
==== Front
J Neurosurg Case Lessons
J Neurosurg Case Lessons
J Neurosurg Case Lessons
Journal of Neurosurgery: Case Lessons
2694-1902
American Association of Neurological Surgeons

39186823
10.3171/CASE24174
CASE24174
CongenitalCongenitalDeformityDeformitySpineSpineCervicalCervicalCase Lesson
Surgical management of congenital cervical spondylolytic spondylolisthesis: illustrative case
Baram Ali MD 1
Capo Gabriele MD 1
Brembilla Carlo MD 1
Ortolina Alessandro MD 1
Cracchiolo Giorgio MS 3
Riva Marco MD 2
Pessina Federico MD 2
Fornari Maurizio MD 1
1 Department of Neurosurgery, IRCCS Humanitas Research Hospital, Milan, Italy
2 Department of Biomedical Sciences, Humanitas University, Milan, Italy
3 University of Milano-Bicocca, School of Medicine and Surgery, Bergamo, Italy
Correspondence Ali Baram: IRCCS Humanitas Research Hospital, Milan, Italy. ali.baram@humanitas.it.
INCLUDE WHEN CITING Published August 26, 2024; DOI: 10.3171/CASE24174.

Disclosures The authors report no conflict of interest concerning the materials or methods used in this study or the findings specified in this paper.

26 8 2024
26 8 2024
8 9 CASE2417416 3 2024
24 5 2024
© 2024 the authors
2024
the authors
https://creativecommons.org/licenses/by-nc-nd/4.0/ CC BY-NC-ND 4.0 (http://creativecommons.org/licenses/by-nc-nd/4.0/)

BACKGROUND

Congenital cervical spondylolytic spondylolisthesis is a rare and complex disorder of the cervical spine. Surgical treatment is reserved for those symptomatic patients who do not improve with conservative management.

OBSERVATIONS

A 34-year-old man presented with bilateral C7 radiculopathy for the past 6 months. Magnetic resonance imaging of the cervical spine revealed grade II C6–7 spondylolisthesis. Computed tomography showed the presence of spondyloarthritis, bilateral pedicle dysplasia, bilateral isthmic defect, and spinous process schisis. Dynamic radiographs showed no signs of vertebral instability. Dynamic magnetic resonance imaging showed kinking of the spinal cord over the fulcrum of C6–7 kyphosis during flexion, with no signs of myelopathy. The patient underwent C6–7 anterior fusion surgery. His symptoms improved postoperatively, with a 2-month computed tomography scan showing initial bony bridging.

LESSONS

The absence of evident instability on radiography does not always correspond to the absence of actual functional compression of neurological structures. Spinal misalignment, muscle dysfunction, and kyphotic deformity with kinking of the spinal cord and stretching of the nerve roots may also contribute to the development of symptoms. In this setting, dynamic magnetic resonance imaging can be extremely useful. Single-level anterior fusion surgery without posterior fixation can achieve solid fusion and improve the clinical conditions of patients.

https://thejns.org/doi/10.3171/CASE24174

cervical spondylolytic spondylolisthesis
myelopathy
radiculopathy
ACDF
case report
ABBREVIATIONS

ACDF = anterior cervical discectomy and fusion
CT = computed tomography
MRI = magnetic resonance imaging.
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pmcCongenital cervical spondylolytic spondylolisthesis is a rare and complex malformation of the cervical spine. First described by Perlman and Hawes in 1951,1 it is characterized by bilaterally hypoplastic or dysplastic pedicles, normal transverse processes, and a well-corticated mono- or bilateral pars interarticularis defect. Articular facets are usually present, but they can appear dysplastic. A spina bifida defect of the spinous process is common.2 The most commonly affected vertebra is C6, a transitional vertebra.3–6 In the approximately 100 cases reported in the literature, only a few have been surgically treated.7 Indeed, surgery is reserved for only those patients with segmental instability who present with consequent neurological deficits or axial pain, or for those who have been treated conservatively without benefit.

Illustrative Case

History and Presentation

A 34-year-old male drummer and music teacher with no prior medical history had been experiencing continuous paresthesias on the lateral aspect of the left arm and forearm, with irradiation to the second and third fingers, for the past 6 months. Additionally, he reported difficulties in playing the drums due to easy fatigue and weakness in the supination of the left wrist. He also complained of cervical pain that intensified while playing the drums or during other physical activities. Similar symptoms subsequently appeared in the right arm, albeit with less intensity. A history of minor cervical trauma (whiplash injury in a car accident) 2 years earlier was reported, but no imaging was performed at that time.

The patient underwent cervical magnetic resonance imaging (MRI), revealing C6–7 spondylolisthesis with reduced disc height and the absence of foraminal stenosis. No signs of myelopathy were shown on MRI. Cervical computed tomography (CT) scanning showed significant anterior osteophytes, bilateral pedicle dysplasia, bilateral isthmic defects, spinous process schisis, and mildly dysplastic upper and lower facet joints (Fig. 1). Despite worsening symptoms during physical activities, dynamic radiographs did not show signs of vertebral macroinstability (Fig. 2). Furthermore, dynamic MRI confirmed substantial segmental stability and also showed dynamic kinking of the spinal cord over the fulcrum of the kyphosis during flexion (Video 1). FIG. 1. Preoperative MRI showed grade II C6–7 spondylolisthesis and regional kyphosis (A) with a normal spinal canal and foraminal width (B). Computed tomography showed significant spondyloarthritis of the C6 and C7 vertebral bodies (C), hypoplastic pedicles, a well-corticated bilateral pars interarticularis defect, and schisis of the spinous process (D).

FIG. 2. Dynamic radiographs in maximal extension (A) and flexion (B) did not show any sign of C6–7 macroinstability.

VIDEO 1. Clip showing preoperative cervical dynamic T2-weighted MRI. Click here to view.

Conservative therapy, such as wearing a rigid cervical collar for 5 months and undergoing 3 cycles of anti-inflammatory and corticosteroid treatment, did not achieve symptom relief. Therefore, surgical intervention was indicated.

Surgical Procedure

Anterior cervical discectomy and fusion (ACDF) was performed. With the patient under general anesthesia and in a supine position with the head slightly extended, the vertebral plane was exposed through a standard right anterolateral approach. Following the drilling of anterior osteophytes and incision of the disc annulus, significant mobility between the 2 vertebral bodies was noted. Subsequently, a discectomy was performed with lateral extension toward the foramina bilaterally, and a porous titanium cage measuring 9 mm filled with synthetic bone graft was placed. To enhance construct stability, a titanium plate anchored with 4 fixed self-tapping screws was also positioned anteriorly.

Postoperative Course and Outcomes

The surgery was free from surgical or anesthesiological complications. The patient was discharged on the 1st postoperative day with instructions to wear a rigid collar for 30 days.

At the 1-month follow-up, the patient exhibited complete resolution of paresthesias and regained full strength in the supination movement of both hands. The preoperative Neck Disability Index score was 21, and at 1 month postoperatively, it was 4. There was also a complete return to work and music-teaching activities. Postoperative radiographs at 1 month demonstrated the correct positioning of the cage and plate. The regional kyphosis had significantly decreased from approximately 21° to approximately 7°. Furthermore, as evidence of the reduction in regional kyphosis, there was a decrease in compensatory hyperlordosis at the adjacent levels. A postoperative CT scan at 2 months demonstrated initial bony bridging with no signs of construct failure (Fig. 3). At his latest clinical follow-up, 11 months after surgery, the patient appeared to be in good health with no residual symptoms. FIG. 3. Postoperative CT scans at 2 months (A and B) demonstrated initial bony bridging with no signs of construct failure. Postoperative upright radiographs at 1 month (C and D) showed a significant reduction in regional kyphosis from approximately 21° to 7°. Furthermore, compensatory lordosis on the adjacent segments has decreased.

Patient Informed Consent

The necessary patient informed consent was obtained in this study.

Discussion

Observations

Cervical spondylolytic spondylolisthesis is a rare condition with limited recent literature documentation. Epidemiologically, being a congenital disorder, it predominantly affects young adults. The vertebra commonly involved in this malformation is C6, which is anatomically considered a transitional vertebra. Furthermore, as highlighted by Schwartz, C6 undergoes higher biomechanical forces compared to other segments, emphasizing the developmental anomaly arising from a congenital malformation.8

The correct diagnosis involves both a CT scan to thoroughly examine the bone structure9 and a cervical MRI to rule out spinal cord and soft tissue lesions.10 In patients with past or recent cervical trauma, it is important to differentiate incidental cervical spondylolysis from a fracture.11 In these cases, the axial plane provides a detailed analysis of the posterior arch, while the sagittal plane is most useful in outlining the anatomy of the spondylolytic defect and associated dysplastic and degenerative pedicular and articular mass anomalies. Contrary to a congenital anomaly, an acute articular mass fracture does not exhibit smooth cortication. Instead, distinguishing a chronic nonunited articular mass fracture from cervical spondylolysis can be challenging, as both cases can present with displaced fragments having smooth cortical borders. Additional features, such as the presence of spinous process schisis or hypoplasia/dysplasia of pedicles and articular facets, as observed in our case, are certainly more indicative of a congenital anomaly.2 The history reported by the patient of a whiplash injury in a minor car accident 2 years before, though without short-term consequences, could have served as the catalyst for the degeneration of a level already affected by a congenital anomaly. As stated by Ahn et al.,7 almost all patients undergoing surgery for this condition have a history of minor or major cervical trauma.

The development of symptoms is usually attributed to a mechanism of intervertebral instability. The preferred treatment in most cases is conservative management using a rigid collar and anti-inflammatory medications. Surgery should be reserved for patients with neurological symptoms or those with axial pain unresponsive to conservative treatment. Of the reported cases, only 12 patients underwent surgical intervention. The chosen surgical approach varies, with some authors favoring only ACDF,7, 12–14 while others favor only posterior fusion,15–17 or a circumferential procedure involving both anterior and posterior decompression with or without fusion.18, 19 Our patient represents the 13th case documented in the literature18 (Table 1). TABLE 1. Surgical cases of congenital cervical spondylolysis

Authors & Year	Age (yrs)	Level	Symptoms	Surgical Approach	
Durbin, 195617	25	C4	Myelopathy	Posterior fixation	
Dawley, 197113	11	C6	None	ACDF 6–7	
Bellamy et al., 197415	16	C5	Myelopathy	Posterior fixation	
Prioleau & Wilson, 197512	46	C6	Myelopathy	ACDF 6–7	
Schwartz, 20018	14	C6	None	Posterior fixation	
Hirota et al., 198819	38	C6	Neck pain	ACDF 6–7 + posterior fixation	
Faure et al., 199016	24	C6	None	Posterior fixation	
Bhojraj & Shahane, 199214	8	C6	Myelopathy	ACDF 6–7	
Redla et al., 199910	29	C6	Neck pain	ACDF 6–7	
Ahn et al., 20107	54	C6	Neck pain	ACDF 6–7	
Ahn et al., 20107	52	C6	Neck pain	ACDF 6–7	
Woo & Choi, 202118	45	C6	Radiculopathy	ACDF 6–7 + posterior fixation	
Present case	34	C6	Radiculopathy	ACDF 6–7	

The patient exhibited listhesis of C6 over C7 with significant spondyloarthritis. Dynamic tests to radiologically demonstrate instability are crucial in such cases. Despite radicular symptoms worsening during physical activities such as playing the drums, dynamic radiographs and dynamic MRI did not show any signs of instability. Nonetheless, we chose to operate due to clinical nonresponsiveness to conservative therapy. We hypothesized that microinstability was present, as later revealed intraoperatively, even if it was not evident on preoperative examinations. In this context, anterior osteophyte formation and spondyloarthritis processes were considered likely dysfunctional para-physiological attempts to compensate for vertebral instability.

Moreover, listhesis associated with hyperkyphosis likely led to dysfunctional paravertebral muscle functioning, contributing, especially during physical activity, to axial pain and nerve root stretching, with consequent C7 radicular symptoms. This mechanism, in our opinion, was exacerbated by spinal cord kinking at the fulcrum of kyphosis, as observed in dynamic MRI, emphasizing nerve root stretching.

Regarding the surgical technique, we opted for an exclusively anterior C6–7 surgical approach, considering a 360° approach unnecessary. Conversely, posterior fixation would have involved at least C5 and C7, as C6 had bilateral peduncular dysplasia. However, this approach would have only posteriorly locked C5–6, potentially posing a risk of system mobilization. Eventually, to address this issue, one would add an ACDF also at C5–6 to enhance construct solidity. In a young and high-performing patient, with no signs of disc degeneration at the cranial level, we chose to avoid fusion of an additional cervical level to maintain cervical mobility and reduce biomechanical forces on the other nonfused adjacent levels. Secondarily, we decided against adding a posterior approach to prevent potential iatrogenic muscle insufficiency. The option of posterior fixation was reserved only if the anterior surgery with a cage and plate did not yield the expected benefits.

Limitations

The main limitation of our study is the limited duration of follow-up. In this context, it is essential to always consider that some complications, such as pseudarthrosis or adjacent segment disease, can occur even years after surgery, even in patients without risk factors who underwent a construct considered mechanically rigid, such as cage and plating.20 As for the role of cervical dynamic MRI, it is important to emphasize that this method still has significant limitations in terms of normative values in symptomatic and asymptomatic adults. This imaging technique is of scientific interest concerning degenerative cervical myelopathy but is less studied in other clinical areas.21 Therefore, dynamic MRI can be subject to interpretation bias.

Lessons

Congenital cervical spondylolytic spondylolisthesis is an exceptionally rare congenital condition. The absence of evident instability on radiographs, as observed in our case, does not always correspond to the absence of actual functional compression of neurological structures. We believe that instability is just one of the mechanisms involved in the genesis of symptoms. Spinal misalignment, muscle dysfunction, and kyphotic deformity with kinking of the spinal cord and stretching of the nerve roots may also contribute to the development of symptoms. In this setting, dynamic MRI can be useful. In our view, if conservative treatment is not successful, the preferred surgical approach involves a single-segment ACDF without the need for posterior fixation, reducing invasiveness and potential complications.

Acknowledgments

Dr. Baram reported receiving a grant from the General Directorate for Health Research and Innovation in Healthcare of the Ministry of Health (PNRR-MAD-2022-12376623).

Disclosures

The authors report no conflict of interest concerning the materials or methods used in this study or the findings specified in this paper.

Author Contributions

Conception and design: Baram, Capo, Cracchiolo, Pessina. Analysis and interpretation of data: Capo, Pessina. Drafting the article: Baram, Cracchiolo, Pessina. Critically revising the article: Capo, Brembilla, Ortolina, Cracchiolo, Riva, Pessina, Fornari. Reviewed submitted version of manuscript: Baram, Capo, Brembilla, Riva, Fornari. Approved the final version of the manuscript on behalf of all authors: Baram.

Supplemental Information

Videos

  Video 1. https://vimeo.com/952412109.

Correspondence

Ali Baram: IRCCS Humanitas Research Hospital, Milan, Italy. ali.baram@humanitas.it.
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