Surgery for cervical spondylitic myelopathy offers improvement at 2-years follow-up

PHILADELPHIA — Surgical treatment for cases of mild to severe cervical spondylitic myelopathy has shown objective improvements in generic and disease-specific health outcomes in a large prospective clinical study presented here.

“Cervical spondylotic myelopathy is the most common cause of spinal cord impairment, and a significant cause of morbidity,” Michael G. Fehlings, MD, PhD, FRCSC, said. “Despite the fact this is commonly treated by neurosurgeons, there is a surprising paucity of outcomes data validating the surgery.”

Fehlings presented the results of the AO North America multi-centered, prospective, controlled study at the 78th Annual Meeting of the American Association of Neurological Surgeons.

2-year follow-up

Overall, the study included 278 patients who underwent surgical treatment for cervical spondylitic myelopathy (CSM), 194 of whom had 2 years postoperative follow-up.

The CSM was graded as mild, moderate or severe, based on a modified Japanese Orthopedic Association (mJOA) scale. The patient group with 2-year data averaged 56 years old and was 60% men. Outcomes were assessed by the mJOA scale, Neck Disability Index (NDI), Nurick score and SF-36.

“The patients underwent either an anterior, posterior or a combined surgery based on the techniques that were chosen by the operating team,” Fehlings said.

According to the study abstract, the investigators found that all outcome parameters improved postoperatively in patients with mild, moderate and severe CSM. Improvements reached a plateau at 12 months after surgery and were maintained at 2 years.

Myelopathy severity

“The patients with severe myelopathy are older and you use different techniques to treat patients based on the severity of the myelopathy,” Fehlings said describing how the data can be interpreted depending on CSM severity. “Patients with milder myelopathy are usually treated with anterior procedures. We have taken these factors into consideration for our multivariate analysis.”

He reported that mJOA improved on average by 3.00 points; NDI improved from 37.75 to 27.10, with an average improvement of 10.64; Nurick scores improved from 4.05 to 2.43, with an average improvement of 1.62; and the SF-36 physical component score improved from 38.30 to 42.82 and the mental component scores improved from 41.70 to 46.07, with an average improvement of 4.53.

In terms of the SF-36 scores, Fehlings said, “These improvements are similar to improvements seen with hip replacement surgery or cataract surgery. These highly impact the patient’s quality of life.”

Reference:
Fehlings MG, Kopjar B, Arnold P, et al. Does Surgical Treatment for Cervical Spondylotic Myelopathy Result in Long Term Benefit? Two Year Outcomes of the AO Spine North America CSM Multi-Center Prospective Study in 280 Subjects. Presented at the 78th Annual Meeting of the American Association of Neurological Surgeons. May 1-5, 2010. Philadelphia.
The study was funded by AO North America.

The investigators and members of the AO Spine group should be congratulated on their efforts to collect prospective data on the surgical treatment of cervical spondylitic myelopathy. Of the 278 patients, only 70% of the patients were available for follow-up at 2 years. The patients were categorized, rather tightly, based on their mJOA scores. If we look at the group with the severe myelopathy, the follow-up there drops to only 61%, so one shortcoming is a lack of good follow-up.

In terms of patients who were treated anteriorly, they received anterior decompression and fusion, whereas the posterior strategy included laminectomy, fusion or laminoplasty. The good news is the choice of approach didn’t seem to matter in terms of benefits to the patient or the durability of the benefits.

The major shortcoming has to do with the lack of information on the operative approaches. We see from this study that posterior decompression was used in older patients, those with lower mJOA scores and those with greater numbers of diseased segments. However, that doesn’t mean that is the appropriate choice. There are no data that tell us whether the anterior of posterior procedure was truly beneficial in these patients. It is interesting to note that the NSDI scores were lower with the anterior-procedure patients, whether that was due to the number of segments treated or lack of posterior muscle destruction, we will not know.

This work supports the role of decompression for cervical myelopathy, but does little to address the optimal surgical strategy.

– Vincent C. Traynelis, MD
Director, Neurosurgery Spine Service
Vice Chairperson and Professor, Department of Neurosurgery
Rush University Medical Center

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