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Dentomaxillofacial Radiology (2002) 31, 328 ± 330 2002 Nature Publishing Group. All rights reserved 0250 ± 832X/02 $25.00 www.nature.com/dmfr
CASE REPORT
Radiographic diagnosis of Limbus vertebra on a lateral cephalometric ®lm: report of a case M Mupparapu*,1, A Vuppalapati2 and E Mozaari1 1
University of Pennsylvania School of Dental Medicine, Philadelphia, Pennsylvania, USA; 2City of Philadelphia Department of Public Health, Division of Ambulatory Care Services, Philadelphia, Pennsylvania, USA
Although Limbus vertebra is not an uncommon radiological ®nding in an adult, it is a rare ®nding in the child or adolescent. The most common site for the presence of Limbus vertebra is the mid-lumbar region and less commonly occurs in the mid cervical region. It is a defect (tiny unfused apophyseal fragment) in the anterior margin of the vertebral body usually at the superior anterior margin in the lumbar vertebrae and at the anteroinferior margin in the cervical vertebrae. These margins are the sites of epiphyseal centers on vertebrae. A case of Limbus vertebra seen on a routine lateral cephalometric radiograph taken prior to Orthodontic treatment is reported and the literature is reviewed. The Limbus vertebra is thought to result from herniation of the nucleus pulposus through the ring apophysis prior to fusion isolating a small segment of the vertebral rim. This could be mistaken for a fracture, infection or tumor resulting in further invasive diagnostic procedures. It is important to recognize that this represents the sequela of a remote injury in an immature skeleton. A sound knowledge of this anomaly is essential for all clinicians so that appropriate measures can be taken without unduly alarming patients. Dentomaxillofacial Radiology (2002) 31, 328 ± 330. doi:10.1038/sj.dmfr.4600698 Keywords: Limbus vertebra; spine, lumbar vertebrae; spine, cervical vertebrae Case report A 14-year-old male patient attending the Orthodontic clinic was referred to the Radiology department for a routine lateral cephalometric radiograph. The patient had a thorough head and neck evaluation and a complete medical history before the initiation of the orthodontic evaluation. There was no known history of trauma. The systems review was within normal limits. The patient was apparently healthy and only sought orthodontic treatment for an existing malocclusion. A standard lateral cephalometric radiograph was obtained using a Quint Sectograph1 (Los Angeles, CA, USA) operated at 200 mA and 78 kVp. The radiograph revealed normal skull anatomy and at the level of the fourth cervical vertebra, anteroinferiorly a small triangular bone like fragment was noticed separated from the vertebral body but positioned in close *Correspondence to: M Mupparapu, Assistant Professor of Radiology, Department of Oral Medicine, University of Pennsylvania, School of Dental Medicine, 4001 Spruce Street, Philadelphia, PA 19104, USA; E-mail:
[email protected] Received 16 November 2001; revised 1 February 2002; accepted 5 February 2002
proximity (Figure 1). The cervical vertebrae did not show any changes suggestive of degenerative joint disease and the possibility of an osteophyte being present in the area is ruled out. A second opinion was sought which concurred with our initial radiographic diagnosis of Limbus vertebra. Patient's records were updated regarding the presence and benign nature of this fragment of cartilage. Discussion The anterior intra-osseous herniation of the nucleus pulposus producing a Limbus vertebra was ®rst described by Christian Georg Schmorl1 and since then has been a subject of occasional occurrence and careful review. Despite our early knowledge about the Limbus vertebra, it is often misdiagnosed as a fracture. This misinterpretation can cause a great deal of concern for the patient and the treating practitioner. A review of literature showed very few reports discussing the Limbus vertebrae within the cervical
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Figure 1 Lateral cephalometric radiograph of the patient showing the Limbus vertebra (small arrows) positioned anteroinferior to the vertebral body of C4
region. McCarron2 reported case of limbus annulare misdiagnosed as fracture of L-4. Ghelman and Freiberger3 presented a case in which the lesion was diagnosed by discography. Discograms are very useful diagnostic tools where they opacify the anteriorly herniated portion of the nucleus pulposus. Yagan4 presented a case of Limbus vertebra in a young patient that was ®rst diagnosed as a possible fracture on plain radiographs. Later, CT led to the diagnosis of Limbus vertebra. In another separate study, Swischuk et al5 studied 12 patients with MRI suspected of having degenerative disc disease in childhood and concluded that all had various disc problems including Scheuermann's disease, Schmorl's nodes and Limbus vertebrae. Most investigators agree with Schmorl's initial ®ndings1 that the Limbus vertebra resulted from an intrabody herniation of disc material. Schmorl's node is a more central herniation into the vertebral end plate, while the Limbus vertebra is caused by marginal herniation. The anterior herniation of nucleus pulposus may cause separation of a triangular smooth bone fragment which apparently represents the ring apophyses. These apophyses then remain separate from the vertebral body. Although in adults, this separated triangular fragment is well formed and easily discernible, in children or adolescents, only an
irregular destructive appearing process is present on the vertebral margin. The key for radiographic identi®cation of the Limbus is the fact that the cortical margins of the Limbus remain within confines of the vertebral body. Once identi®ed, usually no further investigative procedures are necessary. Limbus vertebra is commonly seen in patients who have had Scheuermann's Disease, more recently known as Juvenile Discogenic Disease (JDD)6 and the lesions are called `rim lesions'. Scheuermann's disease more commonly aects thoracic vertebrae or upper lumbar spine. The normal intervertebral disc functions as a shock absorber and occasionally, in areas of stress (lumbosacral and cervical), the annulus ®brosus may tear allowing the nucleus to protrude forming a herniated or slipped disc. This condition should be identi®ed and separated from the Limbus vertebra due to the fact that Limbus vertebra is not debilitating and requires no immediate treatment. Acknowledgements We thank Ralph Khan, DO, for his valuable assistance and Robert W Beideman, DMD for his guidance and review of the manuscript. Dentomaxillofacial Radiology
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References 1. Schmorl GC. Die pathologische Anatomie der Wirbelsaule. Verhandlungen der Deutschen Orthopadeschen Gesellschaft 1926; 21: 3 ± 41. 2. McCarron RF. A Case of mistaken identity, annulare mimics fracture. Orthop Rev 1987; 16: 173 ± 175. 3. Ghelman B, Freiberger RH. The limbus vertebra: an anterior disc herniation demonstrated by discography. Am J Roentgenol 1976; 127: 854 ± 855.
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4. Yagan R. CT diagnosis of limbus vertebra. J Comput Assist Tomogr 1984; 8: 149 ± 151. 5. Swischuk LE, John SD, Allbery S. Disk degenerative disease in childhood: Scheuermann's disease, Schmorl's nodes and limbus vertebra: MRI ®ndings in 12 patients. Pediatr Radiol 1998; 28: 334 ± 338. 6. Heitho KB, Gundry CR, Burton CV, Winter RB. Juvenile discogenic disease. Spine 1994; 19: 335 ± 340.
