Cervical laminectomy of limited width prevents postoperative C5 palsy: a multivariate analysis of 263 muscle-preserving posterior decompression cases

Between 2006 and 2010, we performed wide laminectomy (wide LAM) alone, with decompression performed between the bilateral medial margin of the zygapophyseal joints, or double-door laminoplasty (DL) combined with wide LAM for cervical compressive myelopathy (CCM). From 2010, instead of wide LAM and DL, we began to perform narrow LAM, where the laminectomy width was no more than 2-3 mm wider than the spinal cord width (SW). This study aimed to elucidate the risk factors for C5 palsy by reviewing surgical outcomes. The clinical features and radiological findings of 263 CCM patients with or without C5 palsy were compared. Risk factors for C5 palsy were assessed using logistic regression analysis. The decompression width (DW) was defined as the laminectomy width or the width between the bilateral medial margins of the bony gutters in DL. Narrow LAM reduced the incidence of C5 palsy from 9.2 to 1.2%. DL was performed more frequently in the C5 palsy group. The difference between the DW and the SW (DW - SW) was significantly greater in the C5 palsy group. Posterior spinal cord shift, aging, and the number of consecutive laminae surgically treated were significantly higher in the C5 palsy group. The diameter of the foramen (DF) at C4/5 was significantly smaller in the C5 palsy patients. The logistic regression analysis revealed that DL, DW - SW, DF, and aging were risk factors for C5 palsy. Cervical laminectomy of limited width prevented postoperative C5 palsy without compromising the functional recovery.