Incidence of C5 palsy in anterior cervical decompression & fusion, posterior cervical decompression & fusion and laminoplasty for degenerative cervical myelopathy: systematic review and meta-analysis of 21,231 cases

C5 palsy (C5P) is a common, yet poorly understood complication of cervical decompressive surgery, causing substantial disability and impacting postoperative quality of life. Despite extensive research, the actual incidence and distribution of C5P across different cervical surgical approaches over the past decade remain unclear. A comprehensive literature search was conducted on October 15, 2024, across Google Scholar, Embase, PubMed, Web of Science, and Cochrane Library databases. Studies reporting C5P incidence following surgery for degenerative cervical conditions, published until 2024, were included, excluding reviews, opinions, letters, and non-English manuscripts. Ninety-seven articles were included, encompassing 21,231 patients undergoing decompressive cervical surgery for degenerative cervical myelopathy. The overall incidence of postoperative C5P was 7% (95% confidence interval [CI], 4%-10%). The highest incidence was observed with circumferential fusion (combined anterior-posterior approach) at 16% (95% CI, 8%-24%), while the lowest was with anterior cervical decompression and fusion at 4% (95% CI, 3%-5%). Incidence rates following laminoplasty and laminectomy and fusion were 6% (95% CI, 5%-7%) and 10% (95% CI, 8%-12%), respectively. Recovery time ranged from 20.9 to 35 weeks, with 19.1%-33% of patients experiencing residual weakness. Significant risk factors included male sex, preoperative intervertebral foraminal stenosis, ossified posterior longitudinal ligament, open-door laminoplasty, laminectomy (with/without fusion), and excessive spinal cord shift. The role of C4-5 foraminotomy remains contested. Our meta-analysis identifies the posterior surgical approach as a significant risk factor for C5P. Circumferential fusion poses the highest risk, while laminoplasty can reduce the risk compared to laminectomy (alone or with instrumented fusion).