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.
Hypoxia differs from hypoxemia and anoxemia in that hypoxia refers to a state in which oxygen supply is insufficient, whereas hypoxemia and anoxemia refer specifically to states that have low or zero arterial oxygen supply. Hypoxia in which there is complete deprivation of oxygen supply is referred to as anoxia.