Geographic Variations in Outcomes of Decompression Surgery for Degenerative Cervical Myelopathy

New findings show regional differences in demographics, causation, and surgical approaches for patients with degenerative cervical myelopathy, but similar efficacy worldwide. The multicenter international prospective cohort study was published online ahead of print in The Spine Journal.
Man touching a data transfer concept on a touch screen with his fingerThe results of this degenerative myelopathy study, published in The Spine Journal, involved research conducted on four continents.In the AOSpine CSM-North America study (Cervical Spondylotic Myelopathy), patients undergoing surgical treatment for degenerative cervical myelopathy “exhibited considerable improvement with low complications and excellent neurologic outcomes,” regardless of the severity of their condition, said lead author Michael G. Fehlings, MD, PhD, FRCSC, FACS, Professor of Neurosurgery and Co-Director of the Spine Program at the University of Toronto in Ontario, and Chair of the AOSpine International Spinal Cord Injury Knowledge Forum.

The present study combined data from the CSM-North America study with the CSM-International study to determine if these findings are applicable worldwide, Dr. Fehlings told SpineUniverse. The researchers speculated that differences in the underlying cause of degenerative cervical myelopathy (DCM) by geographic area may lead to different surgical outcomes.

For example, while the most common cause of DCM in North America is degenerative disc disease, ossification of the posterior longitudinal ligament also is a common underlying cause in Asia, Dr. Fehlings explained. In addition, cultural variations in the perception of illness and differing surgical techniques also may result in differing outcomes, he said.

Outcomes From 4 Continents Were Evaluated
The researchers evaluated data from 757 patients with symptomatic DCM undergoing surgical decompression of the cervical spine at one of 16 clinics in Europe, Asia-Pacific, Latin America, and North America.

Surgical decompression appeared to be effective in all regions despite differences in demographics, causation of DCM, and surgical approach. The extent of improvement in functional improvement, as measured using the modified Japanese Orthopaedic Association (mJOA) scale scores and Nurick grades, was greater among patients in North America and Asia-Pacific than among those in Europe and Latin America at both 12- and 24-month follow-up (Table).
Table. Changes in Functional Outcomes at 24 Months Following Decompression Surgery for Degenerative Cervical MyelopathyOutcomes from four continents were evaluated in the study.In contrast, patients from Asia-Pacific and Latin America showed the most improvement on the Neck Disability Index and the Short Form-36 (SF-36) version 2.

Dr. Fehlings speculated that the greater impact of surgery on self-reported health-related quality of life on the SF-36 found in patients in these regions may reflect cultural differences in the sense of gratitude regarding the improvements in health. For example, access to high-quality health care may be more challenging in Latin America than in North America and Europe; thus, when patients in Latin America underwent surgical decompression, it may have a greater impact on their quality of life than in areas where high-quality surgery is more readily available, Dr. Fehlings suggested.

Differences in Surgical Approach and Patient Demographics
The anterior approach was most commonly used among cases in Europe (71.43%), Asia-Pacific (60.67%), and North America (59.10%). In contrast, the posterior approach was more commonly used in Latin America (66.25%).

“The majority of patients were treated with anterior techniques for more focal pathology, and posterior techniques were generally used for posterior pathology,” Dr. Fehlings said. “There appeared to be equipoise between laminectomy and fusion and laminoplasty in terms of the effectiveness of posterior techniques,” he added.

Patients with DCM in Latin America and Asia-Pacific were significantly younger than those in North America and Asia-Pacific (P=0.0055). These differences may reflect the relatively young population in Latin America, as well as the predisposition to narrow spinal canals in people from the Asia-Pacific region.

Implications for the AOSpine Guidelines
Overall, the findings suggest that the recently released AOSpine Guidelines on DCM are applicable around the world, Dr. Fehlings said. The findings also “help us try to develop evidence-based protocols that will serve to better standardize care,” he said.

“For example, we can now teach our residents and doctors in training that for focal pathology, the anterior approach is the way to go,” Dr. Fehling said. “For more diffuse degeneration of the spine where a relative degree of cervical lordosis is maintained, posterior approaches are applicable.”

Knowledge Gaps Remain
Dr. Fehlings concluded that more research is needed to define when it is best to apply laminoplasty versus laminectomy and fusion.

“These do appear to both be excellent techniques, but it needs to be emphasized that the majority of patients undergoing laminectomy and fusion were in the Americas where cervical spondylosis predominates,” Dr. Fehlings said. “In the Asia-Pacific region where laminoplasty predominated, patients have higher rates of ossification of the posterior longitudinal ligament. It would be an oversimplification to say that these two techniques can be used interchangeably.”

“These techniques likely do have their own advantages and disadvantages, and this will require further prospective comparative effectiveness studies to determine,” Dr. Fehlings noted.

The study was funded by AOSpine International and AOSpine North America.

Disclosure
Dr. Fehlings has no relevant disclosures.

Updated on: 11/15/17
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