C4/5 Facetectomy Is Associated With Improved Recovery of C5 Palsy in Severe Foraminal Stenosis After Posterior Cervical Decompression and Fusion

Introduction: C5 palsy is a disabling complication after posterior cervical decompression and fusion (PCDF). Whether C4/5 facetectomy reduces the incidence or improves the outcomes of C5 palsy remains uncertain. Therefore, this study aimed to (1) test the association of C4/5 facetectomy with the incidence and recovery of C5 palsy and (2) identify radiological risk factors for C5 palsy. Methods: A single-center retrospective cohort study was conducted between April 2013 and January 2024. Adults with degenerative cervical myelopathy, including ossification of the posterior longitudinal ligament, who underwent PCDF that included C4/5 were included. Deltoid manual muscle testing (MMT) was assessed preoperatively at discharge and at the final follow-up. Axial CT was used to measure the bilateral C4/5 foraminal diameter (FD). MRI was used to evaluate posterior cord shift at C4/5 and intramedullary T2 high-signal intensity (T2HI) at C3/4 and C4/5. C5 palsy was defined as a decrease from MMT grade ≥3 to ≤2; recovery was defined as improvement to MMT grade ≥3 at the final follow-up. A prespecified severe stenosis subgroup was defined as FD<2.6 mm. Group comparisons included Fisher’s exact test and unpaired t tests; multivariable logistic regression was used to identify risk factors. Results: Ninety-four patients were included; C5 palsy occurred in 20 (21.3%) patients. Facetectomy was not associated with C5 palsy incidence. T2HI at C3/4 was independently associated with C5 palsy (OR: 3.11, 95% CI: 1.05-9.74; p=0.04). In the severe stenosis subgroup, facetectomy did not reduce the incidence of C5 palsy but was associated with improved recovery from C5 palsy (100% (7/7) vs. 25% (1/4); p=0.02). Conclusions: In patients who underwent PCDF including C4/5, C4/5 facetectomy was not associated with a lower occurrence of postoperative C5 palsy. However, in patients with severe preoperative foraminal stenosis, facetectomy was associated with improved recovery after C5 palsy occurred. T2HI at C3/4 was independently associated with C5 palsy development. These findings do not support routine facetectomy for prophylaxis. The observed association between facetectomy and improved recovery in selected patients with marked foraminal stenosis should be interpreted as exploratory, given the retrospective design and small subgroup size.