KISEP J Korean Neurosurg Soc 36 : 337-339, 2004

Case Report Cervical Spondylolysis : Report of Two Cases

Young-Mun Choi, M.D., Young-Min Han, M.D. Department of Neurosurgery, Our Lady of Mercy Hospital, College of Medicine, The Catholic University of Korea, Incheon, Korea

Cervical spondylolysis is a rare vertebral anomaly defined as a corticated cleft between the superior and inferior articular pillar, the cervical equivalent of the pars interarticularis in the lumbar spine. Recognition of this anomaly and differentiation from acute traumatic fractures is of great importance because this lesion is usually diagnosed in patients after minor trauma or as an incidental finding on routine radiographs. The authors present two cases of this anomaly.

KEY WORDS : Cervical spine∙Spondylolysis∙Spondylisthesis .

Introduction attention. And then he was transferred to our emergency unit for further evaluation via a neighboring hospital. Results of pondylolysis of the lumbar spine is a relatively common neurological examination were normal. Radiographic S condition which is found in approximately 5% of the examination of his cervical spine revealed bilateral pedicular general population. However, cervical spondylolysis(CS) is a defects at C6(Fig. 2). Flexion and extension radiographs of rare condition demonstrating a long standing, perhaps the cervical spine demonstrated no instability(Fig. 1). congenital defect of the pars interarticularis of the cervical Computed tomography(CT) scan and magnetic resonance spine2). The etiology of cervical spondylolysis is unknown. image(MRI) demonstrated a spina bifida and discontinuity of Other associated dysplastic changes such as spina bifida in the superior and inferior articular facets of the C6 by a well- the cervical spine strongly support its congenital origin3,5). corticated cleft(Fig. 2, 3). Bone scan was normal, confirming Alternative theory of etiology is nonunion of a birth or the absence of recent bone injury. The patient was given sym- infantile fracture, which means a chronic problem3,6). Both ptomatic care. Surgical intervention was not required. theories imply that CS is not an acute fracture. But recent history of trauma may lead clinicians to misdiagnosis it as an Case 2 acute fracture. So, recognition of this condition is of great A 27-year-old male was involved in a rear end collision importance in order to prevent misdiagnosis and misman- with another vehicle. At that time, he had no clinical symp- agement. toms and/or signs. He performed his normal activities without any symptoms. He fell out of bed in his room, 7 days after the Case Report traffic accident. He complained of neck pain and referred to our hospital. Radiographic examination revealed a spondy- Case 1 lolisthesis with bipedicular bony defects at C6. On the basis A 32-year-old male was referred with the diagnosis of of the plain film examination, the emegency physician misdi- unstable fracture of the sixth cervical vertebra(C6). He fell agnosed it as an acute fracture with associated subluxation of forward onto his face in his room. Following this injury, he the C6. Neurological consultation was requested. Neurol- experienced a mild degree of nuchal pain. However, he ogical examination was normal at the time of presentation continued to carry out his normal activities for the next three and a CT scan was performed. CT scan demonstrated a spina days. Mild but persistent neck pain made him seek medical bifida of the C6 and bilateral wellcorticated pedicle def- ects(Fig. 5). No abnormal motion was identified on flexion or �Received：May 27, 2004 �Accepted：June 10, 2004 extension radiographs of the cervical spine(Fig. 4). �Address for reprints：Young-Min Han, M.D., Department of Because of the patient's lack of neurological symptoms and Neurosurgery, Our Lady of Mercy Hospital, College of Medicine, The Catholic University of Korea, 665 Bupyeong-dong, structural instability, conservative treatment was chosen. Bupyeong-gu, Incheon 403-720, Korea After 2-week conservative treatment, follow-up radiographs Tel : 032) 510-5515, Fax : 032) 511-2370 showed a stable spine with a full range of motion. He was E-mail : [email protected] discharged with full resolution of symptoms.

VOLUME 36 October, 2004 337 Cervical Spondylolysis

confirmed these find- ings and delineated the abnormal anatomy more precisely2). Magnetic Resonan- ce Imaging has been reported to be unhelp- ful for the diagnosis of CS due to poor bone resolution. In our cas- A B C D es, MRI demonstrated pars defects and spina Fig. 1. Case 1. A : Anteroposterior radiograph of the cervical spine showing spina bifida occulta at C6. B : Lateral radiograph revealing a well-corticated defect (arrow) between the superior and inferior articular pillars, dysplastic bifida on axial ima- changes of the facet and a grade 1 spondylolisthesis of C6 on C7. C,D : Flexion and extension views showing the ges. Although MRI is spondylolisthesis but no evidences of instability. not suitable for ident- ifying bony defects, it Discussion can be helpful in cases with neurological involvement9). The exact etiology of CS is still debatable. The frequent associa- pondylolysis with or without spondylolisthesis is rarely tion with other anomalies such as spina bifida and hypoplastic S found in the cervical spine while it is a relatively com- pedicle suggests a congenital origin. Poggi et al8) suggested mon condition in the lumbar spine. CS is defined as a that CS was caused by incomplete formation of the cartilagi- corticated cleft between the superior and inferior articular nous ring secondary to the failure of the lateral and posterior facets of the articular pillar, the cervical equivalent of the pars ring chondrification centers on one side or both sides to unite. interarticularis in the lumbar spine2). This clinical entity was However, autopsy studies of neonates have never revealed a first described by Perlman and Hawes in 19517). Since then, spondylolytic defect1). Morvan et al6) proposed that CS was less than 100 cases have been reported in the world liter- caused by repetitive microtrauma resulting in stress fractures ature2,3,5,8). The sixth cervical vertebra is the most common to the pars region. Dysplastic deformities such as hypolastic site of involvement which accounts for 70% of the reported pedicle and articular pillar may be more susceptible to trauma cases2,4-6,9). It has been reported to occur at any level with the or stress. Posttraumatic nonunion have been presumed but exception of C1 and C72). The characteristic features are there were no definitive evidences to support this theory2). spondylolytic defect with spina bifida occulta and dysplastic Clinically, the patients present with a variety of symptoms, changes of the affected articular mass. ranging from asympt-omatic to mild neck pain, upper Radiographically, the defects show well corticated margins extremity pain and myelo-radiculopathy. However, most with no evidence of acute fracture. Spina bifida occulta is a patients including our cases have been reported to have a mild common finding symptom and normal neurological exa-mination results2,6,8,9). which is observ- ed in more than 50 % of the cas- es9). Dysplastic c- hanges consisting of hypoplasia or hyperplasia are commonly found in the articular pi- A B llar above and/or Fig. 2. Case 1. Computed tomography scan below the involv- Fig. 3. Case 1. A : Mid-sagittal T-2weighted magnetic resonance at the level of the pedicle of C6 revealing a image demonstrating non-visualization of C6 spinous process well-corticated clefts (arrows) and spina ed site. Compu- (arrow). B : Axial T-2 weighted magnetic resonance image showing bifida. ted Tomography the spondylolytic defects (arrow) and spina bifida (arrowhead).

338 J Korean Neurosurg Soc 36 YM Choi and YM Han

acute fracture. Acute fracture will not be smoothly corticated. The absence of soft tissue swelling and/or neurological symptoms would favor CS2-4,9). The presence of associated anomalies such as dysplastic pillar and spina bifida would favor CS2-5,9). But recent history of trauma may lead clinicians to misdiagnosis it as an acute fracture. An initial misdiagnosis may lead clinicians to unnecessary surgical management. Recognition of this condition will decrease the potential for misdiagnosis and inappropriate treatment.

Conclusion A B pondylolysis with or without sondylolisthesis is a rare Fig. 4. Case 2. A : Anteroposterior radiograph of the cervical spine S condition in the cervical spine. Due to the risk of misdia- showing the spina bifida (arrow). B : Lateral radiograph showing lytic gnosis, clinicians should be aware that it can also occur in the defect and dysplastic changes of the articular pillars (arrow). cervical spine. The majority of the patients have References

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