Presentation
27yo male motorbike accident. Right brachial plexus injury.
Patient Data
The right C5, C6 and C7 roots (especially C5) are thickened beyond their dorsal root ganglia. There is buckling of these nerves (trunks) posterior to the clavicle. The thickening and buckling also extends laterally into at least one of the cords. The dorsal root ganglia have normal appearances. There is no "pseudo-meningocoele". The central vertebral canal and neural exit foramina and capacious. The cervical spinal cord shows normal signal.There are prominent lymph nodes in the neck bilaterally. These are larger on the left, for example level IIa (18 x 11 mm axially) and Vb (12 x 11 mm).
Conclusion: Thickening and buckling of the right C5, C6 and C7 roots. The roots are intact, however. The findings are thought to represent previous traction injury. Incidental cervical lymph node enlargement, which warrants clinical correlation in the first instance.
Case Discussion
It is necessary to differentiate between pre-ganglionic and post-ganglionic injuries, as post-ganglionic injuries can be managed with nerve grafting to provide a better prognosis. For pre-ganglionic lesions pseudomeningocoeles are common after nerve root avulsion but can also be present with intact nerve roots 1,2.
Typical MRI features of acute brachial plexus injury are described below 1,2:
- Affected nerves appear hypointense on T1-weighted and hyperintense on T2-weighted imaging
- Swelling, hemorrhage, compression, disruption, diaplacement and retraction of plexus components
- Nerve ruptures seen as discontinuity in the neural structures
- Nerve retraction balls on distal end of ruptured nerves
- Can have denervation edema in muscles supplied by the affected nerves\
- In the subacute period, fat degeneration and muscular trophism alteration may occur
- Direct compression by of the brachial plexus may be visible by - hematomas, pseudoaneurysm (especially of subclavian vessels), fracture fragment, callus
Case courtesy of A/Prof Pramit Phal.