AB0952 ASSESSING PIRIFORMIS SYNDROME IN AXIAL SPONDYLOARTHRITIS: A MAGNETIC RESONANCE IMAGING STUDY
Authors: K. Erol, E. Akyildiz Tezcan, S. Erol
Journal: Annals of the Rheumatic Diseases (2024)

<h3>Background:</h3> Piriformis syndrome, a significant non-discogenic cause of sciatica, results from the irritation or compression of the sciatic nerve by the piriformis muscle. This neuromuscular condition leads to hip and buttock pain, sometimes radiating down the leg, significantly impacting patients' quality of life. The etiology of piriformis syndrome is multifactorial, with sacroiliitis, often linked to rheumatic diseases, being a notably influential factor. Axial spondyloarthritis (axSpA), characterized by the involvement of the spine and sacroiliac joint, is a primary rheumatic cause of inflammatory sacroiliac joint involvement. <h3>Objectives:</h3> This study pioneers the investigation into the relationship between piriformis syndrome and axSpA. It aims to comprehensively examine sacroiliac magnetic resonance imaging (MRI) scans of patients diagnosed with axSpA, with a specific focus on identifying and analyzing indicators of piriformis syndrome. <h3>Methods:</h3> The study included 100 patients diagnosed with axSpA, divided into two groups of 50 each - one with radiographic axSpA (r-axSpA) and the other with non-radiographic axSpA (nr-axSpA). Participants were selected from those who received care at the Rheumatology outpatient clinic of Selcuk University Medical Faculty and had undergone sacroiliac MRI examinations. The MRI scans were analyzed by an experienced radiologist. The size and signal intensity of the piriformis muscle were assessed, with asymmetry exceeding 8 mm deemed abnormal. The presence of sciatic neuritis was evaluated based on the enlargement of the sciatic nerve and increased signal intensity on T2-weighted or STIR imaging. <h3>Results:</h3> In this study, we initially observed no significant differences in demographic characteristics and smoking habits between patients with r-axSpA and nr-axSpA axial spondyloarthritis. The median ages were similar (r-axSpA: 40.14 years; nr-axSpA: 38.94 years, p=0.608), as were the gender distributions (r-axSpA: 56% male; nr-axSpA: 46% male, p=0.424). Additionally, the proportion of smokers in both groups was not significantly different (r-axSpA: 42%; nr-axSpA: 26%, p=0.139), suggesting comparable demographic and lifestyle factors. Regarding the prevalence of specific conditions, 8% of r-axSpA patients showed signs of sciatic neuritis, slightly higher than the 4% in the nr-axSpA group (p=0.678), with 66.7% of these cases being bilateral. Piriformis asymmetry greater than 8 mm was noted equally in 4% of both groups. The incidence of radiological signs indicative of piriformis syndrome was slightly higher in r-axSpA cases (12%) compared to nr-axSpA cases (8%), but this difference was not statistically significant (p=0.739). Focusing on patients with and without MRI evidence of piriformis syndrome, the median ages were 43.1(11.47) years and 39.14 (11.62) years, respectively, showing no significant difference (p=0.309). Gender distribution was also similar across both groups (60% female in the piriformis syndrome group vs. 47.8% in the other group, p=0.521). Crucially, when assessing BASDAI, BASFI, and BASMI scores, significant differences emerged. While BASDAI (p=0.119) and BASMI (p=0.130) scores showed no significant divergence between the groups, BASFI scores were notably higher in patients with piriformis syndrome compared to those without, indicating a statistically significant increase in functional impairment (5.45 (2.76, 6.4); 2.7 (1.5, 4.5) p = 0.041). This highlights the significant impact of piriformis syndrome on patient functionality, a key finding of this study. <h3>Conclusion:</h3> This study reveals a 10% incidence of piriformis syndrome in patients with axSpA, highlighting its significant impact on patient functionality, particularly as measured by BASFI scores. These findings suggest the importance of considering piriformis syndrome in the differential diagnosis of chronic back pain in axSpA and underscore the need for further research to improve management strategies for patients with these coexisting conditions. <h3>REFERENCES:</h3> <b>NIL.</b> <h3>Acknowledgements:</h3> <b>NIL.</b> <h3>Disclosure of Interests:</h3> <b>None declared.</b>