Congenital cervical block vertebrae are associated with caudally adjacent discs

Congenitally Fused Cervical Spine Is Associated With Adjacent-Level Degeneration in the Absence of Cervical Spine Surgery

BACKGROUND

Cervical fusion surgery is associated with adjacent-level degeneration, but surgical and technical factors are difficult to dissociate from the mechanical effects of the fusion itself.

OBJECTIVE

To determine the effect of fusion on adjacent-level degeneration in unoperated patients using a cohort of patients with congenitally fused cervical vertebrae.

METHODS

We identified 96 patients with incidental single-level cervical congenital fusion on computed tomography imaging. We compared these patients to an age-matched control cohort of 80 patients without congenital fusion. We quantified adjacent-level degeneration through direct measurements of intervertebral disk parameters as well as the validated Kellgren & Lawrence classification scale for cervical disk degeneration. Ordinal logistic regression and 2-way analysis of variance testing were performed to correlate extent of degeneration with the congenitally fused segment.

RESULTS

Nine hundred fifty-five motion segments were analyzed. The numbers of patients with C2-3, C3-4, C4-5, C5-6, and C6-7 congenitally fused segments were 47, 11, 11, 17, and 9, respectively. We found that patients with congenital fusion at C4-C5 and C5-C6 had a significantly greater extent of degeneration at adjacent levels compared with the degree of degeneration at the same levels in control patients and in patients with congenital fusion at other cervical levels, even while controlling for expected degeneration and age.

CONCLUSION

Taken together, our data suggest that congenitally fused cervical spinal segments at C4-C5 and C5-C6 are associated with adjacent-level degeneration independent of fixation instrumentation. This study design removes surgical factors that might contribute to adjacent-level degeneration.

Are Congenital Cervical Block Vertebrae a Risk Factor for Adjacent Segment Disease? A Retrospective Cross-Sectional CT and MR Imaging Study

Adjacent segment disease (ASDI) is a well-described complication of spinal fusion surgery that may ultimately lead to spinal stenosis and repeated surgical intervention. Although congenital block vertebrae also present with degenerative changes in the adjacent segments, this has not yet been systematically investigated. The aim of this study was to assess the presence and degree of ASDI in congenital cervical block vertebrae. Methods: A total of 51 patients with congenital vertebral fusion in one cervical segment were analysed in this IRB-approved retrospective cross-sectional study using available CT/MR imaging. Exclusion criteria were prior spinal surgery and the presence of additional hereditary abnormalities. We assessed the severity of degenerative changes using a sum score. The sum score for adjacent and non-adjacent segments was then divided by the highest possible degeneration score, which resulted in a ratio of severity for adjacent and remaining segments (ranging from 0 to 1). Results: Overall, 35 of 51 patients (68.6%) showed evidence of ASDI, and 34 of 51 patients (66.7%) also showed degenerative changes in the remaining segments. The severity score was significantly higher (p = 0.025) in the segments adjacent to the congenital block vertebrae (mean value 0.307) compared to the non-adjacent segments (mean value 0.188). Conclusions: Our results suggest that ASDI is also caused by congenital block vertebrae of the cervical spine.

Congenital Cervical Hemivertebrae and Block Vertebrae in a 43-Year-Old Male

Congenital deformities of the spine are a consequence of anomalous vertebral development in the embryo and may be identified at birth or remain unnoticed until adulthood. Minor bony malformations of all types occur in up to 12% of the general population and are usually not apparent. In contrast, congenital spinal malformations that result in progressive spinal deformity are relatively rare. Klippel-Feil syndrome is a complex heterogeneous entity that results in cervical vertebral fusion and sometimes can occur associated to hemivertebra. We present a case of a 43-year-old male who presented to the emergency department after a fall. The patient had severe cervicalgia and generalized loss of active movement and sensation on his limbs. On physical examination, the patient presented reduced cervical range of motion and tetraplegia. Cervical magnetic resonance imaging revealed complete atlanto-occipital assimilation, left C3 hemivertebra with partial fusion in the right lateral portion of C2 and C4. Finally, there was a C5-C6 fusion. Surgical cervical stabilization was attempted but the procedure was aborted due to lack of space for placing the anterior plate safely. During hospitalization, the patient wore a cervical collar and started a rehabilitation program including muscle strengthening, balance, and gait training. The rehabilitation treatment led to a favorable clinical evolution. At discharge, the patient maintained a slight deficit of strength in his left upper and lower extremities, but he was functionally autonomous and was able to walk with a walker.

Effect of Congenital C4-5 Synostosis on Adjacent Mobile Segments: Radiographic Assessment

STUDY DESIGN

Prospective case series.

PURPOSE

To assess the corporal morphology of the fused body and adjacent segment conditions.

OVERVIEW OF LITERATURE

It is known that two fused vertebral bodies take the similar shape of the single body with inwaisting, with or without caudal flaring of the fused body, and that the fused body can cause the fusion disease at the adjacent segment that can be a risk factor for potential neurological compromise.

METHODS

Radiograms of the 11 study subjects (six men and five women), aged 22-90 years who visited the outpatients' clinic for various neck complaints without trauma history were examined. C4-5 synostosis was an incidental finding in all the subjects.

RESULTS

All the fused bodies were inwaisted and had anterior caudal breaking but no interior corporal flaring. Adjacent segment disease was not found in eight patients aged <40 years. Disk degeneration was found at C3-4 and C5-6 in three patients each and at C6-7 in two patients. Disk degeneration was limited to the adjacent segments.

CONCLUSIONS

Degenerative disk changes are associated with the natural aging process, and the corporal morphology of the fused vertebral becomes inwaisted similar to that in the single vertebrae.

Anatomical Variations That Can Lead to Spine Surgery at the Wrong Level: Part I, Cervical Spine

Spine surgery at the wrong level is an adversity that many spine surgeons will encounter in their career, and it falls under the wrong-site surgery sentinel events reporting system. The cervical spine is the second most common location in the spine at which surgery is performed at the wrong level. Anatomical variations of the cervical spine are one of the most important incriminating risk factors. These anomalies include craniocervical junction abnormalities, cervical ribs, hemivertebrae, and block/fused vertebrae. In addition, patient characteristics, such as tumors, infection, previous cervical spine surgery, obesity, and osteoporosis, play an important role in the development of cervical surgery at the wrong level. These were described, and several effective techniques to prevent this error were provided. A thorough review of the English-language literature was performed in the database PubMed between 1981 and 2019 to review and summarize these risk factors. Compulsive attention to these factors is essential to ensure patient safety. Therefore, the surgeon must carefully review the patient's anatomy and characteristics through imaging and collaborate with radiologists to reduce the likelihood of performing cervical spine surgery at the wrong level.

Radiological Assessment of the Effect of Congenital C3-4 Synostosis on Adjacent Segments

Study Design

Retrospective case series.

Purpose

To assess the effect of non-kyphotic aligned congenital C3-4 synostosis on the adjacent segment in 10 patients.

Overview of Literature

In the cervical spine, fusion disease at the adjacent motion segments may be a risk factor for potential neurological compromise and death.

Methods

Radiograms of 10 patients 13 to 69 years of age presenting with neck/shoulder discomfort or pain with or without trauma history were examined. C3-4 synostosis was found incidentally in all patients on routine examination radiographs of cervical spine.

Results

Adjacent segment disease (ASD) was not found in the three patients younger than 39 years of age. Five of the 10 (50%) patients, including a 67-year-old man, did not develop spondylosis in any of the cervical mobile segments. Spondylosis was observed only in the caudal 1-2 mobile segments in the remaining five patients. The youngest was a 40-year-old male who had spondylosis in the two caudal mobile segments (C4-5 and C5-6). Spondylosis was limited to the two close caudal mobile segments and was not in the cranial segments. Flaring of the lower part of synostotic vertebra associated with advanced narrowed degenerate disc was evident in five patients.

Conclusions

Mobile segment spondylosis in the individuals with congenital monosegment C3-4 synostosis over age of 40 years may be a natural manifestation of aging and is not solely an adjacent segment disease directly and fully related with congenital C3-4 synostosis.

Radiographic Assessment of Effect of Congenital Monosegment Synostosis of Lower Cervical Spine between C2-C6 on Adjacent Mobile Segments

Study Design

A prospective radiographic study of cervical spine with congenital monosegment fusion.

Purpose

To evaluate the effect of cervical synostosis on adjacent segments and the vertebral morphology.

Overview of Literature

There are numerous clinical studies of adjacent segment disease (ASD) after monosegment surgical fusion. However, there was no report on ASD in the cervical spine with congenital monosegment synostosis.

Methods

Radiograms of 52 patients, aged 5 to 90 years, with congenital monosegment synostosis (CMS) between C2 and C6, who complained of neck/shoulder discomfort or pain were studied. 51 were normally aligned and one was kyphotically aligned.

Results

Spondylosis was not found in the patients below 35 years of age. Only 12 out of 24 patients with normally aligned C2-3 synostosis had spondylosis in 19 more caudal segments, and only one at C3-4. A patient with kyphotic C2-3 had spondylolysis at C3-4. In 8 patients with C3-4 synostosis, spondylosis was found in only 9 caudal segments (4 at C4-5, 4 at C5-6, and 1 at C6-7). The caudate C4-5 disc was the most liable to degenerate in comparison with other caudate segments. Caudal corporal flaring and inwaisting of the synostotic vertebra were the features that were the most evident. In 2 of 9 C4-5 and 7 out of 10 C5-6 synostosis patients, spondylosis was found at the two adjacent cephalad and caudate segments, respectively. Only corporal inwaisting without flaring was found. In all cases, spondylosis was confined to the adjacent segments. More advanced spondylosis was found in the immediate caudal segment than the cephalad one.

Conclusions

It is concluded that spondylosis at the mobile segments in a synostotic spine is thought to be a fusion-related pathology rather than solely age-related disc degeneration. Those data suggested that CMS definitely precipitated the disc degeneration in the adjacent segments.

Evidence of spondyloarthropathy in the spine of a phytosaur (Reptilia: Archosauriformes) from the Late Triassic of Halberstadt, Germany

Pathologies in the skeleton of phytosaurs, extinct archosauriform reptiles restricted to the Late Triassic, have only been rarely described. The only known postcranial pathologies of a phytosaur are two pairs of fused vertebrae of "Angistorhinopsis ruetimeyeri" from Halberstadt, Germany, as initially described by the paleontologist Friedrich von Huene. These pathologic vertebrae are redescribed in more detail in this study in the light of modern paleopathologic methods. Four different pathologic observations can be made in the vertebral column of this individual: 1) fusion of two thoracic vertebral bodies by new bone formation within the synovial membrane and articular capsule of the intervertebral joint; 2) fusion and conspicuous antero-posterior shortening of last presacral and first sacral vertebral bodies; 3) destruction and erosion of the anterior articular surface of the last presacral vertebra; and 4) a smooth depression on the ventral surface of the fused last presacral and first sacral vertebral bodies. Observations 1-3 can most plausibly and parsimoniously be attributed to one disease: spondyloarthropathy, an aseptic inflammatory process in which affected vertebrae show typical types of reactive new bone formation and erosion of subchondral bone. The kind of vertebral shortening present in the fused lumbosacral vertebrae suggests that the phytosaur acquired this disease in its early life. Observation 4, the smooth ventral depression in the fused lumbosacral vertebrae, is most probably not connected to the spondyloarthropathy, and can be regarded as a separate abnormality. It remains of uncertain origin, but may be the result of pressure, perhaps caused by a benign mass such as an aneurysm or cyst of unknown type. Reports of spondyloarthropathy in Paleozoic and Mesozoic reptiles are still exceptional, and our report of spondyloarthropathy in fossil material from Halberstadt is the first unequivocal occurrence of this disease in a Triassic tetrapod and in a phytosaur.

Spine segmentation and enumeration and normal variants

This article provides a comprehensive review of spine segmentation and enumeration. This important and relatively underappreciated issue, when neglected, frequently results in confusion in vertebral numbering and ultimately may result in wrong segment interventions. The authors supplement this topic with a discussion of normal variants.

Incidental vertebral lesions

Incidental vertebral lesions on imaging of the spine are commonly encountered in clinical practice. Contributing factors include the aging population, the increasing prevalence of back pain, and increased usage of MR imaging. Additionally, refinements in CT and MR imaging have increased the number of demonstrable lesions. The management of incidental findings varies among practitioners and commonly depends more on practice style than on data or guidelines. In this article we review incidental findings within the vertebral column and review management of these lesions, based on available Class III data.

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.

Assessment of adjacent-segment mobility after cervical disc replacement versus fusion: RCT with 1 year's results

Disc prostheses have been designed to restore and maintain cervical segmental motion and reduce the accelerated degeneration of the adjacent level. There is no knowledge about the reaction of the neighboured asymptomatic segments after implantation of prostheses or fusion. The effects of these procedures to segmental movement of the uninvolved vertebrae have not been subjected to studies so far. The objective of this study was to compare the segmental motion following cervical disc replacement versus fusion and the correlation to the clinical outcome. Another aim was to compare the segmental motion of the asymptomatic segments above the treated ones and to compare both with Roentgen stereometric analysis (RSA) including the asymptomatic segments. 20 patients with one-level cervical radiculopathy scheduled for surgery were randomized to arthroplasty (10 patients, study group) or anterior cervical discectomy and fusion (10 patients, control group). Clinical results were evaluated using Visual Analogue Scale and Neck Disability Index. RSA was performed immediately postoperative, after 6 and 12 months. The adjacent segment showed a significantly higher segmental motion in all three-dimensional axes in comparison to the segment treated with prostheses (P < 0.05). In the fusion group the segmental motion of the adjacent segment was significantly higher in all three-dimensional axes (P < 0.05) at each examination time. When the adjacent level of both groups is compared, the fusion group could show a higher segmental motion in all three-dimensional axes, but without significant difference (P > 0.05) 1 year after surgery. Regarding the clinical results, there was no significant difference in pain relief between both groups (P > 0.05). In conclusion, the adjacent segment could show a higher segmental motion, when compared with the segment either treated with prostheses or fusion. There was no significant difference in segmental motion adjacent to prosthesis or fusion. Clinical results did also show no significant difference in pain relief between both groups.

Radiographic assessment of congenital C2-3 synostosis

PURPOSE

To evaluate the morphologies of congenital C2-3 synostosis in 25 patients.

METHODS

Radiographs of 11 males and 14 females aged 5 to 74 years with congenital C2-3 synostosis were reviewed. All cases were found incidentally on radiographs when presenting with neck/shoulder discomfort/pain.

RESULTS

13 of the patients had spondylosis in 21 segments: C1-2 (n=1) and C3-4 (n=1), C4-5 (n=7), C5-6 (n=9), and C6-7 (n=3). Of whom 12 had normal sagittal alignment and one had kyphotic synostosis (who developed compensatory hyperlordosis of the caudal mobile segments and subsequent spondylosis at C3-4 and C5 retrolisthesis). The remaining 12 patients had no spondylosis and had normal sagittal alignment, but had other associated pathologies including disc herniation at C3-4, C1 ring hypoplasia, and calcification of the nuchal ligament.

CONCLUSION

Normally aligned congenital synostosis of C2-3 is rarely associated with a junctional problem, whereas a kyphotic synostosis is associated with a caudal junctional problem. Spondylosis developing after age 40 years is not associated with C2-3 synostosis.

Anterior cervical arthrodesis using a "stand alone" cylindrical titanium cage: prospective analysis of radiographic parameters

STUDY DESIGN

Prospective, observational study.

OBJECTIVE

To evaluate biomechanical changes associated with cervical arthrodesis using a cylindrical titanium cage.

SUMMARY OF BACKGROUND DATA

Anterior cervical discectomy and fusion (ACDF) is the "gold standard" for treating cervical disc disease. In an effort to avoid the morbidity associated with autogenous bone graft harvesting, cervical cages are used to achieve fusion. The cages should allow for restoration and maintenance of natural disc height, angulations, and displacements at the operated levels.

METHODS

Fifty-four patients underwent standard ACDF using a "stand alone" cylindrical cage implant. Lateral radiographic views of the cervical spine were obtained before surgery, on the first day postoperatively, and at 12 months postoperatively. Disc height, vertebral alignment, angle of lordosis, and range of motion at operated levels were quantified prospectively by distortion compensated Roentgen analysis.

RESULTS

At 12 months postoperatively, solid fusion was achieved but the cylindrical cage failed to preserve disc height, prevent kyphosis, and preserve natural intervertebral alignment. We observed significant cage subsidence and malalignment.

CONCLUSION

We noticed several unfavorable outcomes when performing an analysis of radiographic parameters after ACDF using a cylindrical titanium cage. Thus, the use of a "stand alone" cylindrical cage in ACDF should be considered with caution.

Segmental motion adjacent to anterior cervical arthrodesis: a prospective study

STUDY DESIGN

Prospective, observational study.

OBJECTIVE

The present study describes in a prospective setting the kinematics changes occurring at segments adjacent to a one-level cervical arthrodesis.

SUMMARY OF BACKGROUND DATA

The development of adjacent segment disease has been noticed by many clinicians. Whether symptoms develop due to fusion induced accelerated spondylosis or due to a natural development in a predisposed person is currently under debate. The motivation for introducing motion preservation procedures in the neck is primarily to protect the patients from developing symptomatic adjacent disc disease. To accept this rationale, it has to be demonstrated that a fusion creates an unfavorable biomechanical situation at adjacent levels.

METHODS

Forty-six patients underwent standard anterior cervical decompression and fusion using a cylindrical cage implant. Lateral radiographic views of the cervical spine in flexion and extension were obtained before surgery, and at 12 months of follow-up. Employing Distortion Compensated Roentgen Analysis, rotational and translational motion at adjacent levels was quantified prospectively.

RESULTS

Rotational and translational motion at adjacent cranial and caudal levels did not exhibit a significant change between the preoperative state and the state 12 months after the operation.

CONCLUSION

The assumption of an iatrogenically caused increased mobility by a one-level cervical fusion could not be confirmed 12 months after surgery.

Morphological adaptation of the bone graft and fused bodies after non-instrumented anterior interbody fusion of the lower cervical spine

PURPOSE

To assess the remodelling process of the bone graft and fused bodies after non-instrumented anterior interbody fusion with autogenous iliac graft in patients with spondylosis, infections, fractures, or disorders of the cervical spine.

METHODS

68 patients aged 18 to 58 years who underwent non-plated anterior lower cervical interbody fusion with an iliac graft were retrospectively studied. Diagnoses of the patients were degenerative disc diseases (n=32), disc herniation (n=15), fractures (n=13), and tuberculosis (n=8). The Robinson and Smith technique was used to treat degenerative disc diseases and protruded disc, and the Bailey and Badgley procedure for fractures or tuberculosis of the cervical spine. 34, 25, and 9 patients underwent one-, 2-, and 3-segment fusions, respectively. 18 of the 25 patients underwent two-segment fusion with a single large bone block, and 7 with 2 separate bone blocks for each segment. Four of the 9 patients underwent three-segment fusion with a single large bone block, and 5 used separate grafts for each segment independently. Plain and stress radiography was primarily used to assess the fusion. Computed tomography and magnetic resonance imaging were also used in some patients. Some anterior graft extrusion (amounting to less than 10% of corresponding anteroposterior body width) was used to observe the remodelling during graft-take and thereafter. Postoperative cervical traction for 2 to 4 weeks, then cervical collar immobilisation for 4 to 12 weeks were strictly followed according to the numbers of fused segments. A halo vest was applied in 4 patients with fracture undergoing 3-segment fusion as they could not tolerate the prolonged bed rest or rigid cervical brace.

RESULTS

The mean time for the graft to fuse was 8.6 (range, 7-14) weeks in patients who underwent each segment fusion with independent free grafts, and 10 and 14 weeks in those who underwent 2- and 3-segment single large graft fusion, respectively. The final loss of disc height and joint angle were negligible, regardless of the extent of fusion. Bony absorption of the anteriorly protruded part of the graft began at postoperative week 10 (range, 6-28), which coincided with the time of graft-take and initiation of remodelling.

CONCLUSION

The earliest sign of bony absorption of the anteriorly protruded part of the graft indicated the initiation of the graft-take and the graft remodelling. The inwaisting sign of the surgically fused block of vertebral bodies was a morphological adaptation. Despite the altered biomechanics of the spine in the fused area, the inwaisting sign indicated maintenance of normal function at the parafusion motion segments.