Recurrence of piriformis syndrome: One year follow up post ultrasound guided injection therapy

Background. Piriformis syndrome is a common cause of low back pain sometimes underdiagnosed due to a lack of distinguishing symptoms and patterns. Two methods of ultrasound-guided intramuscular injection (using a local anesthetic agent and combined with corticosteroids) have become the treatments of choice. However, some studies suggest these methods may result in recurrence even though data regarding the prevalence of recurrence and triggering factors are still lacking. Objective. To identify the prevalence of and factors triggering the recurrence of piriformis syndrome treated with steroid and local anesthetic injections. Methods. This is a prospective cohort following patients diagnosed with piriformis syndrome and treated with either a local anesthetic or a combination with the addition of corticosteroids. Demographic, risk factors, and the onset of pain recurrence data were taken and analyzed. Results. From the 66 patients included in this study, 68.2% (n:45) reported recurrence of pain, with the majority occurring within the first three months post-injection. Subjects treated with combination therapy had a pain-free interval 13.45 weeks longer than subjects treated with a local anesthetic injection. There were no significant differences in risk factors between both groups. Conclusion. Recurrence of piriformis syndrome was most commonly found within the first and third months of treatment. Both methods did not differ significantly, even though combination therapy tends to give longer pain-relief intervals.