C5 root palsy after posterior cervical decompression and fusion surgeries: role of Intraoperative Neurophysiological Monitoring (IONM)

Abstract Objectives Upper limb paresis resulting from damage to the fifth cervical root (C5) is a relatively rare complication following cervical spine surgery, with reported prevalence rates ranging from 0% to 30% across various centers. This condition is typically unilateral and transient. This study discusses the incidence of this complication and evaluates the role of intraoperative neuromonitoring (IONM) in its diagnosis. Materials and methods This study analyzed 137 patients who underwent posterior decompression and fusion for cervical spinal diseases at levels C2-C7. IONM employed somatosensory evoked potentials (SSEP), motor evoked potentials (MEP), and free-running electromyography (EMG), in accordance with the standards set by the International Society of Intraoperative Neurophysiology. Results Intraoperative EMG identified fifth cervical root irritation in 15 patients, subsequently reported to the surgeon. The incidence of C5 palsy (C5P) in our cohort was 6.8%, with one patient experiencing permanent C5P, while two patients recovered after several months, and three achieved full recovery within weeks. Nine patients exhibited no motor weakness, radicular pain, or numbness postoperatively. MEP amplitude changes were observed in two patients. Notably, SEP waves remained unchanged. Among the two patients who experienced transient weakness due to C5 root injury, no abnormal findings were recorded during IONM, and both fully recovered. Conclusion IONM has the capability to detect fifth cervical root injury in approximately 75% of cases. However, the interventions required by surgeons in these instances are complex, and consensus on the best practices remains elusive, despite evidence derived from the experiences of skilled surgeons.