SYNONYMS : Lumbosacral transitional segment, lumbarization, sacralization, lumbosacral transanomaly, borderline vertebra.
A lumbar segment with enlarged transverse elements and an upper sacral segment with lumbar-type posterior elements are the two most common presentations.
The relationship of LSTV to back and leg pain has long been a subject of debate.
The association of back pain with antalgic scoliosis was first described by Bertolotti in 1917
(sacralization douleureuse, Bertolotti’s syndrome).
Radiological Findings:
LSTV is characterized by enlargement of the transverse process(es). Frontal and lateral views should be performed and preferably supplemented with an angulated view of the lumbosacral junction (Ferguson-Hibb view).
Note: L3 has the longest transverse process and L4 has a pointed TP.
Castellvi et al described a radiographic classification system identifying 4 types of LSTVs on the basis of morphologic characteristics.
Type I includes unilateral (Ia) or bilateral (Ib) dysplastic transverse processes, measuring at least 19 mm in width (craniocaudad dimension).Here the transverse process is expanded toward its tip as a spatulated bony process that is < 19 mm with no obvious connection to the sacral ala. This anomaly has a dubious role in back pain syndromes.
Type II exhibits incomplete unilateral (IIa) or bilateral (IIb) lumbarization/sacralization with an enlarged transverse process that has a diarthrodial joint between itself and the sacrum. The joint is usually referred to as a pseudo-articulation and is marked radiologically by corticated opposing bony surfaces with a 1- to 2-mm joint space. The vertebral body is often small and wedged laterally with narrowing on the side of attempted union, often precipitating a scoliosis. On the lateral view, a transitional vertebral body will be wedged posteriorly and the inferior endplate length will typically be less than the superior endplate length by a ratio of 1.37 or less (squaring sign). The intervening disc and facet joints are usually hypoplastic.
Type III LSTV describes unilateral (IIIa) or bilateral (IIIb) lumbarization/sacralization with complete osseous fusion of the transverse process(es) to the sacrum, with no visible joint.
Type IV involves a unilateral type II (pseudo-joint type) transition with a type III (osseous fusion) on the contralateral side.
Ref : Lumbosacral Transitional Vertebrae @ AJNR
ESR 3rd Edition.
A lumbar segment with enlarged transverse elements and an upper sacral segment with lumbar-type posterior elements are the two most common presentations.
The relationship of LSTV to back and leg pain has long been a subject of debate.
The association of back pain with antalgic scoliosis was first described by Bertolotti in 1917
(sacralization douleureuse, Bertolotti’s syndrome).
Radiological Findings:
LSTV is characterized by enlargement of the transverse process(es). Frontal and lateral views should be performed and preferably supplemented with an angulated view of the lumbosacral junction (Ferguson-Hibb view).
Note: L3 has the longest transverse process and L4 has a pointed TP.
Castellvi et al described a radiographic classification system identifying 4 types of LSTVs on the basis of morphologic characteristics.
Type I includes unilateral (Ia) or bilateral (Ib) dysplastic transverse processes, measuring at least 19 mm in width (craniocaudad dimension).Here the transverse process is expanded toward its tip as a spatulated bony process that is < 19 mm with no obvious connection to the sacral ala. This anomaly has a dubious role in back pain syndromes.
Type II exhibits incomplete unilateral (IIa) or bilateral (IIb) lumbarization/sacralization with an enlarged transverse process that has a diarthrodial joint between itself and the sacrum. The joint is usually referred to as a pseudo-articulation and is marked radiologically by corticated opposing bony surfaces with a 1- to 2-mm joint space. The vertebral body is often small and wedged laterally with narrowing on the side of attempted union, often precipitating a scoliosis. On the lateral view, a transitional vertebral body will be wedged posteriorly and the inferior endplate length will typically be less than the superior endplate length by a ratio of 1.37 or less (squaring sign). The intervening disc and facet joints are usually hypoplastic.
Type III LSTV describes unilateral (IIIa) or bilateral (IIIb) lumbarization/sacralization with complete osseous fusion of the transverse process(es) to the sacrum, with no visible joint.
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| A : Ordinary AP View B: Cranially Angulated (tilt-up) X Ray with central beam parallel to L5-S1 Disc shows a right sided type III LSTV. |
Type IV involves a unilateral type II (pseudo-joint type) transition with a type III (osseous fusion) on the contralateral side.
Ref : Lumbosacral Transitional Vertebrae @ AJNR
ESR 3rd Edition.
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