Numbering of lumbosacral transitional vertebrae on MRI: role of the iliolumbar ligaments

Redefining the Treatment of Lumbosacral Transitional Vertebrae for Bertolotti Syndrome: Long-Term Outcomes Utilizing the Jenkins Classification to Determine Treatment

OBJECTIVE

Using the Jenkins classification, we propose a strategy of shaving down hypertrophic bone, unilateral fusion, or bilateral fusion procedures to achieve pain reduction and improve quality of life for patients with Bertolotti syndrome.

METHODS

We reviewed 103 patients from 2012 through 2021 who had surgically treated Bertolotti syndrome. We identified 56 patients with Bertolotti syndrome and at least 6 months of follow-up. Patients with iliac contact preoperatively were presumed to be more likely to have hip pain that could respond to surgical treatment, and those patients were tracked for those outcomes as well.

RESULTS

Type 1 patients (n = 13) underwent resection. Eleven (85%) had improvement, 7 (54%) had good outcome, 1 (7%) had subsequent surgery, 1 (7%) was suggested additional surgery, and 2 (14%) were lost to follow-up. In Type 2 patients (n = 36), 18 underwent decompressions and 18 underwent fusions as a first line. Of the 18 patients treated with resection an interim analysis saw 10 (55%) with failure and needing subsequent procedures. With subsequent procedure, 14 (78%) saw improvement. For fusion surgical patients, 16 (88%) saw some improvement and 13 (72%) had a good outcome. In Type 4 patients (n = 7), 6 (86%) did well with unilateral fusion, with durable benefit at 2 years. In patients who had hip pain preoperatively (n = 27), 21 (78%) had improvement of hip pain postoperatively.

CONCLUSIONS

The Jenkins classification system provides a strategy for patients with Bertolotti syndrome who fail conservative therapy. Patients with Type 1 anatomy respond well to resection procedures. Patients with Type 2 and Type 4 anatomy respond well to fusion procedures. These patients respond well in regard to hip pain.

Redefining the Classification for Bertolotti Syndrome: Anatomical Findings in Lumbosacral Transitional Vertebrae Guide Treatment Selection

OBJECTIVE

We present the Jenkins classification for Bertolotti syndrome or symptomatic lumbosacral transitional vertebra (LSTV) and compare this with the existing Castellvi classification for patients presenting for treatment.

METHODS

We performed a retrospective cohort study of 150 new patients presenting for treatment of back, hip, groin, and/or leg pain from July 2012 through February 2022. Using magnetic resonance imaging, computed tomography, and radiography, the patients with a radiographic finding of LSTV, an appropriate clinical presentation, and identification of LSTV as the primary pain generator via diagnostic injections were diagnosed with Bertolotti syndrome. Patients for whom conservative treatment had failed and who underwent surgery to address their LSTV were included in the present study.

RESULTS

The Castellvi classification excludes 2 types of anatomic variants: the prominent anatomic side and the potential transverse process and iliac crest contact. Of 150 patients with transitional anatomy, 103 (69%) were identified with Bertolotti syndrome using the Jenkins classification and received surgery (46 men [45%] and 57 women [55%]). Of the 103 patients, 90 (87%) underwent minimally invasive surgery. The patients presented with pain localized to the back (n = 101; 98%), leg (n = 79; 77%), hip (n = 51; 49%), and buttock (n = 52; 50%). Only 84 of the Jenkins classification patients (82%) met any of the Castellvi criteria. All 19 patients for whom the Castellvi classification failed had had type 1 anatomy using the Jenkins system and underwent surgery (decompression, n = 16 [84%]; fusion, n = 1 [5%]; fusion plus decompression, n = 2 [11%]). Of these 19 patients, 17 (89%) had improved pain scores. The 19 patients exclusively diagnosed via the Jenkins classification had no significant differences in improved pain compared with those diagnosed using the Castellvi classification.

CONCLUSIONS

The Jenkins classification improves on the prior Castellvi classification to more comprehensively describe the functional anatomy, identify uncaptured anatomy, and better predict optimal surgical procedures to treat those with Bertolotti syndrome.

Prevalence of Lumbosacral Transition Vertebrae in Symptomatic Adults and the Levels of Degeneration in the Suprajacent Disc

Lumbosacral transition vertebra (LSTV) is a common occurrence and its prevalence ranges from 2.6% to 35.6%. Our aim is to study this phenomenon in the adult Singaporean population and assess the level of degeneration of the suprajacent disc in those with LSTV. Retrospectively, 545 patients (Age = 57.6 ± 18.3 years; Male = 277; Female = 268) who underwent radiographic evaluation of the lumbar spine for lower back pain or radicular symptoms were shortlisted. LSTV was found to be present in 106 patients (19.4%) with sacralization of L5 and lumbarization of S1 occurring in 96 patients (17.6%) and 10 patients (1.8%), respectively. The most common form of LSTV was Castellvi type IIA (46 patients; 43.4%). Based on Pfirrmann grading, Grade IV disc degeneration was most common in both the LSTV level (63%) and the unfused suprajacent level (77%) in those with LSTV. There was a significantly higher number of patients with grade IV and above degeneration in the suprajacent disc level among those with LSTV when compared to the last unfused (L5-S1) disc level in those without LSTV (84% vs. 65%; p = 0.0001). This suprajacent disc degeneration seen in patients with LSTV may contribute to low back pain and related problems in these patients.

If you look this way, you will see it: cranial shift in adolescent idiopathic scoliosis

INTRODUCTION

Anatomical variations in the spine can be seen in each transitional border, either toward the skull as 'cranial shifts' or away as caudal shifts. Cranial shifting (CS) occurs when there is presence of occipitalization, C7 cervical costae or prominent transverse processes, thoracolumbar transitional vertebrae (TLTV) at T12 level, L5 sacralization, and sacrococcygeal fusion. We termed the coexistence of sacralization of L5 and absence or remarkable reduction of T12 rib size in AIS as Abul cranial shift (ACS). In this descriptive clinical study, primary aim was to investigate the incidence of ACS in AIS.

METHODS

Retrospective analysis of 187 surgically treated AIS cases was performed. Demographic data were recorded. The incidence of the specific set of anatomic variations including lumbosacral transitional vertebrae, TLTV, transverse process changes in C7 vertebrae, and posterior lumbosacral neural arch cleft formations (NACf) were evaluated in the radiological images.

RESULTS

36 (19%) of 187 cases had ACS. ACS was detected in only 1 of 19 male cases (5%), while in 35 of 168 female cases (21%). Forty-one cases had sacralization of L5 (22%). There were only eleven pair of ribs in 14 (7%) of 187 cases and 10 (28%) of 36 ACS cases. Forty cases had NACf (21%). ACS and NACf coexistence were observed in 8 (22%) of 36 ACS cases.

CONCLUSION

Accurate spinal column assessment is critical in adolescent idiopathic scoliosis (AIS). ACS may be observed in up to one in five AIS cases and its presence should not be neglected to avoid wrong level surgery.

Prevalence of lumbosacral transitional vertebra among 4816 consecutive patients with low back pain: A computed tomography, magnetic resonance imaging, and plain radiographic study with novel classification schema

Study Design

A retrospective single-center study.

Background

The prevalence of the lumbosacral anomalies remains controversial. The existing classification to characterize these anomalies is more complex than necessary for clinical use.

Purpose

To assessment of the prevalence of lumbosacral transitional vertebra (LSTV) in patients with low back pain and the development of clinically relevant classification to describe these anomalies.

Materials and Methods

During the period from 2007 to 2017, all cases of LSTV were preoperatively verified, and classified according to Castellvi, as well as O'Driscoll. We then developed modifications of those classifications that are simpler, easier to remember, and clinically relevant. At the surgical level, this was assessed intervertebral disc and facet joint degeneration.

Results

The prevalence of the LSTV was 8.1% (389/4816). The most common L5 transverse process anomaly type was fused, unilaterally or bilaterally (48%), to the sacrum and were O'Driscoll's III (40.1%) and IV (35.8%). The most common type of S1-2 disc was a lumbarized disc (75.9%), where the disc's anterior-posterior diameter was equal to the L5-S1 disc diameter. In most cases, neurological compression symptoms (85.5%) were verified to be due to spinal stenosis (41.5%) or herniated disc (39.5%). In the majority of patients without neural compression, the clinical symptoms were due to mechanical back pain (58.8%).

Conclusions

LSTV is a fairly common pathology of the lumbosacral junction, occurring in 8.1% of the patients in our series (389 out of 4,816 cases). The most common types were Castellvi's type IIA (30.9%) and IIIA (34.9%) and were O'Driscoll's III (40.1%) and IV (35.8%).

The morphological consequences of segmentation anomalies in the human sacrum

OBJECTIVES

Despite the high frequency of segmentation anomalies in the human sacrum, their evolutionary and clinical implications remain controversial. Specifically, inconsistencies involving the classification and counting methods obscure accurate assessment of lumbosacral transitional vertebrae. Therefore, we aim to establish more reliable morphological and morphometric methods for differentiating between sacralizations and lumbarizations in clinical and paleontological contexts.

MATERIALS AND METHODS

Using clinical CT data from 145 individuals aged 14-47 years, vertebral counts and the spatial relationship between the sacrum and adjoining bony structures were assessed, while the morphological variation of the sacrum was assessed using geometric morphometrics based on varied landmark configurations.

RESULTS

The prevalence of lumbosacral and sacrococcygeal segmentation anomalies was 40%. Lumbarizations and sacralizations were reliably distinguishable based on the spatial relationship between the iliac crest and the upward or downward trajectory of the linea terminalis on the sacrum. Different craniocaudal orientations of the alae relative to the corpus of the first sacral vertebra were also reflected in the geometric morphometric analyses. The fusion of the coccyx (32%) was frequently coupled with lumbarizations, suggesting that the six-element sacra more often incorporate the coccyx rather than the fifth lumbar vertebra.

CONCLUSIONS

Our approach allowed the consistent identification of segmentation anomalies even in isolated sacra. Additionally, our outcomes either suggest that homeotic border shifts often affect multiple spinal regions in a unidirectional way, or that sacrum length is highly conserved perhaps due to functional constraints. Our results elucidate the potential clinical, biomechanical, and evolutionary significance of lumbosacral transitional vertebrae.

Quantitative measurements at the lumbosacral junction are more reliable parameters for identifying and numbering lumbosacral transitional vertebrae

OBJECTIVES

To evaluate quantitative parameters to identify the anatomic variation lumbosacral transitional vertebrae (LSTV) and compare them with the landmarks commonly used at present.

METHODS

A total of 2,845 PET/CT scans were reviewed, and the patients with 23 and 25 presacral vertebrae were included. The quantitative parameters, including the anterior-edge vertebral angle (AVA) of the lowest lumbar-type vertebra, the ratio of the length of the inferior endplate to that of the superior endplate (RISE) of the uppermost sacral-type vertebra and the lumbosacral intervertebral disc angle (LSIVDA), and the anatomical landmarks, including the iliac crest tangent (ICT) level, the iliolumbar ligament (ILL) origin level and psoas proximal insertion, were all evaluated to determine their ability to identify LSTV.

RESULTS

The values of AVA and RISE were significantly different between the LSTV group and the control group, and between subgroups of LSTV. The cutoff value for AVA was 73.0°, with an accuracy, sensitivity, and specificity of 91.1%, 77.5%, and 88.3%, and that for RISE was 0.79, with an accuracy, sensitivity, and specificity of 90.3%, 77.5%, and 94.2%, while that for LSIVDA was 14.15°, with an accuracy, sensitivity, and specificity of 75.9%, 65.7%, and 78.3%, to differentiate L5 sacralization from S1 lumbarization. For differentiating the controls from LSTV, the accuracy, sensitivity, and specificity of the ICT level and proximal psoas insertion were 78.0%, 70.2%, and 95.0%, versus 71.7%, 61.7%, and 94.0%.

CONCLUSIONS

Compared with the anatomical landmarks, the quantitative measurements at the lumbosacral junction, including AVA and RISE, may be more helpful for differentiating subgroups of LSTV especially if only lumbar spine imaging is available.

KEY POINTS

• The quantitative parameters, the anterior-edge vertebral angle (AVA) of the lowest lumbar-type vertebra and the ratio of the length of the inferior endplate to that of the superior endplate (RISE) of the uppermost sacral-type vertebra, are more helpful for distinguishing L5 sacralization from S1 lumbarization than the previously proposed anatomic landmarks. • AVA and RISE represent relevant changes in the curvature at the lumbosacral region and the shape of the transitional vertebral body, respectively. • AVA and RISE are easily assessed, with high intra- and inter-reader reliability.

[Analysis of unfavorable postoperative outcomes in patients with lumbosacral junction anomalies]

BACKGROUND

The absence of a unified diagnostic approach and heterogeneous treatment strategies in patients with lumbosacral transitional vertebra contribute to registration of contradictory data on postoperative outcomes in these patients.

OBJECTIVE

A retrospective analysis of postoperative outcomes in patients with degenerative lumbar spine diseases associated with lumbosacral junction anomalies and causes of unfavorable results.

MATERIAL AND METHODS

Lumbosacral transitional vertebra was preoperatively verified and classified according to Castellvi A.E. in 352 cases between 2007 and 2017. Full-time examination, phone and e-mail survey covered 314 (89.2%) patients throughout 5.2-year follow-up period. There were unfavorable clinical outcomes in 42 cases. We analyzed the causes of these results and relationship of surgical strategy with the type of lumbosacral junction anomaly.

RESULTS

Lumbosacral transitional vertebra Castellvi type IIA (30.9%) and IIIA (34.9%) prevailed. Unfavorable outcomes occurred in 7 cases after percutaneous interventions, in 12 patients after decompression surgery and in 23 patients after decompression and stabilization procedures. In all cases (n=42), redo surgery was performed: rigid fixation or extension of stabilization system in 16 cases, additional intracanal decompression in 10 patients, foraminal/extraforaminal decompression in 8 patients. Seven patients underwent repeated laser denervation. Of these, 5 patients underwent dorsal decompression without discectomy due to ineffective denervation. Correlation analysis showed the relationship between unfavorable outcomes after percutaneous procedures with L_V transverse process dysplasia and sacralization, decompressive interventions with additional articular joints and lumbarization, decompression/stabilization procedures with L_V transverse process dysplasia and sacralization.

CONCLUSION

Unfavorable outcomes occurred after percutaneous interventions for anomaly type IB and IIIB, decompressive procedures for anomaly type IIA, IIB and IV, decompression/ stabilization procedures for types IA and IIIA. It is the first report devoted to analysis of relationships between unsatisfactory postoperative outcomes, surgical technique and type of lumbosacral dysgenesis.

Clinical assessment and management of Bertolotti Syndrome: a review of the literature

Bertolotti Syndrome is a diagnosis given to patients experiencing pain caused by the presence of a lumbosacral transitional vertebra (LSTV), which is characterized by enlargement of the L5 transverse process(es), with potential pseudoarticulation or fusion with the sacrum. The Castellvi classification system is commonly utilized to grade LSTVs based on the degree of contact between the L5 transverse process(es) and the sacrum. LSTVs present a diagnostic dilemma to the treating clinician, as they may remain unidentified on plain x-rays and even advanced imaging; additionally, even if the malformation is identified, patients with a LSTV may be asymptomatic or have nonspecific symptoms, such as low back pain with or without radicular symptoms. With low back pain being extremely prevalent in the general population; it can be difficult to implicate the LSTV as the source of this pain. Care should be taken however, to exclude Bertolotti Syndrome in patients under 30 years old presenting with persisting low back pain given its congenital origin. If a LSTV is identified, typically with acquisition of a MRI or CT scan of the lumbosacral spine, and there is an absence of a more compelling or obvious source for the patient's symptoms, a conservative, step-wise management plan is recommended. This may include assessing for improvement in symptoms with injections prior to proceeding with surgical intervention. Additional concerns arise from the biomechanical alterations that a LSTV induces in adjacent spinal levels, predisposing this patient population to a more rapid-onset of adjacent segment disease, raising the question as to the most appropriate surgery (resection of LSTV pseudoarticulation with or without fusion). Postoperative outcome data for patients undergoing surgical treatment is limited in the literature with promising, but variable, results. More large-scale, controlled studies must be performed to gain further insight into the ideal work-up and management of this pathology.

The prevalence and clinical significance of transitional vertebrae: a radiologic investigation using whole spine spiral three-dimensional computed tomographic images

Background

Errors in counting spinal segments are common during interventional procedures when there are transitional vertebrae. In this study, we investigated the prevalence of the transitional vertebrae including thoracolumbar transitional vertebra (TLTV) and lumbosacral transitional vertebrae (LSTV). The relationship between the existence of TLTV and abnormal rib count or the existence of LSTV were also evaluated.

Methods

The vertebral levels were counted craniocaudally, starting from C1, based on the assumption of 7 cervical, 12 thoracic, and 5 lumbar vertebrae, using whole spine spiral three-dimensional computed tomographic images. The 20th and 25th vertebrae were defined as L1 and S1, respectively.

Results

In total, 150 patients had TLTV, with a prevalence of 11.2% (150/1,340). LSTV was observed in 111 of 1,340 cases (8.3%). Sacralization was observed in 68 of 1,340 cases (5.1%) and lumbarization in 43 of 1,340 cases (3.2%). There was a significant relationship between the existence of TLTV and the abnormal rib count (odds ratio [OR]: 117.26, 95% confidence interval [95% CI]: 60.77-226.27; P < 0.001) and LSTV (OR: 7.38, 95% CI: 3.99-13.63; P < 0.001).

Conclusions

Our study results suggest that patients with TLTV are more likely to have an abnormal rib count or LSTV. If a TLTV or LSTV is seen on the fluoroscopic image, a whole spine image is necessary to permit accurate numbering of the lumbar vertebra.

Role of iliac crest tangent in correct numbering of lumbosacral transitional vertebrae

Background/aim

The iliac crest tangent (ICT) has recently emerged as a reliable landmark to correctly number the lumbosacral transitional vertebrae (LSTV). We retrospectively evaluated the reproducibility and accuracy of the ICT as a landmark in subjects without disc degeneration.

Materials and methods

Fifty-eight patients with LSTV [19 female, 41 (26–52) years] and 55 controls without LSTV [23 female, 40 (26–55) years] who had undergone spinal computed tomography were included. The ICT was drawn on the coronal images, with the cursor in the sagittal view set to the posterior ⅓ of the vertebral body located one level above the LSTV. When more than 1.25 vertebral body was counted below the ICT, the LSTV was considered as S1, otherwise it was considered as L5. The gold standard was counting the vertebrae craniocaudally.

Results

The interobserver agreement was good for determining ICT level (Cohen’s kappa = 0.78, P < 0.001). The rate of correct numbering by ICT in the LSTV group was significantly less than in the controls (43.1% vs. 96.4%, respectively, P < 0.001). Patients with sacralization had a significantly lower correct numbering rate than patients with lumbarization (33.3% vs. 63.2%, respectively, P = 0.03).

Conclusion

ICT does not seem to be a reliable landmark for correct numbering of LSTV in patients with no intervertebral disc degeneration.

Spinal Enumeration by Morphologic Analysis of Spinal Variants: Comparison to Counting in a Cranial-To-Caudal Manner

Objective

To compare the spinal enumeration methods that establish the first lumbar vertebra in patients with spinal variants.

Materials and Methods

Of the 1446 consecutive patients who had undergone computed tomography of the spine from March 2012 to July 2016, 100 patients (62 men, 38 women; mean age, 47.9 years; age range, 19-88 years) with spinal variants were included. Two radiologists (readers 1 and 2) established the first lumbar vertebra through morphologic analysis of the thoracolumbar junction, and labeled the vertebra by counting in a cranial-to-caudal manner. Inter-observer agreement was established. Additionally, reader 1 detected the 20th vertebra under the assumption that there are 12 thoracic vertebra, and then classified it as a thoracic vertebra, lumbar vertebra, or thoracolumbar transitional vertebra (TLTV), on the basis of morphologic analysis.

Results

The first lumbar vertebra, as established by morphologic analysis, was labeled by each reader as the 21st segment in 65.0% of the patients, as the 20th segment in 31.0%, and as the 19th segment in 4.0%. Inter-observer agreement between the two readers in determining the first lumbar vertebra, based on morphologic analysis, was nearly perfect (κ value: 1.00). The 20th vertebra was morphologically classified as a TLTV in 60.0% of the patients, as the first lumbar segment in 31.0%, as the second lumbar segment in 4.0%, and as a thoracic segment in 5.0%.

Conclusion

The establishment of the first lumbar vertebra using morphologic characteristics of the thoracolumbar junction in patients with spinal variants was consistent with the morphologic traits of vertebral segmentation.

Lumbosacral transitional vertebrae: significance of local bone marrow edema at the transverse processes

OBJECTIVE

To evaluate the association between low back pain and bone marrow edema in lumbosacral transitional vertebra (LSTV) transverse processes, and to assess the prevalence of LSTV in a physically active population.

MATERIALS AND METHODS

Individuals with LSTV on coronal MRI studies were identified in a retrospective review by keyword search from PACS. In total, 140 cases were reviewed by two fellowship-trained musculoskeletal radiologists. Data on associated low back pain were collected from patient records at the time of the imaging.

RESULTS

Bone marrow edema was observed in 44% of the cases, but no correlation with low back pain was found. On coronal MRI, the prevalence of LSTV was 2.6%, with type II LSTV being the most common subtype.

CONCLUSIONS

No correlation with bone marrow edema at the transverse processes of the LSTV and low back pain was observed. In our selected study population, the prevalence of LSTV was low.

Lumbosacral Transitional Vertebrae Cause Spinal Level Misconception in Surgeries for Degenerative Lumbar Spine Disorders

Human lumbar spine usually consists of five vertebrae; however, some individuals have vertebral anomalies with four or six lumbar vertebrae because of sacralized fifth lumbar vertebra (L5 sacralization) or lumbarized first sacral vertebra (S1 lumbarization), respectively. These vertebral anomalies are called lumbosacral transitional vertebra (LSTV). Although LSTV is an asymptomatic anomaly, it is known to cause misconception in spinal counts and in spinal level at lumbar spinal surgery. The purpose of this study is to evaluate how LSTV affects the diagnosis and surgeries in lumbar spine disorders. In 550 consecutive patients who underwent lumbar spinal surgeries, a whole-spine X-ray was taken on admission to assess the true number of lumbar vertebrae. We assessed the coherence between the neurological level diagnosis and the level of spinal canal stenosis on imaging studies before and after the recognition of LSTV to clarify how recognition of LSTV affected pre-operative surgical planning. Out of 550 patients, LSTV was found in 71 (12.9%) patients: 37 cases with L5 sacralization and 34 cases with S1 lumbarization. The number of vertebrae was miscounted at the outpatient department (OPD) in 38 cases (54%): 10 L5-sacralization cases and 28 S1-lumbarization cases. Moreover, surgical spinal levels were altered from the original surgical plans at OPD in 11 cases (15%; 3 L5-sacralization and 8 S1-lumbarization cases), after recognizing the true spinal counts by the whole spine X-ray. To avoid errors in spinal level diagnosis, we should recognize the possibility of LSTV that could be assessed by a whole spine X-ray.

Determination of lumbosacral transitional vertebrae in kidney urinary bladder x-ray films in the Saudi population

OBJECTIVES

To investigated the rate of occurrence of lumbosacral transitional vertebrae (LSTV), spinal variant, in kidney urinary bladder (KUB) plain radiographs in a Saudi population.  Methods: Between January 2012 to January 2015, KUB plain films obtained from patients at King Abdulaziz University Hospital, Jeddah, Saudi Arabia, were reviewed, and the presence or absence of LSTV was documented and classified as incomplete or complete. Patients who had evidence of spinal surgery that would obscure the view were excluded.  Results: A total of 2078 patients underwent KUB examinations during the study period; LSTV anomalies were detected in 158 of these. Sacralization was present in 153 (96.8%) of this cohort, while lumbarization was present in 5 (3.2%). A total of 136 (86.1%) of the sacralized segments were of the incomplete type, whereas 17 (10.7%) were complete. Of the lumbarized vertebrae, 3 (1.8%) were incomplete, and 2 (1.2%) were complete. The most frequent type in men was type Ib (28.5%) for sacralized segments, and type IIb for lumbarized segments (0.6%). In women, type Ia was the most common form of sacralized segments (11.3%) and type IIb was the most common form of lumbarized segments (2.8%). Conclusion: The prevalence of LSTV in Saudi patients is 7.6%, with a higher incidence of sacralization than lumbarization. Further studies with larger sample sizes and longer follow-up time are needed to demonstrate the clinical significance thereof.

Lumbosacral Transitional Segments: An Interventional Spine Specialist's Practical Approach

The presence of a lumbosacral transitional vertebrae (LSTV) should prompt a more detailed preprocedural evaluation of the vertebral column to accurately determine spinal levels. An LSTV should prompt the use of corroborating intraprocedural imaging to verify morphology. The most important factors in treating lumbosacral transitional segments are communication among treating physicians to ensure segmental enumeration consistency and associated appropriate patient treatment.

Localizing the L5 Vertebra Using Nerve Morphology on MRI: An Accurate and Reliable Technique

BACKGROUND AND PURPOSE

Multiple methods have been used to determine the lumbar vertebral level on MR imaging, particularly when full spine imaging is unavailable. Because postmortem studies show 95% accuracy of numbering the lumbar vertebral bodies by counting the lumbar nerve roots, attention to lumbar nerve morphology on axial MR imaging can provide numbering clues. We sought to determine whether the L5 vertebra could be accurately localized by using nerve morphology on MR imaging.

MATERIALS AND METHODS

One hundred eight cases with full spine MR imaging were numbered from the C2 vertebral body to the sacrum with note of thoracolumbar and lumbosacral transitional states. The origin level of the L5 nerve and iliolumbar ligament were documented in all cases. The reference standard of numbering by full spine imaging was compared with the nerve morphology numbering method. Five blinded raters evaluated all lumbar MRIs with nerve morphology technique twice. Prevalence and bias-adjusted κ were used to measure interrater and intrarater reliability.

RESULTS

The L5 nerve arose from the 24th presacral vertebra (L5) in 106/108 cases. The percentage of perfect agreement with the reference standard was 98.1% (95% CI, 93.5%-99.8%), which was preserved in transitional and numeric variation states. The iliolumbar ligament localization method showed 83.3% (95% CI, 74.9%-89.8%) perfect agreement with the reference standard. Inter- and intrarater reliability when using the nerve morphology method was strong.

CONCLUSIONS

The exiting L5 nerve can allow accurate localization of the corresponding vertebrae, which is essential for preprocedure planning in cases where full spine imaging is not available. This neuroanatomic method displays higher agreement with the reference standard compared with previously described methods, with strong inter- and intrarater reliability.

Role of Anatomical Landmarks in Identifying Normal and Transitional Vertebra in Lumbar Spine Magnetic Resonance Imaging

Study Design

Retrospective study.

Purpose

Identification of transitional vertebra is important in spine imaging, especially in presurgical planning. Pasted images of the whole spine obtained using high-field magnetic resonance imaging (MRI) are helpful in counting vertebrae and identifying transitional vertebrae. Counting vertebrae and identifying transitional vertebrae is challenging in isolated studies of lumbar spine and in studies conducted in low-field MRI. An incorrect evaluation may lead to wrong-level treatment. Here, we identify the location of different anatomical structures that can help in counting and identifying vertebrae.

Overview of Literature

Many studies have assessed the vertebral segments using various anatomical structures such as costal facets (CF), aortic bifurcation (AB), inferior vena cava confluence (IC), right renal artery (RRA), celiac trunk (CT), superior mesenteric artery root (SR), iliolumbar ligament (ILL) psoas muscle (PM) origin, and conus medullaris. However, none have yielded any consistent results.

Methods

We studied the locations of the anatomical structures CF, AB, IC, RRA, CT, SR, ILL, and PM in patients who underwent whole spine MRI at our department.

Results

In our study, 81.4% patients had normal spinal segmentation, 14.7% had sacralization, and 3.8% had lumbarization. Vascular landmarks had variable origin. There were caudal and cranial shifts with respect to lumbarization and sacralization. In 93.8% of cases in the normal group, ILL emerged from either L5 alone or the adjacent disc. In the sacralization group, ILL was commonly seen in L5. In the lumbarization group, ILL emerged from L5 and the adjacent disc (66.6%). CFs were identified at D12 in 96.9% and 91.7% of patients in the normal and lumbarization groups, respectively. The PM origin was observed from D12 or D12–L1 in most patients in the normal and sacralization groups.

Conclusions

CF, PM, and ILL were good identification markers for D12 and L5, but none were 100% accurate.

Incidence of numerical variants and transitional lumbosacral vertebrae on whole-spine MRI

Objectives

This study sets out to prospectively investigate the incidence of transitional vertebrae and numerical variants of the spine.

Materials and methods

Over a period of 28 months, MRIs of the whole spine were prospectively evaluated for the presence of transitional lumbosacral vertebrae and numerical variants of the spine.

Results

MRI of the whole spine was evaluated in 420 patients, comprising 211 female and 209 male subjects. Two patients had more complex anomalies. Lumbosacral transitional vertebrae were seen in 12 patients: eight sacralised L5 (3 male, 5 female) and four lumbarised S1 (3 male, 1 female). The incidence of transitional vertebrae was approximately 3.3. % (14/418). Thirty-two (7.7 %) of 418 patients had numerical variants of mobile vertebrae of the spine without transitional vertebrae. The number of mobile vertebrae was increased by one in 18 patients (12 male, 6 female), and the number was decreased by one in 14 patients (4 male, 10 female).

Conclusions

Numerical variants of the spine are common, and were found to be almost 2.5 times as frequent as transitional lumbosacral vertebrae in the study population. Only whole-spine imaging can identify numerical variants and the anatomical nature of transitional vertebrae. The tendency is toward an increased number of mobile vertebrae in men and a decreased number in women.

Main messages

• Numerical variants of the spine are more common than transitional vertebrae.

• Spinal numerical variants can be reliably identified only with whole-spine imaging.

• Increased numbers of vertebrae are more common in men than women.

• Transitional lumbosacral vertebrae occurred in about 3.3 % of the study population.

• The incidence of numerical variants of the spine was about 7.7 %.

Utility of Interobserver Agreement Statistics in Establishing Radiology Resident Learning Curves During Self-directed Radiologic Anatomy Training

RATIONALE AND OBJECTIVES

The aim of the study was to ascertain the learning curves for the radiology residents when first introduced to an anatomic structure in magnetic resonance images (MRI) to which they have not been previously exposed to.

MATERIALS AND METHODS

The iliolumbar ligament is a good marker for testing learning curves of radiology residents because the ligament is not part of a routine lumbar MRI reporting and has high variability in detection. Four radiologists, three residents without previous training and one mentor, studied standard axial T1- and T2-weighted images of routine lumbar MRI examinations. Radiologists had to define iliolumbar ligament while blinded to each other's findings. Interobserver agreement analyses, namely Cohen and Fleiss κ statistics, were performed for groups of 20 cases to evaluate the self-learning curve of radiology residents.

RESULTS

Mean κ values of resident-mentor pairs were 0.431, 0.608, 0.604, 0.826, and 0.963 in the analysis of successive groups (P < .001). The results indicate that the concordance between the experienced and inexperienced radiologists started as weak (κ <0.5) and gradually became very acceptable (κ >0.8). Therefore, a junior radiology resident can obtain enough experience in identifying a rather ambiguous anatomic structure in routine MRI after a brief instruction of a few minutes by a mentor and studying approximately 80 cases by oneself.

CONCLUSIONS

Implementing this methodology will help radiology educators obtain more concrete ideas on the optimal time and effort required for supported self-directed visual learning processes in resident education.

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

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.

A comprehensive review of the sub-axial ligaments of the vertebral column: part II histology and embryology

BACKGROUND

As important as the vertebral ligaments are in maintaining the integrity of the spinal column and protecting the contents of the spinal canal, a single detailed review of their histology and embryology is missing in the literature.

METHODS

A literature search using online search engines was conducted.

RESULTS

Single comprehensive reviews of the histology and embryology of the spinal ligaments are not found in the extant medical literature.

CONCLUSIONS

This review will be useful to those who study or treat patients with pathology of the spine.

Lumbosacral transitional vertebrae and its prevalence in the Australian population

Study Design Retrospective cohort study. Objective Lumbosacral transitional vertebrae (LSTV) are a common congenital anomaly, and they can be accurately identified on anteroposterior (AP) radiographs of the lumbosacral spine. This study attempts to determine the prevalence of this congenital anomaly and to increase awareness among all clinicians to reduce the risk of surgical and procedural errors in patients with LSTV. Methods A retrospective review of 5,941 AP and lateral lumbar radiographs was performed. Transitional vertebrae were identified and categorized under the Castellvi classification. Results The prevalence of LSTV in the study population was 9.9%. Lumbarized S1 and sacralized L5 were seen in 5.8 and 4.1% of patients, respectively. Conclusion LSTV are a common normal variant and can be a factor in spinal surgery at incorrect levels. It is essential that all clinicians are aware of this common congenital anomaly.

Merits of different anatomical landmarks for correct numbering of the lumbar vertebrae in lumbosacral transitional anomalies

PURPOSE

Anatomical landmarks and their relation to the lumbar vertebrae are well described in subjects with normal spine anatomy, but not for subjects with lumbosacral transitional vertebra (LSTV), in whom correct numbering of the vertebrae is challenging and can lead to wrong-level treatment. The aim of this study was to quantify the value of different anatomical landmarks for correct identification of the lumbar vertebra level in subjects with LSTV.

METHODS

After IRB approval, 71 subjects (57 ± 17 years) with and 62 without LSTV (57 ± 17 years), all with imaging studies that allowed correct numbering of the lumbar vertebrae by counting down from C2 (n = 118) or T1 (n = 15) were included. Commonly used anatomical landmarks (ribs, aortic bifurcation (AB), right renal artery (RRA) and iliac crest height) were documented to determine the ability to correctly number the lumbar vertebrae. Further, a tangent to the top of the iliac crests was drawn on coronal MRI images by two blinded, independent readers and named the 'iliac crest tangent sign'. The sensitivity, specificity and the interreader agreement were calculated.

RESULTS

While the level of the AB and the RRA were found to be unreliable in correct numbering of the lumbar vertebrae in LSTV subjects, the iliac crest tangent sign had a sensitivity and specificity of 81 % and 64-88 %, respectively, with an interreader agreement of k = 0.75.

CONCLUSION

While anatomical landmarks are not always reliable, the 'iliac crest tangent sign' can be used without advanced knowledge in MRI to most accurately number the vertebrae in subjects with LSTV, if only a lumbar spine MRI is available.

Is the iliolumbar ligament a reliable identifier of the L5 vertebra in lumbosacral transitional anomalies?

OBJECTIVE

Sufficiently sized studies to determine the value of the iliolumbar ligament (ILL) as an identifier of the L5 vertebra in cases of a lumbosacral transitional vertebra (LSTV) are lacking.

METHODS

Seventy-one of 770 patients with LSTV (case group) and 62 of 611 subjects without LSTV with confirmed L5 level were included. Two independent radiologists using coronal MR images documented the level(s) of origin of the ILL. The interobserver agreement was analysed using weighted kappa/kappa (wκ/κ) and a Fischer's exact test to assess the value of the ILL as an identifier of the L5 vertebra.

RESULTS

The ILL identified the L5 vertebra by originating solely from L5 in 95 % of the controls; additional origins were observed in 5 %. In the case group, the ILL was able to identify the L5 vertebra by originating solely from L5 in 25-38 %. Partial origin from L5, including origins from other vertebra was observed in 39-59 % and no origin from L5 at all in 15-23 % (wκ = 0.69). Both readers agreed that an ILL was always present and its origin always involved the last lumbar vertebra.

CONCLUSION

The level of the origin of the ILL is unreliable for identification of the L5 vertebra in the setting of an LSTV or segmentation anomalies.

KEY POINTS

• The origin of the ILL is evaluated in subjects with an LSTV. • The origin of the ILL is anatomically highly variable in LSTV. • The ILL is not a reliable landmark of the L5 vertebra in LSTV.

Is any landmark reliable in vertebral enumeration? A study of 3.0-Tesla lumbar MRI comparing skeletal, neural, and vascular markers

PURPOSE

This study aimed to determine the reliability of the iliolumbar ligament (ILL), 12th costa, aortic bifurcation (AB), right renal artery (RRA), and conus medullaris (CM) for numbering of vertebral segments.

SUBJECTS AND METHODS

Five hundred five patients underwent routine lumbar MRI examinations including a cervicothoracic sagittal scout and T1 and T2-weighted sagittal and axial turbo spin echo images. Images were evaluated by two radiologists separately.

RESULTS

The identifiability of ILL and 12th costa were 85.7% and 48.1%. AB, RRA, and CM were located more caudally in lumbarized S1 and more cranially in sacralized L5 cases.

CONCLUSION

Landmarks suggested by previous studies are not reliable alternatives to cervicothoracic scout images due to wide ranges of distribution and inconsistencies in identification.

Are spinal or paraspinal anatomic markers helpful for vertebral numbering and diagnosing lumbosacral transitional vertebrae?

Objective

To evaluate the value of spinal and paraspinal anatomic markers in both the diagnosis of lumbosacral transitional vertebrae (LSTVs) and identification of vertebral levels on lumbar MRI.

Materials and Methods

Lumbar MRI from 1049 adult patients were studied. By comparing with the whole-spine localizer, the diagnostic errors in numbering vertebral segments on lumbar MRI were evaluated. The morphology of S1-2 disc, L5 and S1 body, and lumbar spinous processes (SPs) were evaluated by using sagittal MRI. The positions of right renal artery (RRA), superior mesenteric artery, aortic bifurcation (AB) and conus medullaris (CM) were described.

Results

The diagnostic error for evaluation of vertebral segmentation on lumbar MRI alone was 14.1%. In lumbarization, all patients revealed a well-formed S1-2 disc with squared S1 body. A rhombus-shaped L5 body in sacralization and a rectangular-shaped S1 body in lumbarization were found. The L3 had the longest SP. The most common sites of spinal and paraspinal structures were: RRA at L1 body (53.6%) and L1-2 disc (34.1%), superior mesenteric artery at L1 body (55.1%) and T12-L1 disc (31.6%), and AB at L4 body (71.1%). CM had variable locations, changing from the T12-L1 disc to L2 body. They were located at higher sacralization and lower lumbarization.

Conclusion

The spinal morphologic features and locations of the spinal and paraspinal structures on lumbar MRI are not completely reliable for the diagnosis of LSTVs and identification on the vertebral levels.

The prevalence of morphological changes in the thoracolumbar spine on whole-spine computed tomographic images

OBJECTIVES

This article reviews the prevalence of lumbarisation, sacralisation and lumbar ribs, and their morphological relevance by evaluating multi-slice computed tomography (MSCT) images. These segment variations can cause miscounting of vertebrae at the lumbar spinal level.

METHODS

A retrospective radiographic analysis of 226 cases scanned by MSCT prior to forensic autopsy was undertaken. MSCT scans of the entire spine were obtained. Radiological data were evaluated on a three-dimensional image workstation. Vertebral levels were determined by counting downward from the first cervical vertebra, based on the assumption of seven cervical, 12 thoracic and five lumbar vertebrae. The prevalence of lumbarisation, sacralisation and lumbar ribs was assessed.

RESULTS

Lumbar ribs were observed in 13 of the 226 cases (5.8 %). Lumbarisation and sacralisation were observed in 14 cases (6.2 %) and six cases (2.7 %), respectively. Lumbar ribs were present in 11 of the 14 cases with lumbarisation, and in two of the 206 cases with normal lumbar vertebral configuration. Lumbarisation had a statistically significant association with lumbar ribs (p < 0.01).

CONCLUSIONS

There was a strong association between lumbar ribs and lumbarisation, with a resulting miscount rate for the lumbar spine of slightly less than 10 %.

TEACHING POINTS

• Lumbarisation and sacralisation are observed 6.2 % and 2.7 %, respectively. • Thoracolumbar segment variations can cause a miscount rate for the lumbar spine of less than 10 %. • Lumbar rib is significantly associated to lumbarisation.

Ten percent of patients with adolescent idiopathic scoliosis have variations in the number of thoracic or lumbar vertebrae

BACKGROUND

Surveys have demonstrated that wrong-site surgery of the spine is performed by up to 50% of spine surgeons over the course of a career. Inaccurate identification of appropriate vertebral levels is a common reason for wrong-site spine surgery. The present study examined the prevalence of variations in the number of vertebrae in patients with adolescent idiopathic scoliosis.

METHODS

A retrospective review of radiographs and reports of 364 consecutive patients undergoing operative treatment for adolescent idiopathic scoliosis at a single center was performed. The study included eighty-eight male patients (24%) and 276 female patients (76%) with a mean age of fourteen years (range, ten to twenty years). Radiographs were reviewed to assess the number of thoracic and lumbar vertebrae and the presence of a lumbosacral transitional vertebra.

RESULTS

Ten percent of the patients (thirty-eight) had an atypical number of vertebrae in the thoracic and/or lumbar spine. Twenty-one patients (5.8%) had an atypical number of thoracic vertebrae, with fourteen having eleven thoracic vertebrae and seven patients having thirteen. Twenty-four patients (6.6%) had an atypical number of lumbar vertebrae, with four having four lumbar vertebrae and twenty patients having six. A lumbosacral transitional vertebra was present in 6.3% (twenty-three) of the patients. Multilevel vertebral anomalies were present in 1.9% of the patients (seven of 364). A variation in the number of vertebrae had been identified in 0.5% (two) of the reports by the radiologist.

CONCLUSIONS

Variations in the number of thoracic or lumbar vertebrae were found in 10% of patients with adolescent idiopathic scoliosis but had been identified in only 0.5% of the radiology reports.

Numbering of vertebrae on MRI using a PACS cross-referencing tool

BACKGROUND

For the detection and documentation of numeric variations on spine magnetic resonance imaging (MRI), different techniques have previously been introduced. However, these methods require additional special imaging algorithms, software, or devices. We intend to introduce a vertebral numbering method using the existing picture archiving and communication system (PACS) and MRI system.

PURPOSE

To assess the accuracy of a method for numbering presacral vertebrae based on the cross-referencing of two sagittal MRI series.

MATERIAL AND METHODS

This study was a retrospective review of 224 consecutive patients who underwent both lumbar MRI with cervicothoracic scan and whole spine radiographic examinations. A radiologist and a neurosurgeon independently counted the number of presacral vertebrae in a cranial-to-caudal approach with cross-referencing of cervicothoracic and lumbar MRI sagittal series on the PACS workstation. Radiographic numbering from the cervical through the thoracic to the lumbar vertebrae, as a reference standard, was completed independently by the two reviewers. An analysis of the inter-observer and intermodality agreements of radiography and MRI was done.

RESULTS

In all cases except one, concordant numbering existed between the two modalities of MRI cross-referencing and radiographs combination. Both observers agreed completely, with no inter-observer discordance.

CONCLUSION

The number of vertebrae could be identified consistently by counting caudally from C2 with cross-referencing cervicothoracic and lumbosacral sagittal MRI scans on the PACS workstation.

Direct lateral interbody fusion (DLIF) at the lumbosacral junction L5-S1

The direct lateral interbody fusion (DLIF), a minimally invasive lateral approach for placement of an interbody fusion device, does not require nerve root retraction or any contact with the great vessels and can lead to short operative times with little blood loss. Due to anatomical restrictions, this procedure has not been used at the lumbosacral (L5-S1) junction. Lumbosacral transitional vertebrae (LSTV), a structural anomaly of the lumbosacral spine associated with low back pain, can result in a level being wrongly identified pre-operatively due to misnumbering of the vertebral levels. To our knowledge, use of the DLIF graft in this patient is the first report of an interbody fusion graft being placed at the disc space between the LSTV and S1 via the transpsoas route. We present a review of the literature regarding the LSTV variation as well as the lateral placement of interbody fusion grafts at the lumbosacral junction.

Prediction of transitional lumbosacral anatomy on magnetic resonance imaging of the lumbar spine

AIM: To evaluate two simple angle measurements for predicting lumbosacral transitional vertebra (LSTV) in magnetic resonance imaging (MRI) studies of the spine.

METHODS: The lumbar spine MRI studies of 50 subjects with LSTV and 50 subjects with normal lumbosacral anatomy were retrospectively evaluated. In each study, the mid-sagittal T2-weighted image was used to measure the angle formed by a line parallel to the superior surface of the sacrum and a line perpendicular to the axis of the scan table (A-angle), as well as the angle formed by a line parallel to the superior endplate of the L3 vertebra and a line parallel to the superior surface of the sacrum (B-angle).

RESULTS: The total study population consisted of 100 subjects (46 males, 54 females, 51 ± 16 years old). There were no differences in age and sex between the two groups. Both A-angle and B-angle were significantly increased in subjects with LSTV compared to controls (P < 0.05). The optimal cut-off values of A-angle and B-angle for the prediction of LSTV were 39.8° (sensitivity = 80%, specificity = 80%, accuracy = 83%; 95% confidence interval = 74%-89%, P = 0.0001) and 35.9° (sensitivity = 80%, specificity = 54%, accuracy = 69%; 95% confidence interval = 59%-78%, P = 0.0005), respectively.

CONCLUSION: On sagittal MR images of the lumbar spine, an increased A-angle and/or B-angle should alert the radiologist to the presence of LSTV.

Disc spaces, vertebral dimensions, and angle values at the lumbar region: a radioanatomical perspective in spines with L5–S1 transitions

Object

Low-back pain (LBP) has been associated with lumbar spines of normal morphology as well as those with L5–S1 “transitional” vertebrae. It is hard to find literature that quantifies the overall morphological changes in lumbar spines as related to transitional states. The object of this study was to investigate lumbar spine changes resulting from the presence of these transitional states.

Methods

The author quantified dimensions and angles and statistically compared the morphology of lumbar spines with or without L5–S1 transitions in the context of LBP. Anteroposterior and lateral radiographs were obtained from 50 patients suffering from LBP without transitional anomalies at the L5–S1 junction. These radiographs were compared with anteroposterior and lateral radiographs from patients suffering from LBP with L5–S1 transitional states involving accessory L5–S1 articulations, and with anteroposterior and lateral radiographs from patients with L5–S1 unilateral or bilateral fusions. Twelve linear dimensions from the anteroposterior views and 8 angles from the lateral radiographs were measured.

Results

The mean values of linear dimensions differed in 1) disc heights, 2) vertebral heights and widths, 3) pedicles and interpedicular distances, 4) angle values, and 5) overall configuration of the lumbar curvatures.

Conclusions

The L5–S1 accessory articulations led to increased lordotic curves, L-5 vertebral heights, and pedicle and angular dimensions. The L5–S1 fusions were related to smaller disc heights at all spaces, short and wide L-5 pedicles, taller and less wide transverse processes, and overall straighter spines with the least measures for all lumbar angles. Dimensional differences provided in this study may help in placing instrumentation at the lumbar vertebrae and working on intervertebral disc replacements in spines with specific L5–S1 transitional anomalies.

The prevalence of transitional vertebrae in the lumbar spine

BACKGROUND CONTEXT

Lumbosacral transitional vertebrae (LSTVs) are a congenital vertebral anomaly of the L5-S1 junction in the spine. This alteration may contribute to incorrect identification of a vertebral segment, leading to wrong-level spine surgery and poor correlation with clinical symptoms. Although several studies describe the occurrence of this anomaly in back pain populations, investigation of the prevalence in the American general population is lacking.

PURPOSE

To establish the prevalence rates for LSTVs in the general population.

STUDY DESIGN

Retrospective review.

PATIENT SAMPLE

Consecutive kidney-urinary bladder (KUB) radiographs of subjects from the past 2 years (2008-2009).

OUTCOME MEASURES

Clinical demographics, number of lumbar vertebrae, L5-S1 transverse process (TP) height, and rib length.

METHODS

Consecutive adult KUB studies of adult subjects were queried with clear visibility of the last rib's vertebral body articulation, all lumbar TPs, and complete sacral wings. Exclusion criteria consisted of any radiologic evidence of previous lumbosacral surgery that would obstruct our measurements. A total of 1,100 abdominal films were reviewed, and 211 were identified as being adequate for the measurement of the desired parameters.

RESULTS

Two hundred eleven subjects were identified as eligible for the study, and 75 (35.6%) were classified as positive for a transitional lumbosacral vertebra. The most common anatomical variant was the Castellvi Type IA (14.7%). The average age at the time of the KUB study was 59.8 years (18-95 years). One hundred ninety-seven subjects (93.4%) presented five lumbar (nonribbed) vertebrae, and only 14 (6.6%) had six lumbar vertebrae.

CONCLUSIONS

The significance of lumbosacral transitional level changes to the establishment of pain, degenerative changes, stenosis, and disc disease have been well documented in symptomatic patients. Although LSTV's role in low back pain remains controversial, our study has shown that, when the same criteria are used for classification, prevalence among the general population and symptomatic patients may be similar.

MR imaging features of common variant spinal anatomy

The spine is one of the most commonly imaged body parts for all age groups, with indications ranging from congenital abnormalities at birth to degenerative pathology toward the end of life. Because of the importance of softtissue contrast when imaging the spine, MR imaging has become the most important modality in its evaluation. One of the key challenges in the clinical analysis of spinal MR imaging lies in the wide range of so-called normal variability. The goal of this article is not to provide the reader with an exhaustive atlas detailing the appearance of every known variant. Instead, the authors review the MR appearance of the most important variants and provide a logical and, they hope, memorable framework for assimilating this information into practice. To understand why these variations occur, the authors examine the aberrant pathways of embryology, growth, and development that lead to their formation.

Lumbosacral transitional vertebrae: classification, imaging findings, and clinical relevance

SUMMARY

LSTVs are common within the spine, and their association with low back pain has been debated in the literature for nearly a century. LSTVs include sacralization of the lowest lumbar vertebral body and lumbarization of the uppermost sacral segment. These vertebral bodies demonstrate varying morphology, ranging from broadened transverse processes to complete fusion. Low back pain associated with an LSTV may arise from the level above the transition, the contralateral facet when unilateral, and/or the anomalous articulation when present. Although this association is still somewhat controversial, beyond dispute is the importance of identifying an LSTV in patients in whom a surgical or interventional procedure is planned. This is essential to avoid an intervention or surgery at an incorrect level. In this article, each of these issues will be addressed with attention to identifying and correctly numbering LSTVs as well as detecting imaging findings related to the genesis of low back pain.

Transitional lumbosacral vertebrae and low back pain: diagnostic pitfalls and management of Bertolotti's syndrome

OBJECTIVE

Bertolotti's syndrome is a spine disorder characterized by the occurrence of a congenital lumbar transverse mega-apophysis in a transitional vertebral body that usually articulates with the sacrum or the iliac bone. It has been considered a possible cause of low back pain.

METHOD

We analyzed the cases of Bertolotti's syndrome that failed clinical treatment and reviewed the literature concerning this subject.

RESULTS

Five patients in our series had severe low back pain due to the neo-articulation and two of them were successfully submitted to surgical resection of the transverse mega-apophysis. Taking into account the clinical and surgical experience acquired with these cases, we propose a diagnostic-therapeutic algorithm.

CONCLUSION

There is still no consensus about the most appropriate therapy for Bertolotti's syndrome. In patients in whom the mega-apophysis itself may be the source of back pain, surgical resection may be a safe and effective procedure.

Dermatomyotomal supply in patients with variations in the number of lumbar vertebrae

OBJECT

Variation in the number of lumbar vertebrae occurs in a small portion of the population. Either the fifth lumbar vertebra shows assimilation to the sacrum or the first sacral vertebra shows a lumbar configuration, resulting in 4 or 6 lumbar vertebrae, respectively. Etiologically, lumbar nerve root syndrome is diagnosed by comparing the anatomical level of the disc herniation to the compressed nerve root and to the pattern of the peripheral sensory and motor deficit. In case of a variation in the number of lumbar vertebrae, defining the lumbar nerve roots becomes difficult. Variations in the number of lumbar vertebrae make the landmarks (the twelfth rib and the first sacral vertebra) unreliable clues to define the nerve roots. The allocation of the clinically damaged segment to the spinal disorder seen in imaging studies is essential for differential diagnosis and spine surgery.

METHODS

A retrospective study was conducted of clinical, electrophysiological, and imaging data among inpatients over a period of 21 months. Eight patients who had isolated monosegmental discogenic nerve root compression and a variation in the number of lumbar vertebrae were selected.

RESULTS

Seven patients presented with 6 lumbar vertebrae, and 1 patient presented with 4 lumbar vertebrae and disc herniation on 1 of the 2 caudal levels. Compression of the second-to-last nerve root in patients with 6 lumbar vertebrae resulted either in clinical L-5 or S-1 syndrome, or a combination of both. Compression of the last caudal nerve root resulted in a clinical S-1 nerve root syndrome.

CONCLUSIONS

The findings suggest that the dermatomyotomal supply of the lumbosacral nerve roots can vary in patients with a variation in the number of lumbar vertebrae, and a meticulous clinical, radiological, and electrophysiological examination is essential.

Sagittal whole-spine magnetic resonance imaging in 750 consecutive outpatients: accurate determination of the number of lumbar vertebral bodies

Object

When the number of lumbar and sacral vertebrae is being assessed, variations from typical lumbosacral anatomy may confuse the practitioner, potentially leading to significant clinical errors. In this study, the authors describe the statistical variation in lumbar spine anatomy in an outpatient imaging setting, evaluate the potential implications for clinical practice based on the variation in the number of lumbar-type vertebrae identified, and recommend a method for rapidly determining the number of lumbar spine vertebral bodies (VBs) in outpatients referred for lumbar spine MR imaging.

Methods

A total of 762 patients (male and female) who presented with low back–related medical conditions underwent whole-spine MR imaging in an outpatient setting.

Results

The high-speed whole-spine evaluation was successful for determining the number of lumbar-type VBs in 750 (98%) of 762 consecutive patients. The sagittal whole-spine 3-T MR imaging system images obtained between the beginning of January 2005 and the end of February 2007 were reviewed. The VBs were counted successively from the level of C-2 inferiorly to the intervertebral disc below the most inferior lumbar-type VB. Numbers of disc herniations were also evaluated in the context of the number of VBs.

Conclusions

One in 5 of these outpatients did not have 5 lumbar-type vertebrae: 14.5% had 6; 5.3% had 4; and 1 (0.13%) had the rare finding of 3 lumbar-type vertebrae. Two-thirds of the individuals with 6 lumbar-type vertebrae were male and two-thirds of the individuals with 4 lumbar-type vertebrae were female. Sagittal whole-spine MR imaging can be performed rapidly and efficiently in the majority of patients (98%), and provides improved accuracy for the determination of the number of lumbar-type VBs. A supplementary coronal MR, Ferguson view radiograph or intraoperative fluoroscopic determination for the presence of lumbosacral transitional vertebrae may add additional information when indicated for clinical treatment or surgical planning.

Magnetic resonance imaging of the sacral plexus and piriformis muscles

OBJECTIVE

The objective was to evaluate the piriformis muscles and their relationship to the sacral nerve roots on T1-weighted MRI in patients with no history or clinical suspicion of piriformis syndrome.

PATIENTS AND METHODS

Axial oblique and sagittal T1-weighted images of the sacrum were obtained in 100 sequential patients (200 pairs of sacral roots) undergoing routine MRI examinations. The relationship of the sacral nerve roots to the piriformis muscles and piriformis muscle size were evaluated, as were clinical symptoms via a questionnaire.

RESULTS

The S1 nerve roots were located above the piriformis muscle in 99.5% of cases (n=199). The S2 nerve roots were located above the piriformis muscle in 25% of cases (n=50), and traversed the muscle in 75% (n=150). The S3 nerve roots were located above the piriformis muscle in 0.5% of cases (n=1), below the muscle in 2.5% (n=5), and traversed the muscle in 97% (n=194). The S4 nerve roots were located below the muscle in 95% (n=190). The piriformis muscles ranged in size from 0.8-3.2 cm, with an average size of 1.9 cm. Nineteen percent of patients had greater than 3 mm of asymmetry in the size of the piriformis muscle, with a maximum asymmetry of 8 mm noted.

CONCLUSION

The S1 nerve roots course above the piriformis muscle in more than 99% of patients. The S2 roots traverse the piriformis muscle in 75% of patients. The S3 nerve roots traverse the piriformis muscle in 97% of patients. Piriformis muscle size asymmetry is common, with muscle asymmetry of up to 8 mm identified.

Identification and prediction of transitional vertebrae on imaging studies: anatomical significance of paraspinal structures

The aim of our study was to examine the locational distribution of paraspinal structures on MRI and to determine any predictable parameters that may be used for the identification of transitional vertebra (TV). We enrolled 534 patients who underwent MRI of their lumbosacral spine. The locations of the paraspinal structures, such as aortic bifurcation (AB), IVC confluence (IC), right renal artery (RRA), celiac trunk (CT), SMA root (SR), and iliolumbar ligament (ILL), were determined using "cross link" in PACS. We also assessed the morphology of the TV. The MRI showed that the most common site of the paraspinal structures in the normal group was AB at the lower L4, IC at the L4-5 disc space, RRA at the L1-2 disc space, CT at the T12-L1 disc space, SR at the upper L1, and ILL at the L5. The frequency of TV was 23.8% (lumbarization, 9.9%; sacralization, 13.9%). The paraspinal structures of the S1 lumbarization were positioned more toward the caudal location, whereas the paraspinal structures of the L5 sacralization were positioned more toward the cephalic location (P < 0.01). In conclusion, AB, IC, RRA, CT, SR, and ILL are useful landmarks for predicting the presence of TV on MRI. TV is possible when these paraspinal structures are in positions outside of the frequent locations.