Predisposing factors for poor outcome of surgery for cervical spondylotic amyotrophy: a multivariate analysis.

The purpose of this study was to characterize risk factors for poor surgical outcome in patients with cervical spondylotic amyotrophy (CSA). We retrospectively reviewed 88 cases of CSA surgery and investigated age, sex, duration of symptoms, atrophy type, preoperative muscle power, signal changes on MRI, anterior horn (AH) or ventral nerve root (VNR) compression, compression levels, surgical approach and postoperative recovery. Fifty (56.8%) patients had good surgical outcome. Logistic regression, with poor outcome as dependent variable, showed independent risks associated with duration of symptoms (OR; 1 for symptom duration less than 3 months versus 3.961 [95% CI; 1.203-13.039, p = 0.024] for symptom duration of 3-6 months versus 18.724 [95% CI; 3.967-88.367, p < 0.001] for symptom duration greater than 6 months), compression type (OR; 1 for VNR versus 4.931 [95% CI; 1.457-16.685, p = 0.010] for AH versus 5.538 [95% CI; 1.170-26.218, p = 0.031] for VNR + AH), and atrophy type (OR; 1 for proximal type versus 6.456 [95% CI; 1.938-21.508, p = 0.002] for distal type). These findings suggest that a long duration of symptoms, AH or both AH and VNR compression, and distal type are risk factors for poor surgical outcome in patients with CSA.