Cervical Sagittal Range of Motion as a Predictor of Symptom Severity in Cervical Spondylotic Myelopathy

A retrospective review of radiographic data and functional outcomes.

The aim of this study was to evaluate whether myelopathy symptom severity upon presentation corresponds to sagittal plane alignment or nonmyelopathy symptoms, such as pain, in patients with cervical spondylotic myelopathy (CSM).

Cervical sagittal balance is an important parameter in the outcome of surgical reconstruction. However, the effect of sagittal alignment on symptom severity in patients who have not undergone spine surgery is not well defined.

A consecutive series of CSM patients was identified at an academic institution. Preoperative radiographs were analyzed for sagittal vertical axis (C2SVA), C7 slope (C7S), C2-C7 angle in neutral (C27N), flexion (C27F), and extension (C27E), and range of motion (C27ROM). Neutral alignment was categorized as lordotic, kyphotic, or sigmoid/straight. Outcomes collected were SF-12, neck disability index, arm pain, neck pain, and modified JOA (mJOA). Pearson coefficients determined correlations between radiographic and outcome parameters. Multivariate regression evaluated predictive factors of mJOA.

Radiographic parameters did not correlate with pain. Increasing age, smaller C27ROM, and smaller flexion angles correlated to lower (more severe) baseline mJOA scores. ROM (and not static alignment) was the only significant predictor of mJOA in the multivariate regression. Despite significant radiographic differences between lordotic, kyphotic, and sigmoid/straight alignment groups, myelopathy severity did not differ between these groups.

Static, neutral alignment, including SVA and lordosis, did not correlate with myelopathy or pain symptoms. Greater C27ROM and increased maximal flexion corresponded to milder myelopathy symptoms, suggesting that patients with myelopathy may compensate for cervical stenosis with hyperflexion, similar to that which is observed in the lumbar spine. In a CSM patient population, dynamic motion and compensatory deformities may play a more significant role in myelopathy symptom severity than what can be discerned from standard, neutral position radiographs.

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