Figure 1 (A) Anterior view (patient No 5) and (B) lateral view (patient No 4) of two patients from the present series with flail arm syndrome attempting shoulder abduction. There is marked wasting of the anterior and posterior shoulder girdle muscles, with an inability to abduct the shoulders, with a resultant “man‐in‐the‐barrel” syndrome. (C) Stimulus–response curves obtained following transcranial magnetic stimulation stimulation in 8 flail arm patients, 26 patients with other amyotrophic lateral sclerosis (ALS) phenotypes and 39 normal controls. The motor evoked potential (MEP) is expressed as a percentage of the compound muscle action potential (CMAP) amplitude, recorded following electrical stimulation. The MEP amplitude was significantly increased in flail arm and other ALS patients compared with controls over stimulus intensities from 110 to 150% (p<0.05) of resting motor threshold (RMT). (D) Short interval intracortical inhibition, defined as the stimulus intensity required to maintain a target output of 0.2 mV, was reduced in both flail arm (n = 8, p<0.0001) and other ALS patients (n = 26, p<0.001) compared with controls. Informed consent was obtained for publication of this figure.