Piriformis syndrome: Pain response outcomes following CT-guided injection and incremental value of botulinum toxin injection

PURPOSE Piriformis syndrome is a common pain condition affecting the buttock and posterior hip with or without radiation to the leg, and management of the condition involves many treatments. In this study, we hypothesize that a CT-guided injection with botulinum toxin is more effective in providing pain relief than a CT-guided injection without Botox. METHODS Overall, 97 consecutive patients with piriformis syndrome presented for a CT-guided injection of the piriformis muscle and perineural injection of the sciatic nerve. After the injection, the patients received a visual analog scale pain log to record their pain level until the follow-up ap-pointment. Values of p < 0.2 were considered as confounder and adjusted by inverse probability of treatment weighting (IPTW) via propensity score. The effect of botulinum toxin on 48-hour response and duration of response was tested using weighted chi-square test and weighted Ka-plan-Meier analysis. RESULTS There was a total of 97 patients in the study, and 111 injections, as some patients had bilateral in-jections. Patients in the Botox group had more 48-hour response than patients in the non-botuli-num toxin group (p < 0.001 with IPTW, p = 0.005 without IPTW). Median pain-free survival was 30 days for Botox group and 1 day for non-Botox group (p = 0.059 with IPTW, p = 0.10 without IPTW). CONCLUSION CT-guided injections with botulinum toxin for patients with piriformis syndrome are more likely to lead to a positive response and a longer duration of response than patients who receive a CT-guided injection without botulinum toxin. We hope that this study facilitates future prospec-tive randomized blind trials for patients with suspected piriformis syndrome.