Wednesday, September 26, 2018 7:35 AM–9:00 AM ePosters: P109. Effect of cervical deformity correction on stenosis, spinal canal and cord compression utilizing magnetic resonance and computed tomography imaging modalities

Abstract

BACKGROUND CONTEXT Cervical deformity (CD), often degenerative in etiology, is typically accompanied by the onset of symptomatic spinal stenosis. It is hypothesized that causation of spinal canal and cord compressive forces is multifactorial, with reduction of compressive forces being a key driver of symptom alleviation. PURPOSE To quantify and assess the relationship between postoperative changes to sagittal alignment, canal or cord decompression, and symptom alleviation. STUDY DESIGN/SETTING Retrospective review of a prospective CD database. PATIENT SAMPLE Twenty-seven CD patients. OUTCOME MEASURES Stenotic Levels, Pavlov Ratio, Spinal Canal Cross-Sectional Area, Spinal Cord Cross-Sectional Area, mJOA scores, NSR Neck Pain scores. METHODS ConsecutiveCD patients (C2–C7 Cobb>10°, CL>10°, cSVA>4 cm, or CBVA>25°) undergoing multilevel fusion. Those with pre-operative magnetic resonance imagings (MRIs) and 1-year post-operative cervical MRI or CT scans were assessed for spinal canal and cord cross-sectional area, using dedicated imaging software at each interspace and body from C2–C7, and the apex of deformity[apex]. Stenotic vertebral levels were measured using Pavlov's method from C2 to C7: a ratio of canal to vertebral body RESULTS A total of 27 patients were included (61±10 years, 64.2%F, BMI: 29.6±8.0, CCI: 0.81±1.1). BL radiographic assessment: TS-CL: 34.0±17.2; Cervical Lordosis: −1.6±15.7; cSVA: 36.3±18.5; PI-LL: 0.12±19.3; Pelvic Tilt: 20.1±11.6; SVA: 0.94±71.6. Ames classification deformity descriptors: C: 57.7%, CT: 30.8%, T: 7.7%, S: 3.8%. Surgical approach included 7.4% anterior, 51.9% posterior, 40.7% combined; 23(79%) patients had decompression procedures, all patients had an osteotomy, and mean fusion length was 8.6±4.2 levels. Following surgical intervention, mean canal cross-sectional area (267.5 mm2 vs. 320.5 mm2, p=.025), apex canal cross-sectional area (240 mm2 vs. 301.3 mm2, p=.039), and apex cord cross-sectional area (60.6 mm2 vs. 70.1 mm2, p=.019) all increased (regardless of decompression procedure status). Decreased stenotic levels (4.11vs. 2.97, p=.003) and improved apex pavlov ratios (0.76vs. 0.91, p=.032) were also observed. Cervical kyphosis correction correlated with Δ in stenotic levels (rs: 0.664, p=.001), Δ in mean C2–C7 pavlov ratio (rs: 0.601, p=.004), and Δ in apex canal area (rs: 0.562, p=.024). TS-CL correction correlated with Δ in stenotic levels (rs: 0.751, p CONCLUSIONS Sagittal realignment was associated with reduction of symptomatic stenosis and cord compressive forces, regardless of decompression status. Stenotic level reduction was associated with improved mJOA scores, while alleviation of dynamic radial compressive forces at the apex of deformity significantly reduced patient neck pain.