The brachial plexus is a group of nerves located in the armpit area, where the front leg joins the shoulder blade and the chest, that is responsible for movement and feeling. A brachial plexus avulsion occurs when these nerves are completely torn. A partial injury can occur when the nerves are only damaged or stretched. Trauma is by far the most common cause. Clinical signs occur immediately after the injury and consist of weakness / lameness (partial injury) or complete paralysis without feeling to the leg (complete avulsion). A condition called Horner’s syndrome can also occur following brachial plexus injury. Horner’s syndrome affects the sympathetic innervation to the eye on the same side as the injury resulting in a small pupil, a droopy upper eyelid, a raised third eyelid, and a sunken appearance to the eye. Their vision is not affected.
A diagnosis is typically made from the neurological exam and recent history of trauma. Radiographs may be recommended to look for concurrent injury to the bones. Electrodiagnostic studies (EMG / NCV) may be recommended to determine the severity of injury and to help determine the prognosis of recovery.
There is no specific treatment for this injury. The prognosis depends on the severity of the injury. If the limb has lost all feeling, the prognosis for recovery is poor. If a partial injury exists recovery can occur but may take months depending on the severity. Physical therapy can speed up this process. Pain medications are often used to reduce neuropathic pain. In cases where a recovery is not anticipated amputation may be recommended to prevent the limb from being accidentally injured and to remove the source of neuropathic pain.