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Diagnosis, Heritability, and Outcome Assessment in Cervical Myelopathy: A Consensus Statement

Wilson, Jefferson R., MD*; Fehlings, Michael G., MD, PhD*; Kalsi-Ryan, Sukhvinder, PT, PhD*; Shamji, Mohammed F., MD, PhD*; Tetreault, Lindsay A., HBSc*; Rhee, John M., MD; Chapman, Jens R., MD

doi: 10.1097/BRS.0b013e3182a7f4bf
Diagnosis, Work-Up, and Treatment Planning
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This section of the cervical spondylotic myelopathy (CSM) Spine focus issue collates evidence related to diagnosis, outcome assessment, and genetics. Given that a variety of different disease states can present similarly, a guide for diagnosing and differentiating CSM from other neurological conditions is initially presented. Although the value of magnetic resonance imaging in diagnosing CSM is cemented, its value as a tool to predict future outcome is less well established. To this end, the existing evidence suggests that although increased T2 cord signal is of limited value, the pairing of high T2 signal with low T1 signal, or a high T2 to T1 signal ratio, is associated with a reduced potential for neurological recovery at follow-up. Outcome assessment in CSM is of paramount importance when monitoring patients’ clinical course or measuring the efficacy of therapeutic interventions. Here, the main outcome measures that have been used to assess patients with CSM are reviewed. At present, we recommend that clinicians acquire the modified Japanese Orthopaedic Association scale score and the Neck Disability Index on all patients with CSM at presentation and follow-up. Finally, in regard to genetics, the existing evidence seems to support the principle of an inherited predisposition to both CSM and ossification of the posterior longitudinal ligament. Although several genetic polymorphisms have been consistently associated with ossification of the posterior longitudinal ligament, no specific polymorphisms were consistently associated with CSM.

*University of Toronto, Toronto, Ontario, Canada

Emory University, Atlanta, GA; and

University of Washington, Seattle, WA.

Address correspondence and reprint requests to Michael G. Fehlings, MD, PhD, FRCS, University of Toronto, 27 King's College Circle, Toronto, Ontario, Canada M5S 1A1; E-mail: michael.fehlings@uhn.on.ca.

Acknowledgment date: June 4, 2013. First revision date: July 12, 2013. Acceptance date: July 25, 2013.

The manuscript submitted does not contain information about medical device(s)/drug(s).

Supported by AOSpine North America, Inc. Analytic support for this work was provided by Spectrum Research, Inc., with funding from the AOSpine North America.

Relevant financial activities outside the submitted work: support for travel, board membership, consultancy, royalties, grants/grants pending, stock/stock options, and payment for lectures.

In the context of cervical myelopathy, and in medicine in general, our ability to offer effective treatment is contingent upon our ability to make an accurate diagnosis. Once a diagnosis is made, focus moves to selecting the treatment approach best suited to the characteristics of the patient under consideration. In addition to steering management, these patient and disease characteristics are also used to predict both perioperative and postoperative outcomes. However, such predictions depend on our ability to assess outcome through the use of valid and reliable outcome measurement tools that are sensitive to change in patient status over time. This section includes articles pertinent to diagnosis, outcome assessment, and the use of imaging in the evaluation of the patient with myelopathy. In addition, the topic of genetic predictors of disease development and surgical outcome is also explored.

The first article of this section by Kim et al provides a framework to help clinicians approach the diagnosis of cervical myelopathy while remaining cognizant of additional neurological conditions that may present similarly. This article will be of particular value for primary care physicians who are often required to triage patients for additional investigation and consultation on the basis of nonspecific symptoms. After starting with a comprehensive differential diagnosis, the authors provide an approach to differentiate cervical myelopathy from conditions that may mimic cervical spondylotic myelopathy (CSM), such as amyotrophic lateral sclerosis or multiple sclerosis, on the basis of the presence or absence of specific discriminative symptoms, signs, imaging findings, and/or electrophysiological results.

Magnetic resonance imaging (MRI) has become a cornerstone in the diagnosis of CSM, allowing for direct visualization and characterization of cord compression.1 However, the role of MRI in guiding treatment decisions (surgery vs. conservative management) and in predicting clinical outcomes remains is less well defined.2 In the second article in this section, Tetreault et al perform a systematic review of the literature to assess how MRI can be used as a tool to predict outcomes and steer management for patients with symptomatic CSM. In the context of symptomatic nonsurgically treated patients, the presence of circumferential cord compression was the only MRI finding associated with future neurological deterioration.3 However, given the paucity of evidence, the authors recommend against the use of MRI findings to guide decision of operative versus nonoperative care for patients with symptomatic CSM. In surgically treated patients, although the preoperative presence of high T2 spinal cord signal in isolation was not found to be predictive of outcome, the pairing of high T2 signal with low T1 signal or a high T2 to T1 signal ratio seemed to be associated with a reduced potential for neurological recovery at follow-up. As a result, the authors recommend that, if used as a predictive tool, T1- and T2-weighted MRI sequences be considered in combination when predicting likely postsurgical outcomes. In addition to preoperative MRI, we also recommend that an additional MRI be completed in the postoperative period to ensure the adequacy and completeness of cord decompression. Recently, MRI findings including persistent abnormal T2 cord signal and lack of cord re-expansion after surgery were found to portend worse long-term neurological status.4

The clinical tools used to characterize the degree of deficit and disability at patient presentation are also the measures used to track patients’ status throughout follow-up. As a result, identifying and developing reliable methods for capturing clinically important change in the CSM population is the first step in monitoring natural history and measuring the efficacy of current and future treatment strategies.5 Consequently, consensus regarding the most appropriate outcome measures for collection in the CSM population has important clinical and research implications. Accordingly, in the third article in this section, Kalsi-Ryan et al summarize literature on the main outcome measures used in assessing and classifying the deficits seen in CSM in order to identify those that are most useful and sensitive for assessment of patients with CSM. Although a number of outcome measures have been used in the context of CSM, the disease-specific psychometrics of many of these measures remain inadequately studied. The authors have assembled a suggested list of the most appropriate measures for use in CSM related to (1) upper limb assessment (QuickDASH, GRASSP, grip strength), (2) balance (Berg Balance Scale), (3) gait (10-m walk test, 30-m walk test, and 6-min walk test), and (4) overall global status (modified Japanese Orthopaedic Association Scale, Neck Disability Index, and SF-36). Of these outcome measures, it is recommended that clinicians acquire the modified Japanese Orthopaedic Association Scale and Neck Disability Index on all patients with CSM at presentation and throughout follow-up. This will allow for consistency across centers and provide added information to assist in clinical decision making.

Finally, the last topic covered in this section relates to the genetics of CSM and ossification of the posterior longitudinal ligament (OPLL). Although routine genetic testing is not performed or recommended for either of these conditions at present, such testing may one day be useful to help estimate individuals’ risk of myelopathy development or to help predict postsurgical outcomes. In the article by Wilson et al, a systematic review was performed to evaluate for literature evidence of a familial predisposition to both of these conditions as well as for their association with specific genetic polymorphisms. In sum, the existing low level of evidence seemed to support the principle of an inherited predisposition to both CSM and OPLL. With respect to OPLL, 2 single nucleotide polymorphisms, related to collagen-encoding genes, were consistently seen at higher frequencies in case patients than in controls. In contrast, however, no specific polymorphisms were consistently associated with CSM. Finally, although 1 CSM study associated the presence of the apo-lipoprotein IV allele with worse postsurgical neurological outcomes, there was insufficient evidence to support the use of a specific genetic predictor of surgical outcome for either condition.6

The articles in this section will help update the clinician as to the current state of evidence surrounding the diagnosis, evaluation, and heritability of cervical myelopathy. In addition, by illuminating questions and topics in which evidence is limited, this work serves as a launching point for future research and investigation.

Summary Statements.

Statement 1: If used as a predictive tool, T1- and T2-weighted MRI sequences should be considered in combination when predicting likely postsurgical outcomes. An additional MRI should be completed in the postoperative period to ensure the adequacy and completeness of cord decompression.

Statement 2: Based on the literature reviewed, the most appropriate measures for use in CSM are (1) QuickDASH, GRASSP, and grip strength for upper limb assessment; (2) Berg Balance Scale for balance; (3) 10-m walk test, 30-m walk test, and 6-minute walk test for gait; and (4) modified Japanese Orthopaedic Association Scale, Neck Disability Index, and SF-36 for overall global status.

Statement 3: Although the existing literature provides only a low level of evidence, this evidence supports the principle of an inherited predisposition to both CSM and OPLL.

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References

1. Kalsi-Ryan S, Karadimas SK, Fehlings MG. Cervical spondylotic myelopathy: the clinical phenomenon and the current pathobiology of an increasingly prevalent and devastating disorder [published online ahead of print November 30, 2012]. Neuroscientist 2013;19:409–21. doi:10.1177/1073858412467377.
2. Fehlings MG, Arvin B. Magnetic resonance imaging and outcome. J Neurosurg Spine 2010;12:56–8.
3. Shimomura T, Sumi M, Nishida K, et al. Prognostic factors for deterioration of patients with cervical spondylotic myelopathy after nonsurgical treatment. Spine (Phila Pa 1976) 2007;32:2474–9.
4. Arvin B, Kalsi-Ryan S, Karpova A, et al. Postoperative magnetic resonance imaging can predict neurological recovery after surgery for cervical spondylotic myelopathy: a prospective study with blinded assessments. Neurosurgery 2011;69:362–8.
5. Holly LT, Matz PG, Anderson PA, et al. Functional outcomes assessment for cervical degenerative disease. J Neurosurg Spine 2009;11:238–44.
6. Setzer M, Vrionis FD, Hermann EJ, et al. Effect of apolipoprotein E genotype on the outcome after anterior cervical decompression and fusion in patients with cervical spondylotic myelopathy. J Neurosurg Spine 2009;11:659–66.
Keywords:

cervical spondylotic myelopathy; diagnosis; imaging; outcome assessment; genetics; heritability; ossification of the posterior longitudinal ligament

© 2013 by Lippincott Williams & Wilkins