Presentation
Right upper limb weakness after motorcycle accident.
Patient Data
Right C6-7 small pseudomeningocele; denoting C7 nerve root (preganglionic) avulsion injury.
Anterior rootlet of right C6 nerve root is also seen attenuated.
Right C5 posterior rootlet partial injury with focal abnormal signal of the adjacent cord.
Abnormal signal intensity of the upper division of the right brachial plexus denoting functional injury.
Supraspinatus, infraspinatus and subscapularis muscle denervation injury characterized by muscle belly edema.
Case Discussion
This case demonstrates multiple direct and indirect signs of pre-ganglionic nerve root injuries. The presence of pseudomeningocele, which usually appears three to four weeks after injury, at the C6-7 level with non-visualization of the nerve rootlets. The discontinuity of the C5 posterior rootlet with focal cord abnormal signal are also direct signs of avulsion injury. The marked muscle edema signal seen in the right rotator cuff muscles denotes denervation injury and confirms the C5-6 level injuries.
Mild relative thickening and edema signal of the distal brachial plexus divisions could be due to associated neuropraxia or early Wallerian degeneration secondary to proximal root injury.
The extensive injuries explain the unfortunate muscle weakness of this patient as neurologic examination later revealed right upper limb weakness 0/5 except hand grip 3/5 and wrist extension 4/5.
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