title: Long-term assessment of clinical outcomes of ultrasound-guided steroid injections in patients with piriformis syndrome.
abstract: OBJECTIVE
  The purpose of this study was to evaluate the long-term efficacy of ultrasound (US)-guided steroid injections in patients with piriformis syndrome.
  
  
  METHODS
  Between January 2010 and October 2012, 63 patients (23 men and 40 women; average age, 63.2 years; range, 24 to 90 years) were diagnosed with piriformis syndrome based on clinical history, electromyography, and flexion-adduction-internal rotation test results. They were divided into two groups. The first group (37 subjects) received a US-guided steroid injection around the piriformis muscle. The second group (26 subjects) received both piriformis muscle and spinal epidural injections. The therapeutic effect was categorized as improvement, partial improvement, or failure depending on the degree of symptom alleviation one month after injection, based on a review of each patient's medical records.
  
  
  RESULTS
  In the first group, 15 patients (40.5%) showed improvement, seven (18.9%) showed partial improvement, and 15 (40.5%) failed to respond to the initial treatment. In the second group, eight patients (30.8%) showed improvement, 11 (42.3%) showed partial improvement, and seven (26.9%) failed to respond to the initial treatment. A second piriformis injection was performed in four cases, after which two patients showed improvement within 3 years, but the other two showed no therapeutic effect.
  
  
  CONCLUSIONS
  US-guided steroid injection may be an effective treatment option for patients with piriformis syndrome.
authors: Department of Radiology, Seoul National University Bundang Hospital, Seongnam, Korea.
authors: Hee Seok
authors: 0000-0002-8459-1260
authors: HS
authors: Jeong
authors: Department of Radiology, Seoul National University Bundang Hospital, Seongnam, Korea.
authors: Guen Young
authors: 0000-0002-6906-5182
authors: GY
authors: Lee
authors: Department of Radiology, Seoul National University Bundang Hospital, Seongnam, Korea.
authors: Eu Gene
authors: 0000-0003-4205-2362
authors: EG
authors: Lee
authors: Department of Radiology, Seoul National University Bundang Hospital, Seongnam, Korea.
authors: Eu Gene
authors: 0000-0001-6604-5787
authors: EG
authors: Joe
authors: Department of Radiology, Seoul National University Bundang Hospital, Seongnam, Korea.
authors: Joon Woo
authors: 0000-0002-7106-5229
authors: JW
authors: Lee
authors: Department of Radiology, Seoul National University Bundang Hospital, Seongnam, Korea.
authors: Heung Sik
authors: 0000-0002-7024-388X
authors: HS
authors: Kang
keywords: Injections, epidural; Piriformis muscle syndrome; Steroids; Ultrasonography