Spinal Cord Injury ll: Pathophysiology

Primary spinal cord injury involves several mechanical damage mechanisms. Compression occurs when fractured vertebrae, herniated discs, or hematomas press directly on the cord. Contusion refers to bruising from blunt force, causing localized bleeding and swelling. Laceration involves partial tearing or complete severing from penetrating trauma. Distraction results from excessive stretching or pulling of the cord, typically in high-speed crashes or falls.

Vascular disruption ruptures blood vessels, leading to hemorrhage and ischemia. This deprives surrounding tissue of oxygen and nutrients, causing additional cell failure. The combination of bleeding and reduced blood flow creates a hostile microenvironment that damages neurons and supporting cells at the injury site, amplifying the initial mechanical trauma.

Primary injury damages neurons and supporting cells including astrocytes, oligodendrocytes, and microglia. Axonal shearing further worsens injury, as long nerve fibers in pathways such as the corticospinal and spinothalamic tracts are stretched or severed. This disrupts the spinal cord's microenvironment and impairs motor and sensory transmission.

Primary injury causes immediate mechanical damage and cellular destruction. These combined effects—cell destruction, axonal damage, swelling, and hemorrhage—initiate the secondary spinal cord injury lli pathophysiology phase. This delayed cascade develops over hours to days, amplifying damage through inflammation, oxidative stress, and progressive cell death.

Compression occurs when fractured vertebrae, herniated discs, or accumulating blood press directly against the spinal cord, distorting its normal shape and function. This mechanical pressure disrupts the cord's structural integrity and impairs its ability to transmit neural signals, contributing to neurological deficits.

Laceration involves partial tearing or complete severing of the spinal cord, often resulting from penetrating trauma. Unlike compression or contusion, which may allow some structural recovery, laceration causes direct disruption of nerve fibers and can result in permanent loss of function below the injury site.

Distraction results from excessive stretching or pulling of the spinal cord, typically occurring in high-speed crashes or falls. This mechanism stretches or severs long nerve fibers within major pathways, causing axonal damage and disrupting neural communication. The injury can occur without direct impact, making it a distinct form of primary mechanical trauma.