Changes in the cross-sectional area of deep posterior extensor muscles of the cervical spine after anterior decompression and fusion: 10-year follow-up study using MRI.

PURPOSE: To evaluate changes in the transverse area of deep posterior muscles of the cervical spine 10 years after anterior cervical decompression and fusion (ACDF), in comparison with healthy volunteers.

METHODS

Thirty-one patients (22 males, 9 females, mean age at follow-up 59.3 years, mean follow-up 12.1 years) who had undergone preoperative MRI and non-instrumented ACDF within levels C3-4 to C5-6 were enrolled. 32 asymptomatic volunteers (17 males, 15 females; mean age, 54.7 years; mean follow-up, 11.7 years) who underwent MRI between 1993 and 1996 served as controls. Follow-up MRI was performed on both patients and control subjects, and the cross-sectional areas of deep posterior muscles were measured digitally at levels C3-4, 4-5, and 5-6.

RESULTS

The mean total cross-sectional area in the ACDF and control groups was 4,693.6 ± 1,140.9 and 4,825.8 ± 1,048.2 mm(2) in the first MR study (P = 0.63), and 4,616.7 ± 1,086.0 and 5,036.7 ± 1,105.6 mm(2) at follow-up (P = 0.13). The total cross-sectional area in the ACDF group slightly decreased, while that in the control group increased (-77.1 ± 889.7 vs. 210.9 ± 622.0 mm(2), P = 0.14). The mean change in the cross-sectional area had no significant correlation with clinical symptoms, including neck pain or JOA score.

CONCLUSIONS

ACDF patients did not show a marked decrease in the cross-sectional area of the deep posterior cervical muscles, but as compared with control subjects there was a slight decrease. A decrease in the cross-sectional area of these muscles after ACDF may not result in the axial symptoms as seen in patients treated by posterior surgery.