What is a characteristic of secondary spinal cord injury?

The characteristic of secondary spinal cord injury is primarily associated with inflammation and progression of neurologic damage. Secondary injuries may not occur immediately at the moment of impact; instead, they are a result of a cascade of biological processes that unfold over days to weeks following the initial trauma. After a spinal cord injury, the surrounding tissues can become inflamed, which can exacerbate neuronal damage. This inflammatory response can lead to further loss of neurons, demyelination, and impairment of blood flow, all of which can worsen the initial injury and may have the potential for targeting and damaging both upper and lower motor neurons, manifesting in various levels of neurological deficits.

In contrast, immediate tissue death directly after impact typically describes the primary injury rather than the secondary consequence which evolves over time. The statement regarding irreversible damage at the time of injury relates more to primary injuries, where damage occurs at the moment of impact. Lastly, the idea that only upper motor neurons are affected is an oversimplification, as spinal cord injuries can impact both upper and lower motor neurons depending on the level and severity of the injury. Thus, the inflammation and ongoing neurologic damage resulting from secondary injury are crucial aspects warranting close attention in the treatment and management of spinal cord injuries.