Lumbosacral Transitional Vertebrae and Their Relationship With Lumbar Extradural Defects

TLDR

The study examined how lumbosacral transitional vertebrae affect the location of herniated lumbar discs and introduced a new classification based on morphologic and clinical features. The authors retrospectively reviewed 200 consecutive patients with myelographically confirmed lumbar disc herniation. Among 60 patients with lumbosacral transitional vertebrae, Type II was associated with disc herniation at the transition level and a higher incidence just above it, while Types III and IV showed no herniations at the transition level or increased proximal incidence, and Type I had no difference in herniation location.

Abstract

The relationship between herniated lumbar disc and abnormalities of the transverse process of the lumbosacral junction was investigated. Two hundred consecutive patients with positive myelographic findings of herniated lumbar disc were reviewed. Sixty patients presented abnormalities of the transverse process to satisfy the criteria for lumbosacral transitional vertebra. A new classification of lumbosacral transitional vertebra is presented based upon the morphologic and clinical characteristics with respect to herniated nucleus pulposus. Type I represents a “forme fruste” of lumbosacral transitional vertebra and shows no difference in the incidence of the location of herniations. In Types III and IV, there are no herniations at the level of the lumbosacral transitional vertebra and no increase in the incidence of herniations just proximal to the lumbosacral transitional vertebra. The Type II lumbosacral transitional vertebra presents herniated lumbar disc at the level of transition. It also presents a greater than normal incidence of herniations at the level just above the lumbosacral transitional vertebra.