The Prevalence of Incidental and Symptomatic Lumbar Synovial Facet Cysts.

ABSTRACT

STUDY DESIGN: This was a retrospective cohort study from 2 affiliated tertiary care referral centers for spine disease. OBJECTIVE: The purpose of this article was to assess the prevalence of incidental (ie, asymptomatic) and symptomatic lumbar synovial facet cysts on magnetic resonance imaging. Secondarily, we assessed whether the prevalence increases with age. In addition, we assessed differences in patient and cyst characteristics between asymptomatic and symptomatic facet cysts. SUMMARY OF BACKGROUND: The prevalence of symptomatic and asymptomatic synovial facet cysts in the lumbar spine has been incompletely established, and, although many studies demonstrate an association with degenerative spine disease, no cumulative increase in prevalence of synovial facet cysts with increasing age has been presented. METHODS: We included 19,010 consecutive patients who underwent a dedicated lumbar spine magnetic resonance imaging between 2004 and 2015. Our outcome measures were symptomatic and asymptomatic facet cysts. A symptomatic cyst was defined as a cyst with symptoms of radiculopathy on the same side as the cyst. RESULTS: The overall synovial facet cyst prevalence was 6.5% [95% confidence interval (CI), 6.1-6.8]; 46% of the facet cysts were incidental and 54% were symptomatic. Increased age was independently associated with a higher likelihood of having a synovial facet cyst [odds ratio (per 10 y), 1.24, 95% CI, 1.20-1.29; P<0.001]. Large cyst size (odds ratio, 1.64; 95% CI, 1.23-2.20; P=0.001) and anterior location (odds ratio, 1.39; 95% CI, 1.08-1.79; P=0.010) of the synovial facet cyst were the only factors independently associated with having radiculopathy. CONCLUSIONS: Approximately 1 in 15 patients have at least 1 synovial facet cyst. Having a facet cyst-symptomatic and asymptomatic-is strongly associated with increased age supporting the theory that degenerative disease underlies its development. Large cyst size and anterior location of the cyst are associated with an increased likelihood of having neurological symptoms. LEVEL OF EVIDENCE Level III, diagnostic study.