Traction lesion of the brachial plexus during bodyflying

Abstract

Bodyflying is a flying sport similar to skydiving. The experience of bodyflying is close to that of skydiving, however, bodyflying does not require a jump out of a plane or a parachute, the flight is enabled by a vertical air stream column with a speed of up to 180 km/h in a vertical wind tunnel. Bodyflying has been considered to be a sports activity in a completely safe environment with no serious complications. We report two cases of traction lesions of the brachial plexus during first-time bodyflying with predominant affection of the root C6. To the best of our knowledge, this pattern of traction injury of the brachial plexus has not yet been reported. Immediately following a bodyflying teaching session, a 35-year-old male noticed a marked weakness in arm and finger flexion and to a lesser degree in arm extension of the left upper limb. Furthermore, he observed numbness of the radial side of the left forearm. Contrast-enhanced magnetic resonance imaging of the cervical spine was unremarkable. On examination of the left upper limb, there was weakness in biceps flexion [grade 4-/5 according to the British Medical Research Council grading system (BMRC)], triceps extension (grade 4?/5), and wrist/finger flexors (grade 4?/5). Examination of sensation was diminished over the radial aspect of the left forearm extending down over the first three digits (C6). The biceps and brachioradialis reflexes were absent on the left side. Electroneurographic examinations of nerve conduction velocities and amplitudes of the left median and ulnar nerve were unremarkable, but F-wave studies of the left median nerve (see Fig. 1) demonstrated an increased latency on the left (C6). Electromyographic needle examination (EMG) revealed no abnormal spontaneous activity, but recruitment was predominantly reduced in the left biceps (see Fig. 2) and slightly reduced in the left deltoid (C5/C6), whereas it was normal in the left triceps (C7). Because of acute weakness of the left arm during a firsttime bodyflying session, a 17-year-old female had to interrupt the session. Immediately following the session, the patient was unable to move her left arm and she noticed a numbness of the radial side of the left forearm. On examination of the left upper limb, strength testing demonstrated flaccid paresis in shoulder abduction and anteversion (grade 4/5), biceps flexion and supination/ pronation of the forearm (grade 2/5), and wrist/finger flexors (grade 4/5) without affection of intrinsic muscles of the hand. Sensation was diminished over the radial aspect of the left forearm extending down over the first two digits. The biceps reflex was absent and the brachioradialis reflex was diminished on the left. Nerve conduction velocity studies of sensory nerves demonstrated a slightly decreased left median nerve response (C6). The EMG revealed abnormal spontaneous activity in the left biceps brachii muscle and recruitment was markedly reduced. There was no abnormal spontaneous activity in the left deltoideus and brachioradialis, but recruitment was reduced, indicative of a lesion of the C5 and C6 segment. Misjudgement of vertical air stream with a speed of up to 180 km/h can result in uncoordinated compensating movements of the arms. In this situation, an inadvertent relaxation of the arm muscles can cause the arm to be overextended or overelevated by the strong vertical air stream and may thereby cause a traction lesion of the brachial plexus. Additionally, the bodyflying instructor’s N. Galldiks (&) K. A. M. Pauls G. R. Fink W. F. Haupt Department of Neurology, University Hospital of Cologne, Kerpener Str. 62, 50924 Cologne, Germany e-mail: norbert.galldiks@uk-koeln.de