CLINICAL INVESTIGATION Piriformis Syndrome: Long-Term Follow-up in Patients Treated with Percutaneous Injection of Anesthetic and Corticosteroid Under CT Guidance Salvatore Masala • Sonia Crusco • Alessandro Meschini • Amedeo Taglieri • Eros Calabria • Giovanni Simonetti Received: 19 November 2010 / Accepted: 9 May 2011 / Published online: 24 May 2011 Ó Springer Science+Business Media, LLC and the Cardiovascular and Interventional Radiological Society of Europe (CIRSE) 2011 Abstract Purpose This study was designed to evaluate the efficacy of CT-guided injection of anesthetic and corticosteroid for the treatment of pain in patients with piriformis syndrome unresponsive to conservative treatment. Methods We enrolled 23 patients with piriformis syndrome, proposing a percutaneous intramuscular injection of methyl- prednisone-lidocaine. Among them, 13 patients accepted and 10 refused to undergo the procedure; the second group was used as a control group. Clinical evaluation was performed with four maneuvers (Lase `gue sign, FAIR test, Beatty and Freiberg maneuver) and a VAS questionnaire before the injection, after 5–7 days, and after 2 months. A telephonic follow-up was conducted to 3, 6, and 12 months. Results Procedural success was achieved in all patients who were treated without any complications. After 2 months, among 13 treated subjects, 2 of 13 patients showed positivity to FAIR test (hip flexion, adduction, and internal rotation), 2 of 13 were positive to Lase `gue sign, and the Beatty maneuver was positive in 1 patient. Patients who underwent conservative treatment were positive respectively in 7 of 10 (p = 0.01), 6 of 10 (p = 0.03), and 6 of 10 (p = 0.01). The VAS score showed a difference between patients treated with percutaneous approach and those managed with conservative therapy at the baseline evaluation (p = 0.04), after 2 months (p = 0.02), and 12 months (p = 0.002). We observed a significant reduc- tion in pain for patients treated percutaneously, who were evaluated with the VAS scale at 5–7 days, 2 months, 3, 6, and 12 months (p \ 0.001). Conclusions Our findings suggested potential benefit from the percutaneous injection of anesthetics and corti- costeroids under CT guidance for the treatment of pirifor- mis syndrome. Keywords Clinical practice Á Non-vascular interventions Á Combined treatments Á Musculoskeletal Á Pain Introduction Piriformis syndrome (PS), a term first coined by Robinson, affects 5–8% of all patients with low back pain and sciatica [1, 2]. It can be caused by a trauma that affects the pelvis or buttocks [3], hypertrophy of the piriformis muscle (PM) [4, 5], anatomic abnormalities of the PM or the sciatic nerve [6], differences in leg length (a minimum of 0.5-inch asymmetry of the legs), or piriformis myositis [7]. Some investigators consider PS as a form of myofascial pain syndrome [8]. A history of trauma is typically elicited in approxi- mately 50% of cases of the syndrome. Usually, the trauma S. Masala Á S. Crusco (&) Á A. Meschini Á A. Taglieri Á E. Calabria Á G. Simonetti Department of Diagnostic and Molecular Imaging, Interventional Radiology and Radiation Therapy, Fondazione Policlinico ‘‘Tor Vergata,’’, viale Oxford 81, 00133 Rome, Italy e-mail: sonia.crusco@fastwebnet.it S. Masala e-mail: salva.masala@tiscali.it A. Meschini e-mail: a.mesko@libero.it A. Taglieri e-mail: Amedeo.Taglieri@libero.it E. Calabria e-mail: eros.calabria@libero.it G. Simonetti e-mail: Giovanni.Simonetti@uniroma2.it 123 Cardiovasc Intervent Radiol (2012) 35:375–382 DOI 10.1007/s00270-011-0185-z