The influence of concomitant syringomyelia on patient reported outcome following hind brain decompression

Objectives: To evaluate the impact of concomitant syringomyelia and self-reported complications on patient reported outcome measures in patients undergoing hindbrain decompression for a Chiari 1 malformation.Methods: Prospective data collection of 95 patients who underwent Foramen magnum decompression between March 2011 and March 2015. Outcome evaluation was performed using the Core Outcome Measure Index questionnaire for neck (COMI-neck) and Gestalt impression (to assess improvement of headaches). Patients were split into two cohorts, those with and those without syringomyelia. Both cohorts were compared in all domains of the COMI neck questionnaires, headache, and complications. Non-parametric data were analysed with Wilcoxon signed rank, Mann-Whitney U and Fisher exact tests. Parametric data were analysed with Student T-test. SPSS Software was used for analysis.Results: 79 patients returned 1 year follow-up COMI-neck questionnaires. Thirty three had concomitant syringomyelia and 46 had no syringomyelia present. There was no statistically significant difference in patient reported outcomes (COMI-neck index median 4.5 +/- 3.3 vs 4.2+/-3.2; p = .376) between the syrinx and non-syrinx cohorts. However postoperative neck pain (median 4 +/- 3.35 vs 1 +/- 3.17; p 0.041) and arm/shoulder pain scores (2 +/- 3.38 vs. 0+/- 2.628; p 0.049) were significantly lower in the non-syrinx cohort. In both cohorts 57% patients had an improvement in headache. 92% patients were 'satisfied' with treatment and 63% stated that the operation 'helped'. 54% patients in the syrinx and 59% in the non-syrinx cohort self-reported complications. There was no statistical difference in outcomes of the patients with and without self-reported complications (p = .121).Conclusions: This study demonstrates that the clinical effectiveness of FMD is lower and reported complications are higher when evaluated by patient reported outcome measures as opposed to surgeon reported complications. Patients with and without concomitant syringomyelia showed equal overall outcomes, although neck and arm pain was worse in syrinx patients.