[Lateral intra- and extraforaminal lumbar disk hernia: clinical aspects and therapy]

Lateral lumbar disc herniations in or beyond the intervertebral foramen account for nearly 10% of all lumbar herniations. They affect the nerve root exiting at the same level. Such a lateral herniation of disc L4, for example, would impinge on nerve root L4, while a common herniation inside the spinal canal would compromise root L5. Myelography most often provides false-negative results. High-resolution CT scanning is completely accurate in demonstrating these lesions and therefore is considered the diagnostic method of choice. We review the anatomo-pathological and clinical features and propose guidelines for radiological examination of these herniations. Finally, the lateral microsurgical approach to the intervertebral foramen is described. It permits exposure of the lateral disc prolapse without opening the spinal canal or performing facetectomy.