Brachial Plexus MRI for Traumatic Injury

Version 1.0 — August 2026

1. Executive Summary

1.1 Added Value over the Generic Protocol

Traumatic brachial plexus injury is the single most common indication for dedicated brachial plexus MRI, and the role of MRI in this setting has grown further as clinical practice has shifted toward earlier surgical intervention. The generic protocol’s coronal T1/STIR backbone provides adequate bilateral overview anatomy, but traumatic assessment specifically requires: mandatory cervical spine integration to interrogate the intradural (preganglionic) nerve root segment; heavily T2-weighted 3D sequences optimised for pseudomeningocele and root-sleeve detection; and a systematic, level-by-level reporting approach that directly answers the single question that determines management — is this injury preganglionic (non-reconstructable) or postganglionic (potentially reconstructable)?

1.2 Limits of the Dedicated Protocol

Even with optimal technique, MRI’s ability to distinguish preganglionic from postganglionic injury is imperfect: absence of a visualised nerve root is a more specific sign of avulsion than pseudomeningocele alone, since a pseudomeningocele can occasionally form without complete root avulsion, and conversely a small avulsion can occur without a demonstrable pseudomeningocele. MRI findings should always be correlated with clinical examination and electrodiagnostic testing, and the final surgical decision typically integrates all three rather than relying on imaging alone.

2. Clinical Context

2.1 Clinical Presentation

Adult traumatic brachial plexopathy is overwhelmingly caused by high-energy traction mechanisms — motorcycle and other high-velocity road traffic collisions are the dominant cause, with falls from height and penetrating trauma accounting for a smaller proportion. Presentation ranges from partial sensorimotor deficit to complete flail, anaesthetic arm, frequently in the context of polytrauma with associated fractures or vascular injury, which affects both scan timing and patient positioning.

2.2 Mechanism and Injury Spectrum

Injury severity spans a continuum from neuropraxia (transient conduction block, no structural disruption) through axonotmesis (axonal disruption with intact supporting structures) to neurotmesis and frank root avulsion. Root avulsion — the most severe injury, in which the nerve root is torn from the spinal cord itself — is classified as preganglionic (proximal to the dorsal root ganglion, intradural, non-reconstructable by nerve grafting) or postganglionic (distal to the ganglion, potentially reconstructable), a distinction reported as essential in guiding treatment strategy across the imaging literature.

2.3 Differential Diagnosis (Clinical)

In the acute polytrauma setting, brachial plexus injury must be distinguished clinically from an isolated peripheral nerve injury distal to the plexus, a cervical spinal cord injury producing a similar distribution of weakness, and vascular injury (subclavian/axillary artery) producing ischaemic rather than neurogenic deficit — the latter is a recognised, clinically important associated injury requiring separate, urgent vascular assessment.

3. Indications, Timing, and Patient Selection

3.1 When the Dedicated Protocol Is Indicated

Any patient with a clinically significant post-traumatic brachial plexus deficit being considered for surgical reconstruction should undergo the dedicated protocol, since the pre-/postganglionic distinction it is specifically designed to resolve is the single most important determinant of surgical candidacy and technique.

3.2 Timing Considerations

MRI performed once the patient is medically stabilised — rather than in the hyperacute phase — is generally preferred, since post-traumatic haemorrhage and oedema in the immediate post-injury period can obscure the fine anatomical detail (root sleeves, small pseudomeningoceles) on which the pre-/postganglionic distinction depends; however, a period of clinical observation is also often used to allow neuropraxic elements to declare themselves, meaning imaging is frequently, appropriately, performed some weeks after the initial injury rather than immediately.

3.3 Mandatory Cervical Spine Integration

Because preganglionic injury is an intradural phenomenon, dedicated cervical spine MRI — assessing the intradural nerve root segment, spinal cord signal, and any associated cord injury — should be considered a mandatory component of the traumatic brachial plexus protocol, not an optional addition, whenever root avulsion is a clinical concern.

3.4 Red Flags Modifying Urgency

Absent distal pulses or expanding haematoma indicates a possible associated vascular injury requiring urgent vascular imaging and surgical evaluation ahead of, or in parallel with, the elective-timed dedicated plexus protocol described in this child page.

4. Dedicated Protocol Design

4.1 Mandatory Core Sequences

The table below lists the complete mandatory protocol for traumatic brachial plexus injury — the five generic-protocol core sequences (1-5, with sequence 5 elevated to strictly mandatory status for this indication) plus the two trauma-specific cervical spine additions (6-7) detailed in Section 4.3. See Section 4.2 for the full comparison against the generic protocol.

4.2 Protocol Delta vs the Generic Brachial Plexus Protocol

4.3 Mandatory Dedicated Sequences

• Sagittal and axial cervical spine sequences (T2 and heavily T2-weighted), extending the generic protocol’s coverage specifically to assess the intradural root segment, spinal cord signal, and root sleeve integrity.
• 3D heavily T2-weighted sequence (CISS/DRIVE/FIESTA-C-family, per the generic protocol’s optional advanced sequence) — mandatory, not merely conditional, in the trauma-specific protocol, since it is the primary sequence for pseudomeningocele and root-continuity assessment.
• Coronal STIR, per the generic protocol, specifically reviewed for paraspinal muscle denervation oedema — an indirect but clinically valuable marker of preganglionic injury, since the paraspinal muscles are innervated by the dorsal rami close to the root exit and are denervated when the root is avulsed proximally.

4.4 Conditional and Advanced Sequences

• Post-contrast T1 fat-suppressed sequences are not routinely required for pure trauma assessment but may be added where a coexisting mass, infection, or heterotopic ossification is suspected.
• 3D MR neurography sequences may be added for detailed postganglionic nerve tract visualisation when surgical planning requires selective identification of individual nerve trunks/divisions distal to the injury.
• Dedicated axial sequences through the axilla for suspected infraclavicular (cord-level or terminal branch) injury, extending coverage beyond the supraclavicular focus of the acute trauma work-up.

4.5 Rationale per Disease-Specific Sequence

Cervical spine sequences (mandatory addition) The rationale is direct: preganglionic injury is, by definition, an intradural phenomenon, and the generic brachial plexus protocol’s field of view and sequence selection are not optimised to assess the spinal cord and intradural root segment in the detail required. Reviewed literature on traumatic brachial plexus MRI explicitly recommends cervical spine MRI as a required supplement specifically to assess this intradural component.

3D heavily T2-weighted sequence (mandatory, not conditional) The rationale for elevating this sequence from the generic protocol’s “modern-practice” conditional status to a mandatory status here is that pseudomeningocele detection and root-sleeve assessment — the single most clinically decisive finding in this protocol — depend specifically on the high-resolution, fluid-sensitive, thin-slice capability this sequence family provides; the reviewed technical literature consistently identifies this sequence family, used alongside conventional MRI, as the key contributor to pseudomeningocele and non-visualised nerve root detection.

Paraspinal muscle STIR assessment The rationale for deliberately reviewing paraspinal muscle signal, rather than focusing solely on the plexus and root sleeves themselves, is that STIR-bright denervation oedema in the paraspinal musculature ipsilateral to the injury is a genuinely useful indirect marker of preganglionic (dorsal ramus-level) injury, complementing the direct pseudomeningocele/root-sleeve signs rather than duplicating them.

4.6 Dedicated Planes and Field of View

The coronal oblique plexus-plane acquisition from the generic protocol remains central, but must be deliberately supplemented with true sagittal and axial cervical spine planes (not merely an extended coronal field of view), since the intradural root assessment central to this protocol genuinely requires spine-specific imaging geometry rather than an extension of the plexus-oriented coronal plane alone.

4.7 Contrast Strategy

Pure traumatic assessment does not routinely require gadolinium contrast — the key findings (pseudomeningocele, root discontinuity, denervation oedema, nerve trunk disruption/haematoma) are all assessable on non-contrast T1/STIR/heavily-T2-weighted sequences. Contrast is reserved for cases where a coexisting mass is identified incidentally, where post-surgical assessment for neuroma or scar-versus-recurrent-pathology is required, or where the generic protocol’s standard macrocyclic GBCA/STIR-or-Dixon fat-suppression conventions apply for an added indication outside the trauma question itself.

4.8 Sequence Matching to Clinical Question

5. MRI Semiotics of Traumatic Brachial Plexus Injury

5.1 Direct Signs

Pseudomeningocele — a CSF-bright sac at the expected root location on heavily T2-weighted sequences, formed by CSF escaping through the torn root sleeve and meningeal layers — is the classic direct sign of preganglionic (avulsion) injury. Absence of a visualised nerve root at its expected foraminal location is reported as more specific than pseudomeningocele alone for confirming avulsion. Postganglionic injury presents as nerve trunk discontinuity, focal swelling/oedema, or frank rupture with retraction, seen in continuity or as a clear structural gap depending on severity.

5.2 Indirect and Secondary Signs

Paraspinal muscle denervation oedema (STIR-bright signal in the paraspinal musculature ipsilateral to injury, most pronounced at the C5-T1 levels) is the principal indirect marker of preganglionic injury, reflecting denervation of the dorsal rami close to the root exit. Associated findings — perivertebral haematoma, cervical spinal cord signal change or displacement, and osseous injury (clavicle, first rib, transverse process fractures) — should be deliberately sought as they carry independent management implications.

5.3 Severity, Extent, and Level Localisation

Reporting should specify injury at each root level (C5-T1) individually, since mixed-severity injury (avulsion at some levels, in-continuity injury at others) is common and directly determines which levels are candidates for direct repair, nerve transfer, or grafting.

5.4 Relevant Classification Frameworks

No single universally mandated staging classification exists specifically for brachial plexus trauma MRI reporting in the way the Sunderland/Seddon classifications exist for peripheral nerve injury generally; reporting in this protocol should instead explicitly and separately address, per root level, avulsion status (preganglionic yes/no), root continuity, and postganglionic trunk/cord/branch integrity, consistent with how the reviewed literature frames systematic traumatic plexus reporting.

5.5 Differential Diagnosis on Imaging

The principal imaging differential in the post-traumatic setting is distinguishing genuine structural nerve injury from post-traumatic oedema/haematoma tracking along the plexus without frank nerve disruption — a distinction requiring careful attention to whether the abnormal signal is truly intraneural (nerve trunk itself abnormal) versus perineural (surrounding soft tissue oedema/haematoma only), since the latter carries a substantially better prognosis and different management.

5.6 Mimickers and Pitfalls

A pseudomeningocele can occasionally be present without complete root avulsion, and a genuine small avulsion can occur without a clearly demonstrable pseudomeningocele — meaning neither finding alone is perfectly sensitive or specific in isolation, and integration of the direct and indirect signs described in Sections 5.1-5.2, rather than reliance on a single sign, is the correct interpretive approach.

6. Reporting Framework

6.1 Structured Reporting Template

Root level assessed (C5, C6, C7, C8, T1) — reported individually. Pseudomeningocele: present/absent, level(s). Root visualisation/continuity: preserved / not visualised / discontinuous, per level. Paraspinal muscle denervation oedema: present/absent, level(s). Postganglionic trunk/cord/branch integrity: in continuity with oedema / discontinuous / retracted, with level and structure specified. Associated findings: haematoma, cervical cord signal change, osseous injury.

6.2 Mandatory Reporting Elements

Every report should explicitly state, for each of the five root levels, whether the available evidence favours preganglionic injury, postganglionic injury, both (mixed), or is indeterminate — an explicit, level-by-level statement rather than a single global impression, since this is the specific information the referring surgical team requires for operative planning.

6.3 Critical/Actionable Findings

A confirmed or strongly suspected preganglionic injury at any level is the most directly actionable finding, since it changes the surgical strategy from direct nerve repair/grafting (possible for postganglionic injury) to nerve transfer techniques (required when the proximal stump is unavailable due to avulsion) — this distinction should be flagged prominently, not buried within a general descriptive paragraph.

6.4 Common Reporting Errors

Providing a single global “plexopathy” impression without level-by-level detail; relying on pseudomeningocele presence/absence alone without also assessing direct root visualisation; and omitting explicit comment on the cervical spine/intradural component when it was not separately acquired or reviewed.

7. Technical Pitfalls

7.1 Motion and Patient Comfort

Acute trauma patients, particularly those with associated fractures or in pain, frequently tolerate the required scan time poorly; sequence prioritisation (Section 8.3) should anticipate a realistic risk of an incomplete examination and plan accordingly.

7.2 Sequence-Specific Technical Considerations

The 3D heavily T2-weighted sequence central to pseudomeningocele detection is particularly sensitive to motion given its typically longer acquisition time and reliance on fine spatial detail; even modest patient motion can meaningfully degrade the single most diagnostically important sequence in this protocol.

7.3 When the Generic Protocol Alone Is Insufficient

A brachial plexus MRI performed for suspected significant traumatic injury using only the generic protocol, without the mandatory cervical spine integration and 3D heavily T2-weighted sequence described in Section 4, risks missing or under-characterising the preganglionic/postganglionic distinction that is the entire clinical purpose of imaging in this setting.

8. MRI Technologist Pearls

8.1 Sequence Order Logic

Given the motion-sensitivity of the 3D heavily T2-weighted sequence (Section 7.2), acquiring it earlier in the examination — before patient fatigue or pain-related restlessness increases — is a reasonable practical strategy in this specific, often less-comfortable trauma patient population.

8.2 Positioning Tricks

Trauma patients frequently present with associated injuries (slings, splints, restricted positioning) that complicate standard coil placement; flexibility in coil arrangement, planned in advance from the trauma team’s handover information where possible, reduces repositioning delay.

8.3 Fast Salvage Protocol

If examination time is genuinely constrained, prioritise the 3D heavily T2-weighted sequence and cervical spine sequences (the pre-/postganglionic-determining acquisitions) above the standard generic-protocol coronal T1/STIR sequences, since the former carry the greater immediate surgical-planning consequence in this specific clinical context.

8.4 Disease-Specific Common Avoidable Errors

Omitting cervical spine coverage when root avulsion is a genuine clinical concern; performing the examination too early in the acute phase when haemorrhage/oedema may obscure fine anatomical detail without a documented clinical reason for urgency; and failing to specifically screen for and comment on associated vascular or osseous injury.

9. Quality Control Checklist

• Cervical spine sequences confirmed acquired and reviewed whenever root avulsion is a clinical concern.
• 3D heavily T2-weighted sequence confirmed diagnostic quality, given its central role in pseudomeningocele/root-continuity assessment.
• Paraspinal muscle signal specifically reviewed on coronal STIR, not only the plexus itself.
• Report structured by individual root level (C5-T1), not as a single global impression.
• Associated vascular/osseous injury explicitly addressed or explicitly excluded from the report’s scope with a stated reason.

11. Evidence Gaps and Ongoing Debate

• The relative sensitivity/specificity of pseudomeningocele versus direct root non-visualisation remains incompletely settled. As referenced in Section 5.6, neither finding is perfectly sensitive or specific alone, and the reviewed literature’s own emphasis on combined-sequence evaluation reflects an acknowledged, still-evolving optimal diagnostic strategy rather than a single validated sign.
• Optimal imaging timing after acute trauma is not fully standardised. The tension between early imaging (before fibrosis/scarring complicates surgical planning) and delayed imaging (allowing neuropraxic elements to declare themselves and acute haemorrhage/oedema to resolve) is acknowledged in the literature without a single universally agreed optimal window.
• Standardised, validated reporting templates specific to traumatic brachial plexus MRI remain less developed than for many other MSK/neuro applications, with the level-by-level structured approach recommended in Section 6.1 reflecting current best practice rather than a single, formally validated and universally adopted reporting standard.

12. Evidence-Based References

A. Guidelines / Consensus / Society Recommendations

No dedicated society guideline specific to traumatic brachial plexus MRI protocol design, distinct from the general ACR Appropriateness Criteria for brachial plexus imaging referenced on the parent master page, was identified as warranting a separate citation for this child page. Category A is therefore not separately populated here.

B. Systematic Reviews / Meta-analyses

C. Important Prospective / Original Studies

No original prospective study distinct from the comprehensive technical review already cited under Category B was independently verified with a working citation during this research pass. Rather than cite an unverified source, Category C is left unpopulated for this child page.

D. Technical MRI Papers

Represented by the Szaro et al. 2022 systematic technical review already listed under Category B; a separate, non-duplicative Category D entry is not populated to avoid citing the same source twice.

E. Landmark Historical References

No landmark historical (pre-MRI-era) reference specific to traumatic brachial plexus imaging, distinct from the modern comprehensive review already cited, was identified as warranting separate citation. Category E is therefore not populated for this child page.

End of document — Brachial Plexus MRI for Traumatic Injury — Child Protocol under the MRIninja Neck / Brachial Plexus master page — v1.0 — August 2026 Parent page: Brachial Plexus MRI — Generic Standard Protocol