A Review of Symptomatic Lumbosacral Transitional Vertebrae: Bertolotti's Syndrome

Abstract

Background: Lumbosacral transitional vertebrae (LSTV) are increasingly recognized as a common anatomical variant associated with altered patterns of degenerative spine changes. This review will focus on the clinical significance of LSTV, disruptions in normal spine biomechanics, imaging techniques, diagnosis, and treatment.

Methods: A Pubmed search using the specific key words "LSTV," "lumbosacral transitional vertebrae," and "Bertolotti's Syndrome" was performed. The resulting group of manuscripts from our search was evaluated.

Results: LSTV are associated with alterations in biomechanics and anatomy of spinal and paraspinal structures, which have important implications on surgical approaches and techniques. LSTV are often inaccurately detected and classified on standard AP radiographs and MRI. The use of whole-spine images as well as geometric relationships between the sacrum and lumbar vertebra increase accuracy. Uncertainty regarding the cause, clinical significance, and treatment of LSTV persists. Some authors suggest an association between LSTV types II and IV and low back pain. Pseudoarticulation between the transverse process and the sacrum creates a "false joint" susceptible to arthritic changes and osteophyte formation potentially leading to nerve root entrapment. The diagnosis of symptomatic LSTV is considered with appropriate patient history, imaging studies, and diagnostic injections. A positive radionuclide study along with a positive effect from a local injection helps distinguish the transitional vertebra as a significant pain source. Surgical resection is reserved for a subgroup of LSTV patients who fail conservative treatment and whose pain is definitively attributed to the anomalous pseudoarticulation.

Conclusions: Due to the common finding of low back pain and the wide prevalence of LSTV in the general population, it is essential to differentiate between symptoms originating from an anomalous psuedoarticulation from other potential sources of low back pain. Further studies with larger sample sizes and longer follow-up time would better demonstrate the effectiveness of surgical resection and help guide treatment.

Keywords: Bertolotti's Syndrome; LSTV; transitional vertebrae.

Fig. 1

Castellvi radiographic classification system.

Fig. 2

Appearances of LSTV based on Castellvi et al. (a) Type 1b with bilaterally enlarged L5 transverse process but no articulation with the sacrum. (b) Type 2a with unilateral pseudarthrosis. (c) Type 2b with bilateral pseudarthroses. (d) Type 3a with unilateral fusion of the enlarged transverse process to the sacral ala. (e) Type 3b with bilateral fusion. (f) Type 4 appearance with fusion on the left side and a pseudarthrosis on the right.

Fig. 3

Lateral radiograph of the lumbosacral junction showing the typical appearance of an LSTV with “squaring” of the transitional vertebral body and reduced height of the transitional disc.

Fig. 4

A case of L6 vertebra with type IIa transition. Left, T2-weighted sagittal cervicothoracic and (right) lumbar images in the cross-referencing mode of the picture archiving and communication system. This simultaneously demonstrates the marker at the T12–L1 disc space. Counting the vertebral levels caudally from C2 reveals this patient to have 25 presacral vertebrae or 6 lumbar vertebrae.

Fig. 5

Female patient age 62 with low back pain and with degenerative type IIA LSTV articulation (arrows) on the right side on plain film. (B) Non-focal, moderately increased uptake (large arrow) on the upper sacroiliac joint area at the planar scan. Note also the non-focal, minimal, tracer activity (small arrow) corresponding to the right enlarged transverse process. (C) Coronal SPECT image demonstrates focal, markedly increased activity (arrow) located in the degenerative anomalous articulation area. This patient was diagnosed as having active degenerative disease.

Fig. 6

Proposed diagnostic-therapeutic algorithm for evaluation and treatment of Bertolotti's Syndrome.