All three can occur. Cells and axons are stretched and sheared when compression displaces the spinal cord.

At the compression site, there are axons, neurons, astrocytes, and oligodendroglial cells. Depending on the velocity and extent of the stretching and shearing, cellular damage occurs to these cells. If the injury causes bleeding, the blood is toxic to cells and contributes to the injury.

Finally, the injured tissues release a variety of chemicals that causes further tissue damage. These include free radicals, inflammatory cytokines, neurotoxic neurotransmitters, and other chemicals.