Neuroradiology DOI 10.1007/s00234-014-1361-z
DIAGNOSTIC NEURORADIOLOGY
Lumbosacral transitional vertebra and S1 radiculopathy: the value of coronal MR imaging Abraham Fourie Bezuidenhout & Jan Willem Lotz
Received: 25 February 2014 / Accepted: 31 March 2014 # Springer-Verlag Berlin Heidelberg 2014
Abstract Introduction The association of a lumbosacral transitional vertebra with accelerated degeneration of the disc above has been described. Lumbosacral transitional vertebrae have also been reported as a cause of extraforaminal entrapment of the L5 nerve root between the transverse segment of the transitional vertebra and the sacral ala optimally demonstrated by coronal MRI. The association of the lumbosacral transitional vertebra pseudoarthroses and S1 nerve root entrapment due to degenerative stenosis of the nerve root canal has never been described. Methods We present 12 patients with lumbosacral transitional vertebrae that were referred for symptoms and signs of S1 nerve root radiculopathy in which the sagittal and axial MRI sequences failed to identify a plausible cause for the patients’ S1 nerve root symptoms. A coronal T1-weighted imaging (T1WI) MRI sequence was consequently added to the investigation. Results The coronal T1WI MRI sequence demonstrated hypertrophic degenerative stenosis of the S1 nerve root canal at the level of the lumbosacral transitional vertebra pseudoarthrosis, with entrapment of the respective S1 nerve root in all patients. Conclusion We emphasize the value of coronal T1WI MRI of the lumbosacral junction and sacrum if the cause for S1 radicular symptoms was not identified on conventional sagittal and axial MRI sequences in patients with lumbosacral transitional vertebrae. Keywords LSTV (lumbosacral transitional vertebra) . S1 radiculopathy A. F. Bezuidenhout (*) : J. W. Lotz Division of Radiodiagnosis, Department of Medical Imaging and Clinical Oncology, Faculty of Medicine and Health Sciences, Stellenbosch University, PO Box 19179, Tygerberg 7505, South Africa e-mail: [email protected]
Introduction A lumbosacral transitional vertebra (LSTV) is an anomalous vertebra with intermediate morphology resulting from either sacralisation of the lowest lumbar segment or lumbarisation of the most superior sacral segment of the spine. LSTV are commonly found in the general population with a reported prevalence of 5–30 % [1]. In 1984, Castellvi et al. [2] formulated a radiographic classification system describing four types of LSTV on the basis of morphologic characteristics. Type I represents an enlarged, dysplastic transverse process with a height more than 19 mm. Type IIa has a unilateral pseudoarthrosis, and IIb bilateral pseudoarthroses. Type IIIa has complete fusion on one side, and IIIb complete fusion on both sides. Type IV has a pseudoarthrosis on one side and complete fusion on the other side (Fig. 1) [3]. In a large cohort of patients with LSTV, the prevalence of the subtypes was type I in 42 %, type II in 41 %, type III in 12 %, and 5 % had LSTV type IV [1]. The association of LSTV with accelerated degeneration of the disc above has been described extensively [2]. Elster [4] found the overall incidence of structural pathology no higher in patients with LSTV, but emphasized the proportion of prolapses in the interspace immediately above the transition. LSTV has been reported as a cause for extraforaminal entrapment of the L5 nerve root between the transverse segment of the LSTV and the sacral ala optimally demonstrated by coronal MRI [5]. Abe et al. [6] described a case of anterior decompression of foraminal stenosis below a LSTV. A report on the results from threedimensional MRI reconstructions emphasized the value of the coronal plane in identifying extraforaminal L5 nerve root compression [7]. In an extensive literature search, we were unable to find documentation of S1 nerve root entrapment due to degenerative stenosis of the nerve root canal in association with LSTV pseudoarthroses. This case series will demonstrate the utility
Neuroradiology
time period of 1 September 2012 to 31 January 2014. All patient imaging was performed at the same institution. All patients had prior radiographs consisting of AP and lateral views of the lumbosacral spine. Vertebral levels were determined by designating the last vertebral body with a rib element as T12, which is common practice at our institution. A Ferguson view [2] (30° cranial angulation) of the lumbosacral junction was added if there was any suggestion of a LSTV on the initial AP view (Fig. 2a). CT studies were not performed as routine procedure. MRI studies were performed on a 1.5 Tesla scanner. Sagittal T1-weighted imaging (T1WI) (821/13 [repetition time msec/echo time msec]), turbo T2WI (4500/115), axial T1WI (583/15) and turbo T2WI (4810/104) of the lumbar spine with slice thickness of 4 mm were performed as standard procedure. A coronal T1WI sequence (642 ms/14 ms) with slice thickness of 3.5 mm, sectioned parallel to the cauda equina at L3 to L5 vertebral body levels, was constructed on a sagittal topogram. Coronal T1WI sequences were chosen as the authors believe that epidural and foraminal T1 fat hyperintensity provides an ideal background for identifying masses and disc components in these spaces. All imaging studies were read by a senior consultant radiologist.
Results
Fig. 1 Castellvi classification of LSTV. Type I represents an enlarged, dysplastic transverse process with a height more than 19 mm. Type IIa has a unilateral and IIb bilateral pseudoarthroses. Type IIIa has complete fusion on one side, and IIIb complete fusion on both sides. Type IV has a pseudoarthrosis on one side and complete fusion on the other. Courtesy of Daniel M. Walz, M.D. [3]
of coronal MR imaging in evaluating for S1 nerve root entrapment associated with Castellvi type IIa, IIb and IV LSTVs.
Materials and methods Institutional Health Research Ethics Committee approval was obtained. We present 12 patients with LSTV that were referred for symptoms and signs of S1 nerve root radiculopathy during the
LSTVs were identified and classified on a Ferguson view radiograph of the lumbosacral junction in all cases. In one case, a CT referral to exclude unrelated pelvic pathology afforded us an opportunity to reconstruct a coronal maximum intensity projection image. The combination of LSTV and nerve root canal stenosis was eloquently demonstrated on this image (Fig. 2b). Castellvi IIa was identified in seven, type IIb in four, and type IV in one case. Conventional MRI scans of the lumbar spine in sagittal and axial planes demonstrated a variety of degenerative pathology of the lower lumbar articulations. A definitive cause for S1 nerve root symptoms could, however, not be identified on any of the sequences. A coronal T1WI MRI sequence was consequently added to the investigation, and in this imaging plane, hypertrophic stenosis of the S1 nerve root canal at the level of the pseudoarthrosis, with entrapment of the respective S1 nerve root, was demonstrated in all patients. The following four patients are representative of the findings encountered in the case series (Table 1). Figure 3 shows the coronal T1WI MRI of a 42-year-old female patient who was referred from an orthopaedic outpatient clinic with unexplained left S1 nerve root symptomatology. A Ferguson view radiograph demonstrated a Castellvi IIa pseudoarthrosis with markedly sclerotic margins on the left. The coronal MRI identified marked hypertrophic stenosis
Neuroradiology Fig. 2 a Ferguson view radiograph demonstrating a Castellvi IIa LSTV with a rightsided pseudoarthrosis (white arrow) and marked degenerative bony hypertrophy (black arrows). b Coronal CT maximum intensity projection image confirming the Ferguson view radiograph findings of a Castellvi IIa LSTV with a right-sided pseudoarthrosis (black arrows) and associated stenosis of the nerve root canal (white arrows)
with osteophyte formation within the S1 nerve root canal resulting in entrapment and compression of the S1 nerve root. A 54-year-old female presented with symptoms and signs of neurogenic claudication and bilateral S1 radiculopathy, more profound on the left. A Castellvi IIa pseudoarthrosis with degenerative sclerotic marginal changes was present on the left. Sagittal and axial MRI confirmed degenerative spinal canal stenosis at the lower intervertebral disc levels, but failed to show a definitive cause for her severe left sided S1 nerve root pain. A coronal T1WI MRI of the lumbosacral junction identified entrapment of the left S1 nerve root by hypertrophic stenosis directly below the level of the pseudoarthrosis (Fig. 4). A 62-year-old male with incapacitating bilateral S1 radiculopathy presented with a Castellvi IIb LSTV with bilateral hypertrophic pseudoarthroses. The coronal T1WI MRI revealed marked bilateral S1 nerve root canal stenosis. On the right, the S1 nerve root was compressed by an osteophyte
originating from the inferior margin of the pseudoarthrosis. A smaller osteophyte compressed the left S1 root medially at a lower level (Fig. 5). A 49-year-old female, complaining of severe right-sided S1 radiculopathy, was shown to have a Castellvi IIa LSTV. The coronal T1WI MRI identified an osteophyte originating medially from a transitional disc margin directly opposite the level of the pseudoarthrosis. The exiting S1 nerve root was indented and angulated by extrinsic mass effect (Fig. 6).
Discussion In this case series, we present 12 patients referred for MRI of the lumbar spine for investigation of S1 nerve root symptoms. An LSTV was identified on plain film radiography in all patients. The sagittal and axial MRI sequences failed to
Table 1 Summary of patient characteristics and clinical and imaging findings Patient number
Age (years), sex
LSTV type (Castellvi classification)
S1 radiculopathy (left, right, bilateral or none)
S1 nerve root compression identified by coronal T1W1 MRI?
1 2 3 4
42, female 56, female 57, female 62, male
IIa left IIa left IIa right IIb
Left Bilateral (left more than right) Right Bilateral
Yes Yes Yes Yes
5 6 7 8 9 10 11 12
69, female 50, female 75, male 51, male 49, female 40, female 38, female 57, female
IIa right IIa left IIb IIa left IIa right IIb IV (pseudoarthrosis on the left) IIb
Right Left Left Left Right Bilateral (left more than right) Bilateral (left more than right) Bilateral
Yes Yes Yes Yes Yes Yes Yes Yes
Neuroradiology
Fig. 3 Coronal T1WI MRI identifying a Castellvi IIa LSTV with a leftsided pseudoarthrosis (black arrows) and associated entrapment of the S1 nerve root due to hypertrophic stenosis and osteophyte formation (white arrow)
identify a plausible cause for the patients’ S1 nerve root symptoms in all cases. A coronal T1WI MRI sequence was additionally performed according to standardized technical parameters. S1 nerve root canal stenosis secondary to degenerative hypertrophy at or near the LSTV pseudoarthrosis was identified in all patients. It was also possible to demonstrate S1 nerve root entrapment and to make a definitive imaging diagnosis for unexplained S1 nerve root symptomatology. Our case series highlights the importance of evaluating for S1 nerve root entrapment, which is often due to hypertrophic
Fig. 4 Coronal T1WI MRI identifying a Castellvi IIa LSTV with a leftsided pseudoarthrosis (black arrows) and associated entrapment of the S1 nerve root due to hypertrophic stenosis (white arrows)
Fig. 5 Coronal T1WI MRI identifying a Castellvi IIb LSTV with bilateral pseudoarthroses (black arrows) and associated osteophytic compression of the S1 nerve roots bilateral (white arrows)
degenerative stenosis associated with Castellvi type IIa, IIb and IV LSTVs.
Conclusion This case series emphasizes the value of coronal T1WI MRI of the lumbosacral junction and sacrum if the cause for S1 radicular symptoms was not identified on conventional sagittal and axial MRI sequences in patients with LSTV.
Fig. 6 Coronal T1WI MRI identifying a Castellvi IIA LSTV with a right-sided pseudoarthrosis (black arrows). An osteophyte originating medially from a transitional disc margin directly opposite the level of the pseudoarthrosis indents and angulates the exiting S1 root (white arrow)
Neuroradiology Ethical standards This research project was approved by the appropriate ethics committee and has therefore been performed in accordance with the ethical standards laid down in the 1964 Declaration of Helsinki and its later amendments. We declare that patient consent was waived for this study. Conflict of interest We declare that we have no conflict of interest.
References 1. Nardo L, Alizai H, Virayavanich W et al (2012) Lumbosacral transitional vertebrae: association with low back pain. Radiology 265(2):497–503 2. Castellvi AE, Goldstein LA, Chan DP (1984) Lumbosacral transitional vertebrae and their relationship with lumbar extradural defects. Spine 9(5):493–495
3. Konin GP, Walz DM (2010) Lumbosacral transitional vertebrae: classification, imaging findings, and clinical relevance. Am J Neuroradiol 31(10):1778–1786 4. Elster AD (1989) Bertolotti’s syndrome revisited. Transitional vertebrae of the lumbar spine. Spine 14(12):1373–1377 5. Hashimoto M, Watanabe O, Hirano H (1996) Extraforaminal stenosis in the lumbosacral spine. Efficacy of MR imaging in the coronal plane. Acta Radiol 37(5):610–613 6. Abe E, Sato K, Shimada Y et al (1997) Anterior decompression of foraminal stenosis below a lumbosacral transitional vertebra. A case report. Spine 22:823–826 7. Byun WM, Kim JW, Lee JK (2012) Differentiation between symptomatic and asymptomatic extraforaminal stenosis in lumbosacral transitional vertebra: role of three-dimensional magnetic resonance lumbosacral radiculography. Korean J Radiol 13(4): 403–411
DIAGNOSTIC NEURORADIOLOGY
Lumbosacral transitional vertebra and S1 radiculopathy: the value of coronal MR imaging Abraham Fourie Bezuidenhout & Jan Willem Lotz
Received: 25 February 2014 / Accepted: 31 March 2014 # Springer-Verlag Berlin Heidelberg 2014
Abstract Introduction The association of a lumbosacral transitional vertebra with accelerated degeneration of the disc above has been described. Lumbosacral transitional vertebrae have also been reported as a cause of extraforaminal entrapment of the L5 nerve root between the transverse segment of the transitional vertebra and the sacral ala optimally demonstrated by coronal MRI. The association of the lumbosacral transitional vertebra pseudoarthroses and S1 nerve root entrapment due to degenerative stenosis of the nerve root canal has never been described. Methods We present 12 patients with lumbosacral transitional vertebrae that were referred for symptoms and signs of S1 nerve root radiculopathy in which the sagittal and axial MRI sequences failed to identify a plausible cause for the patients’ S1 nerve root symptoms. A coronal T1-weighted imaging (T1WI) MRI sequence was consequently added to the investigation. Results The coronal T1WI MRI sequence demonstrated hypertrophic degenerative stenosis of the S1 nerve root canal at the level of the lumbosacral transitional vertebra pseudoarthrosis, with entrapment of the respective S1 nerve root in all patients. Conclusion We emphasize the value of coronal T1WI MRI of the lumbosacral junction and sacrum if the cause for S1 radicular symptoms was not identified on conventional sagittal and axial MRI sequences in patients with lumbosacral transitional vertebrae. Keywords LSTV (lumbosacral transitional vertebra) . S1 radiculopathy A. F. Bezuidenhout (*) : J. W. Lotz Division of Radiodiagnosis, Department of Medical Imaging and Clinical Oncology, Faculty of Medicine and Health Sciences, Stellenbosch University, PO Box 19179, Tygerberg 7505, South Africa e-mail: [email protected]
Introduction A lumbosacral transitional vertebra (LSTV) is an anomalous vertebra with intermediate morphology resulting from either sacralisation of the lowest lumbar segment or lumbarisation of the most superior sacral segment of the spine. LSTV are commonly found in the general population with a reported prevalence of 5–30 % [1]. In 1984, Castellvi et al. [2] formulated a radiographic classification system describing four types of LSTV on the basis of morphologic characteristics. Type I represents an enlarged, dysplastic transverse process with a height more than 19 mm. Type IIa has a unilateral pseudoarthrosis, and IIb bilateral pseudoarthroses. Type IIIa has complete fusion on one side, and IIIb complete fusion on both sides. Type IV has a pseudoarthrosis on one side and complete fusion on the other side (Fig. 1) [3]. In a large cohort of patients with LSTV, the prevalence of the subtypes was type I in 42 %, type II in 41 %, type III in 12 %, and 5 % had LSTV type IV [1]. The association of LSTV with accelerated degeneration of the disc above has been described extensively [2]. Elster [4] found the overall incidence of structural pathology no higher in patients with LSTV, but emphasized the proportion of prolapses in the interspace immediately above the transition. LSTV has been reported as a cause for extraforaminal entrapment of the L5 nerve root between the transverse segment of the LSTV and the sacral ala optimally demonstrated by coronal MRI [5]. Abe et al. [6] described a case of anterior decompression of foraminal stenosis below a LSTV. A report on the results from threedimensional MRI reconstructions emphasized the value of the coronal plane in identifying extraforaminal L5 nerve root compression [7]. In an extensive literature search, we were unable to find documentation of S1 nerve root entrapment due to degenerative stenosis of the nerve root canal in association with LSTV pseudoarthroses. This case series will demonstrate the utility
Neuroradiology
time period of 1 September 2012 to 31 January 2014. All patient imaging was performed at the same institution. All patients had prior radiographs consisting of AP and lateral views of the lumbosacral spine. Vertebral levels were determined by designating the last vertebral body with a rib element as T12, which is common practice at our institution. A Ferguson view [2] (30° cranial angulation) of the lumbosacral junction was added if there was any suggestion of a LSTV on the initial AP view (Fig. 2a). CT studies were not performed as routine procedure. MRI studies were performed on a 1.5 Tesla scanner. Sagittal T1-weighted imaging (T1WI) (821/13 [repetition time msec/echo time msec]), turbo T2WI (4500/115), axial T1WI (583/15) and turbo T2WI (4810/104) of the lumbar spine with slice thickness of 4 mm were performed as standard procedure. A coronal T1WI sequence (642 ms/14 ms) with slice thickness of 3.5 mm, sectioned parallel to the cauda equina at L3 to L5 vertebral body levels, was constructed on a sagittal topogram. Coronal T1WI sequences were chosen as the authors believe that epidural and foraminal T1 fat hyperintensity provides an ideal background for identifying masses and disc components in these spaces. All imaging studies were read by a senior consultant radiologist.
Results
Fig. 1 Castellvi classification of LSTV. Type I represents an enlarged, dysplastic transverse process with a height more than 19 mm. Type IIa has a unilateral and IIb bilateral pseudoarthroses. Type IIIa has complete fusion on one side, and IIIb complete fusion on both sides. Type IV has a pseudoarthrosis on one side and complete fusion on the other. Courtesy of Daniel M. Walz, M.D. [3]
of coronal MR imaging in evaluating for S1 nerve root entrapment associated with Castellvi type IIa, IIb and IV LSTVs.
Materials and methods Institutional Health Research Ethics Committee approval was obtained. We present 12 patients with LSTV that were referred for symptoms and signs of S1 nerve root radiculopathy during the
LSTVs were identified and classified on a Ferguson view radiograph of the lumbosacral junction in all cases. In one case, a CT referral to exclude unrelated pelvic pathology afforded us an opportunity to reconstruct a coronal maximum intensity projection image. The combination of LSTV and nerve root canal stenosis was eloquently demonstrated on this image (Fig. 2b). Castellvi IIa was identified in seven, type IIb in four, and type IV in one case. Conventional MRI scans of the lumbar spine in sagittal and axial planes demonstrated a variety of degenerative pathology of the lower lumbar articulations. A definitive cause for S1 nerve root symptoms could, however, not be identified on any of the sequences. A coronal T1WI MRI sequence was consequently added to the investigation, and in this imaging plane, hypertrophic stenosis of the S1 nerve root canal at the level of the pseudoarthrosis, with entrapment of the respective S1 nerve root, was demonstrated in all patients. The following four patients are representative of the findings encountered in the case series (Table 1). Figure 3 shows the coronal T1WI MRI of a 42-year-old female patient who was referred from an orthopaedic outpatient clinic with unexplained left S1 nerve root symptomatology. A Ferguson view radiograph demonstrated a Castellvi IIa pseudoarthrosis with markedly sclerotic margins on the left. The coronal MRI identified marked hypertrophic stenosis
Neuroradiology Fig. 2 a Ferguson view radiograph demonstrating a Castellvi IIa LSTV with a rightsided pseudoarthrosis (white arrow) and marked degenerative bony hypertrophy (black arrows). b Coronal CT maximum intensity projection image confirming the Ferguson view radiograph findings of a Castellvi IIa LSTV with a right-sided pseudoarthrosis (black arrows) and associated stenosis of the nerve root canal (white arrows)
with osteophyte formation within the S1 nerve root canal resulting in entrapment and compression of the S1 nerve root. A 54-year-old female presented with symptoms and signs of neurogenic claudication and bilateral S1 radiculopathy, more profound on the left. A Castellvi IIa pseudoarthrosis with degenerative sclerotic marginal changes was present on the left. Sagittal and axial MRI confirmed degenerative spinal canal stenosis at the lower intervertebral disc levels, but failed to show a definitive cause for her severe left sided S1 nerve root pain. A coronal T1WI MRI of the lumbosacral junction identified entrapment of the left S1 nerve root by hypertrophic stenosis directly below the level of the pseudoarthrosis (Fig. 4). A 62-year-old male with incapacitating bilateral S1 radiculopathy presented with a Castellvi IIb LSTV with bilateral hypertrophic pseudoarthroses. The coronal T1WI MRI revealed marked bilateral S1 nerve root canal stenosis. On the right, the S1 nerve root was compressed by an osteophyte
originating from the inferior margin of the pseudoarthrosis. A smaller osteophyte compressed the left S1 root medially at a lower level (Fig. 5). A 49-year-old female, complaining of severe right-sided S1 radiculopathy, was shown to have a Castellvi IIa LSTV. The coronal T1WI MRI identified an osteophyte originating medially from a transitional disc margin directly opposite the level of the pseudoarthrosis. The exiting S1 nerve root was indented and angulated by extrinsic mass effect (Fig. 6).
Discussion In this case series, we present 12 patients referred for MRI of the lumbar spine for investigation of S1 nerve root symptoms. An LSTV was identified on plain film radiography in all patients. The sagittal and axial MRI sequences failed to
Table 1 Summary of patient characteristics and clinical and imaging findings Patient number
Age (years), sex
LSTV type (Castellvi classification)
S1 radiculopathy (left, right, bilateral or none)
S1 nerve root compression identified by coronal T1W1 MRI?
1 2 3 4
42, female 56, female 57, female 62, male
IIa left IIa left IIa right IIb
Left Bilateral (left more than right) Right Bilateral
Yes Yes Yes Yes
5 6 7 8 9 10 11 12
69, female 50, female 75, male 51, male 49, female 40, female 38, female 57, female
IIa right IIa left IIb IIa left IIa right IIb IV (pseudoarthrosis on the left) IIb
Right Left Left Left Right Bilateral (left more than right) Bilateral (left more than right) Bilateral
Yes Yes Yes Yes Yes Yes Yes Yes
Neuroradiology
Fig. 3 Coronal T1WI MRI identifying a Castellvi IIa LSTV with a leftsided pseudoarthrosis (black arrows) and associated entrapment of the S1 nerve root due to hypertrophic stenosis and osteophyte formation (white arrow)
identify a plausible cause for the patients’ S1 nerve root symptoms in all cases. A coronal T1WI MRI sequence was additionally performed according to standardized technical parameters. S1 nerve root canal stenosis secondary to degenerative hypertrophy at or near the LSTV pseudoarthrosis was identified in all patients. It was also possible to demonstrate S1 nerve root entrapment and to make a definitive imaging diagnosis for unexplained S1 nerve root symptomatology. Our case series highlights the importance of evaluating for S1 nerve root entrapment, which is often due to hypertrophic
Fig. 4 Coronal T1WI MRI identifying a Castellvi IIa LSTV with a leftsided pseudoarthrosis (black arrows) and associated entrapment of the S1 nerve root due to hypertrophic stenosis (white arrows)
Fig. 5 Coronal T1WI MRI identifying a Castellvi IIb LSTV with bilateral pseudoarthroses (black arrows) and associated osteophytic compression of the S1 nerve roots bilateral (white arrows)
degenerative stenosis associated with Castellvi type IIa, IIb and IV LSTVs.
Conclusion This case series emphasizes the value of coronal T1WI MRI of the lumbosacral junction and sacrum if the cause for S1 radicular symptoms was not identified on conventional sagittal and axial MRI sequences in patients with LSTV.
Fig. 6 Coronal T1WI MRI identifying a Castellvi IIA LSTV with a right-sided pseudoarthrosis (black arrows). An osteophyte originating medially from a transitional disc margin directly opposite the level of the pseudoarthrosis indents and angulates the exiting S1 root (white arrow)
Neuroradiology Ethical standards This research project was approved by the appropriate ethics committee and has therefore been performed in accordance with the ethical standards laid down in the 1964 Declaration of Helsinki and its later amendments. We declare that patient consent was waived for this study. Conflict of interest We declare that we have no conflict of interest.
References 1. Nardo L, Alizai H, Virayavanich W et al (2012) Lumbosacral transitional vertebrae: association with low back pain. Radiology 265(2):497–503 2. Castellvi AE, Goldstein LA, Chan DP (1984) Lumbosacral transitional vertebrae and their relationship with lumbar extradural defects. Spine 9(5):493–495
3. Konin GP, Walz DM (2010) Lumbosacral transitional vertebrae: classification, imaging findings, and clinical relevance. Am J Neuroradiol 31(10):1778–1786 4. Elster AD (1989) Bertolotti’s syndrome revisited. Transitional vertebrae of the lumbar spine. Spine 14(12):1373–1377 5. Hashimoto M, Watanabe O, Hirano H (1996) Extraforaminal stenosis in the lumbosacral spine. Efficacy of MR imaging in the coronal plane. Acta Radiol 37(5):610–613 6. Abe E, Sato K, Shimada Y et al (1997) Anterior decompression of foraminal stenosis below a lumbosacral transitional vertebra. A case report. Spine 22:823–826 7. Byun WM, Kim JW, Lee JK (2012) Differentiation between symptomatic and asymptomatic extraforaminal stenosis in lumbosacral transitional vertebra: role of three-dimensional magnetic resonance lumbosacral radiculography. Korean J Radiol 13(4): 403–411
