Impact of the surgical strategy on the incidence of C5 nerve root palsy in decompressive cervical surgery

Abstract

Objective: Our aim was to identify the impact of different surgical strategies on the incidence of C5 palsy.

Background: Degenerative cervical spinal stenosis is a steadily increasing morbidity in the ageing population. Postoperative C5 nerve root palsy is a common complication with severe impact on the patients´ quality of life.

Methods: We identified 1708 consecutive patients who underwent cervical decompression surgery due to degenerative changes. The incidence of C5 palsy and surgical parameters including type and level of surgery were recorded to identify predictors for C5 nerve palsy.

Results: The overall C5 palsy rate was 4.8%, with 18.3% of cases being bilateral. For ACDF alone the palsy rate was low (1.13%), compared to 14.0% of C5 palsy rate after corpectomy. The risk increased with extension of the procedures. Hybrid constructs with corpectomy plus ACDF at C3-6 showed significantly lower rates of C5 palsy (10.7%) than corpectomy of two vertebrae (p = 0.005). Multiple regression analysis identified corpectomy of C4 or C5 as a significant predictor. We observed a lower overall incidence for ventral (4.3%) compared to dorsal (10.9%) approaches (p<0.001). When imaging detected a postoperative shift of the spinal cord at index segment C4/5, palsy rate increased significantly (33.3% vs. 12.5%, p = 0.034).

Conclusions: Extended surgical strategies, such as dorsal laminectomies, multilevel corpectomies and procedures with extensive spinal cord shift were shown to display a high risk of C5 palsy. The use of extended procedures should therefore be employed cautiously. Switching to combined surgical methods like ACDF plus corpectomy can reduce the rate of C5 palsy.

Fig 1

Schematic overview of C5 palsy rate for single level ACDF (A), single level corpectomy (B) or two level corpectomy (C) for the respective cervical level (not all levels shown). The cervical spine is shown in the sagittal view with the spinal cord marked in blue, the surrounding cerebrospinal fluid in yellow and a schematic stenotic narrowing in red. D-F shows representative corresponding lateral X-ray images of the surgical results. Single level ACDF (D), single level corpectomy (E) and two level corpectomy (F). Integrated tables G-I display the additional statistical values to the corresponding surgical strategies, including the overall C5 palsy rate for the respective surgical approach. Statistical analysis applied routine cross tables and chi² testing.

Fig 2

Sagittal schematic of the surgical spine to illustrate C5 palsy rate of two level hybrid constructs, i.e. combination of corpectomy and ACDF, for the levels C4-7 (A) and C3-6 (B). Statistical values are summarized in C, including overall C5 incidence rate for hybrid constructs on all levels around the vulnerable level of C4/C5. Additional information on other possible surgical constructs around the level of C4/C5 is presented in D, allowing for the direct comparison of C5 palsy rate of the different surgical strategies. Statistical analysis applied routine cross tables and chi² testing.

Fig 3

Multivariate regression analysis of predictive outcome parameters for C5 palsy rate as illustrated by forest plots (A). Dots indicate the odds-ratio (OR) and whiskers for 95% confidence interval (CI). Integrated table (B) shows the corresponding statistical values including the p-value after regression analysis.

Fig 4

Illustration of the cervical spinal nerve roots exiting the spinal cord (left). The right side schematically depicts the angle, including the superior and inferior rootlets of the individual nerve root, emphasizing the distinct nerve root exit of C5 as formerly described by Hung et al. and Alleyne et al. [19,20]. Sagittal T2w magnetic resonance imaging of the cervical spine before (B) and after (C) dorsal decompression. This image highlights the dorsal shift of the spinal cord due to decompression. Figure D and E schematically explain the postulated hypothesis on the pathophysiological basis of C5 nerve root palsy. A slowly established ventral stenosis (D) results in a dorsal shift of the myelon, leading to a stretched C5 nerve root (blue), as depicted in the axial view. Ventral decompression through ACDF consecutively leads to a ventral shift of the spinal cord with kinking of the nerve root. A dorsal stenosis (E) represents an analogous situation with dorsal shifting of the spinal cord after laminectomy and fusion, as suggested by the screws. Additional information on the pathophysiological basis can be found in supporting information S1 Video.