Insufficient Recovery From C5 Palsy Following Anterior Cervical Decompression and Fusion.

STUDY DESIGN Retrospective study. OBJECTIVE To determine the risk factors for insufficient recovery from C5 palsy (C5P) following anterior cervical decompression and fusion (ADF). SUMMARY OF BACKGROUND DATA Postoperative C5P is a frequent but unsolved complication following cervical decompression surgery. Although most patients gradually recover, some recover only partially. When we encounter new-onset C5P following ADF, the question that often arises is whether the palsy will sufficiently resolve. METHODS We retrospectively reviewed consecutive patients who underwent ADF at our institution. We defined C5P as postoperative deterioration of deltoid muscle strength by two or more grades determined by manual muscle testing (MMT). We evaluated the following demographic data: patient factors, surgical factors, and radiological findings. C5P patients were divided into two groups: sufficient recovery (MMT grade≧4) and insufficient recovery (MMT grade < 4). Each parameter was compared between the two groups. RESULTS Of 839 patients initially included in the study, 57 experienced new-onset C5P (6.8%). At the final follow-up (mean, 55 ± 17 months), 41 patients experienced sufficient recovery, whereas 16 (28%) still exhibited insufficient recovery. Compared with the sufficient recovery group, patients with insufficient recovery exhibited a higher decompression combination score, a larger anterior shift in preoperative cervical sagittal balance, less lordosis of the pre- and postoperative C4/C5 segment, more frequent stenosis at the C3/C4 segment, lower deltoid strength at C5P onset, more frequent co-occurrence of biceps weakness, greater postoperative expansion of the dura mater, and more frequent presence of postoperative T2 high-intensity areas. Multivariate analysis revealed that co-occurrence of biceps muscle weakness, less lordosis at the preoperative C4/C5 segment, and postoperative expansion of the dura mater were independent predictors of insufficient recovery. CONCLUSIONS The combination of unfavorable conditions, such as potential spinal cord disorder, cervical malalignment, and excessive expansion of the dura mater after corpectomy, predicts insufficient recovery from C5P.