Posterior atlantoaxial 'facetal' instability associated with cervical spondylotic disease

Defining role of atlantoaxial and subaxial spinal instability in the pathogenesis of cervical spinal degeneration: Experience with "only-fixation" without any decompression as treatment in 374 cases over 10 years

Aim

The authors analyze their published work and update their experience with 374 cases of cervical radiculopathy and/or myelopathy related to spinal degeneration that includes ossification of the posterior longitudinal ligament (OPLL). The role of atlantoaxial and subaxial spinal instability as the nodal point of pathogenesis and focused target of surgical treatment is analyzed.

Materials and Methods

During the period from June 2012 to November 2022, 374 patients presented with acute or chronic symptoms related to radiculopathy and/or myelopathy that were attributed to degenerative cervical spondylotic changes or due to OPLL. There were 339 males and 35 females, and their ages ranged from 39 to 77 years (average 62 years). All patients were treated for subaxial spinal stabilization by Camille's transarticular technique with the aim of arthrodesis of the treated segments. Atlantoaxial stabilization was done in 128 cases by adopting direct atlantoaxial fixation in 55 cases or a modified technique of indirect atlantoaxial fixation in 73 patients. Decompression by laminectomy, laminoplasty, corpectomy, discoidectomy, osteophyte resection, or manipulation of OPLL was not done in any case. Standard monitoring parameters, video recordings, and patient self-assessment scores formed the basis of clinical evaluation.

Results

During the follow-up period that ranged from 3 to 125 months (average: 59 months), all patients had clinical improvement. Of 130 patients who had clinical evidences of severe myelopathy and were either wheelchair or bed bound, 116 patients walked aided (23 patients), or unaided (93 patients) at the last follow-up. One patient in the series was operated on 24 months after the first surgery by anterior cervical route for "adjacent segment" disc herniation. No other patient in the entire series needed any kind of repeat or additional surgery for persistent, recurrent, increased, or additional related symptoms. None of the screws at any level backed out or broke. There were no implant-related infections. Spontaneous regression of the size of osteophytes was observed in 259 patients where a postoperative imaging was possible after at least 12 months of surgery.

Conclusions

Our successful experience with only spinal fixation without any kind of "decompression" identifies the defining role of "instability" in the pathogenesis of spinal degeneration and its related symptoms. OPLL appears to be a secondary manifestation of chronic or longstanding spinal instability.

Evolving Concepts of Craniovertebral and Spinal Instability

Weakness of the muscles of the nape of the neck and back of the spine and its related instability is the nodal point of pathogenesis of a number of clinical and pathological events at the craniovertebral junction and the spine. Whilst acute instability results in sudden and relatively severe symptoms, chronic or long-standing instability is associated with a range of musculoskeletal and structural spinal alterations. Telescoping of the spinal segments results in "vertical" spinal instability in the subaxial spine and central or axial atlantoaxial instability (CAAD) at the craniovertebral junction. Instability in such cases might not be observed on dynamic radiological imaging. Chiari formation, basilar invagination, syringomyelia, and Klippel-Feil alteration are some of the secondary alterations as a result of chronic atlantoaxial instability. Radiculopathy/myelopathy related to spinal degeneration or ossification of posterior longitudinal ligament appears to have their origin from vertical spinal instability. All the secondary alterations in the craniovertebral junction and subaxial spine that are traditionally considered pathological and to have compressive and deforming role are essentially protective in nature, are indicative of instability, and are potentially reversible following atlantoaxial stabilization. Stabilization of unstable spinal segments is the basis of surgical treatment.

Surgical, Clinical, and Radiological Outcomes Analysis of Craniovertebral Junction Anomalies Cases: An Institutional Experience

Objective  The aim of this study was to evaluate the clinical and radiological outcomes analysis of craniovertebral junction (CVJ) anomalies cases. Materials and Methods  Retrospective analysis of 43 CVJ anomalies cases, which were surgically managed at Uttar Pradesh University of Medical Sciences, Saifai, Etawah, Uttar Pradesh, India, from period between June 2015 and June 2019. They were analyzed for age, sex, clinical characteristics, radiological diagnosis, and treatment given. Patient's clinical and radiological status was assessed pre- and postoperatively during time of discharge and at 6 months of follow-up. For clinical assessment we used visual analogue scale (VAS) and Nurick grading system. Radiological assessment was done by atlantodental interval (ADI), craniobasal angle, and craniometric lines. Overall outcomes were depicted as favorable, stabilized, and mortality at 6 to 18 months (mean 12.69 ± 3.77) of follow-up. Results  The age range of our cases was 7 to 71 years (mean 29.93 ± 17.39). Male-to-female ratio was 2.91:1. Majority of the cases were presented with neck pain ( n  = 38; 88.37%), motor weakness ( n  = 35; 81.40%), and sensory deficits ( n  = 25; 58.14%). Congenital atlantoaxial dislocation ( n  = 31; 72.09) was the most common CVJ anomaly. Clinically, there were significant improvements in VAS ( p  = 0.001) and Nurick grade ( p  = 0.007) postoperatively. Radiologically, ADI ( p  = 0.003) had decreased, clivus canal angle ( p  = 0.005) become less acute, and odontoid process ( p  = 0.003 for McRae's line) goes downwards in postoperative period. Bony fusion was achieved in 41 (95.35%) cases. Out of 43, 73% cases had favorable outcomes, 21% were stabilized, and mortality was seen in 2.33% cases at 6 months (mean ± standard deviation = 12.69 ± 3.77) of follow-up. Conclusion  Proper preoperative evaluation and selection of individualized surgical technique was the key for excellent clinical and radiological outcomes with minimal complications.

Cranio-cervical decompression associated with non-instrumented occipito-C2 fusion in children with mucopolysaccharidoses: Report of twenty-one cases

BACKGROUND

Mucopolysaccharidosis (MPS) is a multisystemic storage disorder of glycosaminoglycan deposits. Infiltration of the dura mater and supporting ligaments caused spinal cord compression and consecutive myelopathy, especially at the cranio-cervical junction (CCJ). Craniocervical instability and posterior decompression often raise the problem of fixation in children. The main purpose of this paper was to report the result of an original technique of occipito-cervical arthrodesis using a cranial halo-cast system in pediatric population.

METHODS

We recorded 21 patients with cervical myelopathy. All of them had spinal cord decompression by enlargement of the foramen magnum, C1 laminectomy, and occipito-C2 fusion using corticocancellous bone graft. Only one child has an extended laminectomy from C1 to C3. The occiput-C2 arthrodesis was stabilized by the cranial halo-cast system. This immobilization was performed preoperatively and kept for three months then switched to rigid cervical collar. Clinical assessment, including the Goel grade and mJOA, radiographs and magnetic resonance imaging were performed before surgery. The occipito-cervical arthrodesis was controlled by standard X-rays and CT scan.

RESULTS

According to the type of mucopolysaccharidosis, the patients were divided into MPS type I: n= 3, II: n=7, IV: n=11. The mean age of patients at surgery was 6.76 years. All mucopolysaccharidoses cases required a foramen magnum decompression by craniectomy, C1 laminectomy and occipito-C2 arthrodesis. As major complications, a child had immediate post-operative paraplegia due to spinal cord ischemia. The postoperative follow-up ranged from 1.5 to 4 years, with an average of 3.3 years. The average preoperative mJOA score was 8.9, and it improved to 14 points at the last follow-up.

CONCLUSIONS

Satisfactory fusion and good clinical results were obtained with the 2-stage approach to CCJ anomalies.

Alternative technique of C1-2-3 stabilization-sectioning of muscles attached to C2 spinous process and C2-3 fixation

Aim:

An alternative technique of C1-2-3 fixation is described that blocks the critical anteroposterior odontoid process movements and retains rotatory movement at the atlantoaxial joint. The technique involves sharp section of the muscles attached to the C2 spinous process and C2-3 transarticular interfacetal screw fixation.

Materials and Methods:

We successfully used this technique of fixation in 14 cases wherein in similar case situation; we earlier advocated inclusion of C1 in the fixation construct. Eleven patients had multisegmental spinal degeneration, 1 patient had Hirayama disease, and 2 patients had ossified posterior longitudinal ligament.

Results and Technical Advantages:

The procedure avoids manipulating C1 vertebra and excludes it from the fixation process, disables movement of C2 vertebra but retains rotation movements of the atlantoaxial joint that are executed by the muscles attached to the transverse process of atlas. The net effect is that the anteroposterior odontoid process movements that threaten the cervicomedullary neural structures are blocked and the critical rotatory atlantoaxial movements are retained.

Conclusions:

The discussed technique can be useful for cases undergoing multisegmental fixation that includes atlantoaxial joint.

Adjacent-segment "central" atlantoaxial instability and C2-C3 instability following lower cervical C3-C6 interbody fusion: Report of three cases

Aim:

We report adjacent-segment “central” or “axial” atlantoaxial instability and C2–C3 instability as the cause of delayed neurological worsening following multisegmental cervical spinal stabilization.

Materials and Methods:

Three male patients aged 34, 56, and 70 years had been operated earlier for cervical spondylosis by multilevel C3–C6 cervical interbody fusion 6–11 years earlier. After an initial improvement for few years, the patients observed relatively rapid clinical deterioration. When admitted, all the three patients were severely quadriparetic and were brought to the hospital on a wheelchair. Central atlantoaxial instability was diagnosed on the basis of our previously published clinical and radiological parameters. C2–C3 instability was essentially diagnosed on the intraoperative observations. The patients underwent atlantoaxial and C2–C3 fixation.

Results:

All the three patients had rapid clinical recovery that started in the immediate postoperative period. At an average follow-up of 21 months, the patients walked independently.

Conclusions:

Identification and treatment of adjacent-segment central atlantoaxial and C2–C3 instability can lead to gratifying clinical outcome.

Is C2-3 fusion an evidence of atlantoaxial instability? An analysis based on surgical treatment of seven patients

Objective:

The authors analyze the rationale of atlantoaxial fixation in patients presenting with symptoms related to cervical myelopathy and wherein the radiological images depicted C2–3 fusion and presence of single or multiple level neural compression of the subaxial cervical spinal cord attributed to “degenerative” spine.

Materials and Methods:

Seven adult males were analyzed who presented with long-standing symptoms of progressive cervical myelopathy and where imaging showed presence of C2–3 fusion, no cord compression related to odontoid process, and evidence of single or multiple level lower cervical cord compression conventionally attributed to spinal degeneration. There was no other bone or soft tissue abnormality at the craniovertebral junction. There was no evidence of atlantoaxial instability when assessed by conventional radiological diagnostic parameters. Atlantoaxial instability was diagnosed on the basis of clinical understanding, atlantoaxial facetal malalignment, and manual assessment of instability by bone handling during surgery. All the seven patients underwent atlantoaxial fixation and no surgical manipulation at lower cervical spinal levels.

Results:

At an average follow-up of 34 months, all patients have recovered satisfactorily in their neurological function.

Conclusion:

The presence of C2–3 fusion is an indication of atlantoaxial instability and suggests the need for atlantoaxial stabilization. Effects on the subaxial spine and spinal cord are secondary events and may not be surgically addressed.

Atlantoaxial Instability: Evolving Understanding

The atlantoaxial joint is the most mobile joint in the body. The physical architecture of the joint is characterized by a uniformly round and approximately flat surface, which allows a wide range of unobstructed movements. The standing human posture and lifelong heartbeat like uninterrupted activity of the atlantoaxial joint, and its ability to facilitate saying both 'yes' and 'no' necessarily requires smooth and 'fluid' movements that are supported by strong yet supple ligaments. The magnificent architectural structure that is 'magically' designed and carved by nature to provide both stability and mobility and to allow a smooth and safe transit passage for the most critical neural and vascular structures can only be admired in awe and appreciated.

Role of Subaxial Spinal and Atlantoaxial Instability in Multisegmental Cervical Spondylotic Myelopathy

AIM

In this paper the role of atlantoaxial and multilevel subaxial spinal instability as the primary nodal point of the pathogenesis of degenerative cervical spinal disease-related myelopathy, and the focus of surgical treatment for it, is evaluated.

MATERIALS AND METHODS

The series analyses the treatment of 73 patients with single or multilevel degenerative cervical spinal disease by fixation of the involved spinal segment(s) alone, aimed at arthrodesis. No bone decompression or disc/osteophyte resection was done. In 23 patients, the atlantoaxial joint was included in the spinal fixation, as atlantoaxial instability was identified by facetal malalignment on imaging or by observations on direct bone manipulation during surgery. There were 70 males and 3 females. The ages of the patients ranged from 35 to 76 years (average 57 years). The transarticular screw method was deployed for subaxial spinal fixation and a lateral mass plate/rod and screw technique was used for atlantoaxial fixation.

RESULTS

During the follow-up period, which ranged from 3 to 42 months (average 27 months), all patients improved in terms of their clinical symptoms. There were no surgery- or implant-related complications.

CONCLUSION

Atlantoaxial joint instability is frequently associated with subaxial multilevel spinal instability in degenerative spinal disease. Fixation of the spinal segments provides a safe, effective and rational treatment for single or multilevel spinal degeneration.

Cervical spondylosis in patients presenting with "severe" myelopathy: Analysis of treatment by multisegmental spinal fixation - A case series

Background:

Surgical strategy of multisegmental spinal fixation that includes atlantoaxial joint for patients having cervical spondylosis-related symptoms of severe myelopathy is analyzed.

Objective:

Surgical outcome of patients presenting with “severe” symptoms of cervical myelopathy having multisegmental degenerative cervical spondylosis and treated by multisegmental spinal fixation is analyzed. Atlantoaxial joint was included in the fixation construct in majority of patients. No bone, soft tissue, osteophyte, or disc resection for decompression was done.

Materials and Methods:

Sixty-four patients having multisegmental cervical spondylosis who presented with symptoms of severe myelopathy were surgically treated during the period from March 2013 to December 2018. On the basis of the concept that instability is the primary cause of spinal degeneration, multisegmental spinal fixation was done in all patients. Atlantoaxial joint was included in the fixation construct in 48 patients. The levels of spinal fixation were determined on the basis of direct observation of facet joints and by manual manipulation and were guided by the presenting clinical features and radiological information. Clinical monitoring was done using Goel clinical grading, modified Japanese Orthopedic Association Score, and visual analog score parameters. Patient satisfaction index assessed the functional and symptomatic improvement.

Results:

During the follow-up that ranged from 6 to 75 months, all patients improved in their clinical status. Fifty-five (85.9%) patients could walk independently or with mild support.

Conclusions:

Multisegmental spinal fixation that includes atlantoaxial joint in most patients forms a rational treatment strategy for patients of cervical spondylosis presenting with severe symptoms of myelopathy.

Central or Axial Atlantoaxial Dislocation as a Cause of Cervical Myelopathy: A Report of Outcome of 5 Cases Treated by Atlantoaxial Stabilization

OBJECTIVE

The implications of diagnosis and treatment of central or axial atlantoaxial dislocation (CAAD) as a cause of symptoms of cervical myelopathy are evaluated.

METHODS

This is a report of a series of 5 patients who presented with the primary symptoms of spasticity and motor weakness and paresthesias in all the limbs. There was no evidence of any significant compression of the dural tube or neural structures at the craniovertebral junction. There was no craniovertebral junction instability when assessed by classically described radiologic parameters. CAAD was diagnosed based on our recently discussed parameter of facetal alignment, corroborative clinical and radiologic evidence, and direct observation of atlantoaxial instability by manual manipulation of the bones of the region. All patients underwent atlantoaxial fixation.

RESULTS

There was remarkable improvement in the clinical symptoms in the immediate postoperative period and during the follow-up period of 12-24 months (average, 16 months). All patients have continued to have progressive clinical recovery. Clinical assessments were done using Goel clinical evaluation scale, Japanese Orthopedic Association score, and visual analog scale.

CONCLUSIONS

Identification and treatment of CAAD can have a significant management impact on patients where the cause of spastic quadriparesis is otherwise undiagnosed.

Clinico-Radiological Outcome Analysis in Craniovertebral Junction Diseases: An Institutional Experience of 38 Patients in a Tertiary Care Centre

BACKGROUND

Craniovertebral junction diseases, although considered rare, are common in northern parts of India. This study was conducted to evaluate the clinico-radiologic and surgical outcome of patients with a minimum follow-up of 1 year. Our study also compared bony fusion among various techniques of posterior fusion.

METHODS

This retrospective study was performed with 38 patients who met the inclusion criteria for analysis. These patients were contacted by telephone and letters, and their clinical examination and radiologic investigations were performed at a follow-up visit. The preoperative, postoperative, and follow-up clinical evaluations of the patients were done using the Nurick grading system.

RESULTS

The age range was 4-60 years with an average of 20.5 years. There were 31 male and 7 female patients, with a male:female ratio of 4.43:1. There were 13 cases of fixed atlantoaxial dislocation (AAD), 17 cases of mobile AAD, 6 cases of traumatic AAD, and 2 cases of postinfective AAD. The majority of these patients (n = 29; 76.31%) had neck pain and cerebellovestibular disturbances (n = 27; 71.1%). Sphincter disturbances were observed in 9 patients. An increase in craniovertebral angle was observed in postoperative period in all patients. Initially, 84% of the patients had a poor Nurick grade; this was reduced to 28% after the surgical intervention. One hundred percent bony fusion was attained in patients who underwent rigid fixation technique, and 80% was attained using a semirigid fixation technique.

CONCLUSIONS

The key to successful management of craniovertebral junction disease is individualized selection of judicious surgical intervention from various available techniques.

Role of Atlantoaxial and Subaxial Spinal Instability in Pathogenesis of Spinal "Degeneration"-Related Cervical Kyphosis

BACKGROUNDS

The role of subaxial and atlantoaxial instability in the pathogenesis of "degeneration"-related cervical kyphosis is evaluated.

MATERIAL AND METHODS

During the period 2013-2016, the authors treated 21 patients having cervical kyphosis that was related to degenerative spinal disease. The patients presented with symptoms related to cervical myelopathy. Kyphosis was diagnosed on the basis of described radiologic parameters. The patients were divided into 3 groups. Group A (10 patients) had manifest radiologic evidence of atlantoaxial dislocation, type 1 facetal instability, abnormal increase in atlantodental interval, and evidence of cord compression by the odontoid process. Group B (5 patients) had axial or central atlantoaxial facetal instability (type 2 or 3 atlantoaxial facetal instability) and subaxial spinal instability. Group C (6 patients) had subaxial spinal instability. The patients were treated by only stabilization. Group A patients underwent atlantoaxial fixation, group B patients underwent atlantoaxial and subaxial fixation, and group C patients underwent only subaxial spinal fixation. The operation was aimed at arthrodesis of the spinal segments. No bone or soft tissue decompression was done.

RESULTS

During the minimum follow-up period of 6 months, all patients improved in their neurologic symptoms and demonstrated evidence of spinal arthrodesis. There were no major surgical complications.

CONCLUSIONS

Spinal instability plays a major role in the generation of cervical spinal kyphosis. Atlantoaxial instability may form the primary and nodal site of development of the process of spinal degeneration in general and kyphosis in particular.

Multilevel Spinal Stabilization as a Treatment for Hirayama Disease: Report of an Experience with Five Cases

OBJECTIVE

To analyze the role of multisegmental spinal instability in the pathogenesis of Hirayama disease.

MATERIAL AND METHODS

From June 2014 to January 2016, the authors managed 5 patients with Hirayama disease. The patients were diagnosed on the basis of classical described radiologic and clinical guidelines. All 5 patients were treated with multilevel cervical fixation that included fixation of the atlantoaxial joint in 4 patients by the adoption of the facetal fixation methods. No dural or bone decompression was performed. The follow-up ranged from 7 to 26 months (average 17.6 months).

RESULTS

The most remarkable feature was an immediate postoperative and progressive improvement in the symptoms of weakness, wasting, and deformity of hands in all patients. The other remarkable feature was an immediate postoperative reduction in extradural mass in all patients and its complete disappearance in 2 patients.

CONCLUSIONS

From the observations, it appears that atlantoaxial and subaxial spinal instability plays a major role in the pathogenesis of Hirayama disease.

C2-3 Fusion, C3-4 Cord Compression and C1-2 Posterior Facetal Instability: An Evaluation of Treatment Strategy Based on Four Surgically Treated Cases

STUDY DESIGN

Four patients had C2-3 vertebral fusion and radiologically demonstrated cord compression at C3-4 level related to disc bulge with or without association of osteophytes and C1-2 posterior facetal dislocation. The outcome of treatment by atlantoaxial and subaxial facetal fixation is discussed.

PURPOSE

The article evaluates the significance of atlantoaxial facetal instability in cases having C2-3 vertebral fusion and cord compression at the level of C3-4 disc.

OVERVIEW OF LITERATURE

C2-3 vertebral fusions are frequently encountered in association with basilar invagination and chornic atlantoaxial dislocations. Even when basilar invagination and atlantoaxial dislocation are not identified by conventional parameters, atlantoaxial instability can be the nodal point of pathogenesis in cases with C2-3 vertebral fusion.

METHODS

Between June 2013 and November 2014 four patients having C2-3 fusion presented with progressive symptoms of myelopathy that were related to cord compression at the level opposite the C3-4 disc space. Further investigations revealed C1-2 posterior facetal dislocation.

RESULTS

All patients were males. Ages ranged from 18 to 50 years (average, 36 years). All patients were treated by atlantoaxial facetal plate and screw, and subaxial single or multi-segmental transarticular screw fixation. Follow-up (average, 15 months) using a recently described clinical grading system and the Japanese Orthopaedic Association scoring system confirmed marked improvement of symptoms.

CONCLUSIONS

Identification and treatment of atlantoaxial facetal instability may be crucial for a successful outcome in cases having C2-3 fusion and high cervical (C3-4) disc related cord compression.

Is atlantoaxial instability the cause of "high" cervical ossified posterior longitudinal ligament? Analysis on the basis of surgical treatment of seven patients

BACKGROUND

Multilevel ossified posterior longitudinal ligaments (OPLLs), particularly those that extend into the high cervical region, are formidable and challenging surgical problems. The aim of the presentation is to analyze the results of surgical treatment of seven consecutive patients having high cervical OPLL with atlantoaxial and subaxial facetal fixations.

OBJECTIVES

We analyze the role of atlantoaxial instability in the management of OPLL that extended into the high cervical region, above the lower border of C3 vertebra.

MATERIALS AND METHODS

All patients in the series were males. The age of the patients ranged 48-65 years. Clinical evaluation was done by a 5-point clinical grading scale described by us, Japanese Orthopedic Association (JOA) score, and visual analog scale (VAS). All patients were identified to have relatively "subtle" but definite atlantoaxial facetal instability on sagittal imaging and the instability was confirmed by direct handling of the facets during surgery. All patients were treated by multilevel facetal fixation that included fixation of atlantoaxial facets. The aim of surgery was stabilization and arthrodesis of the involved spinal segments, as instability was considered to be the prime pathogenetic factor of OPLL. Spinal canal decompression, either by anterior corpectomy or discoidectomy or by posterior laminectomy or laminoplasty was not done and no attempts were made to remove the OPLL. At an average follow-up of 8 months, all patients showed progressive symptomatic recovery.

CONCLUSION

Atlantoaxial facetal instability can be a cause or an association of high cervical OPLL. Stabilization of the atlantoaxial joint forms a remarkably effective method of treatment.

Craniovertebral Junction Instability: A Review of Facts about Facets

Craniovertebral junction surgery involves an appropriate philosophical, biomechanical and anatomical understanding apart from high degree of technical skill and ability of controlling venous and arterial bleeding. The author presents his 30-year experience with treating complex craniovertebral junction instability related surgical issues. The facets of atlas and axis form the primary site of movements at the craniovertebral junction. All craniovertebral junction instability is essentially localized to the atlantoaxial facet joint. Direct manipulation and fixation of the facets forms the basis of treatment for instability.