Aug 07, · An adult brachial plexus palsy is usually the result of trauma to the neck and shoulder areas. The mechanism may be a lateral traction injury to the brachial plexus nerves in the neck causing damage to the nerves and a loss of function. Outcomes depend on severity of the brachial plexus injury and the timing of strippe.xyzon: Ann Arbor, MI The brachial plexus is a network of nerves in the shoulder that carries movement and sensory signals from the spinal cord to the arms and hands. Brachial plexus injuries typically stem from trauma to the neck, and can cause pain, weakness and numbness in the arm and hand. Brachial plexus injuries often heal well if they aren’t severe.