The lumbar spine from L1 to L5 is a place where changes that occur as we age can cause a narrowing of the spinal canal. The spinal canal where the spinal cord and/or spinal nerve roots travel. This narrowing is called lumbar spinal stenosis.
But the term narrowing is relative. A one or two millimeter change probably isn’t going to make much difference. But at what point does the narrowing start to lend itself to problems with pinching or compression of the nerve tissues? And is it the same for each person? Evidently not, because studies show that not everyone with narrowing of the spinal canal actually has symptoms of back, buttock, or leg pain to go with it.
Researchers suggest using the terms relative and absolute stenosis to help establish some cut off points for narrowing. Anything 10 millimeters or smaller in diameter is called absolute stenosis. Spinal canal opening between 10 and 12 meters is relative. These cut off points are somewhat arbitrary but seem to be in use by many researchers studying spinal stenosis.
The complicating factor is in how the measurement is taken. Most of these measurements are made from front to back inside the spinal canal. That’s called the anteroposterior diameter. But in some people, the round shape of the spinal canal is more of a triangular shape referred to as trefoil.
It’s harder to get a true measurement when there is a trefoil-shaped spinal canal. There is a greater chance that some people who really have stenosis aren’t recognized because of this factor. So depending on the size and shape of your spinal canal, you may (or may not) have stenosis. And since it’s in question, yours is probably more relative than absolute at this point.