Predicting Unilateral Post-laminectomy C5 Palsy by Measuring C5 Exit Foramen Area on Preoperative Computed Tomography

Background and Aim: Postoperative C5 motor palsy is known as a common complication, not only after cervical laminectomy but also after anterior discectomy. There is no consensus on any of the proposed mechanisms of C5 palsy following posterior cervical decompression. It was found that C5 palsy is more common in patients with smaller C5 root foramen area. The purpose of this study was to define a cut-off value for C4-C5 foraminal area on preoperative computed tomography images to predict post-laminectomy C5 palsy. Methods and Materials/Patients: In this prospective clinical study, C4-C5 foraminal area of 119 patients with cervical spondylotic myelopathy calculated on reformatted pure sagittal computed tomography images value was defined by measuring maximal height and transverse diameter of foramina and a cut-off in which with lesser amounts, post-laminectomy C5 palsy was more common. Results: Of 119 patients with spondylotic myelopathy undergoing cervical laminectomy,23 ones experienced postoperative C5 palsy with mean C4-C5 foraminal area of 44.54±0.72 mm2.Mean C5 root exit foraminal area in patients with intact post-operative root function was calculated 56.78±5.48 mm2 and the difference between these two groups was statistically significant (P<0.05). No patient with C5 exit foraminal area more than 46 mm2had C5 palsy after laminectomy. Conclusion: The incidence of post-laminectomy C5 palsy is significantly higher in patients with C5 exit foraminal area less than 46 mm2. Prophylactic C4-C5 foraminotomy in this group may significantly reduce the risk of postoperative C5 nerve motor palsy, although the effect of this procedure is still debatable.