Extremely Wide and Asymmetric Anterior Decompression Causes Postoperative C5 Palsy An Analysis of 32 Patients With Postoperative C5 Palsy After Anterior Cervical Decompression and Fusion

Study Design. Single-center retrospective study. Objective. We examined whether extremely wide and asymmetric anterior decompression causes postoperative C5 palsy. Summary of Background Data. Postoperative C5 palsy is a complication of cervical decompression surgery. We hypothesized that C5 palsy may be caused by nerve root impairment through extremely wide and asymmetric dural expansion due to unilateral predominant wide anterior decompression with concomitant C4-C5 foraminal stenosis. Methods. The study included 32 patients with postoperative C5 palsy from a cohort of 459 patients who underwent anterior cervical decompression and fusion at the C4-C5 disc level for cervical myelopathy. The 64 upper extremities were divided into 2 groups according to palsy side (n = 35) or nonpalsy side (n = 29). Also, to correlate radiological findings, 66 consecutive patients who underwent anterior cervical decompression and fusion without postoperative C5 palsy were selected as control. Results. In patients with C5 palsy, the unilateral decompression width on the palsy side was significantly larger than that on the nonpalsy side (8.63 vs. 6.92 mm, P = 0.0003). In addition, the decompression width was significantly larger (15.69 vs. 14.38 mm, P = 0.02), the diameter of the C4-C5 foramen was significantly smaller (2.73 vs. 3.24 mm, P = 0.0008), the anterior spinal cord shift was significantly smaller (0.14 vs. 0.73 mm, P < 0.0001), and significant decompression asymmetry (0.74 vs. 0.89, P = 0.0003) was present in the patients with C5 palsy compared with controls. Conclusion. Extremely wide and asymmetric decompression concomitant with pre-existing C4-C5 foraminal stenosis may cause postoperative C5 palsy. Our findings should be valuable for surgeons considering anterior cervical decompression and fusion that includes the C4-C5 level. Surgeons should consider restriction of the decompression width to less than 15 mm and avoiding asymmetric decompression to reduce the incidence of C5 palsy.