[Diagnosis and treatment of lateral disc herniations. II. Classification, pathomechanical aspects of development, radiological demonstration, and operative approach].

Lateral disc herniations can be classified into three types according to their location. Type I is a prolapse within the lateral recess. In myelograms, it compresses the lateral part of the dural sac and the adjacent nerve root which is running to the intervertebral foramen below. Type II is situated at the entrance of the intervertebral foramen and compresses the adjacent nerve root only. The extreme lateral prolapse of type III compresses the ganglion within the intervertebral foramen, but often does not produce myelographic findings. All three types, especially the extreme lateral prolapse without myelographic changes, can also be demonstrated directly by the non-enhanced CT examination. The best operative approach, which depends on the location of each prolapse, is described.