Brachial plexus trauma: the morbidity of hemidiaphragmatic paralysis.

Phrenic nerve palsy has previously been associated with brachial plexus root avulsion; severe unilateral phrenic nerve injury is not uncommonly associated with brachial plexus injury. Brachial plexus injuries can be traumatic (gunshot wounds, lacerations, stretch/contusion and avulsion injuries) or non-traumatic in aetiology (supraclavicular brachial plexus nerve block, subclavian vein catheterisation, cardiac surgeries, or obstetric complications such as birth palsy). Despite the known association, the incidence and morbidity of a phrenic nerve injury and hemidiaphragmatic paralysis associated with traumatic brachial plexus stretch injuries remains ill-defined. The incidence of an associated phrenic nerve injury with brachial plexus trauma ranges from 10% to 20%; however, because unilateral diaphragmatic paralysis often presents without symptoms at rest, a high number of phrenic nerve injuries are likely to be overlooked in the setting of brachial plexus injury. A case report is presented of a unilateral phrenic nerve injury associated with brachial plexus stretch injury presenting with a recalcitrant left lower lobe pneumonia.