Cervical spondylotic myelopathy (CSM), a degenerative spine disease, is the most common cause of spinal cord dysfunction in patients older than 55 years. This disease presents with a wide range of symptoms including impaired gait, numb hands, and weakness. Surgical intervention has proven to be an effective treatment option for patients with mild-to-severe CSM. Determining which clinical variables can predict surgical outcomes can help manage patient expectations.

“Evidence—in the form of high-quality, prospective studies using validated outcome measures—is lacking” said Lindsay Tetreault, HBSc, coauthor of a study presented at the 2012 annual meeting of the Cervical Spine Research Society.

Ms. Tetreault, lead author Michael Fehlings, MD, PhD, FRCSC, and other investigators of the CSM-North American study formulated a clinical prediction rule to determine surgical outcomes in CSM patients using data from a prospective, multicenter study. According to the results, factors such as patient age, duration of symptoms, baseline severity score, psychological comorbidities, impaired gait, and smoking status are valuable predictors.

Collecting data
The researchers analyzed data from 272 patients (160 males, 112 females; mean age, 56.5 years) enrolled in the CSM-North America trial (December 2005 to September 2007). Inclusion criteria were as follows:

• Older than 18 years
• Presenting with symptomatic CSM, with at least one clinical sign of myelopathy
• No previous surgery

All patients received surgical decompression and fusion, with the approach determined by the attending surgeon.

Researchers collected extensive data at baseline, as well as at 6 months, 12 months, and 24 months after surgery. They evaluated patients’ functional status using the modified Japanese Orthopaedic Association (mJOA) scale. Each patient also had a baseline and follow-up MRI. The study’s follow-up rate was 80 percent.

Predictors and results
A successful surgical outcome was defined as having an mJOA score greater than or equal to 16.

The final logistic regression model consisted of the following six predictors:

• Age
• Duration of symptoms
• Smoking status
• Impairment of gait
• Psychological comorbidities
• Baseline severity score

“We found that the odds of a successful outcome were 2.66 times higher when a patient did not have an impaired gait, compared to when a patient did have that symptom,” said Ms. Tetreault. “In addition, odds of a successful outcome were 1.22 times greater for every 1 point increase in baseline mJOA.”

The following factors decreased the odds of a successful surgical outcome:

• Psychological comorbidities (67 percent decrease)
• Longer duration of patient symptoms (22 percent decrease)
• Every 1-year increase in age (3 percent decrease)
• Smoking (50 percent decrease)

“This study confirms that severe, long-standing compression in the spinal cord leads to irreversible damage, as suggested by the significance of baseline severity scores and duration of symptoms,” said Ms. Tetreault. Age and smoking status were found to be important predictors, as were certain comorbidities such as psychological disorders and symptoms such as impaired gait.

This study was sponsored by AOSpine North America.

Dr. Fehlings and Ms. Tetreault’s coauthors on “A Clinical Prediction Rule to Determine Outcomes in Patients with Cervical Spondylotic Myelopathy Undergoing Surgical Treatment: Data from the Prospective, Multicentre AOSpine North America CSM Study” are Branko Kopjar, MD; Sangwook Tim Yoon, MD; Paul M. Arnold, MD, FACS; Eric Massicotte, MD; and Alexander R. Vaccaro, MD, PhD.

Disclosures: Dr. Fehlings—DePuy, A Johnson & Johnson Company; Covidien; Synthes; Bioaxone; Depuy Spine. Ms. Tetreault—no conflicts. Drs. Kopjar and Massicotte—no information available. Dr. Yoon—Meditech; Biomet; Stryker; Phygen; Meditech Advisors; Medyssey; SpineNet. Dr. Arnold—Stryker; K2; Integra; Medtronic Sofamor Danek; Synthes; Smith & Nephew; Medtronic; Orthofix, Inc.; Cerapedics; LANX; ATRM Johnson & Johnson; BHR Pharma; Alphatec Spine. Dr. Vaccaro—Aesculap/B.Braun; DePuy, A Johnson & Johnson Company; Globus Medical; Medtronic Sofamor Danek; Stout Medical; Applied Spine; Progressive Spinal Technologies; Advanced Spinal Intellectual Property; Computational Biodynamics; Paradigm Spine; K2M; Replication Medica; Spinology; Spine Medica; Orthovita; Vertiflex; Small Bone Technologies; NeuCore; Crosscurrent; Syndicom; In Vivo; Flagship Surgical; Location Based Intelligence; Gamma Spine; Spinicity; AO North America; Cerapeutics; Nuvasive.

Jennie McKee, staff writer for AAOS Now, can be reached at mckee@aaos.org

Bottom Line

• This prospective, multicenter study analyzed important predictors of surgical outcomes in CSM patients.
• Investigators created a model with six predictors: age, duration of symptoms, smoking status, impairment of gait, psychological comorbidities, and baseline severity score.
• Severe and long-standing compression in the spinal cord leads to irreversible damage; age, smoking status, and certain comorbidities are also important outcome predictors.