Breathing arms

Abstract

A 63-year-old man presented with radicular upper limb pain and proximal weakness, most pronounced on the left (active shoulder abduction limited to ∼90°). Magnetic resonance imaging demonstrated foraminal stenosis at C4/C5, with bilateral nerve root compression at C5/C6 (Figure, Top), and he underwent a two-level anterior cervical discectomy and fusion. Surgical revision at C5/C6 level was required 3 months later for continuing left-sided pain and weakness (medical research council Grade 4−/5 for left shoulder abduction). Radicular pain affecting the right arm also persisted, and he was referred to the electromyography clinic for investigation into continued compromise of the C5 root. At 16 months after initial surgery, examination revealed slight wasting of both deltoid muscles; power for right shoulder abduction was graded 5/5, left abduction 4+/5. Electromyography revealed recruitment of motor unit potentials in the deltoid muscles of both arms time locked to inspiration (Figure, Middle and Bottom and supplementary video)—the breathing arm. There was no evidence of active denervation.