Neurological Disturbance of the Upper Extremities After Cervical Laminoplasty A Morphological Assessment Focused on the Intervertebral Foramen

Study Design. A retrospective study. Objective. The aim of this study was to explore the relationship between postoperative neurological disturbance of the upper extremities (NDUE) after cervical laminoplasty and intervertebral foraminal stenosis. Summary of Background Data. The relationship between foraminal stenosis and neurological disturbance in the C5 segment (C5 palsy) has been reported, but the relationship at other levels has not been examined before. We evaluated foraminal stenosis morphologically using three-dimensional computed tomography (3D-CT), alongside other risk factors for NDUE. Methods. We retrospectively reviewed patients treated by open-door laminoplasty at the authors' institution between January and June 2016. NDUE was defined as postoperative motor deterioration and/or newly emerged sensory disturbance within 2 weeks of surgery. Radiological measurements were performed in bilateral intervertebral foramina from C5 to C8, using 3D-CT. Investigation using magnetic resonance imaging (MRI) was also performed. Results. Thirty-one patients were reviewed, and 10 (32.3%) developed NDUE. Nineteen NDUE were observed: seven were in the C5 segment, five in the C6 segment, three in the C7 segment, and four in the C8 segment. Four patients (40%) had NDUE from multiple segments. The mean width of the foramen was 2.60 +/- 1.26 mm and 3.66 +/- 1.66 mm (P = 0.007), and cross-sectional area was 32.8 +/- 10.8 mm(2) and 41.6 +/- 12.4 mm(2) (P = 0.003), in symptomatic (n = 19) and nonsymptomatic (n = 187) foramina, respectively. The mean transverse diameter of bony spurs and the maximum shift of the spinal cord on MRI was significantly larger in the NDUE group. The odds ratio of having a foraminal cross-sectional area under 28.0 mm(2) in combination with a maximum spinal shift over 3.10 mm was 14.6 (P < 0.001). Conclusion. Stenosis of the intervertebral foramen could be a risk factor for NDUE after cervical laminoplasty, and could be aggravated by excessive posterior spinal cord shift.