Fig. 8.

TOS with C8 neuropathy. A 17-year-old girl (trumpet player) with left arm and hand weakness in an ulnar distribution, exacerbated by shoulder abduction. Sagittal STIR (A) image shows an asymmetrically enlarged and hyperintense C8 nerve root (large arrow) compared with the other normal nerve roots (small arrows). Notice minimal asymmetric hyperintensity of the T1 nerve root, a common nonspecific finding. Axial T1-weighted (B) MR image through the lower neck shows a prominent flow void (curved arrow) indenting the left C8 nerve root (large arrow). The EMG findings were normal in this case. On surgery, the flow void turned out to be a prominent branch of the left thyrocervical trunk, which was ligated. C8 neurolysis was also performed. The patient's symptoms completely resolved following surgery.