how does it happen?
Injury can occur at any level of the spinal cord and can be "complete injury", with a total loss of sensation and muscle function at lower sacral segments, or "incomplete", meaning some nervous signals are able to travel past the injured area of the cord up to the Sacral S4-5 spinal cord segments.
Spinal cord injury
Injury can occur at any level of the spinal cord and can be "complete injury", with a total loss of sensation and muscle function at lower sacral segments, or "incomplete", meaning some nervous signals are able to travel past the injured area of the cord up to the Sacral S4-5 spinal cord segments. 
1. what assessment findings are associated with injuries of the spinal cord at the thoracic level A spinal cord injury what is this injury? It is damage to the spinal cord that causes temporary or permanent changes in its function.
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Spinal cord injury [SEP] Introduction
Diagnosis is typically based on symptoms and medical imaging. Efforts to prevent SCI include individual measures such as using safety equipment, societal measures such as safety regulations in sports and traffic, and improvements to equipment. Treatment starts with restricting further motion of the spine and maintaining adequate blood pressure. Corticosteroids have not been found to be useful. Other interventions vary depending on the location and extent of the injury, from bed rest to surgery. In many cases, spinal cord injuries require long-term physical and occupational therapy, especially if it interferes with activities of daily living. In the United States, about 12,000 people a year survive a spinal cord injury.