Weakness or paralysis of the shoulder and arm usually caused by injury to the upper roots of the brachial plexus during traumatic childbirth. This may happen if, during a difficult delivery, excess traction applied to the head damages the fifth and sixth cervical roots of the spinal cord. The muscles of the shoulder and the flexors of the elbow are paralysed and the arm hangs at the side internally rotated at the shoulder with the forearm pronated (waiter’s-tip deformity). Recovery may be spontaneous, but in some cases nerve grafts or muscle transfers are required. W. H. Erb (1840–1921), German neurologist
Subjects: Medicine and Health.