C5 Palsy After Cervical Spine Surgery: Epidemiology, Risk Factors, and Management

» C5 palsy is an infrequent but clinically meaningful complication after cervical decompression, classically presenting as new deltoid—and often biceps—weakness (with or without shoulder pain) that is typically delayed in onset (most often postoperative days 2-7) and occurs without global neurologic decline. » Incidence varies by procedure and technique—pooled estimates are roughly 4% to 7% overall, with the highest rates after multilevel posterior laminectomy and fusion (∼9%-12%), lower rates after laminoplasty (∼4%-5%; technique-dependent), and generally lower but nonzero rates after anterior procedures (with corpectomy higher risk than anterior cervical discectomy and fusion). » Risk appears multifactorial, but the most reproducible predictors center on C4-5 anatomy and postoperative cord/foraminal mechanics (notably preexisting C4-5 foraminal stenosis, greater posterior cord drift/shift, and factors such as ossified posterior longitudinal ligament), with additional associations including male sex, older age, multilevel surgery, posterior longitudinal ligament resection, corpectomy (especially ≥3 levels), and asymmetric/wide decompression. » Prevention is best approached as risk-adapted surgical planning rather than a single maneuver: incorporate approach selection when equipoise exists, scrutinize preoperative imaging for C4-5 foraminal and cord morphology, avoid excessive/asymmetric decompression or alignment changes that may exacerbate cord drift, and consider selective prophylactic C4-5 foraminotomy in high-risk patients (recognizing most supporting evidence is observational). » Most patients improve substantially with conservative management, but prognosis depends on initial severity; management should prioritize early imaging to exclude surgically correctable causes, structured rehab/close strength monitoring, and early referral for peripheral nerve evaluation when severe palsy (manual muscle testing ≤2/5) shows little improvement by ∼3 months, given the time-sensitive window for successful nerve transfer reconstruction (often performed within the first ∼6-9 months when indicated).