How dangerous is 4mm movement in my neck rearend car crash . i alredy have a fusion below the instablity how serious is this ?

In : In general, more than a millimeter or so of translation (horizontal displacement) is a potential problem in the cervical spine as this movement can potentially cause spinal cord compression. At the very least, this needs to be evaluated by an experienced spine surgeon. However, there are several factors that can make this translation more or less of a concern. If your spinal canal is small to start with (congenital spinal stenosis), you are much less able to tolerate a subluxation. If there is an associated disc herniation causing acquired spinal stenosis, then similarly you are much less able to tolerate a subluxation. Lastly, if the 4mm of movement worsens when bending your neck forward (meaning there is a dynamic instability rather an a fixed deformity), then the translation is much more worrisome. Finally, it also is important what other symptoms or exam findings you have. If you have signs or symptoms of spinal cord compression, then an urgent surgery may be indicated. At the very least, this needs to be evaluated and, if surgery is not indicated, followed for evidence of a progressive or worsening problem.

I've seen this : Question sitting here for a while, i assume that you or someone you know has an injury with these findings on a radiological study. It is not my field of expertise but if you have had a fusion and have either a new injury or late effects then that is an important question to address with your treating md. I know you are looking for more information but there are too many variables for answering.