Extrapleural Apical Fluid Collection: An Important Sign on Plain X-ray Suggesting a Pre-ganglionic Brachial Plexus Injury

Forty of 136 consecutive patients referred for management of brachial plexus injuries had closed supraclavicular injuries. The results of the initial chest X-rays were available for 29 patients. Nine had avulsion of the C8 and T1 nerve roots from the spinal cord. Eight cases had MR confirmation of lower root avulsion, six of these cases were confirmed surgically and none had any long-term clinical recovery. Twenty had partial brachial plexus injuries without avulsion of these roots. Seven of nine patients with avulsion of C8 and T1 had an extrapleural apical fluid collection. One of these had a fractured first rib. Two of 20 without avulsion had an extrapleural apical fluid collection. Both had fractured the first rib. The difference in incidence of extrapleural apical fluid collection between the two groups, excluding those cases with first rib fractures, was statistically significant. Without a first rib fracture, an ipsilateral extrapleural apical haematoma on a plain chest X-ray of patients with brachial plexus injury strongly suggests pre-ganglionic injury to the lower roots.