How do stretch reflexes find a spinal cord injury?

Reflexes=levels. Stretch reflexes in the arms and legs can all be connected mostly to 1 or 2 spinal cord levels above the injury level reflexes will be normal. Depending on the age and location of the injury reflexes below the injury will either be missing early on or stronger than normal later. Also helpful to diagnosis is that left and right sides may be different from each other.
HYPERREFLEXIA. Strectch reflexes alone cannot diagnose a spinal cord injury. When there is an injury to the spinal cord or brain, we have what is called an upper motor neuron lesion. This type of injury may manifest itself thru hyperreflexia of those tested reflexes below the injury. This must be combined with other tests, including mental status, cranial nerves evaluation, motor examination, etc>.

Related Questions

How does a hyperactive stretch reflex (due to spinal cord injury) result in clonus?

Brakes are released. The quick answer: the brain/spinal cord send electrical fibers to control the muscles. When the fibers are severed, the muscles "do their own thing", unregulated. http://www.livestrong.com/article/197920-causes-of-clonus/. Read more...