumatic Injuries
Penetrating/open injuries: Early surgical exploration is indicated. 1
Closed injuries (based on imaging findings):
- Complete nerve rupture or root avulsion: Early operative management (within 6 months) with nerve grafting, nerve transfers, or reconstruction—delayed surgery significantly worsens outcomes. 3, 5
- Stretching injury with intact continuity: Conservative management with serial examinations and repeat imaging at 3-6 months to assess for spontaneous recovery
Surgical options include neurolysis, nerve grafting, nerve transfers, free functional muscle transfers, tendon transfers, and joint arthrodesis depending on injury pattern and timing. 3, 5
Non-Traumatic Injuries
Management depends on etiology identified on MRI:
- Tumor: Surgical resection or biopsy
- Inflammatory (Parsonage-Turner): Conservative management with physical therapy; most recover spontaneously
- Malignancy-related: Oncologic treatment with radiation/chemotherapy; pain management
Critical Pitfalls to Avoid
Do not image immediately post-trauma: Acute hemorrhage and edema obscure findings. Wait approximately 1 month. 1
Do not rely solely on clinical examination or EMG: These cannot reliably distinguish preganglionic from postganglionic injuries, which fundamentally changes surgical planning. 1
Do not delay surgical referral beyond 6 months for complete injuries: Outcomes for shoulder and elbow function restoration are favorable when treated within this window; delays significantly compromise results. 5
Do not order CT myelography as first-line imaging: It only evaluates preganglionic injuries and misses the majority of postganglionic plexus pathology that MRI readily identifies. 1
Multidisciplinary Team Approach
Coordinate care with peripheral nerve surgeons, hand therapists, pain management specialists, and mental health providers given the profound functional, psychosocial, and economic impacts of brachial plexus injuries. 3, 5 Early referral to a specialized center improves outcomes, particularly for complex reconstructive cases requiring free functional muscle transfers.