Congenital Cervical Spine Stenosis in a Multicenter Global Cohort of Patients With Degenerative Cervical Myelopathy: An Ambispective Report Based on a Magnetic Resonance Imaging Diagnostic Criterion

BACKGROUND Congenital spinal stenosis (CSS) of the cervical spine is a risk factor for acute spinal cord injury and development of degenerative cervical myelopathy (DCM). OBJECTIVE To develop magnetic resonance imaging (MRI)-based criteria to diagnose preexisting CSS and evaluate differences between patients with and without CSS. METHODS A secondary analysis of international prospectively collected data between 2005 and 2011 was conducted. We examined the data of 349 surgical DCM patients and 27 controls. Spinal canal and cord anteroposterior diameters were measured at noncompressed sites to calculate spinal cord occupation ratio (SCOR). Torg–Pavlov ratios and spinal canal diameters from radiographs were correlated with SCOR. Clinical and MRI factors were compared between patients with and without CSS. Surgical outcomes were also assessed. RESULTS Calculation of SCOR was feasible in 311/349 patients. Twenty-six patients with CSS were identified (8.4%). Patients with CSS were younger than patients without CSS (P = .03) and had worse baseline severity as measured by the modified Japanese Orthopedic Association score (P = .04), Nurick scale (P = .05), and Neck Disability Index (P < .01). CSS patients more commonly had T2 cord hyperintensity changes (P = .09, ns) and worse SF-36 Physical Component scores (P = .06, ns). SCOR correlated better with Torg–Pavlov ratio and spinal canal diameter at C3 than C5. Patients with SCOR ≥ 65% were also younger but did not differ in baseline severity. CONCLUSION SCOR ≥ 70% is an effective criterion to diagnose CSS. CSS patients develop myelopathy at a younger age and have greater impairment and disability than other patients with DCM. Despite this, CSS patients have comparable duration of symptoms, MRI presentations, and surgical outcomes to DCM patients without CSS.