[Analysis of outcome and prognostic factors of anterior approach for two-level cervical spondylotic myelopathy]

To investigate the efficacy and possibly prognositic factors of anterior approach on two-level cervical spondylotic myelopathy.A retrospective review was performed on 44 cases of two-level cervical spondylotic mydopathy from Jun. 2007 to Sep. 2009. Among the patients, 24 cases were male and 20 cases female, with an average age of (60.072 +/- 10.77) years (ranged from 39 to 80 years). The affected segments ranged from C(3.4)-C(6.7). Improvements of cervical curvature and segmental height, preoperative sagittal diameter of the spinal cord at the site of maximal compression and signal intensity changes on T2WI were respectively measured. Function of nerves was assessed according to Japanese orthopaedic association system (JOA:17 score) before and after surgery. Operation by anterior approach including: anterior corpectomy and titanium cage fusion with internal fixation, anterior corpectomy body and auto iliac bone fusion with internal fixation. Statistical analysis was made on the correlation between JOA recovery rate and prognostic factors.Improvements of cervical curvature was -9.1 degrees to 16.6 degrees with the mean of (1.30 +/- 5.77) degrees and improvements of segmental height was -0.3 to 12.3 mm with the mean of (4.23 +/- 3.08) mm. Sagittal diameter of the spinal cord at the site of maximal compression was 1.6 to 7.2 mm with the mean of (4.01+/- 1.25) mm. T2WI with high signal changes was in 29 cases, no change in 15 cases. Bleeding amount was 50 to 700 ml with the mean of (242.05 +/- 148.22) ml. Operative time was 90 to 250 min with the mean of (153.75 +/- 34.54) min. All patients were followed up from 6 to 31 months with an average of (17.18 +/- 7.41) months. The mean JOA score preoperatively was (12.73 +/- 2.23); at the final follow-up, the JOA score was(15.09 +/- 1.91); and the recovery rate was (60.01 +/- 26.98)%. According to standard of JOA scoring, 16 cases obtained excellent result, 12 good, 15 fair and 1 poor. The effect of anterior approach had correlations with age, time of course, preoperative JOA score, sagittal diameter of the spinal cord at the site of maximal compression and signal intensity changes on T2WI, but had no correlations with operation time, bleeding amount and improvements of cervical curvature and segmental height.Two-level cervical spondylotic myelopathy can achieve good effect through anterior approach. The extent of the spinal cord compression may be a reliable and direct factor to judge effect.