Degenerative cervical myelopathy

Degenerative cervical myelopathy

The assessment, diagnosis, operative and nonoperative management of degenerative cervical myelopathy (DCM) have evolved rapidly over the last 20 years. A clearer understanding of the pathobiology of DCM has led to attempts to develop objective measurements of the severity of myelopathy, including technology such as multiparametric magnetic resonance imaging, biomarkers, and ancillary clinical testing. New pharmacological treatments have the potential to alter the course of surgical outcomes, and greater innovation in surgical techniques have made surgery safer, more effective and less invasive. Future developments for the treatment of DCM will seek to improve the diagnostic accuracy of imaging, improve the objectivity of clinical assessment, and increase the use of surgical techniques to ensure the best outcome is achieved for each individual patient 1).

Goel was troubled by the fact that his several PubMed and MEDLINE indexed articles on the subject published in leading journals dedicated to the study of the spine have not found any place in the huge reference list of 137 articles 2)

Definition

Epidemiology

Etiology

Pathophysiology

A review of Tetreault et al. summarizes current knowledge of the pathophysiology of DCM and describes the cascade of events that occur after compression of the spinal cord, including ischemia, destruction of the blood-spinal cord barrier, demyelination, and neuronal apoptosis. Important features of the diagnosis of DCM are discussed in detail, and relevant clinical and imaging findings are highlighted. Furthermore, this review outlines valuable assessment tools for evaluating functional status and quality of life in these patients and summarizes the advantages and disadvantages of each. Other topics of this review include epidemiology, the prevalence of degenerative changes in the asymptomatic population, the natural history and rates of progression, risk factors of diagnosis (clinical, imaging and genetic), and management strategies 3).

Clinical features

Patients may initially experience minimal symptoms 4) 5) but subsequently often develop pain, sensory deficits especially affecting their hands and feet, spasticity, imbalance, bladder symptoms, and experience frequent falls 6).

Diagnosing DCSM has traditionally relied on presence of clinical symptoms, including clumsy hands, paralysis of the lower extremities, gait disturbances, urinary/bowel incontinence and severe neurological dysfunction disturbances, urinary/bowel incontinence, and severe neurological dysfunction 7) 8).

Many people with cervical spondylosis or CSM are asymptomatic. However, patients with CSM are at higher risk of spinal cord injury (SCI) following minor injury.

Only a small percentage of people with spondylosis go on to develop symptoms consistent with cervical spondylotic myelopathy (CSM), which can cause significant and disabling neurological deficits, leading to loss of function, morbidity, and mortality.

In addition, diabetes mellitus (DM) is a frequent comorbidity for people of this age and may impact the severity of CCM.

Scales

European myelopathy score.

As a widespread used scale, the Modified Japanese Orthopaedic Association scale (mJOA) should be translated and culturally adapted 9).

see Cervical spine stenosis scales

Diagnosis

Treatment

Outcome

Randomized, controlled trials

A National Institutes of Health-funded (1R13AR065834-01) investigator meeting was held before the initiation of the trial to bring multiple stakeholders together to finalize the study protocol. Study investigators, coordinators, and major stakeholders were able to attend and discuss strengths of, limitations of, and concerns about the study. The final protocol was approved for funding by the Patient-Centered Outcomes Research Institute (CE-1304-6173). The trial began enrollment on April 1, 2014 10).

Case series

References

1)

Wilson JRF, Badhiwala JH, Moghaddamjou A, Martin AR, Fehlings MG. Degenerative Cervical Myelopathy; A Review of the Latest Advances and Future Directions in Management. Neurospine. 2019 Sep;16(3):494-505. doi: 10.14245/ns.1938314.157. Epub 2019 Aug 26. PubMed PMID: 31476852; PubMed Central PMCID: PMC6790745.
2)

Goel A. Degenerative Cervical Myelopathy. Neurospine. 2019 Dec;16(4):793-795. doi: 10.14245/ns.1938384.192. Epub 2019 Dec 31. PubMed PMID: 31905465.
3)

Tetreault L, Goldstein CL, Arnold P, Harrop J, Hilibrand A, Nouri A, Fehlings MG. Degenerative Cervical Myelopathy: A Spectrum of Related Disorders Affecting the Aging Spine. Neurosurgery. 2015 Oct;77 Suppl 4:S51-67. doi: 10.1227/NEU.0000000000000951. PubMed PMID: 26378358.
4)

Kovalova I, Kerkovsky M, Kadanka Z, Kadanka Z Jr, Nemec M, Jurova B, Dusek L, Jarkovsky J, Bednarik J. Prevalence and Imaging Characteristics of Nonmyelopathic and Myelopathic Spondylotic Cervical Cord Compression. Spine (Phila Pa 1976). 2016 Dec 15;41(24):1908-1916. PubMed PMID: 27509189.
5)

Martin AR, De Leener B, Cohen-Adad J, Cadotte DW, Nouri A, Wilson JR, Tetreault L, Crawley AP, Mikulis DJ, Ginsberg H, Fehlings MG. Can microstructural MRI detect subclinical tissue injury in subjects with asymptomatic cervical spinal cord compression? A prospective cohort study. BMJ Open. 2018 Apr 13;8(4):e019809. doi: 10.1136/bmjopen-2017-019809. PubMed PMID: 29654015; PubMed Central PMCID: PMC5905727.
6)

Davies BM, Mowforth OD, Smith EK, Kotter MR. Degenerative cervical myelopathy. BMJ. 2018 Feb 22;360:k186. doi: 10.1136/bmj.k186. Review. PubMed PMID: 29472200; PubMed Central PMCID: PMC6074604.
7)

Guan L, Chen X, Hai Y, et al. High-resolution diffusion tensor imaging in cervical spondylotic myelopathy: A preliminary follow-up study. NMR Biomed. 2017
8)

Sampath P, Bendebba M, Davis JD, et al. Outcome of patients treated for cervical myelopathy. A prospective, multicenter study with independent clinical review. Spine (Phila Pa 1976) 2000;25(6):670–76.
9)

Augusto MT, Diniz JM, Rolemberg Dantas FL, Fernandes de Oliveira M, Rotta JM, Botelho RV. Development of the Portuguese version of the modified Japanese Orthopaedic Association Score: cross-cultural adaptation, reliability, validity and responsiveness. World Neurosurg. 2018 Jun 1. pii: S1878-8750(18)31127-6. doi: 10.1016/j.wneu.2018.05.173. [Epub ahead of print] PubMed PMID: 29864576.
10)

Ghogawala Z, Benzel EC, Heary RF, Riew KD, Albert TJ, Butler WE, Barker FG 2nd, Heller JG, McCormick PC, Whitmore RG, Freund KM, Schwartz JS. Cervical Spondylotic Myelopathy Surgical Trial: Randomized, Controlled Trial Design and Rationale. Neurosurgery. 2014 Oct;75(4):334-346. PubMed PMID: 24991714.

Anterior cervical pseudarthrosis

Anterior cervical pseudarthrosis

Pseudarthrosis may occur with or without supplemental anterior cervical plating.

Incidence

Difficult to assess because of lack of validated criteria. Estimate: 2–20%. Higher with dowel technique (Cloward) than with the keystone technique of Bailey & Badgley or with the interbody method of Smith-Robinson (10%) or with non-fusion advocated by Hirsch. One criterion: motion>2mm between the tips of the spinous processes on lateral flexion/extension X-rays.

Other criteria that are specific but not sensitive: lucencies around the screws of an anterior plate, toggling of the screws on flexion/extension X-rays.

Clinical

Not uniformly associated with symptoms or problems. Some patients may have chronic or recurrent neck pain, some may present with radicular symptoms. (NB: when DePalma’s data is analyzed with patients reclassified as failures if the neck and/or arm symptoms persist, the success rate of surgery is lower with pseudarthrosis)

Diagnosis

More than 2 mm movement between spinous processes on dynamic (flexion-extension) cervical spine X-rays is recommended as a criterion for pseudarthrosis (Level B Class II); this measurement is unreliable when performed by the treating surgeon (Level C Class II).

Visualization of bone trabeculation across the fusion on static films is a less reliable marker for fusion (Level D Class III) (2D reformatted CT increases the accuracy (Level D Class III)).

see Cervical fusion criteria.

Treatment

No treatment is required for asymptomatic pseudarthrosis. Options for symptomatic patients include re-resection of the bone graft with repeat fusion (some recommend using autologous bone if allograft was used; a plate may be considered if one was not used previously), cervical corpectomy with fusion, or posterior cervical fusion.


Revision of symptomatic pseudarthrosis should be considered (Level D Class III). Postrior approaches may be associated with higher fusion rates on revision than anterior approaches (Level D Class III).

Outcome

In 1- and 2-level ACDF with plating involving the same number of fusion levels, there was no statistically significant difference in the pseudarthrosis rate, revision surgery rate, subsidence, and lordosis loss between PEEK cages and structural allograft 1).


Common interbody graft options for anterior cervical discectomy and fusion (ACDF) include structural allograft and polyetheretherketone (PEEK). PEEK has gained popularity due to its radiolucency and its elastic modulus, which is similar to that of bone.

A study sought to compare the rates of pseudarthrosis, a lack of solid bone growth across the disc space, and the need for revision surgery with the use of grafts made of allogeneic bone versus PEEK.

127 cases in which patients had undergone a 1-level ACDF followed by at least 1 year of radiographic follow-up. Data on age, sex, body mass indextobacco use, pseudarthrosis, and the reoperation rate for pseudarthrosis were collected. These data were analyzed by performing a Pearson’s chi-squared test.

Of 127 patients, 56 had received PEEK implants and 71 had received allografts. Forty-six of the PEEK implants (82%) were stand-alone devices. There were no significant differences between the 2 treatment groups with respect to patient age, sex, or body mass index. Twenty-nine (52%) of 56 patients with PEEK implants demonstrated radiographic evidence of pseudarthrosis, compared to 7 (10%) of 71 patients with structural allografts (p < 0.001, OR 9.82; 95% CI 3.836-25.139). Seven patients with PEEK implants required reoperation for pseudarthrosis, compared to 1 patient with an allograft (p = 0.01, OR 10.00; 95% CI 1.192-83.884). There was no significant difference in tobacco use between the PEEK and allograft groups (p = 0.586).

The results of this study demonstrate that the use of PEEK devices in 1-level ACDF is associated with a significantly higher rate of radiographically demonstrated pseudarthrosis and need for revision surgery compared with the use of allografts. Surgeons should be aware of this when deciding on interbody graft options, and reimbursement policies should reflect these discrepancies 2).


The objective of a systematic review done by Kaiser et al. from the Department of Neurological Surgery, Columbia University, New York, USA, was to use evidence-based medicine to identify the best methodology for diagnosis and treatment of anterior pseudarthrosis.

The National Library of Medicine and Cochrane Database were queried using MeSH headings and key words relevant to pseudarthrosis and cervical spine surgery. Abstracts were reviewed, after which studies meeting inclusion criteria were selected. The guidelines group assembled an evidentiary table summarizing the quality of evidence (Classes I-III). Disagreements regarding the level of evidence were resolved through an expert consensus conference. The group formulated recommendations that contained the degree of strength based on the Scottish Intercollegiate Guidelines network. Validation was done through peer review by the Joint Guidelines Committee of the American Association of Neurological Surgeons/Congress of Neurological Surgeons.

Evaluation for pseudarthrosis is warranted, as there may be an association between clinical outcome and pseudarthrosis. The strength of this association cannot be accurately determined because of the variable incidence of symptomatic and asymptomatic pseudarthroses (Class III). Revision of a symptomatic pseudarthrosis may be considered because arthrodesis is associated with improved clinical outcome (Class III). Both posterior and anterior approaches have proven successful for surgical correction of an anterior pseudarthrosis. Posterior approaches may be associated with higher fusion rates following repair of an anterior pseudarthrosis (Class III).

If suspected, pseudarthrosis should be investigated because there may be an association between arthrodesis and outcome. However, the strength of this association cannot be accurately determined. Anterior and posterior approaches have been successful 3).

References

1)

Wang M, Chou D, Chang CC, Hirpara A, Liu Y, Chan AK, Pennicooke B, Mummaneni PV. Anterior cervical discectomy and fusion performed using structural allograft or polyetheretherketone: pseudarthrosis and revision surgery rates with minimum 2-year follow-up. J Neurosurg Spine. 2019 Dec 13:1-8. doi: 10.3171/2019.9.SPINE19879. [Epub ahead of print] PubMed PMID: 31835252.
2)

Fivefold higher rate of pseudarthrosis with polyetheretherketone interbody device than with structural allograft used for 1-level anterior cervical discectomy and fusion. J Neurosurg Spine. 2018 Oct 1:1-6. doi: 10.3171/2018.7.SPINE18531. [Epub ahead of print] PubMed PMID: 30485200.
3)

Kaiser MG, Mummaneni PV, Matz PG, Anderson PA, Groff MW, Heary RF, Holly LT, Ryken TC, Choudhri TF, Vresilovic EJ, Resnick DK; Joint Section on Disorders of the Spine and Peripheral Nerves of the American Association of Neurological Surgeons and Congress of Neurological Surgeons. Management of anterior cervical pseudarthrosis. J Neurosurg Spine. 2009 Aug;11(2):228-37. doi: 10.3171/2009.2.SPINE08729. PubMed PMID: 19769502.

Cervical disc arthroplasty

Cervical disc arthroplasty

An alternative to fusion. Uses an artificial disc to preserve motion at the level of the discectomy.

Trend

In the USA between 2009 and 2017 the utilization of single-level cervical disc arthroplasty (CDA) rose from 5.6 cases for every 100 ACDFs performed in 2009 to 28.8 cases per 100 ACDFs in 2017. The most substantial increases occurred from 2013 onward. The region of highest utilization was the Mountain region (ArizonaColoradoIdahoMontanaNevadaNew MexicoUtah, and Wyoming), where 14.3 CDAs were performed for every 100 ACDFs (averaged over the 9-year period of study). This is in contrast to the East South Central region (AlabamaKentuckyMississippi, and Tennessee), where only 2.1 CDAs were performed for every 100 ACDFs. Patient factors that significantly increased the odds of undergoing a CDR were age younger than 40 years (OR 15.9 [95% CI 10.0-25.5]; p < 0.001), no clinical evidence of myelopathy/myeloradiculopathy (OR 1.5 [95% CI 1.4-1.7]; p < 0.001), and a Charlson Comorbidity Index score of 0 (OR 2.7 [95% CI 1.7-4.2]; p < 0.001). After controlling for these factors, significant differences in utilization rates remained between regions (chi-square test = 830.4; p < 0.001) 1).

Models

Indications

Total disc replacement is used for soft discal hernia resulting in cervicobrachial neuralgia.

Cervical artificial disc replacement (ADR) is supposed to preserve normal cervical range of motion than ACDF. A biomechanical measurement is necessary to identify the advantages and clinical implications of ADR. However, literature is scarce about this topic and in those available studies.

Three-dimensional motion analysis could provide useful information in an objective and quantitative way about cervical motion after surgery. In addition, it allowed to measure not only main motion but also coupled motion in three planes. ADR demonstrated better retained cervical motion mainly in sagittal plane (flexion and extension) and better preserved coupled sagittal and coronal motion during transverse plane motion than ACDF. ADR had the advantage in that it had the ability to preserve more cervical motions after surgery than ACDF 2).


Motion preserving anterior cervical disc arthroplasty (ACDA) in patients with cervical radiculopathy was introduced to prevent symptomatic cervical adjacent segment disease as compared to anterior cervical discectomy and fusion (ACDF).

Goal

Cervical arthroplasty was developed with the goal of preserving mobility of the cervical segment in patients with cervical degenerative disc disease.

Technique

1. position: supine, some use halter traction with this

2. equipment:

a) microscope (not used by all surgeons)

b) C-arm

3. implants: schedule vendor to provide a desired artificial disc

4. neuromonitoring: (optional) some surgeons used SSEP/MEP

5. consent (in lay terms for the patient—not all-inclusive):

a) procedure: surgery through the front of the neck to remove the degenerated disc and bone spurs, and to place an artificial disc

b) alternatives:nonsurgical management,surgical fusion(from the front or the back of the neck)

c) complications: swallowing difficulties are common but usually resolve, hoarseness of the voice (< 4% chance of it being permanent), injury to: foodpipe (esophagus), windpipe (trachea), arteries to the brain (carotid) with stroke, spinal cord with paralysis, nerve root with paralysis, possible seizures with MEPs (if used). The disc may eventually wear out and further surgery may be needed

Post-op orders:

1. no cervical collar (the goal is to preserve motion at the operated level)

2. NSAIDs around the clock for ≈ 2 weeks (this inhibits bone growth which theoretically helps avoid undesirable fusion at the operated level)

Anterior cervical disc arthroplasty versus anterior cervical discectomy and fusion

Indications

Cervical total disc replacement indications.

Cervical artificial disc replacement (ADR) is indicated for the treatment of severe radiculopathy permitting neural decompression and maintenance of motion.

The clinical and radiographic outcomes in cervical ADR patients using the ProDisc-C device (DePuy Synthes, West Chester, PA, USA) with a 5-9 year follow-up were collected through a prospective registry, with retrospective analysis performed on 24 consecutive patients treated with cervical ADR by a single surgeon. All patients underwent single- or two-level ADR with the ProDisc-C device. Outcome measures included neck and arm pain (visual analogue scale), disability (neck disability index [NDI]), complications and secondary surgery rates. Flexion-extension cervical radiographs were performed to assess range of motion (ROM) of the device and adjacent segment disease (ASD). Average follow-up was 7.7 years. Neck and arm pain improved 60% and 79%, respectively, and NDI had an improvement of 58%. There were no episodes of device migration or subsidence. Mean ROM of the device was 6.4°. Heterotopic ossification was present in seven patients (37%). Radiographic ASD below the device developed in four patients (21%) (one single-level and three two-level ADR). No patient required secondary surgery (repeat operations at the index level or adjacent levels). Fourteen out of 19 patients (74%) were able to return to employment, with a median return to work time of 1.3 months. The ProDisc-C device for cervical ADR is a safe option for patients providing excellent clinical outcomes, satisfactory return to work rates and maintenance of segmental motion despite radiographic evidence of heterotopic ossification and ASD on long-term follow-up 3).

Contraindications

Complications

Heterotopic ossification

Heterotopic ossification occurs in three-fourths of the patients after anterior cervical disc arthroplasty at two years after surgery, but does not necessarily correspond to clinical outcome, nor loss or preservation of ROM. The McAfee-Mehren classification should be combined with ROM evaluation to properly study HO 4).

Revision surgery and explantation

Between November 2008 and July 2016, 16 patients with prior implantation underwent removal of the Galileo-type disc prosthesis (Signus, Medizintechnik, Germany) due to a call back by industry. In 10 patients C-ADR was replaced with an alternative prosthesis, 6 patients received an ACDF. Duration of surgery, time to revision, surgical procedure, complication rate, neurological status, histological findings and outcome were examined in two institutions.

The C-ADR was successfully revised in all patients. Surgery was performed through the same anterior approach as the initial access. Duration of the procedure varied between 43 and 80min. Access-related complications included irritation of the recurrent nerve in one patient and mal-positioning of the C-ADR in another patient. Follow up revealed two patients with permanent mild/moderate neurologic deficits, NDI (neck disability index) ranged between 10 and 42%.

Anterior exposure of the cervical spine for explantation and revision of C-ADR performed through the initial approach has an overall complication rate of 18.75%. Replacements of the Galileo-type disc prosthesis with an alternative prosthesis or conversion to ACDF are both suitable surgical options without significant difference in outcome 5).

Case series

References

1)

Witiw CD, Smieliauskas F, Ham SA, Traynelis VC. Cervical disc replacement: examining “real-world” utilization of an emerging technology. J Neurosurg Spine. 2020 Jan 17:1-7. doi: 10.3171/2019.10.SPINE19919. [Epub ahead of print] PubMed PMID: 31952042.
2)

Lee JH, Kim JS, Lee JH, Chung ER, Shim CS, Lee SH. Comparison of cervical kinematics between patients with cervical artificial disc replacement and anterior cervical discectomy and fusion for cervical disc herniation. Spine J. 2013 Oct 30. pii: S1529-9430(13)01457-5. doi: 10.1016/j.spinee.2013.08.010. [Epub ahead of print] PubMed PMID: 24183464.
3)

Malham GM, Parker RM, Ellis NJ, Chan PG, Varma D. Cervical artificial disc replacement with ProDisc-C: Clinical and radiographic outcomes with long-term follow-up. J Clin Neurosci. 2013 Nov 15. pii: S0967-5868(13)00607-3. doi: 10.1016/j.jocn.2013.09.013. [Epub ahead of print] PubMed PMID: 24417795.
4)

Yang X, Bartels RHMA, Donk R, Depreitere B, Walraevens J, Zhai Z, Vleggeert-Lankamp CLA. Does Heterotopic Ossification in Cervical Arthroplasty Affect Clinical Outcome? World Neurosurg. 2019 Jul 31. pii: S1878-8750(19)32103-5. doi: 10.1016/j.wneu.2019.07.187. [Epub ahead of print] PubMed PMID: 31376560.
5)

Onken J, Reinke A, Radke J, Finger T, Bayerl S, Vajkoczy P, Meyer B. Revision surgery for cervical artificial disc: Surgical technique and clinical results. Clin Neurol Neurosurg. 2016 Oct 31;152:39-44. doi: 10.1016/j.clineuro.2016.10.021. [Epub ahead of print] PubMed PMID: 27888676.
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