Peripheral nerve injury of the upper extremity commonly occurs in patients who participate in recreational (e.g., sports) and occupational activities. Nerve injury should be considered when a patient experiences pain, weakness, or paresthesias in the absence of a known bone, soft tissue, or vascular injury.
Brain injury occurs when the tissues of the brain suffer an acute injury that results in temporary, chronic, or permanent damage and/or dysfunction. The brain is a very sensitive organ subject to injury from a variety of insults. Some of the major causes of brain injury include trauma, lack of oxygen (hypoxic/anoxic injury), lack of blood flow (ischemia), infection, and metabolic disorders.
1 Trauma to the brain (i.e. severe head injury caused by a motor vehicle crash, gunshot wound, fall or blow to the head) 2  Cerebrovascular injury (i.e. stroke or aneurysm)  Anoxia (i.e. drowning or heart attack when the patient is revived, but not before a lack or blood flow/oxygen to the brain has caused brain death)