Foraminal disc protrusion (see intervertebral disc disease nomenclature) is an important entity to recognise for a number of reasons.
First of all it is relatively easy to overlook as it does not impinge upon the spinal canal. Secondly as it does not narrow the subarticular recess it compresses the exiting nerve root only, thus clinically mimicking a posterolateral disc at the level above. As posterolateral discs are common as is multilevel disease, missing a foraminal nerve root compression leading to only one level surgical decompression is a cause of failed back surgery. Additionally as the compression occurs lateral to the normal surgical field, the prospective surgeon needs to be made aware of the protrusion's location to be able to adequately treat the lateral component. It may require altered surgical technique.
- 1. Donald Resnick, MD and Mark J. Kransdorf, MD Radiology. 2006;238 (2): . doi:10.1148/radiol.2382052555