PRESENTATION NUMBER
eEdE-212
Disclosure
• No potential conflicts of interest to
disclose.
Lumbosacral Transitional Vertebrae
Classifications & Clinical Significance
Eman Mahdi, MD
Anousheh Sayah, MD
MedStar Georgetown University Hospital; Washington DC
ASNR 2015 – Chicago, IL
Index
1.
2.
3.
4.
5.
Objectives
Introduction
Definition
Classifications
Examples and
Cases
6. Numbering
techniques
7. Clinical
significance
8. Conclusion
9. References
Objectives
• Review the anatomical landmarks and criteria used to
label Lumbosacral Transitional Vertebra (LSTV)
• Review cases to demonstrate this variant anatomy and
the various classifications using different modalities
• Discuss the approach to reporting LSTV
• Demonstrate the clinical significance of transitional
vertebra
Introduction
• Variability in spine numbering in the lumbosacral region is
a common challenge in reporting of spine imaging cases.
• Most worrisome is the possibility of wrong-level spine
surgery based upon imaging reports.
• LSTV have been purported as a cause of low back pain,
notably in the young.
Definition of LSTV
• LSTVs are congenital spinal anomalies defined as
either sacralization of the lowest lumbar segment or
lumbarization of the most superior sacral segment.
• Prevalence is 4%–30% in general population.
• Higher rate in men than in women.
Classification & Identification
• Castellvi classification
• O’Driscoll classification
• Identifying Landmarks:
Iliolumbar ligament
Difference in vertical mid-vertebral angles (DiffVMVA)
Lower Lumbar/Upper Sacral segment shape
Vascular structures
Lumbosacral Intervertebral Disc Angle (LSIVDA)
Castellvi classification
Based on transverse process morphology
Type I: Unilateral (Ia) or bilateral
(Ib) enlarged dysplastic transverse
processes with a height more than
19 mm.
Type II: Unilateral (IIa) or bilateral
(IIb) Pseudoarthrosis of the
transverse process and the
sacrum.
Type III: Unilateral (IIIa) or bilateral
(IIIb) complete osseous fusion of
the transverse process(es) to the
sacrum.
Type IV: Pseudoarthrosis (type II)
on one side and complete fusion
on the other side(type III).
*(1)
Examples of Castellvi
Classification
B
A
Castellvi type I
(Enlarged bilateral
transverse processes)
Castellvi Type IIa (Unilateral
pseudoarthrosis on the right)
A: AP X-ray, B: Axial T2 MRI
Examples of Castellvi
Classification
Castellvi type IIIb (bilateral osseous fusion of the transverse process to the sacrum)
Classification & Identification
• Castellvi classification
• O’Driscoll classification
• Identifying Landmarks:
Iliolumbar ligament
Difference in vertical mid-vertebral angles (DiffVMVA)
Lower Lumbar/Upper Sacral segment shape
Vascular structures
Lumbosacral Intervertebral Disc Angle (LSIVDA)
O’Driscoll Classification
Based on first sacral disk morphology &
AP length by sagittal MR
Type I:
Type II:
Type III:
Type IV:
No disk material
Small residual
disk
Well-formed
disk extending
the entire AP
length of the
sacrum
Similar to type 3
with addition of
squaring
of the presumed
upper sacral
segment
Example of O’Driscoll
Classification
L1
L1
L2
L2
L3
L3
L4
L4
L5
#
L5
S1
#
S1
*
*
Type IV O’Driscoll. Well formed disc* with squaring# of S1
Identifying Landmarks in Assessing LSTV
1. Iliolumbar ligament denoting the lowest lumbar type vertebral
segment and the lumbosacral junction (does not always represent
L5 level). It is a low-signal-intensity structure on both axial T1 and
T2 weighted MR images, extending from the transverse process of
‘L5’ to the posteromedial iliac crest.(3)
Anterior band
L5
Posterior band
Classification & Identification
• Castellvi classification
• O’Driscoll classification
• Identifying Landmarks:
Iliolumbar ligament
Difference in vertical mid-vertebral angles (DiffVMVA)
Lower Lumbar/Upper Sacral segment shape
Vascular structures
Lumbosacral Intervertebral Disc Angle (LSIVDA)
Identifying Landmarks in Assessing LSTV
2. Difference in vertical mid-vertebral angles (DiffVMVA) of the most 2 caudal vertebral segments, in single midsagittal MRI or lumbosacral x-ray. Difference of ≤+10° has 100%
sensitivity and 89% specificity in solid bony bridge (i.e. Castellvi
type 3 & 4). (4)
L4
L4
Diff-VMVA =
VMVA of Lowest
segment –
VMVA One above
lowest segment
A: LSTV ≤+10
(24-27= -3)
B: Normal >+10
(48-6= +42)
A
B
Identifying Landmarks in Assessing LSTV
3. Squaring (* Fig A) of the upper sacral
segment when it is lumbarized and
Wedging (↑ Fig B) of the lowest lumbar
segment when it is sacralized.(8)
L5
S1
*
S2
A
4. Vascular landmarks such as aortic
bifurcation at L4, right renal artery origin
at L1/L2 disc, and IVC confluence at L5.
These are not reliable due to variability
in anatomy and due to the fact that they
are not always imaged.
L4
L5
S1
B
Identifying Landmarks in Assessing LSTV
5. Lumbosacral Intervertebral Disc
Angle (LSIVDA): the angle
between lines drawn along the
inferior endplate of the lowest
lumbar vertebra and the superior
endplate of the first sacral vertebra.
Note -- Recent studies have found no
significant correlation between LSIVDA
and LSTV.(3)
Numbering Technique/Approach to Report LSTV
 The approach used in vertebral numbering should be
mentioned in the report and/or discussed with the referring
physician.
 Discuss number of non-rib bearing lumbar type vertebra.
 Describe presence of any LSTV:
• Lumbarized S1
• Sacralized L5
 Formally label the last lumbar type vertebra, whether it be
L4, L5, L6, or S1, depending on the method chosen.
Numbering Technique/Approach to Report LSTV
 Additional imaging options:
• Sagittal whole spine MR localizer
may be used to better evaluate
LSTV.(5)
• Coronal MR cervicothoracic localizer
increases the accuracy of identifying
LSTV.
Numbering Technique/Approach to Report LSTV
• Coronal T1WI MRI of the lumbosacral junction and sacrum
can also identify LSTV which can sometimes be the cause for
S1 radicular symptoms – in this case, the cause was not
identified on the sagittal and axial MRI sequences.(6)
Castellvi IIb LSTV with bilateral
pseudoarthroses (black arrows) and
osteophytic compression of S1 nerve
roots (white arrows)
Clinical significance
• Relationship of low
back pain and LSTV,
termed “Bertolotti
Syndrome”
• Wrong-Level Spine
Surgery
Clinical significance
• Symptoms can originate from:
The anomalous articulation itself
The contralateral facet joint (when unilateral)
Instability and early degeneration of the level
cephalad to the transitional vertebrae
Nerve root compression from hypertrophy of the
transverse process.
Types II and IV had higher prevalence and severity
of low back pain and buttock pain.(7)
67 year old patient with
right sided radiculopathy
L5
S1
Sagittal and axial T2 MRI shows large right L5 transverse
process with pseudoarthrosis impinging on the right exiting L5
nerve root. Arrow denotes the normal left L5 exiting nerve root.
Conclusion
• Prevalence of LSTV is 4%–30% in the
general population.
• Assessment of LSTV is essential in reporting
spine MRI.
• Describing the method of vertebral
numbering in the report is crucial in helping
to avoid wrong level spine surgery.
References
•
1. Konin GP, Walz DM. Lumbosacral transitional vertebrae: classification, imaging findings, and clinical relevance. AJNR Am
J Neuroradiol. 2010 Nov;31(10):1778-86.
•
2. Hughes RJ, Saifuddin A. Numbering of lumbosacral transitional vertebrae on MRI: role of the iliolumbar ligaments. AJR
Am J Roentgenol. 2006 Jul;187(1):W59-65.
•
3. Carrino JA, Campbell PD Jr, Lin DC, et al. Effect of Spinal Segment Variants on Numbering Vertebral level at Lumbar MR
imaging. Radiology. 2011 Apr;259(1):196-202.
•
4. Farshad M, Aichmair A, Hughes AP, et al. A reliable measurement for identifying a lumbosacral transitional vertebra with a
solid bony bridge on a single-slice midsagittal MRI or plain lateral radiograph. Bone Joint J. 2013 Nov;95-B(11):1533-7.
•
5. Hanson EH, Mishra RK, Chang DS, et al. Sagittal whole-spine magnetic resonance imaging in 750 consecutive
outpatients: accurate determination of the number of lumbar vertebral bodies. J Neurosurg Spine. 2010 Jan;12(1):47-55.
•
6. Bezuidenhout AF, Lotz JW. Lumbosacral transitional vertebra and S1 radiculopathy: the value of coronal MR imaging.
Neuroradiology. 2014 Jun;56(6):453-7.
•
7. Nardo L, Alizai H, Virayavanich W, et al. Lumbosacral transitional vertebrae: association with low back pain. Radiology.
2012 Nov;265(2):497-503.
•
8. Tokgoz N, Ucar M, Erdogan AB, et al. Are spinal or paraspinal anatomic markers helpful for vertebral numbering
and diagnosing lumbosacral transitional vertebrae? Korean J Radiol. 2014 Mar-Apr; 15(2):258-66.