57 - Comparison of postoperative recovery of upper limb motor deficit between anterior spinal fusion and posterior cervical foraminotomy for cervical spondylotic radiculopathy

Introduction
Cervical spondylotic radiculopathy (CSR) can result in motor deficits in the upper limb, in addition to causing radicular pain and sensory disturbances, the distribution of which depends on the nerve affected. Severe muscle atrophy can significantly impact a patient's daily activities. Anterior spinal fusion (ASF) and posterior cervical foraminotomy (PCF) are well-established procedures for CSR without myelopathy. However, it is still unclear which of the two procedures has a greater effect on motor deficits caused by CSR.
Aims/Objectives
This study aims to compare the postoperative outcomes of ASF and PCF for patients with CSR without myelopathy, with a specific focus on the improvement of manual muscle testing (MMT) grades in affected muscles.
Methods
A total of 233 consecutive patients undergoing primary ASF or PCF for CSR at 27 affiliated institutions between 2012 and 2021 were reviewed from a surgeon-maintained database for spinal surgery. Among them, 105 patients (the ASF group, n=51; the PCF group, n=54) suffering from upper limb motor deficit (0–3 MMT grade) due to CSR without myelopathy who were followed up for ≥12 months postoperatively were included. We retrospectively collected detailed information on the two groups including the pre- and postoperative (at 3, 6 and 12 months after surgery and the final follow-up) MMT grades of upper limbs, and the date of onset of preoperative upper limb motor deficit. Postoperative improvement of MMT grades in the most impaired muscles was compared between the two groups. Statistical analyses used were Student’s t-test, Mann-Whitney U test, Fisher’s exact test and Cox regression analysis.
Results
The ASF and PCF groups were comparable in terms of age (mean, 64.5 years vs 61.0 years), sex (female, 14% vs 15%), preoperative MMT grade, duration of symptoms and operative time. Estimated blood loss was significantly lower in the ASF group compared with the PCF group (median, 10 g vs 50 g; p< 0.001). Follow-up period was significantly longer in the ASF group than in the PCF group (median, 36.5 months vs 24.5 months; p=0.004) (Table 1). There was no significant difference in the proportion of patients with excellent recovery (MMT grade 2 or more) at the final follow-up between the ASF and PCF groups (75% vs 83%; p=0.27). The proportions of patients who experienced excellent recovery at 3, 6 and 12 months postoperatively were 18%, 45% and 51% in the ASF group, and 43%, 57% and 80% in the PCF group, respectively. The median time to achieve excellent recovery was 12.0 and 6.0 months in the ASF and PCF groups, respectively. The PCF group showed significantly earlier motor recovery than the ASF group (p=0.019, Cox regression analysis) (table 2).
Conclusions
The study found that the proportion of patients with excellent motor recovery at the final follow-up was similar between the ASF and PCF groups. However, the PCF group showed significantly earlier motor recovery than the ASF group. Irritation to nerve roots by the persistence of intervertebral micro motion until bone union might have contributed to delayed motor improvement after ASF.